AP-T215-12AUSTROADS TECHNICAL REPORT Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Published November 2012 © Austroads Ltd 2012 This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without the prior written permission of Austroads. Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members ISBN 978-1-921991-57-8 Austroads Project No. TT1454 Austroads Publication No. AP–T215-12 Project Manager Andrew Papacostas - VicRoads Prepared by Binh Vuong, Kieran Sharp, John Rebbechi and Susannah Boer ARRB Group Published by Austroads Ltd Level 9, Robell House 287 Elizabeth Street Sydney NSW 2000 Australia Phone: +61 2 9264 7088 Fax: +61 2 9264 1657 Email:
[email protected] www.austroads.com.au Austroads believes this publication to be correct at the time of printing and does not accept responsibility for any consequences arising from the use of information herein. Readers should rely on their own skill and judgement to apply information to particular issues. Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Sydney 2012 . Energy and Resources Tasmania Department of Transport Northern Territory Department of Territory and Municipal Services Australian Capital Territory Commonwealth Department of Infrastructure and Transport Australian Local Government Association New Zealand Transport Agency. The success of Austroads is derived from the collaboration of member organisations and others in the road industry.About Austroads Austroads’ purpose is to: promote improved Australian and New Zealand transport outcomes provide expert technical input to national policy development on road and road transport issues promote improved practice and capability by road agencies. Austroads is governed by a Board consisting of the chief executive officer (or an alternative senior executive officer) of each of its eleven member organisations: Roads and Maritime Services New South Wales Roads Corporation Victoria Department of Transport and Main Roads Queensland Main Roads Western Australia Department of Planning. Transport and Infrastructure South Australia Department of Infrastructure. promote consistency in road and road agency operations. the Commonwealth Department of Infrastructure and Transport. Austroads membership comprises the six state and two territory road transport and traffic authorities. advice and fostering research in the road transport sector. It aims to be the Australasian leader in providing high quality information. the Australian Local Government Association. and NZ Transport Agency. .....2 Development Trials ..2.........................................................................................................................................................................................................Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members CONTENTS 1 1.......................................................................................3........................................................2 South Africa .4 Implementation/Validation Trials ............................................................................................................... 10 Introduction ......................................................................................................................... 6 2........ 18 4............... 18 4.1 2................................................ 1 Austroads Project TT1454 ............................. 19 4......................................................................................................................... 22 3 3....................... 16 WAM-foam® ......... 12 3..........................................................................................1 Development Trials .............................................1 Sequential Aggregate Coating and Binder Foaming Technology ....................................3 Demonstration Trials .....................1 Background .......................................3 Demonstration Trials .............................3....................................... 16 4................ 7 2......................................................... 10 3.....2..........................................................................................1.3.........................4 Chemical Additives .............................................................3 INTRODUCTION ..............3 4 4.....................3 Validation/Implementation Trials .. 20 FIELD TRIALS OF FOAMING TECHNOLOGIES USING WATER-BASED MECHANICAL SYSTEMS .................................3 5 5............ 14 3............... 5 2............. 2 WARM MIX ASPHALT ........................................................................... 7 2................. 21 Double Barrel® Green ..........2 Development Trials ..3.... 19 Low Emission Asphalt (LEA2) ..3.4 Implementation/Validation Trials .........................2 4......................................................................... 3 General .....................................1........................................ 21 5.......................4 Implementation/Validation Trials ......................................2................................................................3......................... 9 FIELD TRIALS OF WMA TECHNOLOGIES.......... 21 5. 17 4...................... 18 Low Energy Asphalt (LEA1) .................................................................. 19 4..........................................................................................................2 Development Trials .... 10 3...1........................................ 3 Categories of WMA Technologies ..........3.........1........................1 3........................................................................................1.................... 19 4......................................................................................2 Binder Foaming Technology Using Water Based Mechanical Systems ......................1 4................2 Development Trials ................2 2................................... 19 4.......1........................................ 3 Commercially-available WMA Technologies .............................................................1 Background ................................................. 21 5.........................................................................................2... 14 FIELD TRIALS OF FOAMING TECHNOLOGIES USING SEQUENTIAL AGGREGATE COATING AND BINDER FOAMING .... 14 3..............................................................3 Demonstration Trials .................................................................................................. 16 4............................1 2 2........................2............................... 8 2...........................3.........2.......1 Background .......... 19 4............................................6 Combined Chemical and Organic Additives ...............................................................................................................................................................1 Australia ..............................................1 Background .................3. 13 Draft WMA Protocols .....3 Demonstration Trials ................................................................................................................................................................................1 Austroads 2012 — i— ........................... 16 4..................... 21 5......1........2 Production/Demonstration Trials ...................3......................................................3.....................................................................2 3.................................................................2..3 Binder Foaming Technology Using Water Bearing Additives .... 18 4.........1..........................................................3.................................... 10 Stages of Field Trials .............................. 4 2....................................5 Organic Additives ......................................4 Implementation/Validation Trials .... ..................1 Background ...2 Development Trials ...................................1.....3 Demonstration Trials ................................................................................. 30 7.................... 33 7..................................... 33 7............5 7................................................... 22 5.............................2.................................................................................................3.....2 Development and Demonstration Trials .......................................................... 25 6..............................................................................................................................................................................4 Implementation/Validation Trials ..................1 Background ..................................................1...............................................1 Ultrafoam GX® System...........................4 Implementation/Validation Trials ............................................. 25 6..............2.............. 37 7.........................................2 5................................4 7...............2 7.................. 31 HyperTherm® ...............................................................................................................................................................................................................................................................................................1............... 35 CECABASE RT® ........................................................................................................................................... 29 7........................1..............1 7.................................................................... 25 6..............................................................................................3..............................2 Development Trials .......................................... 36 7......................................................................................................5.........................1 Background ..................................................................................... 41 LEADCAP® ............................................................ 26 Advera®............4 Implementation/Validation Trials .......................................2 Development Trials ..............................................6 7. 25 6.....................5.........................1 Background ..................3 Demonstration Trials ..............................6...................................4 Implementation/Validation Trials .. 35 7.........................4.......4 Implementation/Validation Trials ...............................1 Background ......................... 29 7.......................................1.......................................................................1........ 35 7...............................................4 Implementation/Validation Trials ........................................................... 26 6...2 Development Trials .. 36 7.............................................................................4............................ 23 5.................................... 36 7.............................................................. 41 6.................................1................................ 41 7............................................................................2 Development Trials ..........................................................................4 Implementation/Validation Trials ...............................3 7..............2...................................... 39 7..........................1 Background ................7 Austroads 2012 — ii — ...........................................................................................................................3 Demonstration Trials ..........................................................................................................................3 Demonstration Trials ...........................................2............ 22 5.............3 Demonstration Trials ....................................................................... 37 Sasobit® ......2....................................2... 34 7............................ 22 5..........1 Background ................... 26 6.......................... 39 Asphaltan B ...............................................................4 Implementation/Validation Trials ................ 36 7...........................2......2.......................................................3......... 27 FIELD TRIALS OF CHEMICAL ADDITIVE TECHNOLOGIES ......1 Background ...3 Implementation/Validation Trials .......2 Development Trials ..........2 Development Trials ...3 Demonstration Trials ..................3 Demonstration Trials ............2......... 35 7........................................... 37 7....................... 26 6................1............................................... 23 Other Mechanical Injection Systems ...........................2 7 7.......4............................................................3..................................... 29 7.....................4.................................................................1 Background ...................................................................2.....2............................................................... 24 FIELD TRIALS OF FOAMING TECHNOLOGIES USING WATER-BEARING ADDITIVES ................2 Development Trials ..6........................................................... 33 7................................................ 35 7......................... 41 7......2...................3 6 6.............Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 5..............................................................................................5...... 41 7.........3 Demonstration Trials .........................................................................................................5............................... 25 Aspha-Min® ..................... 26 6.................. 34 Rediset® WMX ............... 37 7....... 29 Evotherm®.......6.... Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 8 8.1 FIELD TRIALS OF COMBINED BINDER MODIFIER-ORGANIC ADDITIVE TECHNOLOGIES ................................................................................................................ 43 Shell Thiopave® .................................................................................................................. 43 8.1.1 Background ............................................................................................................ 43 8.1.2 Development Trials ................................................................................................ 43 8.1.3 Demonstration Trials .............................................................................................. 44 8.1.4 Implementation/Validation Trials ............................................................................ 44 FIELD TRIALS IN AUSTRALIA AND NEW ZEALAND ....................................................... 46 Australia............................................................................................................................... 46 9.1.1 Brisbane City Council ............................................................................................. 46 9.1.2 Department of Transport and Main Roads (TMR) Queensland............................... 46 9.1.3 Roads and Maritime Services (RMS) NSW ............................................................ 47 9.1.4 Department of Planning, Transport and Infrastructure (DPTI), South Australia ....... 48 9.1.5 VicRoads................................................................................................................ 48 9.1.6 Main Roads Western Australia (MRWA)................................................................. 49 9.1.7 Northern Territory Department of Transport (DOT) ................................................. 50 9.1.8 Department of Infrastructure, Energy and Resources (DIER) Tasmania................. 50 9.1.9 Department of Territory and Municipal Services (TAMS) ACT ................................ 50 9.1.10 Industry .................................................................................................................. 50 New Zealand........................................................................................................................ 50 9.2.1 Hayward and Pidwerbesky ..................................................................................... 50 9.2.2 Ball ......................................................................................................................... 52 ON-GOING STUDIES AND IMPLEMENTATION OF WMA PRACTICES ........................... 53 9 9.1 9.2 10 10.1 On-going Studies and Implementation of WMA Practices in USA ........................................ 53 10.1.1 Laboratory and Field Trials of WMA Technologies ................................................. 53 10.1.2 National Studies of WMA Technologies ................................................................. 54 10.1.3 Implementation of WMA Practice in the USA ......................................................... 56 10.2 On-going Studies and Implementation Practices in Europe.................................................. 57 10.3 On-going Studies and Implementation Practices in Asia ...................................................... 57 10.3.1 Korea: Development of WMA Production and Construction Methods ..................... 57 10.4 Implementation of WMA Practices in Australia ..................................................................... 58 10.4.1 Proposed Further Studies to Implement WMA Practices in Australia...................... 58 10.4.2 Revisions to WMA Protocol .................................................................................... 58 11 CONCLUSIONS .................................................................................................................. 59 REFERENCES ............................................................................................................................. 62 Austroads 2012 — iii — Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members TABLES Table 2.1: Table 2.2: Table 2.3: Table 2.4: Table 2.5: Table 2.6: Table 2.7: Table 3.1: Table 8.1: Commercially available WMA technologies .............................................................. 4 WMA technologies using sequential mixing stages of aggregate coating and binder foaming .................................................................................................. 5 WMA foaming technologies using water-based mechanical system ......................... 6 WMA foaming technologies using water-bearing additives ....................................... 7 WMA technologies using chemical additives ............................................................ 8 WMA technologies using organic additives .............................................................. 9 WMA technologies using combined chemical and organic additives ........................ 9 Laboratory assessment methods used in asphalt mix design in different countries ................................................................................................................ 11 Composition of Shell Thiopave® asphalt test sections at NCAT test track.............. 45 Austroads 2012 — iv — Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members SUMMARY The Australia Government has set a target of reducing greenhouse gas (GHG) emissions by 25% by 2020 compared with 2000 levels assuming there is global agreement to an ambitious program to stabilise the levels of GHGs in the atmosphere. Australia has undertaken to unconditionally reduce its emissions by 5% compared with 2000 levels by 2020 and by up to 15% by 2020 if the global agreement falls short of securing atmospheric stabilisation at 450 ppm carbon dioxide equivalent (CO2-eq). The aim in the longer-term is, by 2050, to reduce GHG emissions in Australia by 80% compared with the 2000 levels. The asphalt industry, like any other, wants to manage and use resources efficiently and continually improve their environmental performance. Reducing greenhouse gas emissions that contribute to global warming is of increasing interest and concern to the industry. Industry across all sectors can achieve a significant reduction in CO2-eq emissions by improving energy efficiency in their manufacturing processes. Unlike other pavement construction processes, asphalt requires that the aggregates and bituminous binders be heated and dried in its production process. This is an energy intensive production process. Although construction sector emissions represented only about 1.5% of overall greenhouse emissions in Australia in 1997–98, this sector is showing a willingness to adopt strategies that will lead to the use of energy more efficiently and respond to the challenge of meeting emissions targets to avoid dangerous climate change. In a practical sense this means more sustainable and less carbon intensive products and processes, which are recognised within procurement policies and valued by infrastructure construction and maintenance practitioners. On behalf of its members Austroads sponsored a project (TT1454: Performance of Warm Mix Asphalt Pavements) to evaluate WMA technologies for Australian road conditions. A major element of the project was the planning and conduct of a comprehensive field validation assessment of a range of WMA and hotmix asphalt (HMA) surfacings in order that their performance could be compared and a draft WMA Evaluation Protocol for the conduct of validation trials assessed and appropriate changes made. An extensive laboratory testing program was also conducted to support the validation trial. This report presents a review of field trials of WMA technologies conducted in various countries in the world, with the emphasis on performance differences between WMA and conventional HMA and the identification of field performance data that could be used to complement the Austroads WMA evaluation field trials for Australian road conditions. A large number of demonstration or validation trials of WMA technologies have been established in the USA to demonstrate the benefits of WMA technology compared to HMA, and to improve the quality and efficiency of construction (i.e. improved workability, improved compaction and more consistent field density). These trials have demonstrated that most WMA technologies associated with chemical and organic additives can be successfully implemented with minor modifications to the asphalt plant and, in the case of several products, successful paving could still occur at low temperatures. The amount of published material relating to demonstration or validation trials in Australia is extremely limited. Despite this, however, the use of some WMA technologies is now being accepted by many road agencies. Austroads 2012 — v— Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 1 INTRODUCTION The Australia Government has set a target of reducing greenhouse gas (GHG) emissions by 25% by 2020 compared with 2000 levels assuming there is global agreement to an ambitious program to stabilise the levels of GHGs in the atmosphere. Australia has undertaken to unconditionally reduce its emissions by 5% compared with 2000 levels by 2020 and by up to 15% by 2020 if the global agreement falls short of securing atmospheric stabilisation at 450 ppm carbon dioxide equivalent 1 (CO2-eq). The aim in the longer-term is, by 2050, to reduce GHG emissions in Australia by 80% compared with the 2000 levels. Emissions in Australia are projected to average about 580 Mt CO2-eq per year from 2008 to 2012, or 106% of the 1990 levels. Without further policy action, Australia's emissions are projected to continue to increase. By 2020, emissions are projected to reach 686 Mt CO2-eq, or 24% above the 2000 levels. Australia's unconditional target of 5% represents a 23% decline below ‘business as usual’ (Department of Climate Change and Energy Efficiency 2010). The Australian Government has introduced a carbon pricing scheme that takes effect from 1 July 2012. The Clean Energy Bill 2011 was passed in the Lower House in October 2011. The carbon price will commence at $23 per tonne and be fixed for the first three years. On 1 July 2015 the carbon price will transition to a fully-flexible price under an emissions trading scheme where the carbon price will be determined by the market. Under the scheme, about 500 of Australia’s largest emitters will be required to buy permits for each tonne emitted. The asphalt industry worldwide is committed to reducing the impacts of its operations on global warming and there are many global agreements and national and state legislative requirements which industry is obliged to meet. For example, the European Union (EU) is committed to reducing greenhouse gases under the terms of the Kyoto Agreement. There are also potentially attractive competitive advantages if lower-cost, reliable technologies can be developed and implemented. The Australian asphalt industry wants to manage and use resources efficiently and to continually improve its environmental performance. Reducing greenhouse gas emissions that contribute to global warming is of increasing interest and concern to the industry. Industry across all sectors can achieve a significant reduction in CO2-eq emissions by improving energy efficiency in their manufacturing processes. The main source of emissions in the asphalt sector arises from the heating and drying of aggregates. Although construction sector emissions represented only about 1.5% of overall greenhouse emissions in Australia in 1997–98 2, this sector is showing a willingness to adopt strategies that will lead to using energy more efficiently and to respond to the challenge of meeting emissions targets to avoid climate change. In a practical sense, this refers to the use of more sustainable and less carbon-intensive products and processes, which are recognised within procurement policies and valued by infrastructure construction and maintenance practitioners. There are several products comprising warm mix asphalt (WMA) being used in Australia and overseas. From an Austroads Member Authority perspective these need to be better understood in terms of their relative environmental benefits and performance, including structural performance. All the issues associated with the adoption of WMA also need to be fully explored and understood. 1 Carbon dioxide equivalent (CO2-eq) is a way of converting all greenhouse gases to a single value for ease of comparison. It is calculated by multiplying the mass of a gas by its global warming potential. Based on 1997–98 figures, the direct greenhouse gas emissions generated by the construction industry comprised 1.46% of the national emissions (Trewin 2003, p. 644). 2 Austroads 2012 — 1— Europe. The project was strongly supported by the Australian Asphalt Pavement Association (AAPA). means that any further work would need to be in line with this recommendation. Austroads 2012 — 2— . These include tools to determine the carbon footprint of road infrastructure and life cycle analysis methodologies to assist with materials and technologies selection. surfactants and foamed bitumen. and the recommendation that it be adopted as a national standard. The planning and conduct of a comprehensive field assessment of a range of WMA and HMA surfacings in order that their performance can be compared and the draft Evaluation Protocol for the conduct of validation trials assessed and appropriate changes made. The Protocol sets out the conduct of appropriate laboratory tests and field validation projects in order that the performance of WMA and conventional HMA can be compared. with the emphasis on field performance data that could be used to complement the Austroads WMA evaluation field trial. The project involved the following components: 1. in the absence of sufficient Australian-based emissions factors. it was premature to recommend a carbon calculation system for inclusion in the Austroads WMA Evaluation Protocol. with market share reaching double digits (Nadeau 2012). In his opening remarks. More than 40 papers were presented at that conference. Federal Highway Administration (FHWA). the recent work of the Transport Authorities Greenhouse Group (TAGG) in coordinating the development of a greenhouse workbook and calculator. the purpose of which is to provide a guide to the evaluation of specific WMA technologies and processes such as additives. held in St Louis in October 2011. An extensive laboratory testing program was also conducted. reported that more than 40 million tons of WMA was produced in the USA in 2010. with a further six States indicating that they would be adopting specifications by December 2011. The project was also strongly supported by VicRoads who also made a substantial in-kind contribution to the trial. Asia and South Africa. However. The Protocol is an evaluation tool only. One of the main outputs of this project is the final version of the Protocol. A literature review of existing CO2 emission calculators with a view to recommending a system for inclusion into the WMA Evaluation Protocol.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 1. Canada. should be added to that report before it was published. The development of a WMA Evaluation Protocol. 4. Deputy Administrator. It is an update of an earlier report which was endorsed for publication by Austroads in December 2011. This will facilitate a more consistent approach to the calculation of carbon footprints. members of which made extensive in-kind contributions to the laboratory and field testing elements of the project. It was concluded that. Greg Nadeau. They provided a comprehensive overview of the latest developments and implementation of WMA technology in the USA. A review of field trials of WMA technologies conducted in various countries in the world. it is not a specification. 3. This report addresses Task 3 of this project. 2. However.1 Austroads Project TT1454 Austroads sponsored a project (TT1454: Performance of Warm Mix Asphalt Pavements) to evaluate WMA technologies for Australian road conditions. it was agreed that a review of relevant material presented at the 2nd International Conference on Warm Mix Asphalt Pavements. At the time of the conference 41 State Departments of Transportation had specifications or contract language that allowed WMA. Differences between current HMA practices (associated with material selection. Most of the technologies were assessed in terms of laboratory and field validation trials reported as being satisfactory and replicating the relevant HMA specification requirements and early life performance characteristics. material characterisation (specification requirements and performance-related laboratory testing). Mallick. and increasingly used.2 Commercially-available WMA Technologies The various commercially-available WMA technologies examined in this review are presented in Table 2. This is a potentially significant impact on the Australian CO2 balance. 10–30% reduction in carbon monoxide (CO). As WMA technologies (new additives and/or production processes) can have similar transport and workability characteristics as HMA. It is important that the widespread and successful adoption of this technology in Australia is supported by a thorough understanding of overseas experience and the review of the performance of WMA under Australian conditions. improved operational efficiency (earlier trafficking).1 WARM MIX ASPHALT General Warm mix asphalt (WMA) technologies involve additives and/or production processes which allow the temperature at which asphalt mixes can be produced and placed to be reduced – typically by 20–50 °C below that of hotmix asphalt (HMA). they can be used as a compaction aid for stiff mixes. In Australia. Other advantages associated with a reduction in asphalt production and compaction temperatures include: improved conditions for operators (less fumes). In terms of laboratory studies. D'Angelo et al. extended paving seasons (paving in cool weather and/or at night) and the potential to increase haulage distances if the temperature of production is not lowered. several new WMA technologies have been developed in the USA. reduced binder aging during production. 2. More details of each WMA technology can be found in the websites provided by the manufacturers (as listed in the Table). mix design. up to 50% reduction of volatile organic compounds (VOC) and 60–70% reduction in nitrous oxides (NOx). as a replacement for traditional HMA in many countries. a variety of technologies have emerged.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 2 2. Europe and the USA might affect the approach to the implementation of WMA technologies in Australia. A reduction in production temperature through the use of WMA technologies would roughly translate to a reduction of more than 120 000 tonnes of CO2 per annum. since then. Several WMA technologies have already been introduced into Australia. WMA is being evaluated. 20–35% reduction in sulphur dioxide (SO2). about 390 000 tonnes of CO2 are generated annually from the eight million tonnes of asphalt produced (Jenny 2009). The reduction in energy associated with asphalt production at a lower temperature results in a reduction in greenhouse gas emissions. Austroads 2012 — 3— . Bergendahl and Pakula (2009) reported a 32% reduction in CO2 when the WMA mixing temperature was lowered by 20 °C.1. The concept of WMA originated in Europe in the early 1990s and. construction processes and standards and pavement design methodologies used in Australia. Over the last five years. Currently. (2008) reported that the reductions in plant stack emissions from WMA production were very significant: 20–40% reduction in carbon dioxide (CO2). For example. com www.com www.com www.6) Asphaltan B Sasobit® LEADCAP® Shell Thiopave® TLA-X® Supplier LEA-CO (France) Suit-Kote (McConnaughay) Corporation (USA Shell International (UK) / Kolo-Veidekke (Norway) Maxam Equipment.akzonobel.shell.com www.lowemissionasphalt.cocoasphaltengineering.3.com www.3.3 Categories of WMA Technologies The various commercial WMA technologies (Table 2.com www.astecindustries.com Yes Yes Yes Yes Yes Yes Not reported herein 2.2) Binder foaming with water-bearing additive (Section 2.com www.Advera®wma. (Canada) Akzo Nobel NV (The Netherlands) Romonta GmbH (Germany) Sasol Wax (South Africa) Kumho Petrochemical (Korea) Shell Trinidad and Tobago Ltd Web address www. Inc.1: Commercially available WMA technologies Category Product / process Low energy asphalt (LEA1) Low emission asphalt (LEA2) WAM-foam® AQUABlack® Double Barrel® Green Terex® WMA Ultrafoam GX® Advera® WMA Aspha-Min® CECABASE RT® Chemical additive (surfactants / emulsions) (Section 2.com www.com/bitumen www.com www.maxamequipment.3.3.3. Austroads 2012 — 4— .com www.surfactants.3.Terex®rb.shell. Table 2.5) Combined binder modifier / and organic additives (Section 2.leadcapwma.1) Water-based binder foaming (Section 2.com Availability of laboratory / field validation trials Yes Yes Yes Not reported herein Yes Not reported herein Yes Yes Yes Yes Yes Sequential aggregate coating and binder foaming (Section 2. Inc.cecachemicals.1) that are readily available can be grouped into six main categories: sequential aggregate coating and binder foaming techniques binder foaming using water-based mechanical systems binder foaming using water-bearing additives chemical additives organic additives combined chemical-organic additives.4) Evotherm® Evotherm® 3G Evotherm® DAT HyperTherm® Rediset® WMX Organic additives (Section 2.sasobit.evotherm.3) www.gencorgreenmachine.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members There are now at least 21 registered WMA technologies in the USA (compared to only three in 2005) and 45 States are currently conducting demonstration trials of WMA technologies (compared to 15 States in 2007).de www.com www.com www.com www.romonta. (USA) PQ Corporation (USA) Eurovia Services GmbH (Germany) Arkema Group (France) MeadWestvaco Asphalt Innovations (USA) Coco Paving Inc.lea-co.trinidadlakeasphalt. (USA) Astec Industries (USA) Terex® Corporation (USA) Gencor Industries.com www.Aspha-Min®. Italy. where the stream condenses to water. USA (> 90 road trials > 125 000 tonnes) Canada. coating and adhesion agent (0. USA Low energy asphalt (LEA1) Significant plant modification for adding and foaming processes (US$75 000– $100 000)* Water (13 kg/tonne). Shell Bitumen (patent rights worldwide. low energy asphalt. Austroads 2012 — 5— . soft binder (with or without adhesion additive).2: WMA technologies using sequential mixing stages of aggregate coating and binder foaming Technology Manufacturer LEACO. UK. followed by addition of cold wet fine aggregate to create foaming action developed in 2005 As in LEA with chemical additive added to the hot coarse aggregates Two-stage process where softer binder (for aggregate coating) and harder foamed binder are mixed separately Plant modification Additive dosage Production / compaction temperature Reported use France.3. USA. In the foaming action. different aggregate drying temperatures (which may affect bitumen-aggregate bonding and moisture susceptibility).7 kg/tonne). Netherlands. the value of the US$ and A$ is approximately the same. It should be noted that other cold mix and half-WMA technologies. Fairco.g.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members They use different additive contents (which may affect the WMA mechanical properties). the second mixing stage includes a hot hard binder in foamed form. different maximum bitumen temperatures (which may affect long-term asphalt durability and performance) and different requirements in terms of plant modifications (which may affect cost. Table 2. except USA)** BP (patent rights USA) Description Sequential coating process where coarse aggregate is coated with hot binder.1 Sequential Aggregate Coating and Binder Foaming Technology WMA technologies that involve sequential mixing stages of aggregate coating and binder foaming are presented in Table 2. WMA-emulsion which uses bitumen emulsion at 85 °C for the hard binder component (Preston 2007). and EIFFAGE Travaux Publics and Appia (France). thus increasing the volume of the bitumen and reducing its viscosity for a short period until the temperature of the material drops below 100 °C. production efficiency and product consistency). the coarse aggregates are heated at a low temperature (110 °C) and pre-coated using a hot. Switzerland. which use a low binder temperature below 100 °C in production (e.5% by weight of binder) Water and adhesion agent (assumed similar to LEA1) Water (2–5% by mass of hard bitumen fraction. For example. the WAM-foam® technology employs a two-stage mixing process: in the first stage. are not considered as WMA technologies in this report. i. Advanced Concept Engineering (US) McConnaughay Technologies (USA) Kolo Veidekke. the water turns to steam. New Zealand France. low emission asphalt). Spain. Norway. Canada. Sweden. 2. It is marketed as GreenPave®. They employ different mixing stages of aggregate coating and binder foaming. Italy. surfactant and an anti-stripping agent may be added Tprod = 90 °C Tcomp = 60–90 °C Low emission asphalt (LEA2) As above Tprod = 90–95 °C Tcomp = 60 °C WAM-foam® Significant plant modification for adding and foaming processes (US$60 000– $85 000) Tprod = 100–120 °C Tcomp = 80–100 °C * Currently (June 2012). Luxembourg.2. In these technologies. This improves mix workability and allows for improved compaction at a lower temperature.2–0. about 0. ** WAM-foam® (Shell) is available from Citywide in Melbourne. This category includes some early foaming technologies developed in Europe (WAM-foam®. the effective coating of the aggregates is considered critical in order to prevent water (which is added to produce foamed asphalt) from reaching a poor binder-aggregate interface (which could lead to moisture sensitive issues for the asphalt mixes).e. However. As the large dose of water added in this process could negatively influence the moisture susceptibility of mixes. This foaming technology uses a high water dosage (e. an adhesion agent may be added to improve adhesion. coating/adhesion and anti-stripping agent are often added to reduce stripping potential. resulting in WMA at 135 °C.3.3. Ultrafoam GX®. For example. Most existing HMA plants require some modifications to allow for the sequential mixing stages of aggregate coating and binder foaming.3: WMA foaming technologies using water-based mechanical system Technology Manufacturer Description A nozzle to inject a small amount of water into the hot binder stream to create foaming action Pumps to supply the bitumen. AQUABlack® foam and Terex® Warm Mix Asphalt System) which employ mechanical techniques to introduce small amounts of free water (or steam) into the hot bitumen to produce foamed asphalt suitable for a medium production temperature (say between 120–140 °C). They therefore incur the highest initial modification costs but the lowest costs for additives compared to other WMA technologies. The foamed asphalt also has greater workability and allows for improved compaction at temperatures above 100 °C.g.25–2% by weight of total bitumen) Water (1/4 cup of water per tonne) NA Production / compaction temperature Tprod = 120–140 °C Tcomp = 115 °C Reported use USA Developed in 2007 Double Barrel® Green Astec Industries (USA) Greenmachine Ultrafoam GX®2 GenCorp Industries (USA) NA USA AQUABlack® WMA Maxam Equipment (USA) Terex® Roadbuilding (USA) NA USA Warm Mix Asphalt System Up to 30 °C below HMA USA These processes may have less negative influence on the moisture susceptibility of mixes compared with low-temperature aggregate drying and foaming technologies using a high water dosage. In the first stage the coarse aggregates are heated (at a temperature of 120–150 °C) and pre-coated using a hot hard binder with liquid chemical coating/adhesion additive. Double Barrel® Green involves the use of a mechanical nozzle to inject water into a much smaller dose (at a rate of 1 kg of water per tonne of mix) into the hot binder stream for foaming action at a medium temperature range (120–140 °C). no additional chemical coating/adhesive additive is required to promote coating.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members The LEA techniques also employ sequential mixing stages. This category includes various technologies (Double Barrel® Green. Table 2.2 Binder Foaming Technology Using Water Based Mechanical Systems Examples of binder foaming using water-based mechanical systems are presented in Table 2. The second mixing stage includes an additional wet fine sand (with high water content) to foam the pre-coated hard binder. steam is injected into the center of the bitumen flow to create foaming action High-pressure foaming gun (7000 kPa) using MicroBubble™ technology Foamed asphalt produced outside of drum & immediately injected into drum's mixing chamber Significant (installation of mechanical pumps and nozzles and control system) Plant modification Additive dosage Water (1 kg/tonne) Water (1. 2. As the water content added is very low. LEA uses up to 13 kg water per tonne of mix) for the foaming action at production temperatures below 100 °C. Austroads 2012 — 6— . Most existing HMA plants require significant modifications to add the water into the system for the foaming process. The aggregates are heated to a nominal 130–135 °C and the binder is added at a nominal 160 °C. 27/kg) Production / compaction temperature Tprod = 140–150 °C Tcomp = 120 °C (10–20 °C below HMA) Reported use Advera® PQ Corporation (USA) Aspha-Min® Eurovia Services GmbH Some (to add the material to the mix at the same time as the binder and include foaming steps) US$5 000–$40 000 USA Tprod = 125–150 °C Tcomp = 100–130 °C (30 °C below HMA) France. the chemical additives can be added directly to the binder or the hot bitumen emulsion or mixed with water to form a liquid so that it can be injected into the stream just before the mixing chamber.5). some minor modifications may be required. e.4 Chemical Additives This category includes various technologies (Evotherm®. At a mix temperature of about 130–135 °C. Evotherm® 3G.35/kg Water (0.4: WMA foaming technologies using water-bearing additives Technology Manufacturer Description Manufactured Zeolite which releases water during production.25% by total weight of mix) US$1. provides greater workability. and to compact the mix. but act as surfactants to regulate and reduce the frictional forces at the microscopic interface of the aggregates and the bitumen at a range of temperatures. The way the additive is added is specific to each product.3. typically between 85 °C and 140 °C. HyperTherm®. Table 2. This category includes two technologies (Advera® and Aspha-Min®) which involve the addition of zeolite (containing about 20% water of crystallisation) to the mix at the same time as the binder. However.7 kg/tonne) from Zeolite (0. Rediset®.g.65 kg of water per tonne of mix). It is therefore possible to mix the bitumen and aggregates. CECABASE.3% of total mix by mass) US$0. creating foaming action Plant modification Additive dosage Water (0. Otherwise.3. hence. USA 2.4.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 2. Germany.60/lb (US$0. zeolite slowly releases water to create foamed asphalt and. As the amount of zeolite water added into the system is very small (about 0.3 Binder Foaming Technology Using Water Bearing Additives Technology involving binder foaming using water-bearing additives is shown in Table 2. the WMA products may have less negative influence on the moisture susceptibility of mixes compared with low-temperature foaming technologies which involve the use of a high water dosage. an adhesion agent may be added to improve adhesion. creating foaming action Synthetic Zeolite powder which releases water during production. SonneWarmixTM) which use chemical additives (Table 2. the zeolite can generally be added to the mix at the same time as the binder through a spare filler silo (if available). The chemical additives do not change the bitumen viscosity.7 kg/tonne) from Zeolite (0. Depending on the product. During the foaming step. Evotherm® 3G is added to the binder. Austroads 2012 — 7— . at lower temperatures (about 20–30 °C) than those associated with HMA. 6). does not contain water Chemical additives in pellet form.5: WMA technologies using chemical additives Technology Manufacturer Description Plant modification Minor (applied along with emulsion over 100 °C) (US$1000– $5000) Additive dosage Large amount of water in emulsion (25 kg/tonne) and chemical (not known) (7–10% higher than conventional binder) 0.2% by mass of binder Tprod = 130 °C Tcomp = 110 °C Tprod = 120 °C (22–33 °C below HMA) Tcomp = 120 °C (40–75 °C below HMA) Tprod = 120 °C Tcomp = 100 °C (50 °C below HMA) Canada.3. The organic additives. China.5% Tprod = 135–140 °C Tcomp = 115–120 °C Canada.5 Organic Additives This category includes several technologies (Sasobit®. No water is required in this process. does not contain water Additive containing surface active agents composed of at least 50% renewable raw materials (chemical additives in wax-based liquid form) Additive containing paraffinic hydrocarbon Minor (injected to binder line) Tprod = 115–120 °C Tcomp = 100–105 °C Canada. USA HyperTherm® Coco Paving Inc.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Table 2.5% by mass of binder Tprod = 125–135 °C Tcomp= 110–120 °C 2.5–2% by mass of binder USA CECABASE Arkema Group (France) Minor (added to the binder) 2–4% by mass of binder Developed in 2003 80 ktonne in Europe in 2006 USA (previously AD-RAP) SonneWarmixTM Sonneborn (USA) Minor (added to the binder) Typically 1–1. usually waxes or fatty acid amides.5% anti-stripping agents and 5% w/w asphalt Production / compaction temperature Reported use Evotherm® MeadWestvaco Asphalt innovation Chemical package of emulsification agents and anti-stripping agents Tprod = 100–130 °C Tcomp = 60–115 °C (50–75 °C below HMA) France also Canada. does not contain water Chemical package of surfactants and anti-stripping agents. also USA (QualiTherm) Rediset® Akzo Nobel Minor (added to the binder) 1. they are more effective when dispersed in the binder prior to manufacturing the WMA. However. South Africa and USA Evotherm® DAT® MeadWestvaco Asphalt innovation Chemical package of surfactants and anti-stripping agents diluted with small amounts of water Chemical package of surfactants and anti-stripping agents. thus increasing the workability of the compacted mix (Table 2. 0. are in granular form and can be added either to the mixture or to the bitumen. Asphaltan B) which involve the addition of organic additives to the binder to lower the viscosity of the binder (bitumen) at compaction temperatures.3–0. The type of additive must be selected carefully in order that its melting point is higher than the expected in-service temperatures (otherwise permanent deformation may occur) and to minimise embrittlement of the asphalt at low temperatures.5% surfactants.3–0. USA Evotherm® 3G MeadWestvaco Asphalt innovation Minor (added to binder at terminal) Minor (injected to binder line) Nominal 0. 0. Austroads 2012 — 8— . 0–1. Trials have commenced in the USA and Asia as discussed in Section 7. 2.25 (June 2012). TLA-X®) which add both chemical and organic additives to the binder (Table 2.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members LEADCAP®. Portugal. ** €1 ≈ A$1. including Australia* Germany USA. and their proportions in the mix. wax (0.6: WMA technologies using organic additives Technology Manufacturer Description Synthetic wax produced from coal gasification using the FT process Wax extracted from coal Pellets in paper bag or jumbo bag Plant modification Additive dosage and cost No water. produced by Kumho Petrochemical in Korea. wax (2~4% of binder by mass) 1. is a relatively new product. whereas the organic additives will lower the viscosity of the binder (bitumen) at compacting temperatures and hence increase workability. Japan. Table 2. must be selected carefully to achieve optimum levels of improved asphalt performance and improved workability at lower compaction temperatures.7. sulphur) will improve the performance of the binder. Thailand. The type of combined additives. Table 2.7).3. China and Korea Sasobit® Sasol Wax (Germany) Asphaltan B Romonta GmbH (Germany) Kumho Petrochemical Minor (pre-blended with the binder.7: WMA technologies using combined chemical and organic additives Technology Manufacturer Description Combination of sculpture.8~3% of binder by mass)* 2000 €/tonne** No water. The chemical additive (e. or added dry to the mix) Tprod = 115–130 °C Tcomp = 80 °C LEADCAP® No * Generally 1. Italy. Austroads 2012 — 9— .g.5% is used. plasticiser and other additives Uncoated and coated pellets with binder stiffening additive* Plant modification Minor (for use in most batch and drum mix plants) Minor Additive dosage Production / compaction temperature Tprod = 130 °C Tcomp = 110 °C Reported use 150 ktonne in 2010.5~2% into binder Tprod = 120~130 °C Tcomp = 60–115 °C (30~40 °C below HMA) Production / compaction temperature Reported use Germany and 20 other countries worldwide. USA Shell Thiopave® Shell Up to 25% by mass of bitumen TLA-X® Trinidad and Tobago Ltd NA NA USA * The combined chemical and Torganic additives are usually incorporated in pellet form and can be added either to the mixture or to the bitumen.6 Combined Chemical and Organic Additives This category includes several technologies (Thiopave®. investigative method. only about 20% provided sufficient information for them to be classed as validation/implementation trials. Some common frameworks applied in these three stages are now briefly described to facilitate the reporting of previous field trials of WMA technologies. In other cases. foaming technologies). In case where replicated samples can easily be produced in the laboratory (e.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 3 3. Most were development or demonstration trials established to evaluate a product or process in general terms only.1 Development Trials The main aim of a development trial is to meet a manufacturer’s desire to obtain supporting evidences of material workability and performance for the purposes of developing the additives. verification criteria.1 FIELD TRIALS OF WMA TECHNOLOGIES Introduction Over the last ten years.g. there have been a large number of field validation trials of WMA technologies established all over the world by private industry (manufacturers or contractors who now own the patent rights to use those WMA technologies) and road agencies. Emphasis in this report is placed on the validation/implementation trials. The investigative works used during this stage include low-cost laboratory studies to assess workability and performance. the laboratory-prepared samples are often used in the laboratory testing program. However. the asphalt producer’s marketing strategy and the road agency’s implementation strategy. Canada.) depending on the technologies developed (i. South Africa and Australasia. additives/processes used to manufacture the mix and plant modification s required for these technologies). if replicated samples cannot be manufactured in the laboratory without expensive equipment (e. Each type of trial can have a different framework (scope. full-scale mixing plants and road trials are also used to produce production and field samples for laboratory testing. At the time of completing this report (May 2012).2 Stages of Field Trials It was clear from the review that field trials of various WMA technologies have progressed through three stages in an attempt to gain acceptance by the road industry: development trial. Other sources claimed to be validation or implementation trials but insufficient detail was provided to justify this definition. the trials are just commencing and no performance data has yet been published. more than 160 documents had been identified in a literature search of WMA technologies reporting field trials of some form or another in the USA. the WMA technologies are grouped into the six different categories listed in Section 2.g.3 . processes and equipment prototypes used to produce a product (in this case WMA mixes). 3. This should facilitate discussion on the framework adopted in field trials of WMA technologies and the reporting of the WMA field trials in the following sections. 3. production/demonstration trial. Of the approximately 160 references sourced.e. Each category has similar features in terms of the additives/processes used to manufacture the mix and plant modifications required for incorporating the WMA technologies concerned. technologies using chemical and organic additives). and validation/implementation trial. Asia. Austroads 2012 — 10 — . Europe.2. etc. In this report. mix stability (using the dynamic creep test). fixed binder fraction. Dynamic Shear Rheometer. In Europe. The laboratory assessment methods used in for the design of conventional HMA mixes vary between countries. laboratory assessments of WMA are based on the Superpave and/or the AASHTO SHRP laboratory testing protocols used for HMA mix design. A series of performance tests are then conducted. a common strategy when testing both WMA and HMA samples is to use the same equipment. can also be used to assess the performance of WMA mixes. to allow direct comparison between the results. laboratory assessments of WMA generally also include the determination of workability/compactability (using the gyratory compaction test).Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members The laboratory assessment methods used in conventional HMA mix design. with samples prepared and tested by the same operators. creep. The most common laboratory test methods used in different countries is presented in Table 3. Table 3. bulk density Stability Mix design using Marshall procedure Workability Recovered asphalt binder Durability Particle coating Asphalt binder assessment Particle coating Rotational viscosity. Most asphalt producers will generally proceed to the next demonstration (commercial) stage if the laboratory results obtained in the development trial show that: The WMA has equal or better workability (at low temperatures) than conventional HMA (at high temperatures) Austroads 2012 — 11 — . There is always some concern that some laboratory performance tests do not truly represent field performance. Therefore. A series of samples are produced under different compaction temperatures so that the effect on volumetric properties can be assessed. voids filled with binder Wheel tracking Dynamic creep test Marshall stability and flow Superpave gyratory compaction Rolling Thin Film Oven AASHTO T179–05 (2005) Marshall stability and flow Gyratory compaction Europe USA (SHRP/AASHTO) Australia Performance assessment Stiffness Moisture susceptibility/stripping potential Cracking (fatigue) Resilient modulus (indirect tension) RMS/RTA T649 Beam fatigue In the USA for example. abrasion resistance (using the Californian abrasion test) and resistance to permanent deformation (using the Nottingham Asphalt Tester (NAT)).1. stiffness Deformation (rutting) Nottingham Asphalt Tester Hamburg Wheel Tracking Device (HWTD) Californian abrasion test AASHTO T195–67 (2005) AASHTO M320–10 (2010) Asphalt Pavement Analyser AASHTO T324–04 (2004) AASHTO TP31–96 (1996) resilient modulus AASHTO TP62–03 (2005) dynamic modulus Duriez test AASHTO T283 (2007) Asphalt Pavement Analyser AASHTO T321–07 (2007) Effective and free binder volume. and their acceptance performance criteria.1: Laboratory assessment methods used in asphalt mix design in different countries Purpose Parameter Air voids. product consistency. improved workability. climate).Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members when WMA and HMA have similar volumetric properties. A common strategy in the promotion of a new product is to include a ‘control’ HMA section in the demonstration trial which has the same specified asphalt mix and is placed under the same conditions (pavement. many demonstration trials of WMA technologies have been established in the USA (and other developed countries) to demonstrate the benefits of WMA technology compared to HMA. The works during this stage include field studies using full-scale mixing plants of reasonable size to allow a full run of plant-production (to achieve a commercial production rate).1) are also used in the demonstration stage. etc. contractor laying experience.g. and a road trial of reasonable length (to enable an assessment of workability and field performance immediately after compaction). the asphalt producer would conduct the field trials whilst both the asphalt producer and the road agency would conduct performance measurements. the mechanical properties of WMA are similar to those of HMA. However. In addition. foam technologies using water injection nozzles) and emulsions to reduce the amount of water added to the system. Demonstration trials are particularly popular for road applications involving overlays using high RAP content mixes and severe construction conditions (e.). Generally. Over the last few years. e. and to improve the quality and efficiency of construction (i. field testing is also carried out to validate the material quality and consistency (quality control) and assess short-term performance. Most road agencies would proceed to the next (validation/implementation) stage if the field results at the demonstration stage show that: the field compaction of the WMA is equal to or better than the conventional HMA in the case when field WMA and HMA samples have similar volumetric properties. the manufacturers often provide limited information externally. improved compaction and more consistent field density). and as just discussed. It should be noted that different road agencies may require different evidence of production and placement and performance criteria in the field. cold/wet environments).2 Production/Demonstration Trials The aim of a production/demonstration trial is to meet a road agency’s desire to obtain supporting field evidence of the production and placement of a specific WMA product for the purposes of quality control and assurance (in terms of day-to-day production from mixing plants. Austroads 2012 — 12 — . the modulus of WMA could be lower than the modulus of HMA and this will also impact on fatigue life. 3. There have also been further developments and improvements in WMA technologies using water (e.e.2. This allows a direct comparison between workability and field performance of the WMA and HMA mixes.g. The laboratory assessment methods used in the development trial stage (Section 3.2. for reasons of commercial patents and confidentiality. It is also assumed that the asphalt producer will conduct the investigative works and control the reporting of the works. This may not allow a thorough analysis of the trials and the purchaser may be required to take claims of success at face value.g. material quality. the short-term field performance (observed after compaction) of the WMA is at least equal to that of the HMA. and the monitoring of field performance. An example is the 2007 International Technology Scanning Program. Wu & Barros 2010).). In addition.2. evaluation protocols and test section requirements. construction standards and pavement design procedures. Gibson and Corrigan (2011). the effects of chemical additives on the long term performance of the binder. Brown. An emissions testing framework and draft WMA construction specification has also been up-loaded onto this site. recycled asphalt pavement (RAP). As a result. Tabib. This stage may include a large number of field trials involving various asphalt mixes (binders. Barros (2009). traffic and environmental conditions. including detailed (within-pavement) response-to-load data. A common strategy for reducing the number of required implementation field trials is to examine studies of previous. Examples include the work at the National Center for Asphalt Technology (NCAT) in Auburn. in which a team of technologists from the USA examined WMA technologies currently in place in Europe (D’Angelo et al. Copeland. Implementation field trials are the most expensive of the three options. Vargas-Nordcbeck & Timm 2011). the potential for increased moisture susceptibility when utilising WMA processes that involve the use of water. Alabama (Prowell. (2011). Reinke et al. 2008). and the work at the University of California Pavement Research Center (UCPRC) using the Heavy Vehicle Simulator (HVS) (Jones et al. etc. Diefenderfer and Hearon (2010). These trials have involved the production of the mixes. Raymond and Le (2011) and Willis et al.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 3. The emissions testing framework updates are based on the recently completed emissions and fuel Austroads 2012 — 13 — . including incomplete drying of the aggregate (especially with absorptive limestones). Bressette and Johnson (2008). several asphalt producers and road agencies have collaboratively conducted accelerated loading studies of the comparative performance of WMA and HMA technologies under heavy loading. with high RAP content or rubber asphalt). or existing.g. (2011). Jones. the ability of WMA to provide enough radiant energy to heat the reclaimed asphalt component in mixes containing RAP. In addition.3 Validation/Implementation Trials The purpose of a validation/implementation trial is to address a road agency’s desire to obtain information regarding material workability and field performance (including both short-term performance after compaction and long-term performance over the design period) for the purposes of developing/validating mix designs (material specifications). (2011). Many evaluation field trials of WMA technologies have been established in the USA to address various concerns regarding its use. For example. field trials in terms of their relevance to the issues being addressed. (2011). The FHWA and NAPA are currently updating all three documents following consensus being recently agreed regarding test procedures. aggregate types. and the general lack of information regarding the long term performance of new asphalt mix designs (e. Examples of recent studies include Alossta et al. Newcomb and Corrigan (2006) developed a Material Test Framework for WMA Trials which was adopted by the US National Asphalt Pavement Association (NAPA) and the Federal Highway Administration (FHWA). Jones and Peterson (2011). Kvasnak and Neitzke (2008). evaluation protocols of WMA technologies involving the use of field trials have been established to maximise the benefits of these trials. extensive laboratory studies of both field and laboratory samples were carried out in order that the relative performance of WMA with HMA could be compared with recommendations made regarding the implementation of WMA in the current HMA mix design procedures. the construction of test pavements. Barros. Hurley & Crews 2007. 2008 & 2011. Bernier et al.) and applications (pavement structure. Barros. etc. aspx.1. It is expected that the use of this protocol will assist road agencies in the acceptance of the use of WMA without the need for additional testing and trials. surfactants and foamed bitumen.trb. are presented in Section 10.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members measurement work conducted as part of the NCHRP Project 9-47A. South African Bitumen Association (SABITA) 2011a). The construction specification needs updates are based on the recently-completed WMA mix design recommendations work conducted as part of the NCHRP Project 9-43 project 3.3. it is not a specification.2 South Africa A Best Practice Guideline for Warm Mix Asphalt has recently been issued in South Africa (Naidoo et al.3 3. the results can be distributed and discussed across Australian States and New Zealand through the Austroads framework. including mixes containing RAP. A summary of recent field trials of various WMA technologies is presented in Section 4 to Section 8 of this report.org/NCHRP/Public/NCHRPProjects. The purpose of this guideline is to impart best practice in the design. Whilst the protocol could be applied to any asphalt mix. both in the laboratory and during production the testing of asphalt containing foamed bitumen: during production only desirable site conditions for a field validation site the timeframe for the evaluation data and information exchange.3. based on local experience. The protocol addresses: the testing of asphalt containing additives and surfactants. 3. as a type of WMA is evaluated. manufacture and placement of WMA. Austroads 2012 — 14 — . Brief details of these two projects. It is assumed that the asphalt suppliers have conducted their own trials at the plant to ensure that the additives can be incorporated into the asphalt in a consistent manner and also to demonstrate that they are able to manufacture WMA at a specific plant. The purpose of this protocol is to provide a guide to the evaluation of specific WMA technologies and processes such as additives. 3. and NCHRP Project 9-49. The protocol sets out the conduct of appropriate laboratory tests and field validation projects in order that the performance of WMA and conventional HMA can be compared.4. The protocol is an evaluation tool only. as well as that gained from other countries where this process is used. 2011. the scope of the protocol is confined to wearing courses consisting of dense-graded asphalt and conventional binders. 3 Details of all nine NCHRP projects are listed at http://www. The protocol is written in such a way that.1 Draft WMA Protocols Australia An evaluation protocol was drafted for adoption in Australia in 2010. including recommended usage. Paving and compaction. Overview of the main categories of WMA. a WMA technology addition system. preparation work and minimum paving conditions based on ambient air temperature. Handling and quality assurance of mix components including the milling. Quality assurance during the manufacturing process. Phase 3 – approval may be given by the Warm Mix Asphalt Interest Group after assessment of all the available information. including a more detailed description of some of the technologies that are available in each of the categories. reclaimed asphalt and binders. and temperature ranges for mixing and compaction. full-scale plant mix design. Austroads 2012 — 15 — . including recommendations for equipment. The following three-phase approach to approving other new WMA technologies is recommended: — Phase 1 – the WMA technology supplier provides full information on their product. including recommendations for the range of tests to be carried out on mixes sampled at the mixing plant. materials safety data sheets. Considerations regarding HSE – similar precautions and procedures to those for HMA are recommended. and preparation of reclaimed asphalt. documentation of previous field applications. and monitoring and control systems. stockpiling. Manufacturing requirements for both batch and continuous drum mixer plants including binder storage facilities. how they function and how they are utilised. Topics include: Benefits of WMA – environmental. Quality assurance of mix components including lists of appropriate tests to be undertaken on aggregates and fillers. Classification of WMA technologies. The mix approval process. The interim specification will be updated following the practical experience gained in its implementation. Quality assurance at the paving site. which comprises four distinct steps including laboratory mix design. and final approval based on consideration of all the results.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members It is a substantial document. health and engineering and economic benefits. substrate temperature and wind speed. Phase 2 – carry out the four-step mix design approval process. effect of varying dosage rates. as well as the handling of the various categories of WMA technologies. — — An interim WMA specification has been included as an annexure to the Guideline. WMA technologies that have already been tested and thoroughly assessed by the Warm Mix Asphalt Interest Group are listed. Protocol for introducing new WMA technologies. 4. In a second trial in May 2000. the coarse aggregates are heated to 110 °C and coated with about 20% of the total mass of hot.s). A comparison is always made with samples prepared using conventional processes. the resulting binder-water combination also expands (by a factor of about 15 times its original volume). Both existing batch plants and drum plants need to be retrofitted to produce WAM-foam®. 2002). This led to the development of the WAM-foam® process. mix stability (using the dynamic creep test). dense WAM-foam® asphalt mixes were prepared in the laboratory to determine general workability/compactability (using gyratory compaction). 2002). Anti-stripping agents can also be added to the binder. which is now patented and marketed worldwide (except in the USA) by Shell Bitumen (BP has patent rights for the technology in the USA). involving the modification of an existing paver (Midland MixPaver) was conducted in May 1999. A mass flow meter controls the rate of addition for the hard binder. in the early developmental stage. Koenders et al.1 4. The hard bitumen (approximately 70/100 pen PG 58/64-22 or Australian Class 170) is then foamed into the mix by adding water at ambient temperature at a rate of 2–5% by mass of the hard bitumen fraction (about 726 grams of water per tonne of mix) to the binder (at about 175–180 °C). Since a batch plant is not a continuous process. the asphalt was produced in a batch plant. foaming equipment built into the plant enabled the foamed bitumen to be introduced directly into the pugmill (Koenders et al.1. Even though this trial was carried out under extremely adverse weather conditions (even some snowfall). The first development field trial of WAM-foam®. found that. In the WAM-foam® process.1 The WAM concept of blending hard and soft binder components to reduce production temperature was developed by Shell Bitumen in 1996.1. For a batch plant. bitumen foam was produced on the paver (bitumen and water tanks available). the soft binder is added using the plant’s existing binder line and binder weight bucket. it is important to clean the nozzle and expansion chamber with compressed air after each introduction of foam. soft binder.5 Pa. The grade of the soft binder is selected to be applicable at this mixing temperature (as low as a viscosity of 1. A foaming nozzle with an expansion chamber is added above the pugmill. (2002). the performance (stability and adhesion) of the WAM-foam® mixes manufactured in the laboratory was equal to that of the mixes manufactured using the traditional HMA procedures. The resulting mix temperature is between 100 and 120 °C and the foamed mix can be compacted at a temperature between 80 and 100 °C. mixed with the aggregate and then laid on the road. In this trial. abrasion resistance (using the Californian abrasion test) and the resistance of the mix to permanent deformation (using the NAT). Austroads 2012 — 16 — . As the steam expands (by a factor of about 1600). overall. A separate line is added to the plant to supply the hard binder. the entire paving operation was carried out with satisfactory results (Koenders et al. Collaboration with Kolo-Veidekke in Norway led this work in a new direction when the hard bitumen component was added as foam.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 4 FIELD TRIALS OF FOAMING TECHNOLOGIES USING SEQUENTIAL AGGREGATE COATING AND BINDER FOAMING WAM-foam® Background 4.2 Development Trials As reported in Koenders et al. a similar concept to the WAM-foam® process (i. Canada.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 4. (2007) reported a field trial of ‘warm-foam’ in Calgary. Both the WMA and HMA mixes had similar characteristics in terms of aggregate composition. These high RAP mixes were produced at lower than normal hotmix temperatures using foamed WMA technology (Copeland et al. whilst complete blending occurred in the high RAP-HMA control mix. (2011) reported that a comparison of the measured dynamic modulus results with modelling confirmed that. 2011). permeability) were conducted on the HMA and WMA samples. in cooperation with Florida DOT and NCAT. dynamic modulus and flow number. Performance tests conducted by the FHWA included performance grade (PG) determination of binders. The control mix was a Marshall 50 – blow designed HMA. binder properties.) appear to be different. was milled and repaved with 45% reclaimed asphalt pavement (RAP). using 150/200A penetration grade binder. etc. This project was the first large production in which the Florida Department of Transportation allowed the use of high RAP in combination with WMA. mixing ratio. Sweden and the UK during 2000–2004. Plant-produced mix was collected by FHWA for performance testing evaluation. Johnston et al. two-stage mixing of soft and hard binder) was adopted.1. as a result. and in-place air voids. a portion of State Route 11 in Deland. whereas the fatigue properties of the warm-foam product were significantly greater than those of the control mix. It was noted that. Austroads 2012 — 17 — . Copeland et al. fatigue (AASHTO T321-07. compared to the few hours production during the previous field trials. where the high RAP-WMA had a lower flow number than the high RAP-HMA control. This was further confirmed by flow number results. production details (e. Two mixes were produced: a high RAP-HMA control and a high RAP-WMA. Various laboratory performance tests (rutting (Asphalt Pavement Analyzer). 2007). incomplete mixing of RAP and virgin binders may have occurred in the high RAP-WMA mix. resilient modulus (AASHTO T283. In December 2007. however. A production trial of WAM-foam® in Norway in 2001 involved the use of a batch mixing plant and a continuous drum mixing plant for normal (commercial) paving works. Florida. The PG results indicated that the high RAP-WMA mix was softer than the high RAP-HMA control mix. repeated flexural bending. in 2005. soft and hard binder components. the day-to-day production could provide more information on plant operational issues. (2004) reported that several demonstration field trials involving commercial production rates were conducted in Norway. The dynamic modulus results indicated that the high RAP-WMA was slightly softer than the high RAP-HMA. An early WAM-foam® demonstration trial in Norway conducted in September 2000 included a section on a main road. especially at intermediate temperatures. Since then. was on site for production and placement of the high RAP-WMA. The testing showed that the rutting susceptibility and resilient modulus properties of the control mix were marginally superior to the warm-foam mix. resistance to moisture-induced damage. many demonstrations have been established in Norway and other European countries as a means of checking production data.e. particularly when operating at lower temperatures. The FHWA.3 Demonstration Trials Larsen et al. aggregate composition.g. moisture susceptibility could be an issue. 2007). It was also found that the warm-foam mix was more susceptible to moisture damage. In this trial. volumetric properties. The moisture in the sand foams the bitumen. Existing HMA plants require significant modifications to produce LEA1 mixes. where the performance of the WMA was poor. batch mixing plants. the coarse aggregate is dried and heated at a temperature of about 150–160 °C and coated with hot bitumen. overall. The resulting mix temperature can be less than 100 °C and the foamed mix can be compacted at a temperature between 60 and 90 °C. It was therefore concluded that. and some other countries. Two patented sequential mixing processes (enrobé à basse energize (EBE) and enrobé basse temperature (EBT)) were developed by Fairco and EIFF AGE Travaux Publics.2–0. as reported by D’Angelo et al. continuous plants with continuous pugmill mixer and continuous plants with drum dryer mixer) can be transformed and adapted to LEA1 production.4 Implementation/Validation Trials By 2007. A coating and adhesion agent (0. Austroads 2012 — 18 — .1.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 4.5% by weight of binder) is also added. However. By 2007. Of the sites visited. North America. Advanced Concepts Engineering Co. In one of the LEA1 processes. LEA-CO. It was reported in D’Angelo et al. All six sites included HMA control sections. to promote and market LEA1 in Europe.1 Low Energy Asphalt (LEA1) Background Low energy asphalt (LEA1) is a road building process that was developed by the French Company LEA-CO in 2000. 4. it was not directly attributed to the use of WMA. (2008) (who participated in the 2007 International Technology Scanning Program to survey WMA technologies in European countries). allowing the sand to be coated. (2008) that the Norway Public Roads Administration was conducting condition testing on all the WMA sites including roughness. It has been in use in France and much of the European Union since 2003.2 Development Trials It is suspected that LEA-CO conducted some development trials of laboratory compactability/workability and performance trials of LEA-WMA during 2000–2003. respectively. These two companies are cooperating in a joint venture.2 4. representing 17 800 tonnes of asphalt. there were 28 WAM-foam® trial sections in Norway.2. texture. they only visited six sites in Norway with average daily traffic volumes ranging from 3500 to 25 000 vehicles.2. to produce WMA. 4. four were composed of dense-graded asphalt and two were SMA. Although poor performance was observed in limited WMA sections. profile and rutting. (LEA-CO) has listed several examples showing how common HMA plants (continuous mixing plants. it appeared that the performance of the WAM-foam® sections was similar to the HMA sections. Wet sand (as high as 40% of the total mix or 13 kg of water per tonne of mix) is then introduced into the mix. the performance of the HMA was also poor. the results have not been made public. It was also noted that the use of studded tyres caused significant wear to the pavement. However. manifesting itself in the form of rutting in both the HMA and WMA sections. the annual total production for WMA in France was reported as being about 500 ktonne (European Asphalt Pavement Association (EAPA) 2007). 1 Low Emission Asphalt (LEA2) Background In 2006. including compactability (gyratory compaction).5 mm mix and a control HMA section on Route 11 to a compacted depth of 37. details of these chemical additives are not in the public domain. The sites were laid during heavy rainfall. The manufacturer claims that the chemical additives being added in the LEA2 process produce more stable WMA mixes at low compaction temperatures (60 °C). modulus (indirect tensile) and fatigue resistance (fatigue beam) and the same performance requirements as conventional HMA. To date. the performance at all sites has been satisfactory. 4. followed by the introduction of wet sand which created a foaming action). at an application temperature between 60 °C and 80 °C. Laboratory mix design studies were also conducted on LEA1 mixes from these field trials. 4.3. on Highway RD1 towards Saint-Etienne d'Issansac (using 0/10 type A asphalt) and on the Saint-Hilaire Freeway A26 (using very thin asphalt). However. Based on this limited amount of production. they changed the name to low emission asphalt (LEA2). 25 mm thick. As a result.2. A total of 150 tonnes of LEA1 mix was manufactured and applied. including at joint locations.3. The results obtained with mixes produced according to the LEA® process compared with HMA mixes were of the same order and judged to be satisfactory. Austroads 2012 — 19 — .4 Implementation/Validation Trials Olard et al.2 Development Trials No development trials were reported by McConnaughay Technologies. (2008) reported field trials of typical LEA1 mixes in Episy in 2005 (using 430T 0/14 Class-3 asphalt road base and Class-2 semi-granular asphalt with 35/50 binder).3.5 mm mix. 2004). Observations indicated that the LEA1 mixes were homogenous and reproducible and that the workability.2. The initial compaction and the field performance after the first 20 000 passes of trucks were reported to be satisfactory. McConnaughay Technologies improved the chemical additives being added to the hot coarse aggregates (coated with hot binder. The first trial involved the use of 300 tonnes of 9. Those laboratory mix design results are now appearing in the catalogue of licensed LEA® mixing stations.5 mm. A site inspection conducted about six months after construction showed that the HMA control section exhibited approximately seven times the amount of cracking as that of the LEA section. the reduction in energy consumption was measured to be 47%.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 4. moisture sensitivity (Duriez test). 4. The second demonstration trial involved the placement of 1000 tonnes of 9. whilst implementing the LEA1 technology in the USA. 4. on a driveway of the company’s bitumen terminal. It was also reported that the LEA1 mix had a surface appearance comparable to that of the HMA.3 Demonstration Trials Harder (2007a) reported two demonstration trials of LEA2 conducted by McConnaughay Technologies in New York in 2006.3 4. was similar to that of conventional HMA at high temperatures.3 Demonstration Trials A series of demonstration field trials of LEA1 was carried out in the Rhone-Alpes region in France in November 2003 (Romier et al. rutting resistance (wheel tracker). Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 4.2. LEA and HMA samples (both unconditioned and conditioned (aged in an oven of 95 °C for two hours) were tested for compatibility (gyratory shear test).1. moisture sensitivity (Tensile Strength Retained (TSR) test) and modulus NCHRP simple performance test).3.4 USA Implementation/Validation Trials By 2007. conducted in New Zealand. The results are discussed in Section 9. Austroads 2012 — 20 — . New Zealand Hayward and Pidwerbesky (2009) reported the results of trials of an LEA1 product (CoolPave). McConnaughay Technologies had conducted 11 implementation trials involving the use of 34 000 tonnes of 9. Laboratory mix design studies conducted on both the LEA2 and the HMA were also reported. The results were both mixes were of the same order and judged to be satisfactory.5 mm mix on various routes in New York (Harder 2007b). The use of RAP and MSM in conjunction with the DBG process did not significantly influence mix properties and performance based on laboratory testing. Kvasnak (2007) reported two demonstration trials of the Astec DBG technology with asphalt mixes having 30% and 50% RAP in Chattanooga. It was concluded that the Double Barrel® Green process did not negatively influence the moisture susceptibility of mixes. British Columbia. approximately 0.2 Development Trials The DBG foaming system is considered to be an improvement over previous foaming technologies in terms of cost reduction (i. The results of Asphalt Pavement Analyser and Hamburg Wheel Tracking Device (HWTD) testing showed that the DBG-RAP mixes performed better than the virgin mixes. rutting susceptibility (Asphalt Pavement Analyser).1.5 kg of water per tonne of mix is introduced through nozzles.1 5. Laboratory TSR testing for moisture sensitivity was carried out on DBG-RAP and DBG-virgin samples collected during construction.8 respectively. In this process. The system requires an Astec Double Barrel® drum asphalt plant and a multi-nozzle foaming device used to microscopically foam a standard grade binder with water.9.3 Demonstration Trials Middleton and Forfylow (2009) reported a demonstration trial of DBG using a 2007 Double Barrel® Drum Asphalt Plant (400 ton/hour) in Vancouver. causing the hot binder to expand by about 18 times. In order to implement the process on a Double Barrel® drum asphalt plant. It was reported that all mixes were workable with no compaction issues. whilst the values for the DBG 30% and 50% RAP mixes were 0. Tennessee. stiffness (indirect tension) and moisture sensitivity (TSR).Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 5 5. The laboratory testing of the HMA and WMA production samples included workability (gyratory compactor). low initial installation cost and no chemical additives) and low water additive.1 FIELD TRIALS OF FOAMING TECHNOLOGIES USING WATER-BASED MECHANICAL SYSTEMS Double Barrel® Green Background Double Barrel® Green (DBG) is a system developed by Astec Industries in 2007. 5. the only plant modification necessary involves the installation of the foaming manifold over the existing binder injection system on the outer drum of the plant and the installation of corresponding binder and water feed lines into the manifold.e. The resultant production temperatures are typically 120-135 °C with the mix being placed at temperatures as low as 115 °C. and a mix with 50% RAP. recovered binder characteristics (Rolling Thin Film Oven). An upgrade of the plant software control system is also required. a mix with 15% RAP and 5% modified shingle mix (MSM).1.58 to 0.1. Astec Industries also claim that the use of a low water dosage added for the foaming action and high mixing temperatures (120–135 °C) does not negatively influence the moisture susceptibility of mixes compared to conventional HMA. Austroads 2012 — 21 — . The trials were conducted on the Astec parking lot (30% RAP) and on North Terrace Rd (50% RAP) respectively. The results showed that the TSR value for the DBG-virgin samples was greater than 0. satisfactory rutting resistance and adequate stiffness. a mix with 15% RAP. including a virgin mix. Four WMA mixes were produced. It was concluded that the DBG process produced mixes having similar binder and mix properties to HMA. 5. 2 Development Trials No development trials have been reported by Gencor Industries. One trial involved the use of rubber WMA mixes produced by the DBG process in 2008. The moisture susceptibility test results generally suggested that the WMA products were more susceptible to moisture damage than the HMA. Advera® and Sasobit® were used in the other trials.1. (USA). Visual observations of open-graded asphalt (OGA) showed that the WMA mixes were performing equally as well as the conventional hotmix OGA. All trials showed good workability with no compaction issues. Each trial involved the use of about 700–1150 tonnes of WMA. including moisture susceptibility (AASHTO T283. An update of the field trials was reported by Barros et al. 2004).2. 2007). 2005). as the temperatures on the coastal highway in California during the summer are generally cool. The rubber HMA mixes were also included in four trial sections for comparison with other WMA technologies. The performance of the rubber WMA OGA appeared to suggest a longer service life than the conventional rubber OGA with a subsequent recommendation to adopt WMA for all rubber OGA. It was reported that. stiffness and fatigue) was inferior to that of the HMA mix. (2010). 2010) to assess the laboratory performance of WMA products produced by Ultrafoam GX® and HMA.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 5. evenly sized bubbles are generated. (2011). dynamic modulus (AASHTO TP62-03.2 5. Inc. possibly due to the incomplete drying of the aggregate and softer binder at lower WMA production temperatures. 5. Advera® and Sasobit®) in 2009. Barros (2009) reported a series of six field trials of WMA technologies involving the use of asphalt rubber mixes (RMA) which have been investigated by the California Department of Transportation (Caltrans) since 2008. the performance of the WMA exceeded the minimum laboratory performance thresholds in most cases. Austroads 2012 — 22 — . 5.2. Advera® and Sasobit®) failed the moisture susceptibility test. whereas the other mixes (Evotherm® DAT. One trial section used the Astec DBG system whilst Evotherm® DAT.4 Implementation/Validation Trials Kvasnak (2007) also reported four field trials established to compare different WMA technologies in Nashville. HWTD (AASHTO T324-04.1 Ultrafoam GX® System Background The Ultrafoam GX® system was developed by Gencor Industries. while the other trials involve the use of rubber WMA mixes (produced with Evotherm®. However. Tennessee. and repeated simple shear and shear frequency sweep testing (AASHTO T320-10. which result in consistent foaming at all production rates. Kvasnak reported that laboratory TSR testing conducted on samples collected during construction indicated that the mixes produced by the Astec DBG system passed the moisture susceptibility testing. beam fatigue (AASHTO T321-07. Whilst the laboratory performance of the WMA mix (rutting. The binder and water are mixed together in a proportionate and continuous fashion and small. It involves the use of a special foaming generator (dubbed the Green Machine) that can be easily connected to an existing binder injection line leading to a drum mixer. The results of the laboratory testing are reported in Kvasnak et al. 2007). Gencor has contracted NCAT to conduct an intensive laboratory testing program. Two control HMA sections (with PG 64-22) were also included for comparison purposes. WMA offered an excellent pavement alternative. and Sasobit®. 2002) was also conducted to determine changes in tensile strength with aging. higher laboratory workability. Austroads 2012 — 23 — . However. Evotherm®DAT. The early rutting performance of Cecabase®.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Tensile strength testing on aged WMA samples (AASHTO R30-02. Laboratory testing protocols were the same as those followed in Phase 1. Gencor Ultrafoam®. the performance of the three WMA mixes was similar to the conventional HMA mix. and Sasobit® against two hotmix controls in a gap-graded rubberized asphalt mix. Evotherm® DAT®. The City of Calgary conducted road trials using a residential surface mix design containing 15% RAP produced as conventional HMA and as WMA utilising three WMA technologies: two WMA water-foaming processes. than the conventional HMA. (2011) as well as a comparative study of three WMA technologies in the City of Calgary reported by Forfylow and Reyes (2011). low temperature cracking (Thermal Stress Restrained Specimen Test). and the performance of the aged WMA samples was similar to the HMA. The first phase involved laboratory and accelerated load testing of three WAM technologies: Advera®. slightly lower mix stiffness at high temperature. tensile strength and resilient modulus (AASHTO TP31-96) workability (Superpave gyratory) and a rheological evaluation of recovered binders. and a WMA chemical additive. Astec Double-Barrel Green®. GENCOR’s HyperTherm®. Cecabase®. The testing of the recovered binders from the three WMA mixes indicated slightly lower stiffnesses at high and low temperatures than the recovered binder from the conventional mix.4 Implementation/Validation Trials Implementation of the Ultrafoam GX® system was included in the Caltrans study reported by Jones et al. Laboratory evaluation was undertaken for moisture susceptibility (AASHTO T283-2007). Rediset® WMX. These results suggested that any study of the moisture susceptibility of WMA and HMA mixes should consider binder aging effects. that performance improved as the samples aged. Paving emissions were also measured.2. The second phase extended the study to include moisture sensitivity. In addition. It was noted that the aged WMA samples (with different levels of aging) had higher resistance to moisture damage. 5. rutting and fatigue (Asphalt Pavement Analyzer). A new test track was built for the study. 5. no demonstration trials of Ultrafoam GX® (laboratory or field) had been reported. the use of lower plant production temperatures was reflected in the rheology of the recovered binders. ASTEC’s Double Barrel® Green and GENCOR’s Ultrafoam GX® processes. The laboratory evaluation showed that the WMA mixes had similar rutting and fatigue resistance.2. The road performance data showed that. Evotherm®DAT and Gencor Ultrafoam® was found to be slightly superior to that of the control. better low temperature behaviour. The third phase was a laboratory and accelerated loading test of seven different WMAs – Advera®.3 Demonstration Trials At the time of writing of this report. no studies have been reported relating the findings of the laboratory testing to observed field performance. and similar stripping susceptibility. as already stated. after one year of service. The Caltrans study was undertaken in three phases. demonstration or implementation trials of these systems have been reported.3 Other Mechanical Injection Systems AQUABlack® WMA and Terex® WMA also involve the use of a mechanical system to inject water or steam into a binder stream. The Terex® WMA system was developed by the Terex® Roadbuilding Division of the Terex® Corporation in 1998. The foamed asphalt is produced outside of the drum mixer and immediately injected into the mixing chamber to provide an even coating of the aggregate. which ensures a consistent binder/water mix at any production rate. At least three asphalt mix producers have purchased the AQUABlack® foaming device and installed it on at least six plants around Minnesota (Clyne. The system uses a single expansion chamber. Terex® claims mix production temperatures can be reduced by up to 32 °C without the use of additives. Johnson & Garrity 2011). Austroads 2012 — 24 — . This device costs considerably less than many other plant foaming technologies. No development. The Terex® system can be easily adapted to most existing drum mix plants.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 5. and the manufacturer claims that its efficient design will require minimal maintenance over time. AQUABlack® is described as a simple foaming device that is easy to install and operate on an existing asphalt plant. 1.3 Demonstration Trials Prowell and Hurley (2007) reported a trial conducted by the Virginia Department of Transportation in 2004 at the Hubbard equipment yard in Orlando. The Zeolite is produced in granular form.3% Aspha-Min® Zeolite by weight added to a 12. 6. Resistance to moisture damage (AASHTO T283. stiffness (indirect tensile) and fatigue (three point bending.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 6 6. Canada. The trial involved the use of 0.5 mm Superpave mix (contained 20% RAP). The trials also included control HMA sections. Hurley and Prowell (2005a) measured Marshall stability. Austroads 2012 — 25 — .2 Development Trials The manufacturers recommend that. even during the late season construction.1 FIELD TRIALS OF FOAMING TECHNOLOGIES USING WATER-BEARING ADDITIVES Aspha-Min® Background Aspha-Min® is a synthetic zeolite composed of alumino-silicates of alkali metals. It was reported by the contractor that all the sites performed well and that there were no issues with temperature in terms of achieving the required compaction.25% by weight of a parent HMA mix.1 6. rutting resistance (wheel-tracking). which is released as the temperature increases.1. Typically 0. It was developed by Eurovia Services GmbH (Germany). a hotmix drum plant was used. Davidson (2007) reported five demonstration field trials of Aspha-Min® conducted on various routes in Montréal. Overall. They reported that the moisture sensitivity and low temperature properties of the Aspha-Min® were slightly inferior to those of the HMA. which had been modified with a rotary mixer into a continuous type plant. trapezoidal specimens). Florida.1. 6. (2010) measured fatigue cracking and wheel tracking properties of Aspha-Min® and HMA. each involving up to 500 tonnes of asphalt. Typically. causing the binder to foam slowly while mixing with the aggregate. They reported that no extended curing time had been observed and improvements in compaction levels and a higher degree of rutting resistance had been obtained with a reduced void content. The foamed asphalt has greater workability and allows for improved compaction and coating of the aggregate particles. it is easier to place the mix at a lower temperature and offers benefits in base. 2007) was also similar. the binder. or at the same time as. For the first three trials. Work to evaluate the workability and performance of Zeolite mixes compared with HMA has been conducted by Hurley and Prowell (2005a) and Wu et al. The zeolite releases a very small amount of water at temperatures in the range of 100-200 °C. The product contains about 20% water of crystallisation. they do not report on the performance of the WMA mixes or the relative performance of Aspha-Min® compared with HMA. PG 64-34.3% zeolite by weight is slowly added to the mix shortly before. The density of the WMA and HMA sections (using the Nuclear Density Gauge and density testing on field cores) was similar. was used. Wu et al. the mixing temperatures are approximately 120–135 °C with the mixture being placed as low as 115 °C. by adding Zeolite at 0. Five different binders were used in these trials: PG 64-28. a special batch plant. PG 70-28. the addition of the zeolite in the HMA (same mixing temperature) resulted in improved workability (easier to compact) compared to the same mix without zeolite. A control HMA section was also included. binder and wearing courses. (2010). PG 70-28 and PG 58-28. during 2005–2006. However. For the other two trials. many road agencies are now considering implementing zeolite-WMA in applications where the construction of HMA is difficult (e. observations taken 18 months after construction showed that each WMA section was showing various stages of ravelling. 6.2. has been monitored since its construction in September 2006 (Hurley.075 mm sieve. The blending process is also claimed to provide a more consistent WMA. Austroads 2012 — 26 — .4 Implementation/Validation Trials As zeolite-WMA can be produced and placed using similar HMA construction procedures with only minor modifications to the asphalt plant. Advera®-WMA and other WMA technologies such as Evotherm® and Sasobit® in Orlando (Florida). Nashville (Tennessee) and Watsonsville (California). the HMA. They observed that the WMA sections performed as well as. It is similar to Aspha-Min® but has a finer gradation than Aspha-Min®.1. 6. According to this report. low construction temperatures). 6. binder and wearing courses. Various universities and transportation agencies in the USA have reported evaluation field trials to compare the performance of zeolite-WMA mixes against other types of WMA mixes and HMA. It was suggested that this ravelling could possibly be a sign of moisture damage in the pavement or related to handwork conducted during the paving process.1. it is easier to place the mix at a lower temperature and offers benefits in base.2 Development Trials The manufacturer recommended that. Prowell & Kvasnak 2009a). (2008) reported several validation trials of Aspha-Min® in France and Germany in 2007.2. with 100% passing the 0. D’Angelo et al. For example. using the HVS. the control HMA sections. no performance data has been reported.1 Advera® Background Advera® is a synthetic Zeolite produced by PQ Corporation (USA). Sasobit® and Evotherm® in Kimbolton. It is also claimed by the manufacturer that the mix is effective with all grades of asphalt. by adding Zeolite at 0.25% by weight of a parent HMA mix.3 Demonstration Trials At the time of writing of this report. However. was also conducted on a test track in Watsonsville (California). No evidence has been reported to date regarding any negative influences of the zeolite WMA technology on short-term performance compared with HMA.2. Accelerated pavement testing. or better than. Brief details of a trial conducted by Brisbane City Council are presented in Section 9. no demonstration trials of Advera® (laboratory or field) had been reported. Yellowstone National Park (Wyoming). or higher than. PQ Corporation is working on a process to blend Advera® with the binder as it is being introduced into a plant instead of simply blowing it into the mixing chamber like a fibre. (2008) reported several validation trials of Aspha-Min® WMA. Ohio. including polymer modified and rubber mixes. In most cases.g. Brown et al.1. The results have yet to be published. the density of the WMA was very similar to.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 6. A field trial of Aspha-Min®.2 6. Colorado Department of Transportation (CDOT) The Colorado Department of Transportation (2009) reported the results of a field trial of WMA overlays of Highway I-70 (30 000 AADT). Kvasnak Kvasnak (2007) reported an evaluation trial of Advera® (and Evotherm® DAT and Sasobit®) at a mountainous location in Silverthorne. Top-down cracking was noted on all sections. at both the equilibrium and pre-soaked moisture conditions.4 Implementation/Validation Trials Various universities and transportation agencies in the USA have reported evaluation field trials comparing the performance of Advera®. crack length. Evotherm® and Sasobit®) and a control HMA. However. Colorado. no significant difference in the level of moisture sensitivity between the control mix and the mixes with additives. Cracks did not appear to penetrate below the top lift of asphalt on any of the sections. In this trial.2. However. Colorado.1.6 km) long with 1000 tonnes (1016 t) of WMA used. laboratory deformation testing (using the HWTD) performed on slabs compacted with a linear kneading compactor indicated that the performance of the Sasobit® WMA mix was superior to that of the HMA. All trials showed good workability with no compaction issues.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 6. There has been no evidence to date of any negative influence of the zeolite-WMA technology in terms of both short-term and long-term performance compared to HMA. The air voids of the WMA cores were compared to the HMA cores. was used to assess the rutting performance of the WMA and HMA at various pavement moisture conditions. with wheel loads varying between 40 kN and 90 kN. There was. east of Eisenhower tunnel. WMA mixes against other types of WMA mixes and HMA. with no significant difference in the crack patterns. (Note that the work conducted by Barros (2009) has already been reported in Section 5. All sections performed well after the first year of trafficking. (2010 & 2011) reported an evaluation trial conducted by the University of California Pavement Research Center to compare the workability and performance of three WMA products (Advera®. Austroads 2012 — 27 — . equilibrium moisture and pre-soaked with water for a period of 14 days prior to testing. Laboratory compaction testing conducted on the Advera® WMA and HMA mixes immediately after production indicated that the WMA mixes had lower specific gravities and higher air-void contents compared to the HMA control. Construction was conducted at a high elevation and during cold winter temperatures. however. viz. University of California Pavement Research Center Jones et al. there was no significant difference in rutting behaviour between the two HMA sections and the Advera® WMA. Laboratory moisture sensitivity testing (using the HWTD and the TSR test) indicated that all the WMA mixes (including the control) were potentially susceptible to moisture damage. Laboratory performance tests (shear and fatigue beam testing) indicated that the WMA technologies assessed did not influence rutting or fatigue cracking performance. Each section was 1 mile (1. A summary follows. It included a control HMA section and three WMA sections (Advera® with 58-28 binder. the HVS.4). indicating a higher level of compaction of the WMA mixes. Evotherm® 64-22 binder and Sasobit® with 64-22 binder). these results were not representative of measurements after construction of the test track. whilst the Advera®-WMA and Evotherm®-WMA rutted at a higher rate than the HMA. The results indicated that. or crack density. No evidence has been reported to date of any negative influences of the Advera® WMA technology on both the short-term and long-term performance compared to HMA. However. laboratory performance testing (using the HWTD) on slabs (compacted with a linear kneading compactor) indicated that the Advera® slab rutted at a faster rate and did not pass the MDT specification of < 13 mm of rutting. Austroads 2012 — 28 — . Yellowstone National Park and South of Gardiner. The second trial has one section of HMA and one section of Advera® WMA.2 km long and involving the use of 28 000 tons of asphalt – consists of a control HMA mix. and two WMA mixes produced using Advera® and Sasobit®. Whilst the Sasobit® slab passed the rutting specification.11. Montana. West of Cody. The sites have been monitored by the Montana Department of Transportation (MDT) since 2007. indicating a higher degree of compaction of the WMA mixes.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Montana Department of Transport Perkin (2009) reported two field trials involving Advera® and Sasobit® at East Entrance Road. its performance was still inferior to that of the HMA slabs. Perkin (2009) reported that the air voids of field WMA cores were lower than those of the HMA cores. The first trial . adhesion. workability and moisture resistance. There was no evidence of any difference in indirect tensile strength gain with time for the mixes containing Evotherm® additives compared to the control mixes. in which a concentrated solution of Evotherm® additives (using the same chemical package diluted with a small amount of water) is injected into the line (5% w/w bitumen 4) just before the mixing chamber to produce a resulting mix temperature between 115 and 120 °C. e. a bitumen emulsion is produced using a package of chemical additives designed to enhance coating.1 FIELD TRIALS OF CHEMICAL ADDITIVE TECHNOLOGIES Evotherm® Background Evotherm®™ is a process developed by Asphalt Innovations.1. Test results produced using the Asphalt Pavement Analyzer also showed that the addition of Evotherm® additives did not negatively affect the resilient modulus and the rutting potential of an asphalt mix. The initial rolling temperature of Evotherm® 3G-WMA is between 115 and 120 °C. The initial rolling temperature of Evotherm® ET-WMA is between 85 and 90 °C. % bitumen = 5/(95+5) x 100 = 5% w/w. It requires minor plant modification for injecting Evotherm® additives into the system. A new process called Evotherm® 3G (Third Generation) has also been developed in partnership with Paragon Technical Services and Mathy Technology & Engineering. MeadWestvaco also developed a new Evotherm® process called Dispersed Asphalt Technology (DAT). external laboratories (including universities. The initial rolling temperature of Evotherm® DAT-WMA is between 100 and 105 °C. In the original Evotherm® process called emulsion technology (Evotherm®-ET). The majority of the water in the emulsion flashes off as steam when the emulsion is mixed with the aggregates. Hurley and Prowell (2006) reported that the rutting potential increased with decreasing mixing and compaction 4 weight/weight.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 7 7. Evotherm® DAT reduces the water in the mix and eliminates the cost of processing and transporting the emulsion. for 5 kg of bitumen in 95 kg of solution. transportation agencies.2 Development Trials MeadWestvaco does not disclose the additive contents of the Evotherm® chemical package or any details of internal development trials showing the impacts of the chemical additives on workability and performance.1. It is anticipated that Evotherm® 3G will replace previous Evotherm®-ET and Evotherm® DAT processes. They confirmed the improved compactability of Evotherm® mixes at temperatures as low as 88 °C. Nevertheless. Evotherm® ET requires no plant modifications and simply replaces the binder in a conventional HMA design.1 7. Hurley and Prowell (2006) used two aggregate types (granite and limestone) and two binders (PG 64-22 and PG 76-22) when they compared the workability and performance of mixes manufactured with different Evotherm® emulsions and two control binders. The emulsion is then mixed with hot aggregates (at a rate of 25 kg of emulsion per tonne). Austroads 2012 — 29 — .g. and other research organisations in USA and elsewhere) have conducted studies comparing the workability and performance of Evotherm® mixes with equivalent HMA mixes. This process is water-free and is suitable for introduction at the mix plant or bitumen terminal. a MEADWESTVACO business. 7. In 2006. The resulting mix temperature is between 135 and 140 °C. However. in the USA in 2003. a mix temperature between 85 and 115 °C results. which is much lower than the initial rolling temperature for HMA (between 135 and 140 °C). Marshall stability. dynamic shear rheometer. Austroads 2012 — 30 — . and Aspha Min). stability. Liva and McBroom (2009) conducted HWTD testing on a HMA control mix and six different WMA technologies (Sasobit®. TSR. a control HMA (binder grade PG 64-22). this may be related to the decreased aging of the binder resulting from the lower mixing and compaction temperatures. However. maximum theoretical density. Sasobit®. the other synthetic zeolite products (Aspha-Min® and Advera® WMA) and Rediset® WMX did not demonstrate favorable rut resistance and showed signs of stripping. There did not appear to be any differences between the Evotherm® mixes and conventional HMA. The results were also compared with the results of equivalent HMA mixes. It was reported that there were no problems during the mixing process in the plant or with the handling of the Evotherm® emulsion and there did not seem to be any difference in compacting the HMA mix at 140 °C compared to compacting the Evotherm® mixes at 80 °C. It was reported that there were no problems during the production of the WMA in batch plants in all three trials. Laboratory testing (viscosity. 7. In addition. Evotherm® 3G. Xiao. indirect tensile strength.1. film thickness. Davidson (2006) also reported another demonstration trial of Evotherm® ET conducted in 2006 involving the use of 1250 tonnes of base mix (PG 58-28) and surface mix. bulk re-compacted density. the Evotherm® 3G and the Sasobit® modified samples all demonstrated good rut resistance and moisture induced damage resistance and did not strip. and flow of WMA mixes) was performed on all the mixes. and penetration on the recovered binder).Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members temperatures. Wan and Ma (2010) conducted various laboratory performance tests on laboratory-compacted specimens (TSR. moisture content in mix. dynamic stability. Cantabro. the USA and France. drainage. both containing 15% RAP. HWTD rutting) and found that most tests showed similar test results between the HMA and WMA SMA10. the Evotherm® DAT modified. Hu. beam bending rheometer. Production samples and field cores obtained from the Evotherm® ET trials were tested using the SHRP testing protocol for HMA mix design (residual binder content. Amirkhanian and Shen (2010) conducted a laboratory experimental study to evaluate the moisture susceptibility of WMA mixes containing three WMA additives (Aspha-Min®. flow index. low temperature bending strain. Rediset® WMX. They found that the HMA control. Advera® WMA. A control HMA section was also included. It was reported that the DAT system was very easy to use and tied into the existing system. Davidson (2007) also reported various demonstration trials of Evotherm® DAT undertaken in Canada. the performance of the WMA SMA10 with Evotherm® added was superior to the HMA SMA-10 in terms of water sensitivity and reduced rutting. the moisture susceptibility results illustrated that the mixes containing WMA additives generally had slightly lower TSR values than the conventional HMA mixes. TSR. and Evotherm®). The results indicated that the addition of the WMA could lead to a slight decrease in viscosity and an increase in failure temperature.3 Demonstration Trials Davidson (2005 and 2006) reported three demonstration trials of Evotherm® ET involving approximately 1700 tonnes of WMA and conducted in Canada in 2005. Evotherm® DAT. All three trials used bitumen grade PG 58-28. However. and two aggregate sources. air voids. thus allowing the use of the higher RAP content. Evotherm® 3G WMA was used as a means to reduce the occurrence of thermal cracking in dense-graded HMA mixes. limestone as fine aggregates) whilst the target air voids content was 4%. China and Europe). a HMA control mix containing 20% RAP and Evotherm® WMA (contained 30% RAP) were used in this trial as a means of reducing the occurrence of thermal cracks. Since the Evotherm® WMA was produced at approximately 40 °C lower mix temperature. it yielded high binder modulus. SFA (Evotherm®) was selected for the field trial because fatigue performance at low temperatures is the major performance criterion. by 2008. Based on laboratory results. in September 2007. Triangle Asphalt paved 660 tons of the mix on a country road in Indianapolis. when the HMA mix contained 30% RAP. After one year of trafficking (volume of trafficking level not reported) the performance of all sections was reported as being satisfactory.6% and AC-20C in the lower layer with an optimum binder content of 4. Therefore. is that no details of these trials are presented. permeability and density. MeadWestvaco (2009a) reported two evaluation trials of Evotherm® 3G in Crow Wing County. Canada. The second trial was conducted in 2009. The problem. Testing included skid resistance. Austroads 2012 — 31 — . the average number of cracks in the Evotherm® WMA pavement (PG 58-28 binder) was comparable to the average number exhibited by the HMA control pavement (PG 58-34 binder). Mexico. less binder oxidation occurred. SA1 (Sasobit®) and SA2 (a WMA organic wax additive were evaluated in the laboratory). more than 150 projects involving WMA had been successfully completed throughout the world (USA. The first trial was conducted in 2008 using approximately 2000 tonnes of material (PG 58-28 surface mix).1. binders and production equipment. It involved the use of over 20 000 tons of material (PG 58-28 of 12. Liping et al. The mix was produced at 149 °C at the plant and laid at 99 °C and emissions were significantly reduced.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members McKenzie (2006) reported that there were 10 to 12 Evotherm® projects around the world which demonstrated the successful application of the product with a wide range of aggregates. They were placed in two lifts approximately 125–150 mm thick. McKenzie also reported a project in the USA where WMA mixes were produced by Milestone Contractors LP using Evotherm®. namely SFA (Evotherm®). The WMA was placed in both the upper and lower layers: AC-13C in the upper layer with an optimum binder content 4. It was reported that the early performance of both pavements was equal.4 Implementation/Validation Trials It was reported by MeadWestvaco that. The use of a higher RAP content in the Evotherm® WMA (30% RAP) also provided another cost-savings benefit. The authors concluded that successful installation of the SFA mix on the Zhubi Expressway indicated that WMA could achieve the same compaction and performance as HMA. Based on previous experience. The mixes have been manufactured to both Superpave and Marshall designs. involving more than 400 000 tons of mix. 7. Prior to the trial. (2010) reported that the control mix was an AC-13C (coarse aggregate. McKenzie also reported that the presence of water in the Evotherm® mix caused no issues in the baghouse. Minnesota. China.3%.5 mm NMAS Superpave). three mixes. however. leading to early low-temperature thermal cracking. (2010) reported trial sections of Evotherm® WMA technology which were constructed on the Zhubi Expressway in Henan. The length of the trial was 543 metres. Liping et al. After the first winter (2008–2009). Colorado. Both the control and Evotherm® mixes contained 20% RAP. In another trial the performance of Evotherm® DAT and HMA was compared. while the other trial sections used Sasobit® mixes. Various laboratory tests for workability and performance were performed using samples of Evotherm® and control mixes collected at the plant. Alabama (Kvasnak & West 2009). The control mix for the Evotherm® trial was manufactured using the same grade binder (PG 70-22) as the base binder of the Evotherm® emulsion. involving approximately 2050 tons of material (asphalt mix with 15% RAP with a PG 67-22 binder) placed on the State Rd 79 in Birmingham. (2011) reported cooperation between EUROVIA and MeadWestvaco in the development and promotion of WMA resulting in some 1 million tonnes of WMA being manufactured and applied since 2006. Specific reference is made to the placement of 14 000 tonnes of WMA basecourse on a new highway near Strasbourg in France. The density of the Evotherm® WMA was also higher than the HMA control mix. A slight reduction in moisture sensitivity performance of the WMA was still within specification limits. stiffness modulus and fatigue. the Evotherm® DAT-WMA and the other WMA mixes (Advera® and Sasobit®) failed the moisture susceptibility test. A HMA control mix (with polymer-modified PG 64-34 binder) and Evotherm® 3G WMA (with PG 58-28 binder) were used in the re-cconstruction of the taxiways in September 2009.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members MeadWestvaco (2009b) also reported a trial of Evotherm® 3G at the Ted Stevens Anchorage International Airport. Virginia Department of Transportation Diefenderfer. The 0/14 Grave Bitume mix design incorporated 10% RAP and 4. Two control HMA sections (with PG 64-22) were also included in the trial.2. Advera® and Sasobit®) and HMA in Nashville. It was found that the air voids contents of the Evotherm® specimens were slightly higher than those of the control specimens. Some details follow. McGhee and Donaldson (2007) reported a series of field trials of WMA and HMA conducted by the Virginia Department of Transportation over a two-year period. and other research organisations in the USA have also conducted evaluation field trials to compare the performance of various WMA mixes (including that produced by the Evotherm® DAT process) and HMA.1% 35/50 pen bitumen binder. Each of these trials used about 700–1150 tonnes WMA mix. TSR values for the Evotherm® specimens were lower than those for Austroads 2012 — 32 — . There was also very little difference in the rheological properties of the recovered binder. Tennessee. Kvasnak As discussed in Section 6. Kvasnak (2007) reported an evaluation trial of Advera® (and Evotherm® DAT and Sasobit®) at a mountainous location in Silverthorne. A laboratory study of the production asphalt showed similar performance between the WMA and HMA ‘control’ mix in terms of rutting resistance. Various universities. Evotherm® was used in one trial section. transportation agencies. Whilst all trials showed good workability and no compaction issues.4. Delfosse et al. laboratory TSR testing indicated that only the WMA mix produced by the Astec DBG system passed the moisture susceptibility testing. It was found that the Evotherm® WMA was more workable and easier to compact than the HMA at a low working temperature (below 11 °C). All trials showed good workability with no compaction issues. The modulus of the Evotherm® WMA pavement (based on deflection data collected using the FWD) exceeded the stiffness values of the HMA control mix. although the difference was not statistically significant. Kvasnak (2007) also reported a series of four field trials comparing Evotherm® DAT and other WMA technologies (Astec DBG. All trials showed good workability with no compaction issues. The two sections of Evotherm® pavement have been trafficked since 2005.2. Tensile strength ratio testing carried out on field specimens also indicated that field WMA and HMA samples produced similar TSR values. Lafarge does not disclose the additive contents of the HyperTherm® chemical package. 2010 and 2011).Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members the control specimens. The results did not show any negative influence of the Evotherm® on performance. Evotherm® and Sasobit®) and a control HMA is reported in Section 6. It is also claimed that HyperTherm® can also improve coating and adhesion properties.1 HyperTherm® Background HyperTherm®. the level of surface rutting is less than 3 mm on both sections.4 (Jones et al. even at lower temperatures (i.2 7. Evotherm® is being tested on two test sites. After being subjected to more than 10 million equivalent single axle loads (ESAL). University of California Pavement Research Center The work conducted by the California Department of Transportation and the University of California Pavement Research Center to compare the workability and performance of three WMA products Advera®. Lafarge conducted laboratory tests (viscosity and other performance graded (PG) asphalt binder properties using M320-10 specifications) on a control HMA PG 58-28 asphalt mix and a PG 58-28 modified with 0. was developed by Lafarge in Canada.2% HyperTherm® by weight of binder to demonstrate the effects of the warm mix additive on the binder (or impacts of the chemical additives on workability and performance of the mixes). 7.e.2 Development Trials Prior to conducting demonstration trials.e. The additive is either pre-dosed or added in-line into the hot binder. National Center for Asphalt Technology (NCAT) Prowell. It was inferred that HyperTherm® improved workability in the mix via a mechanism other than by reducing the viscosity of the binder. produced at the plant at about 120 °C and compacted at between 75 °C and 90 °C) while the physical properties of the binder remain substantially unchanged. Both the PG 58-28 control and the PG 58-28 HyperTherm® met the required AASHTO M320-10 specifications for PG 58-28 binder. It is claimed by the manufacturer that HyperTherm® improves workability in the mix by allowing it to be produced and placed at lower than conventional hotmix temperatures (i. each of which is about 70 m long. Laboratory testing (including volumetrics and Asphalt Pavement Analyzer and TSR testing) was conducted on samples prepared using materials collected in the field. Density testing performed on cores indicated that the addition of the WMA improved compaction.1% higher than HMA). It was found that the viscosity and other PG properties were only marginally affected by the addition of the HyperTherm®.2. Rut resistance testing showed relatively poorer results for the Evotherm® specimens compared to the control. 7. Hurley and Crews (2007) reported the results of field testing of Evotherm® mixes at the NCAT Pavement Test Track at Auburn University. up to 3. a non-aqueous liquid warm mix additive. Austroads 2012 — 33 — .2. Austroads 2012 — 34 — . Field testing with a nuclear density gauge showed that compaction levels ranged between 92% and 97%.75 mm mix intended for a traffic level of 3–10 million ESAL placed to a nominal thickness of 25 mm. The results obtained on the recovered PG 58-28 were very close to that of the control. The WMA was produced at about 120 °C at the plant and compacted at between 75 °C and 90 °C. 7. the WMA had a high temperature performance grade that was about 1 °C lower than the HMA. From these results it was inferred that residual solvent was not affecting the results obtained on the binders recovered from the mixes. A site visit was made in April 2008 after the road had been in service for four months over the winter. In order to rule out the possibility that residual solvent was affecting the results obtained on the binders recovered from the mixes. By producing the mix at conventional HMA temperatures. The pavement had held up well given the deficiencies in the granular base on which it was paved. In terms of relative properties.3 Demonstration Trials A demonstration trial was conducted in Canada in 2007 to examine whether a binder modified with HyperTherm® could be used to extend the paving season by facilitating paving in cold weather (Manolis et al.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Testing of extracted and recovered binder samples was performed with Rolling Thin Film Oven (RTFO) residues and then aged in the Pressure Aging Vessel prior to being tested with the Bending Beam Rheometer. Ontario (Manolis et al. when the temperature was so cold that paving with the HMA PG 58-28 was not possible.2.0 mm sieve were outside the limits of the specification. 7. The trial was conducted during an overlay project in the City of Ottawa. The improved workability imparted by the warm mix additive counteracted the cold weather conditions. Sections of the road had a rippled appearance. The job involved the City of Ottawa’s new 4. It was found that the recovered binder from both the HMA and WMA samples had different PG properties than had been obtained when the original binder had been aged in the RTFO oven. 2008). while its low temperature performance grade was about 2 °C higher than the HMA. Some of the results for the 16. a sample of PG 58-28 was tested after being recovered with the rotary evaporator.4 Implementation/Validation Trials A trial involving HyperTherm® to extend the paving season in a cold weather application was conducted on Oxford Road 4 in the County of Oxford. 2008). The road was scheduled to be overlaid with a surface course during the 2008 season. This corresponded to reductions in mixing and compaction temperatures compared to conventional HMA using the same grade of bitumen. The two lanes that were paved have been providing access to this section of the road as well as to the truck entrance for the Toyota manufacturing facility in Oxford County since December 2007. Compliance testing against the Ontario Provincial Standard Specification 1150 was performed in the laboratory on field samples taken from the job site.2. This was attributed to the difficulty in maintaining consistent material flow due to the freezing weather conditions. compaction targets were achieved despite the low ambient air temperature and frozen granular grade. PG 58-28 modified with HyperTherm® was used as the binder. The road was paved with PG 58-28 modified with HyperTherm® during the month of December. and softening points of approximately 84 °C) was used in all the mixes. It is described as a chemical modifier formulated with a blend of surfactants and anti-stripping agents. It does not change the PG grade of the binder. 2011). The adhesive properties of Rediset® WMX may eliminate the need for separate treatments of liquid anti-strip or lime. Samples were long-term oven aged to simulate field aging.3 Demonstration Trials At the time of writing of this report. including WMA and HMS control mixes. The WMA had lower dynamic modulus values than the HMA which was in agreement with the trends identified during rutting and fatigue cracking tests. in both the base and surfacing. Plant-produced samples of HMA and WMA achieved acceptable rutting results. The WMA was 60/70 pen for 10% RAP and 80/100 pen for 40% RAP. Construction of the trial sections was conducted in October–December 2010. Acceptable moisture sensitivity results were obtained for both the HMA and the WMA.5 mm FC2 mixes composed of PG 64-28 binder (Lavarato et al. 7. Rediset® WMX comes in a pastille (i. no demonstration trials of Rediset® WMX (laboratory or field) had been reported. and about 25 °C below the average HMA compaction temperature.3. The Rediset® WMX was used in a surfacing mix and in combination with a plastomer modified binder (EVA) in two base mixes for overlays of two-lane carriageways of Durban’s Higginson Highway. It is claimed that the use of the system results in mix production temperatures being reduced by 22–33 °C and paving temperatures reduced by 39–78 °C.3. 7. For the surfacing. with the HMA achieving nominally better results when tested with the Asphalt Pavement Analyzer. 5–6 pen. An aggregate (consisting of 1% hydrated lime) and a RAP (with an average 4.4 Implementation/Validation Trials Needham (2009) reported an implementation field trial to compare the quality and performance characteristics of Rediset® WMX-WMA with conventional HMA. 7. 7. The HMA used in the base was 40/50 penetration grade bitumen for 0–10% RAP and 80/100 pen for 40% RAP to achieve acceptable recovered binder properties.3.2 Development Trials Akzo Nobel NV has reported that mixes containing its product have rutting resistance (HWTD) comparable to mixes treated with hydrated lime.3. bead) form that can be added to the binder or directly to the mixing unit at a rate of 1.5. were significantly improved in the WMA compared to the HMA.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members A WMA paving project utilising HyperTherm® WMA technology was completed on Highway 10 in Ontario with a 2500 tonne HMA control section using Superpave 12.5–2% by mass of binder. and low temperature cracking properties tested with the Thermal Stress Restrained Specimen Test and Bending Beam Rheometer. Fatigue cracking properties measured with the Four Point Bending Beam Fatigue Test.4.e.1 Rediset® WMX Background Rediset® WMX is a product developed by Akzo Nobel NV in the Netherlands.6% binder content on the coarser and fine fractions. the HMA and WMA were 60/70 penetration grade bitumen for 10% RAP and 80/100 pen for 40% RAP mixes. All the Rediset® WMX test sections (including the mixes containing 40% RAP) were successfully paved at approximately 35 °C below the average HMA manufacturing temperature. Austroads 2012 — 35 — .3 7. Follow-up work is discussed in Section 7.4% and 5. Grampré and Barreto (2009) reported a field trial conducted in France in 2005 to compare the field performance of three WMA products using low dosage of chemical additives (0.3 Demonstration Trials González-León. The use of the Rediset® WMX. since 2006. 7. Olesen and Haritonovs (2011) compared the laboratory performance of Rediset® WMX with Sasobit® and HMA in SMA.3–0.2 Development Trials At the time of writing of this report. They found that compaction temperatures could be reduced by around 30 °C for both WMA technologies without compromising mechanical properties. Laboratory performance tests (resilient modulus. 7. the WMA mixes exceeded the target modulus and rutting limits. but that the porosity of the WMA with CECABASE RT® was only slightly higher than the control.4. Some early laboratory performance test results (modulus and rutting) indicated that all the WMA mixes had a lower modulus and similar rutting than the control HMA mixes.5% paraffin wax) with HMA. in the form of additives for warm coated materials. Sasobit® provided higher resistance to deformation and improved elasticity of bitumen. CRRA maintains that the incorporation of CECA into the bitumen (2–4 kg per tonne of asphalt) enables the application temperature to be reduced to 120 °C. the use of these additives reduces energy consumption by 20–50%. which exceeded the target minimum limit of 92%. Early field performance data also indicated that all the WMA mixes have performed well against the fundamental requirement of performance being at least as equivalent as conventional HMA. These additives are very easy to use since the process simply involves their addition to the bitumen.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members All WMA and HMA sections achieved field compaction in the range of 94–97%. It was reported that the porosity of the WMA without additive was higher than the control.1 CECABASE RT® Background CECABASE RT® was developed. A total asphalt production of 300 tonnes (305 tonnes) was used to place a 50 mm thick base in four lanes (including one control and three WMA mixes).4 7. The products use the same technology as conventional paving. Performance grade 70–22 bitumen was used in both the control and WMA mixes. 0. depending on the process. the application temperature on the road surface can be reduced by about 50 °C with no effect on material performance.5% CECABASE RT®. Zaumanis. The trial demonstrated that. suggesting that the additive changes the interaction between the bitumen and the aggregates rather than the bitumen itself. dynamic creep. CECA paid special attention to avoiding reducing construction productivity. Compared to the classical paving process.4. no development trials of CECABASE RT® had been reported. in the Arkema Rhône-Alpes Research Centre (CRRA) in 2003. When designing the CECABASE RT® line. It has been marketed. in the form of the CECABASE RT® product line. At in-service temperatures. at Austroads 2012 — 36 — . When mixed with asphalt. however. at the same time retaining the same properties as paving produced at 160–180 °C. Paraffin was found to be detrimental to porosity. had only a minor effect on the binder properties. However. 7.5% CECA and 2. indirect tensile strength and rutting (MMLS)) were also performed on field samples. The additive contains surface active agents composed of at least 50% renewable raw materials.4. CRRA also claim that dust emission is also considerably reduced. South Africa. South Africa and Asia.5 7. 7. It is a Fischer-Tropsch paraffin wax.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members low percentages.2. microscopic. 2011). stick-shaped particles and are completely soluble in the binder at temperatures higher than 116 °C. The results of dynamic shear rheometer testing before and after RTFO ageing indicated that the addition of Sasobit® reduced the ageing effect of heat and air on the binder. The liquid form of Sasobit® reduces the binder viscosity. USA: laboratory evaluation Hurley and Prowell (2005a) carried out binder tests (using test protocol AASHTO MP1 2004) on various Sasobit®-modified binders and two control binders (PG 64-22 and PG 58-28).5. while having similar (or slightly higher) viscosity at the in-service pavement temperature range (< 80 °C). They solidify in asphalt between 65 °C and 115 °C into regularly distributed. Fischer-Tropsch waxes are long-chain aliphatic hydrocarbon waxes with a melting point of more than 98 °C. The test results indicated no difference in stability or flow compared to premixing with the binder.4 Implementation/Validation Trials Evaluation of CECABASE RT® is included in Phase 3 of the comprehensive Caltrans field and laboratory study already referred to in Section 5. 7. Adding more than 4% is not recommended due to the possible impact on the binder's low temperature properties. Sasobit® has been added directly onto the aggregate as solid grains or molten liquid (Hurley & Prowell 2005a). about ten road paving preparation units had successfully used these products and that 80 000 tonnes of warm paving materials had been produced using these additives. in 2006. in many commercial applications in Europe. Nevertheless.4. It was also reported by the manufacturer that. which is produced by treating hot coal with steam in the presence of a catalyst (Damm et al. 7.1 Sasobit® Background Sasobit® is a product of Sasol Wax (formerly Schümann Sasol). Laboratory evaluations of mixes produced in commercial applications have also been carried out in various countries throughout the world. An initial assessment of rutting performance showed little difference in performance between all of the WMA technologies and the HMA control. They may be used to modify a binder or added directly to the mix. The manufacturer recommends adding Sasobit® up to 3% by weight of the binder. rather than directly adding the material into the mixing chamber of an asphalt plant. This confirmed that Sasobit®-modified binders produced a lower viscosity in the production temperature range (> 110 °C). Austroads 2012 — 37 — . due to concerns related to homogeneous distribution in the mix. thus enabling production temperatures to be reduced by ~10–30 °C.2 Development Trials Brits (2004) performed Marshall testing on mixes produced by adding Sasobit® directly onto the aggregate mix as solid prills or as molten liquid via a dosing meter.5. 2002). The manufacturer also suggests blending Sasobit® into hot binder.4 (Jones et al. the CECABASE RT® additive improved workability and rheological characteristics. and an HMA control mix. However. the addition of Sasobit® generally lowered the air voids in compacted samples. rutting and fatigue resistance. No field trials were conducted. Compaction tests (using the Superpave gyratory compactor and the vibratory compactor) performed on mixes using the above binders. It was found that the modification improved the workability and the fundamental properties in terms of improved rutting and fatigue resistance and higher complex shear modulus. Thailand: laboratory evaluation Kanitpong et al. even at 20–40 °C below the compaction temperature. (2010) reported the results of a laboratory evaluation of three WMA technologies.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members A summary of the Superpave performance grade binder specification is presented in Appendix A. Reduced tensile strength and increased visual stripping were observed in both the control and Sasobit® mixes produced at 121 °C. The softening points in the SA1 and SA2 mixes were significantly higher. (2008) reported the results of an evaluation of the fundamental properties of bitumen modified with Sasobit®. (Kennedy et al. Several laboratory performance tests were also conducted to assess mix stiffness. The addition of the Sasobit® had no effect on the resistance of the asphalt mixes to moisture damage. Liping et al. a synthetic zeolite made from fly ash and manufactured through a series of procedures which mainly involve hydro-thermal synthesis at a rate of 0. The fact that the modified mixes had a greater potential to resist permanent deformation suggested that they would also have a greater resistance to densification under traffic. ductility and viscosity were lower. (This latter finding is perhaps counter-intuitive. rheological properties. rutting potential and moisture sensitivity. USA SA1 (Sasobit®). It was found that the resilient moduli of the Sasobit® mixes were not significantly different to the mixes with the same performance grade (PG) binder. The measurement of the compactability showed that less energy was required to compact the modified mixes to the desired density. The properties evaluated included viscosity. but the penetration. (2010) reported that: The softening point and ductility of the SFA mix at 10 °C was lower but the penetration and viscosity values were similar to the HMA control. The compactability of the mixes was also evaluated to determine whether they could reach the desired density at lower temperatures. compared with the corresponding control mixes. under the same compaction temperatures. 1994). however. The addition of Sasobit® generally improved the rut resistance of the mixes.3% by mass of the mix (SA1) SA2 (a WMA organic wax additive) produced by Shanghai Chenghong Road New Material Co. The HWTD tests indicated good performance of Sasobit® mixes in terms of moisture sensitivity.) Austroads 2012 — 38 — . Ltd. in terms of their possible application in road construction in China: Evotherm® surfactant (SFA) a product developed by MeadWestvaco. under different compaction temperatures (88–149 °C) also indicated that. it was suggested the reduction in the mixing and compaction temperatures could have a detrimental effect on the moisture sensitivity of the mixes. China: laboratory evaluation Liping et al. including SasolWax™ Exp 1655 (a WMA-high performance modifier designed for high RAP applications(Sasolwax 2005)). they still met HMA specification requirements. involving over more than 2 200 000 m2 of pavement. SasolWax Flex™ (a WMA-elastomer technology) in both the surfacing and base mixes. with the HMA control having a significantly lower air-void content (4% from Marshall) than the WMA mixes (4. Asia and Australasia) using Sasobit®. the United States. reported in 2005 that. D’Angelo et al. 7. a distance of approximately 3. An aggregate (consisting of 1% hydrated lime) and a RAP (with an average 4. for both the base and surfacing.5. the SFA (Evotherm®) mix was selected for the field trial.5–4. had been constructed throughout the world (South Africa.5 km. 7. the low temperature properties. The projects included a wide range of aggregate types and mix types. Sasobit® addition rates ranged from 0.4% and 5. or better than. 5–6 pen. and R&B softening points of approximately 84 °C) was used in all the mixes.4 Implementation/Validation Trials South Africa As discussed in Section 7. and NA Foamtec™ (a foamed bitumen technology developed locally by National Asphalt) in a surfacing mix and in combination with EVA modified binder in a base mix. (2008) reported a demonstration trial of Sasobit® WMA in Germany in 2007. As a result.3. There was no significant difference in rut resistance (HWTD) between the control and WMA mixes and all exceeded HMA requirements. In Europe. It was also concluded that the use of the WMA resulted in a decrease in the mixing and compaction temperatures of about 20 °C without affecting performance. There was no significant difference in the TSR of the control mix and the WMA mixes and all exceeded HMA requirements. Europe.3 Demonstration Trials The South African company.8–4% by mass of binder. Several new WMA products were also tested in this trial. fatigue cracking and wheel tracking properties compared with the conventional HMA. The SFA (Evotherm®) mix had the highest fatigue life compared with the other mixes at the same stress level at 20 °C.5% difference in the air void content of Marshall and gyratory compaction testing. over 142 projects. where the Sasobit® was introduced into the existing HMA design for the overlays of two lanes of carriageway of Durban’s Higginson Highway. including: dense-graded mixes. SMA and Gussaphalt. The air void contents of the mixes were notably different. They observed that the WMA sections had performed as well as. including WMA and HMA control mixes. the control HMA sections. South African Bitumen Association (SABITA 2011b) also reported an implementation field trial to compare the quality and performance characteristics of Sasobit® WMA with conventional HMA.4.5. Sasol Wax. It was concluded that the addition of the Sasobit® and Evotherm® slightly affected the resistance to moisture. This report was a follow-up to that prepared by Needham (2009). Rediset® WMX in a surfacing mix and in combination with a plastomer modified binder (EVA) in two base mixes. however.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members There was up to a 1. Austroads 2012 — 39 — .6% binder content on the coarser and fine fractions.6%). since 1997. where the average temperature was below 4. Laboratory rutting susceptibility tests indicated that the rutting in the Sasobit® section was not statistically different from that in the control. The job mix formula used was a 9. An unmodified PG 58-34 binder was used in the virgin mix. All the WMA test sections (including the mixes containing 40% RAP) were successfully paved at approximately 35 °C below the average control HMA manufacturing temperature.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members The HMA used in the base was 40/50 penetration grade bitumen for 0–10% RAP and 80/100 pen for 40% RAP mixes to achieve acceptable recovered binder properties. The WMA was used as an overlay for the top 38 mm (1. Field evaluation of the Sasobit® and control sections two years after construction indicated that neither permanent deformation nor moisture damage appeared to be an issue for either mix. compacted) of the surface course in the passing lane.5% by total weight of binder. Michigan. Some early laboratory performance test results (modulus and rutting) indicated that all WMA mixes produced lower modulus and similar rutting than the HMA mixes. The Sasobit® was introduced into the existing HMA design with no modifications to the mix design for the widening of the north-bound lane of State Highway 95 (M95) in Iron Mountain. Construction of the trial sections took place in October–December 2010. A basalt aggregate source was used in the mix design. Hurley et al. dynamic creep. The control section was placed in the newly-constructed adjacent travel lane. The dynamic modulus of the Sasobit® was statistically the same as the control. Early performance indicated that the Sasobit® WMA could be successfully used in cold weather climates. they exceeded the target modulus and rutting limits. However. The measured tensile strengths were higher in the Sasobit® mix. Prowell and Kvasnak (2009b) reported a field evaluation of the performance of Sasobit® in a cold weather environment. and about 25 °C below the average control HMA compaction temperature. Hurley. The HMA and WMA used in the surfacing was 60/70 penetration grade bitumen for the 10% RAP and 80/100 pen for the 40% RAP. Construction of the test sections took place in September 2006. and MMLS rutting) were also performed on field samples. the results of HWTD testing suggested that both the control and the Sasobit® test sections had the potential for both permanent deformation and moisture damage. The Sasobit® was added at a target rate of 1. Early field performance data also indicated that all the WMA mixes in these trials have performed well in terms of the fundamental requirement of performance being at least as equivalent as conventional HMA.5 mm nominal maximum aggregate size Superpave mix. A total of approximately 15 000 tons (15 240 tonnes) of WMA and HMA was used to pave a 25–30 mm thick asphalt levelling course. Laboratory moisture susceptibility testing also indicated similar performance to the control.4 °C for five months of the year. designed with a compactive effort of 86 gyrations. Laboratory performance tests (resilient modulus. The WMA test section was successfully placed at a compaction temperature 30 °C lower than the control HMA test section. indirect tensile strength. an 80 mm thick asphalt base and a 50 mm thick asphalt surfacing. which exceeded the target limit of 92% minimum.5 inches. Austroads 2012 — 40 — . All the WMA and HMA sections achieved field compaction in the range of 94–97%. The binder used in the WMA was 60/70 pen for 10% RAP and 80/100 pen for 40% RAP. However. it can also be added to polymer-modified binders. Austroads 2012 — 41 — . Two trials were conducted on the highly-trafficked Autobahn between Cologne and Frankfurt. Top-down cracking was noted on all sections. Cracks did not appear to penetrate below the top lift of asphalt on any of the sections. accelerated load. given that the binder content of this mix was significantly lower.g.6 7.6. no development or demonstration trials of Asphaltan B had been reported. Germany. 7. (2008) reported that Asphaltan B had been successfully trialled in Germany. 7. or crack density between the sections.2 Development and Demonstration Trials At the time of writing of this report. laboratory performance tests (shear and fatigue beam testing) indicated that the WMA technologies assessed would not influence rutting or fatigue cracking performance. The manufacturer describes the product as a mixture of substances based on Montan wax constituents and higher molecular weight hydrocarbons. the field results indicated that. Laboratory moisture sensitivity testing indicated that there was no significant difference in the level of moisture sensitivity between the HMA control and the mixes with additives. The manufacturer recommends adding Asphaltan B at 2 to 4% by weight of binder. Both field and laboratory tests for the Asphaltan B-WMA mixes showed similar or better performance than the conventional HMA mixes. It comprises a wax-based composition including crystal controller and adhesion promoter that adjusts the wax crystallisation and improve the low temperature properties of the binder. with no significant difference in the crack patterns.6.7 LEADCAP® LEADCAP®. Amsdorf. Evotherm® and Sasobit®) and a control HMA. under the pre-soaked condition. and full-scale field testing conducted in this extensive study has provided no results to date to suggest that the Sasobit® technology cannot be used in California or elsewhere in the USA with similar climatic conditions. there was a distinct difference in rutting performance of the Sasobit® compared to the HMA. rut resistance) of Asphaltan B appeared to be similar to that of Sasobit®. However. Jones et al. 7. the rutting resistance in the Sasobit® was higher than that in the HMA. is a relatively new product. at equilibrium moisture condition.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members University of California Pavement Research Center As already discussed. compactability. in that the HMA control rutted at a notably faster rate than the Sasobit® section.3 Implementation/Validation Trials D’Angelo et al. (2010 and 2011) reported an evaluation field trial conducted by the California Department of Transportation and the University of California Pavement Research Center to compare workability and performance of three WMA products (produced by Advera®. In terms of the Sasobit®. It can be added to the asphalt mixing plant or directly by the binder producer.6. produced by Kumho Petrochemical in Korea.1 Asphaltan B Background Asphaltan B was developed by Romonta GmbH. crack length. As already discussed. The function and expected performance improvements (e. 7. No further details are available. The laboratory. using two mixes incorporating 50/70 pen and Asphaltan B. Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Lee et al. (2011) report a laboratory study of a reference HMA mixture and WMA mixtures modified by two different wax type LEADCAP® additives. (2011) report a trial study of laboratory and field performance conducted in Portugal. Oliviera et al. Rutting performance was evaluated by the triaxial repeated load permanent deformation (TRLPD) test and the Asphalt Pavement Analyzer (APA) test. the USA and Thailand but no other details are available at this stage. fatigue cracking. whereas the KW3 mixture’s fatigue performance is worse than that of the HMA and KW6 mixtures. the moisture susceptibility results indicate that the KW6 mixture is more susceptible to moisture damage than the HMA mixture. However. In addition. Testing of field samples showed inferior performance to that of the laboratory results but that is attributed to high field air voids as a consequence of variation in grading of aggregates used in manufacture having a similar effect on both HMA and WMA mixes. This increased moisture susceptibility in the KW6 mixture is currently being addressed by modifying the KW6 additive. Japan. Austroads 2012 — 42 — . The report also refers to other trials in Korea. the HMA and KW6 mixtures exhibit approximately the same fatigue resistance. KW3 (powder) and KW6 (chip). Both the TRLPD and APA test results show that the KW3 and KW6 mixtures exhibit more resistance to rutting than the HMA mixture. Italy. The performance characteristics investigated include rutting. and moisture susceptibility. Laboratory results showed improved rutting resistance and similar fatigue and stiffness modulus properties. The development of solid sulphur pellets in the late 1990s began to overcome problems with hot liquid sulphur 5 (Strickland et al. Shell does not recommend using Thiopave® when a plant foaming attachment is active or a warm mix additive containing water is used. previous trials have been successfully conducted using 30–40% Thiopave® (Nicholls 2009). Sulphur has been used to improve asphalt performance since the 1970s. which can be added together with a workability agent (organic wax) to the asphalt mix during the mixing process to lower the mixing temperature of the sulphur-modified mix so that it can be produced as WMA.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 8 8. depending on the temperature and atmospheric conditions. Asphalt mixes using Shell Thiopave® can be placed using conventional paving equipment. store and use safely. Laboratory testing should also identify if there is a need for any type of anti-stripping additive. Shell also advises that Shell Thiopave® should not be used in mixes where a pre-blended PMB is present. 1987). Subsequently. This process can also reduce odours and fumes during production and placement.1 8.2 Development Trials The potential for sulphur to improve asphalt performance has long been recognised (Beatty et al. Shell has sponsored a field trial at the NCAT Test Track to provide field performance data for the WMA-PMB mix (Powell & Taylor 2011). In 2002. The target mixing temperature for asphalt containing Shell Thiopave® (combined with a workability agent) is 130 °C (a reduction of 20–40 °C compared to conventional HMA). Nevertheless. Recently.) and used SEAM in various road projects in Canada and the USA. Shell purchased the original patent of the sulphur-extended asphalt product (known as ‘SEAM’ patented by Rock Binders. However.1. there is a significant risk of hydrogen sulphide being emitted from the mix. Austroads 2012 — 43 — . It is noted that. They release the sulphur to combine chemically with the bitumen with the remainder (crystallising) acting as a structuring agent in the asphalt mix. They melt rapidly on contact with the heated mix (at a melting temperature of 116 °C) and are dispersed throughout the asphalt mix by aggregate shear during mixing (Deme & Kennedy 2004). The Thiopave® modified sulphur pellets can be added to the mixing chamber at ambient temperature (in most batch and drum mix plants).1 FIELD TRIALS OF COMBINED BINDER MODIFIER-ORGANIC ADDITIVE TECHNOLOGIES Shell Thiopave® Background Thiopave® is a sulphur-based product that includes patented additive technologies developed by Shell. Inc. 5 US references use the term ‘sulfur’. Shell recommends that Thiopave® (combined with a workability agent) can be used to reduce the amount of bitumen needed for road construction. However. It is compacted in the same manner as conventional mixes at an initial temperature of > 110 °C. 8. In 2008. Shell incorporated the solid sulphur pellet technology known as Shell Thiopave®. Hydrogen sulphide emissions from the asphalt mix can also occur if the mix is heated to temperatures above 140 °C.1. by replacing a proportion of the bitumen in the asphalt mix by up to 25% by mass of the bitumen. However. paving crews are advised to wear personal protection equipment as the amount of sulphur vapour can vary during production and paving. Shell reported that laboratory results have shown significant performance improvement when Shell Thiopave® was used with PMBs. it is difficult to transport. 2008). if mixing occurs above 140 °C. This therefore represents a severe test of the performance of all the WMA mixes. stability and.1. whilst the purpose of Section N6 was to compare the performance of Shell Thiopave® performance to various other material sections of the same thickness. possibly. W2 and W7) are thin wearing course mill and inlay sections constructed over an existing standard binder and base layer. and (ii) use field performance test results to perform mechanistic pavement structural designs for various pavement structures. These three sections were constructed in May 2009 and were opened to accelerated traffic without any initial curing period to allow the sulphur to crystallise. 30% sulphur-modified WMA with a design air void content of 2%. since the introduction of Shell Thiopave® into the USA.4 Implementation/Validation Trials As discussed in the previous section.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 8. Georgia. which was designed to have 4% design air voids.1.5%) was superior to that of the control HMA mix. Taylor and May (2010) performed laboratory performance evaluation studies (moisture susceptibility. This would result in reduced pavement deflection and thus reduced pavement damage caused by heavy axle load applications during warm conditions or under slow-moving traffic. (2009) and Tran. It was also noted that these modifications may ‘allow reduced pavement thicknesses. All three sections were constructed on super-elevated curves. It was concluded that ‘the primary advantages of Shell Thiopave® modified asphalt are an increase of strength. it takes some time (generally weeks) for the sulphur to crystallise and improve asphalt performance. Austroads 2012 — 44 — . Timm et al. Shell has sponsored a series of pavement testing at the NCAT Test Track to address the need to: (i) document field performance of this product. particularly at higher traffic designed pavements’. This is a severe field performance test for a thin surface lift. because it is very prone to stripping. Sections W2 and W7 were designed to test Shell Thiopave® in conjunction with a polymer. durability’.1. and 40% sulphur-modified WMA with a design air void content of 3. The performance of the sulphur-modified WMA mixes (e. mix stiffness. These two sections were constructed in July 2009 and traffic loading commenced in August 2009. meaning that the mixes will be exposed to high lateral shear stresses in addition to the normal vertical axle loading stresses. Section N5 was designed to demonstrate the performance of Shell Thiopave® as a ‘perpetual’ pavement. rutting and fatigue cracking) of sulphur-modified WMA mixes relative to the performance of a control HMA mixture prior to the field evaluation of the mixes at the NCAT Test Track. 8. The composition of the Shell Thiopave® test sections at the NCAT test track is shown in Table 8.g. A reduction in pavement thickness would only be possible using a mechanistic-based pavement thickness design method that would allow the increased stiffness of the mix at high service temperatures to be accounted for. NCAT selected the granite aggregate from Lithia Springs. including sections incorporating warm mix additives and PMB in the binder course. The other three sections (E9. Section E9 was designed to evaluate Shell Thiopave® against the standards of the WMA certification program which NCAT has developed. However.3 Demonstration Trials Nicholls (2009) reviewed test and performance data from projects where SEAM/Shell Thiopave® had been used around the world. Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Table 8. Although brittleness and crack susceptibility testing created some concern over how the WMA certification mix would perform. acceptance of Thiopave® as an alternative WMA technology in the manner in which it was used at the NCAT Pavement Test Track was recommended.75% polymer (PG 67-22) ARMAZ LOF. laboratory performance and field performance. 6500 liquid E9 Akzo Nobel Redicote E-6 liquid W2 63 mm remaining of existing experimental surface mix Akzo Nobel Redicote E-6 liquid W7 38 mm – 2% air void design 40% Shell Thiopave® mix + 63 mm remaining of existing experimental surface mix 0. 6500 liquid N6 32 mm – 4% air void design (PG 76-22) 38 mm – 3. The opposite trend was observed in the laboratory. This was indicative of no differences in durability.1: Composition of Shell Thiopave® asphalt test sections at NCAT test track Section N5 Wearing course 32 mm – 4% air void design (PG 76-22) Binder course 121 mm – 3.5% air void design 40% Shell Thiopave® mix (PG 67-22) 63 mm remaining of existing experimental surface mix Basecourse 76 mm – 2% air void design.5% air void design 40% Shell Thiopave® mix (PG 67-22) 70 mm – 3. 30% Shell Thiopave® mix (PG 67-22) 38 mm – 3. Although slightly more rutting was observed in the WMA certification section. No cracking was observed in the WMA section.75% polymer (PG 67-22) Akzo Nobel Redicote E-6 liquid Powell and Taylor (2011) reported the following conclusions from the study comparing mix produced using Thiopave® WMA technology to a conventional HMA control mix: No significant problems were encountered producing either mix.5% air void design. 30% Shell Thiopave® mix (PG 67-22) 76 mm – 2% air void design 30% Shell Thiopave® mix (PG 67-22) 152 mm of upper base (PG 76-22) 228 mm lower base (PG 67-22) 152 mm of upper base (PG 76-22) 228 mm lower base (PG 67-22) 152 mm of upper base (PG 76-22) 228 mm lower base (PG 67-22) Anti-strip (all layers) ARMAZ LOF. The HMA control section exhibited minor longitudinal cracking after approximately 2. The surface roughness increased more in the HMA control section that it did in the WMA certification section. Based on a comprehensive assessment of construction.5% air void design. Change in surface macrotexture as a function of traffic was virtually identical for both mixes. Austroads 2012 — 45 — . a rich spot near the end of the HMA section was an indication that the design gradation was subject to segregation during placement. the HMA control section was the only one that actually cracked. High densities were measured in both experimental pavements. which was supported by inspection of the field cores. 30% Shell Thiopave® mix + 0.9 million ESALs. the rutting in both mixes was less than 6 mm. indirect tensile modulus) were performed on the WMA. Technical issues addressed included: compaction temperature and mix volumetrics in situ compacted density resilient modulus rut resistance. road agencies and industry were asked to submit details of any trials (development. demonstration.1. 9. however. Sasobit® trials in the Gold Coast by the Department of Transport and Main Roads (TMR) in 2006 and Sasobit® trials in Sydney by the then Roads and Traffic Authority. The current performance of the pavements has yet to be reported. Queensland.1 9. A small number of demonstration trials of WMA technologies have been established in Australia since 2000.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 9 FIELD TRIALS IN AUSTRALIA AND NEW ZEALAND At the commencement of the project. that a demonstration trial of the Astec Double Barrel® Green (water-based foaming) WMA technology was being conducted as part of TMR’s $1. were constructed using various combinations of WMA and RAP (0% and 15%) and an HMA control section (50 mm polymer modified binder surfacing DG14HS and 270 mm Class 600 bitumen base DG 20HM). Apparent viscosity testing was conducted on cores extracted in November 2008. validation/implementation as defined in Section 3. The mix was Council Type 3 (DG18) with multigrade binder and CECABASE RT® and Aspha-Min® additives.2 Department of Transport and Main Roads (TMR) Queensland It was reported in a series of personal communications (including a PowerPoint presentation to the AAPA/TMR Strategic Alliance Reference Group in May 2010). It was concluded that the Aspha-Min® WMA technology could be successfully implemented with minor modifications to the asphalt plant. 120 Gyratory cycles. Clayfield. Brisbane in 2008. Typical trials are the CECABASE and Aspha-Min® trials in Brisbane.2). (RTA) 6 (Figueroa.95B upgrade of the Ipswich Motorway between Dinmore and Goodna.1 Australia Brisbane City Council Brisbane City Council reported that two sections of WMA (one with Aspha-Min® and the other with CECABASE RT®) were laid at Park Avenue. 9. Four trial sites. The results showed that the binder was aged more by the HMA process than the WMA process. This was an example of the use of a foaming technology using water-bearing additives (Section 6. The results of the resilient modulus testing suggested that there was little difference between the HMA and the WMA. Various laboratory tests (resilient modulus 32 °C. Each site was 100 m long and involved 100 tonnes of asphalt. some of the trial sections were affected by the Queensland floods in early 2011. by Brisbane City Council in 2008. Marshall. These sites will be overlaid with another layer of dense-graded asphalt prior to the completion of the project in 2012. It was found that adequate compaction could be achieved with WMA produced at 140 °C using the Astec Double Barrel® Green technology.1).1. each 200 m long. 6 The Roads and Traffic Authority became Roads and Maritime Services (RMS) during the course of this project. A control section of conventional HMA was also constructed. Austroads 2012 — 46 — . Unfortunately. Hennessy & Hiley 2007). Cores were taken from each layer immediately before the next layer was paved. It was found that: compaction was achieved in all layers despite the very low temperatures on one of the levels the manufacture of the asphalt was achieved at the right temperatures and delivered on site with no problems there were no problems with the workability of the asphalt despite the low temperatures the temperatures of the asphalt as-placed were kept to a minimum. Where an additive is proposed. rather. warm mix additives have been used in many asphalt patching and overlay works on the RMS road network. Warm mix additives were used in certain situations because of the need to increase workability and when long haulage distances were involved. The mix design registration process requires the contractor to nominate all constituents (including additives such as WMA additives) as part of their mix design submission. It should be noted that these mixes were not produced as WMA. For example. as a competitive alternative to HMA). including one at Hope Island Road. Current situation Since the trial reported in Figueroa. TMR will continue to collaborate with asphalt suppliers to trial other WMA technologies as opportunities arise under a permissive arrangement (i. The total amount of asphalt laid was approximately 100 tonnes. typically the contractor and TMR would undertake an evaluation of the mix properties and field performance as part of the registration process. Thermocouples were inserted into the various layers of asphalt by the RMS to measure temperature profiles. The Sasobit® was added via the RAP belt using a modified hopper at a rate of 2 kg of per minute.3 Roads and Maritime Services (RMS) NSW Figueroa.e. giving an end Sasobit® content of approximately 1. Hennessy and Hiley (2007) Figueroa. Hennessy and Hiley (2007). Austroads 2012 — 47 — . 9. each 63 m long (two AC20 60 mm thick layers and two AC14 45 mm thick layers). The AC20 and AC14 asphalt mixes were manufactured and maintained at 130 °C and 140 °C respectively. The main objective of the trial was to lay four layers of asphalt. they were produced at conventional asphalt mix temperature with the warm mix additives. Sasobit® is now included in a significant number of registered mix designs. TMR has made provision for the permissive use of WMA under its technical standard for dense-graded and open-graded asphalt (Department of Transport and Main Roads 2009). and the influence of the additive on asphalt mix performance is not known to TMR. The temperature of the mixes upon arrival at the site varied between 127 °C and 137 °C. Hennessy and Hiley (2007) reported a deep patch trial using Sasobit® conducted in August 2006 at Woodville Road (between Oxford and Guildford Roads).Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members TMR has also undertaken a number of demonstration trials using Sasobit® since 2006. etc.1. Both the WMA and HMA control sections exhibited similar performance.5% in Class 450 binder. in one shift without running the risk of rutting in the wearing surface. Department of Planning. AC14 and AC20. were manufactured and placed at lower temperatures using the foaming technology method. In terms of DPTI specifications: any additive to be used has to be approved by the superintendent the design of mixes with an additive must obtain the target air voids as specified by DPTI the placement temperature is lower than that required by AS2150. The asphalt was manufactured at a batch plant using an Astec foaming module attached to the bitumen line.4 A 500 m long WMA trial was undertaken by Boral Asphalt on Gallipoli Drive.1. the maximum percentage by mass of the total mix must not exceed 0. Numerous other projects have been constructed using Sasobit® to achieve the lower production and/or placement temperatures under a variety of traffic conditions. the maximum percentage by mass of binder must not exceed 2. including AC10. The road was newly constructed and the pavement was not trafficked immediately upon completion. nominate the maximum percentage by mass of binder for water (either directly added or added in the form of water containing crystals). Transport and Infrastructure (DPTI).5 Trial 1 This was the first detailed formal field trial of WMA technology in Victoria. Relevant clauses in their specifications are: WMA additive – the proportion of additive is limited to: — — — for wax.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members The RMS has no preference for a particular WMA. DPTI assume that the performance of WMA is equivalent to that of HMA.1. 9.06%. Laboratory testing of the WMA mix had been undertaken some years earlier to demonstrate that the laboratory properties of HMA and WAM foam asphalt were comparable. All the asphalt layers. South Australia 9. Austroads 2012 — 48 — . Caroline Springs date of placement – February 2009 type of WMA (no RAP) – WAM-foam® method site allows for direct comparison of HMA and WMA testing undertaken is similar to that outlined in the draft WMA protocol additional field samples have been taken after two years of service data is not currently available. Further details are as follows: VicRoads Surfacing WMA trials location of project – Western Freeway/Deer Park Bypass.0% for surfactants. 9. pavement strength and skid resistance (SCRIM)). The double handling results in a significant loss in temperature. In addition. As well as the environmental issues. Anecdotal reports are that conforming levels of compaction can be achieved that were not previously achieved without Sasobit. fatigue and field performance (roughness. Western Ring Rd date of completion – June 2012 WMA used in all asphalt layers including open-graded asphalt surface site allows for direct comparison of HMA and WMA testing undertaken is similar to that outlined in the draft WMA protocol. Mulgrave date of placement – March 2009 type of WMA with 20% RAP – water foaming method site allows for direct comparison of HMA and WMA testing undertaken is similar to that outlined in the draft WMA protocol additional field samples have been taken after two years of service data is not currently available.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Trial 2 General details are as follows: location of project – Princess Hwy East.1. including the City of Melbourne. its engineering properties are being taken advantage of. Deep strength WMA trials Trial 3 location of project – M80. Austroads 2012 — 49 — . placed 16 000 tonnes of WMA foam for various municipalities in the Melbourne metropolitan area.5% (the standard rate for dense-graded asphalt) at hot temperatures to achieve better compaction outcomes for the wearing course when the mix is transported large distances (up to and exceeding 600 km) and then doubled handled from a road train to a small truck for paving. rutting. Trial 4 location of project – Nagambie Bypass. which uses the Shell WAM-foam® technology.6 Main Roads Western Australia (MRWA) There has been limited use of Sasobit® over the last seven or eight years. Nagambie date of completion – December 2012 WMA used in all asphalt layers at the intersection and thin WMA layer used over a granular pavement site allows for direct comparison of HMA and WMA testing includes modulus. between February 2008 and June 2011 Citywide. The use of Sasobit® by MRWA is twofold: Initially dosing at 1. and after an international fact-finding tour. 9. 9. MRWA’s main concerns with the product are the security of supply of Sasobit®. however.10 Industry In addition to the cooperative trials reported in the previous sub-sections.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Dosing Intermediate course mix for mill and fill works where 250 mm and more of asphalt is placed in one shift and then opened to traffic. in 2005. some field trials are planned. One company currently uses Sasobit® (generally 1. 9.1. MRWA were not involved in this contract. One company is currently commissioning a new asphalt plant which will allow the production of WMA by foaming the bitumen in the plant. but may in the future when more is learnt about the process and products. The product has been placed on arterial and minor roads and also on airport taxiways in New Zealand. DIER is not aware of any applications or have any involvement. Details of these trials are. Fulton Hogan began assessing warm mix and half-warm mix technologies available around the world.1. Moisture sensitivity in Sasobit®-WMA can be an issue if plant operators rush the drying of aggregates. and the use of Sasobit® in other than a batch plant. industry has conducted a large number of development and demonstration trials. Energy and Resources (DIER) Tasmania Whilst it is possible that WMA is being used in applications in Tasmania.1. particularly in Victoria and NSW. however.8 Department of Infrastructure. not available.1. TAMS has not encouraged or allowed the use of these types of additives on more heavily-trafficked roads. TAMS has encouraged this innovation and amended its specification to accommodate this technology. Industry has also used Sasobit® in open-graded asphalt during the construction of a full depth asphalt pavement during the winter for an alliance contract.1 New Zealand Hayward and Pidwerbesky Hayward and Pidwerbesky (2009) reported that. especially in drum plants. Austroads 2012 — 50 — . Some field trials of full depth foamed WMA (including RAP) are planned for 2012. 9. 9. MRWA has published specifications for the use of Sasobit®-WMA as wearing and intermediate courses. selected the low emissions asphalt (LEA1) process to implement in the company’s New Zealand asphalt plants. DCI have not conducted any studies but visual inspection definitely suggests ‘harder’ asphalt on the ground.9 Department of Territory and Municipal Services (TAMS) ACT There was some use of Sasobit® several winters ago on minor residential roads but without any reduction in mix temperature.7 Northern Territory Department of Transport (DOT) Currently the NT DOT are not conducting any WMA projects or trials. This has successfully been achieved using PMB and Sasobit. Local government use has been limited to date.5–2%) in their HMA mixes to ensure they meet DCI voids requirements of 7% (larger window for compaction) and to ensure that good wheel tracking results are met.2 9. Performance was similar to HMA.2. Following laboratory development and early pilot trials. Austroads 2012 — 51 — . December 2007 (Christchurch City Council) Montreal Street. A smaller trial involving 38 tonnes of CoolPave with 30% RAP was also conducted on Taxiway F. 515 tonnes (2745 m2) was laid. Christchurch International Airport (CIAL) has a rolling 20-year program which makes it possible to consider paving opportunities that take advantage of opportunities to trial innovations. The use of RAP reduces the amount of virgin binder required. and the same mix design but manufactured using the LEA process (called CoolPave with LEA in New Zealand). As a result. a larger trial.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members The temperature differential compared to traditional HMA resulted in measured fuel reductions of up to 45%. Hayward and Pidwerbesky (2009) reported that the product had a range of other benefits compared to HMA including: more than 50% reduction in production emissions and more than 90% reduction in smoking and fuming during application with minimal to no odour the mix could be placed in colder temperatures and carted further improved longitudinal joints and surface appearance the potential to extend pavement life due to reduced thin film heating of the binder and oxidation during the manufacturing process. making it a highly energy efficient asphalt. Fulton Hogan had produced CoolPave in five of its 14 fixed plants. Performance to that time (2009) had been satisfactory. Plants without RAP rings produce CoolPave at about 105 °C. although plants with baghouse extraction systems often need to be mixed at 115 °C to ensure that there is no moisture in the exhaust gases. February 2008 (CIAL). Christchurch. Cores were taken in August 2008 (four months after construction). resulting in less cost and less fuel being used. Christchurch. but after 10 000 passes the rut depths were similar. The Montreal Street site was constructed in two sections: an AC14 mix manufactured using the conventional HMA process. Typical production temperatures are 95 °C for plants with RAP rings (where a portion of the aggregate stream is added in a damp state through the RAP ring). all of which were continuous drum plants. In addition to the reduction in fuel. the performance was consistent with the first trial. Subsequent testing and inspections of the trial showed that the mix was as stable and as strong as the standard HMA used normally on the airfield. to that time. Fulton Hogan laid 141 tonnes (598 m2) to a depth of 110 mm on one taxiway in February 2008. It was found that the AC14 HMA initially had a higher rate of rut development compared with the CoolPave. Handling the CoolPave was easier and much safer for the paving team than the standard HMA product with no blue smoke and much lower temperatures. the following implementation sites were commissioned: Buckley’s Road. March/April 2008. involving an overlay of another taxiway commenced in February 2009. For this trial. One of the innovations submitted to CIAL for approval was a trial of CoolPave on the airfield taxiway. Fuel savings of 44% were measured when producing at 95 °C compared to the traditional HMA produced at 165 °C at the same plant. (Christchurch City Council) Christchurch International Airport Taxiway. and subjected to laboratory wheel tracking testing. The results of this trial were being assessed at the time the paper was published. It was reported that. At that stage (2009). Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 9. A typical WMA process would. and typical values calculated for the energy needed to produce a tonne of mix. while the LEA could give around double this figure. It was concluded that. if universally adopted throughout New Zealand. but adoption of this process may not be financially justifiable for some asphalt producers. result in an annual reduction of CO2 equivalent emissions of approximately 4700 tonnes. It was also suggested that the lower manufacturing temperatures would result in reduced emissions of CO2 and other organic gases. The low energy asphalt (LEA) process would roughly double this. laying and rolling of asphalt. As measured data were not available for all processes. These indicated that many processes had the potential to give heating energy savings of the order of 20%. The situation with the hot emulsion-based process was not clear. Consequently no recommendation covering all cases could be made. transport. but it was likely that the energy savings at reduced temperatures were negated by the energy expended in manufacturing the emulsion. it was necessary to use calculated figures. The environmental advantages due to reduced fuel consumption would need to be balanced against the costs of the additives and modifying the plant and the varying maturity of the different technologies. Austroads 2012 — 52 — . This placed an upper limit on the proportion of energy expended that can be saved by adopting a WMA manufacturing process.2 Ball Ball (2010) provided details of four WMA technologies. No field trials were reported.2. the surfactant and wax technologies may produce somewhat better savings than this. Published results for fuel and electricity consumption of the HMA process indicated that the energy expended in heating the aggregate and bitumen (approximately 277 MJ/tonne of mix) was about 44% of the total energy involved in production. at that stage in the development of the WMA technologies none appeared to be especially suited to New Zealand conditions. because of the costs associated with the necessary plant refurbishments. As described in Section 3 to Section 9. stiffness) of a WMA mix were found to be inferior to that of the HMA mix. Most of the trials of WMA technologies conducted in the USA appeared to show improvements in quality and efficiency of construction (i. Consequently. rut resistance and durability of WMA products can be more adequately addressed. Subsequently. Subsequently. They have been used in road trials involving overlays with high RAP content mixes and severe construction conditions (construction in cold/wet environments). Evotherm® and Utrafoam GX®). It was also noted that the WMA mixes had a higher resistance to moisture damage with aging (using test protocol AASHTO R30-02. and a comparison with HMA. a large amount of demonstration and validation trials of WMA technologies have been established in the USA. it was noted that some binders foamed readily while others did not foam much at all. For the foam-WMA technology. Some laboratories in the USA have produced foamed asphalt mixes in the laboratory that mirror conditions in the field prior to large-scale production and construction. At the same time. improved compaction and more consistent field density). However.1 Laboratory and Field Trials of WMA Technologies As discussed in Section 3 to Section 9. many demonstration and validation trials in the USA will be monitored over the longer term in order that concerns regarding moisture susceptibility. 10.e. Sasobit®. 41 State Departments of Transportation have developed their own permissive specifications that allow contractors to substitute WMA for HMA on state road projects. in most cases the performance of the WMA exceeded the minimum laboratory performance thresholds and at times was equal or superior to that of HMA. 2010). These laboratory studies have generally shown that the WMA can be more susceptible to moisture damage than the HMA.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 10 10. particularly when comparing the laboratory performance of WMA and HMA. improved workability. laboratory testing of conditioned/aged WMA samples has been adopted for determining binder aging effects. Studies have also indicated that the short-term field performance of WMA mixes has been comparable to HMA mixes. there are now at least 21 registered WMA technologies in the USA compared to only three in 2005. However. particularly for WMA technologies involving the use of chemical and organic additives that can be easily replicated in laboratory and easily incorporated in field construction with minor plant modification.1 ON-GOING STUDIES AND IMPLEMENTATION OF WMA PRACTICES On-going Studies and Implementation of WMA Practices in USA As described in Section 3 to Section 9. Austroads 2012 — 53 — .g. compared to 15 States in 2007. chemical and mineral additives have been successfully produced in the laboratory. moisture susceptibility and rutting resistance testing conducted in the laboratory (obtained from field production) indicated that some WMA technologies have similar rutting properties to HMA but a higher moisture susceptibility than HMA. possibly due to the incomplete drying of the aggregate and the lower binder grade at lower WMA production temperatures. have been successfully conducted using the AASHTO laboratory testing protocols for HMA at NCAT (Hurley & Prowell 2005a and b. Kvasnak et al.1. 2002) and that the aged WMA had similar properties to an HMA. rutting. previous demonstration and validation trials of foam-WMA technologies have been limited to specific binders that are known to foam well. there is concern that some WMA technologies (such as foam-WAM) are difficult to re-create in the laboratory. Whilst some cases of laboratory performance (e. WMA mixes incorporating wax. Typical laboratory assessments of various WMA technologies (Aspha-Min®. Demonstration trials of WMA technologies are now being conducted in 45 States. Rediset® WMX. 2007). and (4) provide relative emissions measurement of WMA technologies compared to conventional HMA technologies. to validate laboratory characterisation methods for WMA mixes for design purposes (Prowell et al. NCHRP Project 9-43 – Phase II (Mix Design Practices for Warm Mix Asphalt). The objectives of this project are to: (1) develop relationships between the engineering properties of WMA binders and mixes and field performance. 10. NCAT has also established a national WMA Certification Program consisting of both field and laboratory performance evaluations to assist with the WMA evaluation and approval process (Section 10. The objectives of this project are to: (1) recommend modifications to the preliminary WMA mix design and analysis procedure under development.1. and (2) develop guidelines for identifying and limiting moisture susceptibility in WMA pavements. For example. (3) compare production and laydown practices and costs between WMA and HMA pavements (including necessary plant adjustments to optimise plant operations when producing WMA). 2010).1. It is also noted that the FHWA Office of Pavement Technology has activated a Mobile Asphalt Mixture Testing Laboratory (MAT) to advance WMA research and validation through material sampling and performance testing. Double Barrel® Green. Evotherm® and Sasobit®). A similar HVS testing program is planned for the Davis test track at UCPRC. heavy vehicles were used on the NCAT test track to test several sections. (2) determine relative measures of the performance between WMA and HMA pavements.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members There have also been several full-scale accelerated pavement trials to compare field performance of WMA with HMA. The objectives of this research are to: (1) assess whether WMA technologies adversely affect the moisture susceptibility of flexible pavements. and Sasobit®) (Jones et al. 2010 and 2011). They include the following. (2) develop a protocol for the laboratory evaluation of WMA performance. including two rubberised gap graded (RHMA-G) control sections and seven WMA technologies (Advera® WMA.2). there are several NCHRP on-going projects that are expected to impact on the future direction of the use of WMA in the USA. Ultrafoam GX®. Caltrans and UCPRC have also used the HVS to traffic a dense-graded HMA control and three WMA technologies (Advera® WMA. and moisture sensitivity (Jones et al. Evotherm®. Those studies will also include laboratory testing of specimens removed from the test pavements. NCHRP Project is now complete with the publication of NCHRP Report No 691 (Bonaquist 2011a and b). and (4) prepare an updated emissions measurement protocol. (3) develop guidelines for WMA production and construction. including Evotherm®. Austroads 2012 — 54 — .2 National Studies of WMA Technologies NCHRP projects Currently. The MAT has been on site at many of the WMA projects across the country. to assess rutting. Jones et al. 2008. CECABASE RT®. and the monitoring of pavements constructed with a range of different mixes on State highways (Jones et al. NCHRP 09-49 – Performance of WMA Technologies: Stage I – Moisture Susceptibility. NCHRP 09-47A – Phase II (Properties and Performance of Warm Mix Asphalt Technologies. fatigue performance. 2008). and the laboratory performance of the WMA versus the control HMA. stiffness. the section will be trafficked and the laboratory testing will be conducted. The last three months of the project will consist of final pavement evaluations and the preparation of a final report. which can result when a WMA technology is not a good match for the selected project or the contractor views the demonstration as more of an inconvenience than an opportunity. etc. Testing will also be conducted on HMA control sections in order that laboratory and field performance can be compared. The evaluation will span 18 months. NCAT will certify a WMA technology if its overall results are at least as good as the control HMA. and bond strength in accordance with the priorities indicated by the States in the national survey. cracking. then NCAT will recommend modifications to improve the performance of the WMA technology. and constructing test sections. Trucks will be used to apply five million ESAL in one year. an interim report will be submitted to the WMA technology provider within the first nine months of project initiation summarising the mix design program. roughness. If the WMA technology does not perform as well as the HMA control. rutting potential. Improved competition from newly-approved WMA technologies can only serve to drive down the cost of pavement construction and maintenance using a mechanism that is leveraged by States’ support of the NCAT Pavement Test Track but funded by the private sector. The WMA Certification Program has been carefully designed to provide States with an assurance that questionable technologies will not earn certification without the risk of demonstration projects on the open infrastructure. laboratory tests will be conducted on plant-produced material to evaluate the mixes for moisture susceptibility.) will be monitored. Following a rigorous laboratory design and verification process. a Superpave mix design is being used for the Certification Program using an aggregate with a history of stripping. ravelling. Concurrently.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members NCAT warm mix asphalt certification program Based on the results of a national survey. As susceptibility to moisture damage ranks high on the list of States’ concerns with WMA technology evaluation. The final report will include pavement performance information. It consists of both field and laboratory performance evaluations to assist States with the WMA evaluation and approval process. it will provide WMA technology providers with an assurance of a fair evaluation without the risk of poor construction quality. Austroads 2012 — 55 — . test section construction. Performance under traffic and over time (e. rutting. The first three months will consist of the development of a mix design with the WMA technology.g. the NCAT established a national WMA Certification Program at its Pavement Test Track in 2010 (National Center for Asphalt Technology 2010). obtaining materials. During the next 12 months. In addition to informal quarterly progress reports. Favourable comparisons will result in the issuing of an acknowledgment certificate and the addition of the WMA technology to a certified list that will be maintained on the NCAT website. laboratory test results. and comparisons of both the laboratory and field performance of the WMA versus the control HMA. cracking resistance. The national scope of the NCAT WMA Certification Program also means that technology providers no longer have to support a new demonstration project in every State market. surface mix will be produced and placed on the NCAT Pavement Test Track and on test sections supported by robust perpetual foundations to ensure that the observed distress is not the result of structural inadequacies. The binder content is selected and rut resistance and moisture damage susceptibility evaluated at standard elevated temperatures without the WMA. Contractors will be allowed to select from a list of DOT-approved WMA technologies.3 Implementation of WMA Practice in the USA Given that there are still lingering questions that are focused primarily on the compatibility of WMA technologies with different binder types. Each project will include an HMA test section (minimum 1000 tons) to allow comparison with the WMA.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 10. In terms of specific guidance.1. This is carried out without introducing WMA additives or simulating any WMA process modifications such as foaming. This has led some binder suppliers being concerned about their ‘downstream liability’ with respect to certificates of compliance and modifications at the plant with WMA additives or foaming processes. New York State DOT (NYSDOT) is embarking on a large-scale WMA evaluation program involving 24 experimental projects over the next two years. they expect to use a ‘data driven’ approach to making future decisions about the use of WMA in the State. different States in the USA have taken different approaches to the implementation of WMA technologies in terms of current HMA practices. This protocol will be discussed in a future report when recommendations are made regarding required amendments to the current draft protocol adopted in Australia. Current HMA practices adopted by the Texas DOT include: (i) laboratory evaluation of a traditional HMA mix during the mix design phase. they evaluate the contractor’s submitted HMA mixture at hot temperatures. These agencies do not necessarily evaluate the WMA mixtures in the laboratory but. for example. introduce additives and lower plant temperatures to produce WMA for the job. Texas DOT can fully evaluate mixes prior to and during production. and (iii) contractor’s requirement to produce a 50-ton trial batch. and their long-term properties associated with moisture damage susceptibility. rut resistance and durability. it is stated in AASHTO R 26-01 (2005) that ‘if any modification…is made at the HMA plant. Texas DOT allowed more than 1 million tons of WMA to be placed in 2010. Prior to production. the HMA is sampled again and tested using the HWTD (at least once). Florida DOT is monitoring the properties of the WMA mixes produced and placed on their projects. the HMA producer shall be the supplier and must provide the certification’. which is sampled and tested at the start of the project. By applying the identical procedures for HMA mixes to WMA mixes. (ii) routine evaluation of rutting and moisture susceptibility of all HMA mixes using the HWTD – a minimum of three times over the course of a project. both the HMA and WMA mixes must be tested for rut resistance and moisture sensitivity and the results submitted to NYSDOT. DOT approves the project to move on to full production. The contractor is then allowed to switch on the water-injection system. Florida DOT. rather. WMA test specimens must be made from plant-produced mix if the laboratory preparation process does not simulate the production process. Florida’s permissive specification allows WMA to be used at the contractor’s option after normal HMA mix design and evaluation. These requirements allow the exact HMA mix to be produced during the project to be evaluated. After an evaluation of the mix properties and performance (HWTD). A growing number of State DOTs have adopted permissive specifications that allow contractors to substitute WMA for HMA. During full production. NYSDOT has recently developed a WMA evaluation protocol which has been adopted by the entire north-east region of the USA (approximately 12 states). had placed 300 000+ tons of WMA on 26 projects by July 2010. Austroads 2012 — 56 — . One of these projects ‘development of materials/design and construction technology-sustainable and environmental pavement’ commenced in 2005. chemical packs or foamed asphalt have so far not gained significant market share as they do not appear to offer adequate economic benefit. 10. On-going field performance will be monitored by annual inspection over a period of five years. 1999.3M. Their share of the total market is relatively small (estimated at 5–8%) but steadily growing. an increase in traffic volumes and the need to develop a low-carbon policy highlighted the need for an urgent review of the design. The budget for the project. the failure of several pavements. WMA or rather ‘viscosity reduced mixes’ are being used in Germany (Damm 2011). In terms of the WMA component of the program. and an organic additive (Sasobit™®).1 On-going Studies and Implementation Practices in Asia Korea: Development of WMA Production and Construction Methods National research into the performance of asphalt pavements in Korea commenced in April. materials and construction technology associated with asphalt pavements (Park 2012). the main objectives are to: implement WMA into road technology in Korea following an evaluation of its properties develop practical processes through field trials develop production and placement processes of foamed WMA pavements develop a standard specification for WMA pavements. Parallel to the growth in the use of WMA is utilisation of reclaimed asphalt pavement (RAP) in road construction.2 On-going Studies and Implementation Practices in Europe After a number of minor trials. Austroads 2012 — 57 — . Wax based modifiers are mainly used.3. 2011). a major trial of the Astec Double Barrel® Green WMA was placed in Sweden in 2010 and 2011 (Ulmgren. high-technology pavement construction and control technology. and procedures to contribute to a high quality. research into asphalt pavements had a very low priority compared to other fields of civil engineering.4m. especially in adverse weather conditions. Lundberg & Lundqvist 2011). The research is being led by the Korea Institute of Construction Technology (KICT).3 10. The main aim is to develop environmentally friendly road pavements. at that time. The main trigger to the adoption of such products is enhanced deformation resistance and workability. The laboratory work was focused on three WMA technologies: water foaming. 10. a chemical additive (Evotherm®). being conducted over five years. However. however.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members It is also noted that a National WMA Technical Working Group has been formed by NAPA and FHWA. Other technologies such as zeolites. cost-effective asphalt pavement system.9m and private industry US$7. of which the Government (Ministry of Land and Transportation (MLTA) and the Korea National Highway Corporation) is providing US$9. practices. Research conducted at the Pennsylvania Transportation Institute for Pennsylvania DOT has been used to develop guidelines for using high percentages of RAP in WMA (Solaimanian et al. is US$17. However. 13 private companies and 13 universities are also involved. Three major research projects are currently being conducted in Korea. This research indicated that it was possible to produce WMA with high RAP having sufficient moisture damage and rutting but that particular attention needed to be paid to those aspects in the mix design. Its mission is to evaluate and validate WMA technologies and to implement WMA policies. most DOTs undertook initial trialling of WMA on low-trafficked roads before trialling the technology on roads subject to higher traffic volumes. In the USA. In this study. 10. As discussed in Section 3. It is recommended that current NCHRP projects be monitored and their outputs examined in terms of any possible application to practice in Australia.4 Implementation of WMA Practices in Australia The successful outcome of a large number of field trials of WMA technologies throughout the world suggests that WMA may eventually be considered as a standard specified option for all pavement classes once contractors and asset owners gain confidence with the long term performance of WMA. Austroads 2012 — 58 — . There are several NCHRP projects (e.g. 10.e.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Jeong et al. 10. The revised Protocol will recommend what laboratory testing should be conducted depending on the complexity. one of the major tasks being undertaken during this project is the conduct of a validation trial of a range of WMA and HMA pavements in order that their performance can be compared.1 Proposed Further Studies to Implement WMA Practices in Australia The successful outcomes of a large number of field trials of WMA technologies throughout the world suggest that WMA should be considered as a standard specified option for all pavement classes. (2010) have recently reported the second part of the project. following this review it appears that little or no revision is needed to the current draft Protocol. It is likely that specific WMA technologies will be driven by the asphalt contracting sector under a permissive specification arrangement. and aims. and validation/implementation trial. It is anticipated that the validation study being conducted in Melbourne as part of this project will demonstrate that the performance of WMA is at least equivalent to that of HMA and that the use of WMA technologies will grow quite rapidly as a result. validation sites were constructed and opened to traffic. some simply approve the contractor to use the WMA technology. the list of approved WMA technologies has been growing quite rapidly over the last three years based on laboratory performance testing and supported by validation trials. three stages of field trials of various WMA technologies have been reported in the literature: development trial. i. However.4. In the USA. The results have yet to be reported. Emphasis should be placed on projects concerned with the relationship between long-term field performance and moisture susceptibility. However.4. One issue that may need to be addressed is the possible impact of the introduction of a carbon tax on the widespread use of WMA in Australia. not all US States work with ‘approved lists’. the list of approved WMA technologies has been growing quite rapidly over the last three years based on laboratory performance testing.2. demonstration trial. validation trials and observed field performance. NCHRP Project 9-47 and NCHRP Project 9-49) that are on-going and expected to impact the future direction of WMA use in the USA. The need for any revisions to the draft WMA Evaluation Protocol will be discussed in the reports on the field trial and the associated laboratory testing. including an extensive laboratory testing program. in terms of the conduct of field trials. of a particular field trial. the aim of which was to evaluate the production and placement of WMA mixes developed during the first part of the project. It would be anticipated that many SRAs in Australia would adopt a similar approach.2 Revisions to WMA Protocol As already discussed. However. different aggregate drying temperatures (which may affect bitumen-aggregate bonding and moisture susceptibility). additives/processes used to manufacture the mix and plant modifications required for these technologies). for each trial will depend on the technologies developed (i.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members 11 CONCLUSIONS This report presents a review of field trials of WMA technologies conducted in various countries in the world. improved compaction and more consistent field density). the asphalt producer’s marketing strategy and the road agency’s implementation strategy.g. only about 30% of the documents sourced provided sufficient information to allow a meaningful review to be conducted.e. Many of the documents sourced presented details of what were clearly ‘development’ trials. Europe. of these.g. The scope. and to improve the quality and efficiency of construction (i. The major application has been overlays using high RAP content mixes and severe construction conditions (e. demonstration and validation/implementation. verification criteria. where there was either no control HMA section involved and/or a lack of data relating to mix type. performance data. They use different additive contents (which may affect the WMA mechanical properties). different maximum bitumen temperatures (which may affect long-term asphalt durability and performance) and different requirements in terms of plant modifications (which may affect cost. improved workability. climate. investigative method. A large number of demonstration or validation trials of WMA technologies have been established in the USA to demonstrate the benefits of WMA technology compared to HMA. However. South Africa. At the time of completing this report (May 2012). The review identified three types of field trials of a WMA technology: development. Canada. etc. foam technologies using water injection nozzles) and emulsion to reduce the amount of water added to the system in order to address the concern of moisture susceptibility issues associated with the use of the water-based WMA products. pavement structure. There are now 23 registered WMA technologies in the USA (as compared to only three in 2005) and 45 States are conducting demonstration trials of WMA technologies (compared to 15 States in 2007). etc. Asia. construction in cold/wet environments). Austroads 2012 — 59 — . There have also been further developments and improvements in the WMA technologies using water (e. production efficiency and product consistency). more than 160 documents had been identified in a literature search of WMA technologies reporting field trials of some form or another in the USA.e. New Zealand and Australia. applied traffic. Commercially-available WMA technologies were identified and grouped into six main categories: — — — — — — sequential aggregate coating and binder foaming techniques binder foaming using water-based mechanical systems binder foaming using water-bearing additives chemical additives organic additives combined chemical-organic additives. with the emphasis on performance differences between WMA and conventional HMA and the identification of field performance data that could be used to complement the Austroads WMA evaluation field trials for Australian road conditions. in the case of Sasobit®. there is no immediate need for an accelerated pavement test in Australia. are TMR and RMS. the ability of WMA to provide enough radiant energy to heat the reclaimed asphalt component in mixes containing RAP. however. details of these trials are often sketchy and little or no material has been published.g. rut resistance and durability) associated with lowering WMA production temperatures (including higher moisture sensitivity due to aggregates that are not adequately dried) and altering of the binder performance grade (when chemical and organic additives are used to produce WMA mixes). should focus on moisture susceptibility. Future laboratory studies. the potential for increased moisture susceptibility when utilising WMA processes that involve the use of water. Evotherm®. whilst it is clear that industry has established a large number of trials. and Sasobit®). if deemed necessary. These trials have demonstrated that most WMA technologies associated with chemical and organic additives can successfully be implemented with minor modifications to the asphalt plant and. The amount of published material relating to demonstration or validation trials in Australia is extremely limited. the work being conducted at NCAT and UCPRC has suggested that the performance of WMA pavements is at least equivalent to that of HMA. the use of some WMA technologies has already been accepted by some Australian road agencies. and the monitoring of field performance. In view of this. and the general lack of information regarding the long term performance of new asphalt mix designs (e. with high RAP content or rubber asphalt). there is still some concern regarding long-term performance (e. successful paving could still occur at low temperatures.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members It also appears that WMA technologies associated with water-bearing. Despite the successful outcomes of the large number of field trials in the USA. Some of the trials also address various concerns regarding the use of WMA. rut resistance and durability. Double Barrel® Green. Alabama. and the monitoring of pavements constructed with a range of different mixes on State highways. The only two SRAs that appear to have been involved in WMA trials. Several asphalt producers and road agencies have collaboratively conducted accelerated loading studies of the comparative performance of WMA and HMA technologies under accelerated heavy loading. Similarly. Those studies will also include laboratory testing of specimens removed from the test pavements. moisture susceptibility. including detailed (within-pavement) response-to-load data. the construction of test pavements. Extensive laboratory studies of both field and laboratory samples were also carried out in order that the relative performance of WMA with HMA could be compared with recommendations made regarding the implementation of WMA into current HMA mix design procedures. Despite the lack of published information. Rediset® WMX. It is noted. NSW. These trials have involved the production of the mixes. the effects of chemical additives on the long term performance of the binder. Ultrafoam GX®. however. chemical and organic additives have received more consideration compared to WMA technologies using water-based mechanical systems. Examples include the work at the National Center for Asphalt Technology (NCAT) in Auburn. in terms of published outputs. including incomplete drying of the aggregate (especially with absorptive limestones). CECABASE RT®.g. presumably mainly for local government applications. and the work at the University of California Pavement Research Center (UCPRC) using the Heavy Vehicle Simulator (HVS). Austroads 2012 — 60 — . that UCPRC is planning a follow-up test program of rubberised gap graded control sections and seven WMA technologies (Advera® WMA. although other SRAs such as VicRoads are cooperating in trials being conducted by industry. Hurley & Frank 2012). NYSDOT has also recently developed a WMA evaluation protocol which has been adopted by the entire north-east region of the USA (approximately 12 states). of a particular field trial. and aims. it is clear that the current provisions for the laboratory testing program in the draft protocol are too demanding. The emissions testing framework updates are based on the recently completed emissions and fuel measurement work conducted as part of the NCHRP Project 9-47A. The FHWA and NAPA are currently updating the first three documents following consensus being recently agreed regarding test procedures. for example. The revised protocol will need to address what laboratory testing should be conducted depending on the complexity. evaluation protocols and test section requirements. However. In terms of the draft WMA Evaluation Protocol. if for no other reason that it is impossible to conduct the amount of testing demanded in the draft protocol in the time available. Austroads 2012 — 61 — . a Material Test Framework for WMA Trials has been adopted by the US National Asphalt Pavement Association (NAPA) and the FHWA (Prowell.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Valuation protocols of WMA technologies involving the use of field trials have been established in the USA to maximise the benefits of validation trials. The recommended construction specification updates are based on the recently-completed WMA mix design work conducted as part of NCHRP Project 9-43. An emissions testing framework and draft WMA construction specification has also been uploaded onto this site. following the review of other field trials it appears that no revisions are needed to the current draft protocol in terms of the conduct of field/validation trials. One issue that may need to be addressed is the possible impact of the introduction of a carbon tax on the widespread use of WMA in Australia. D & Peterson. MO. 2011. 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Wu. USA. International Society of Asphalt Pavements (ISAP). Louis. Standard method of test for determining the fatigue life of compacted hot-mix asphalt (HMA) subjected to repeated flexural bending. Standard method of test for Hamburg wheel-track testing of compacted hot-mix asphalt (HMA). Zaumanis. J. Xiao. 2011. Standard recommended practice for certifying suppliers of performance-graded asphalt binders. nd 2 . K 2011 ‘Combining warm mix asphalt technologies with mixtures containing reclaimed asphalt pavement’. Taylor. MO. NF EN 13036-5:2006. Austroads 2012 — 69 — . Road and airfield surface characteristics: test methods: part 5: determination of longitudinal unevenness indices.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members European Standards NF EN 13036-1:2010. Road and airfield surface characteristics: test methods: part 1: measurement of pavement surface macrotexture depth using a volumetric patch technique. oCd Dynamic Shear. TP 5: G*/sinδ . ASTM D 4402:b Maximum. the dynamic shear test is run on all three simulated binder ages. RTFO residue (simulated short-term aging) and PAV residue (simulated long-term aging) in order to fully characterize the asphalt binder throughout its life. Maximum.00 46 52 58 64 PRESSURE AGING VESSEL RESIDUE (PP 1) PAV Aging Temperature. TP 1 Determine the critical cracking temperature as described in PP 42 Direct Tension. Tests are run on the original binder (no simulated aging). C Dynamic Shear. TP 5:c G*/sinδf. Minimum (oC) Viscosity. The following items may help to decipher this table: The top several rows (all the rows above the ‘original binder’ row) are used to designate the desired PG grade. the same tests are run. PG 58-22) just determines the temperature at which the tests are run. oCa Performance graded asphalt binder specifications PG 46 PG 64 PG 52 PG 58 34 40 46 10 16 22 28 34 40 46 16 22 28 34 40 10 16 22 28 34 40 < 46 < 52 < 58 < 64 -34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 ORIGINAL BINDER Flash Point Temp. percent Dynamic Shear. Maximum. 5000 kPa Test Temp @ 10 rad/s.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members APPENDIX A SUPERPAVE PERFORMANCE GRADE ASPHALT BINDER SPECIFICATION: SUMMARY The table below is the standard summary table presented in the AASHTO MP 1 specification for performance graded asphalt binder. The temperatures directly under the ‘< 58’ cell are selected based on the minimum pavement design temperature in °C. Minimum. T 48. TP 5: G*/sinδf. Table A 1: Performance Grade Average 7-day Maximum Pavement Design Temperature.20 kPa Test Temp @ 10 rad/s. TP 3 Determine the critical cracking temperature as described in PP 42 e 90 10 7 4 90 25 22 19 16 13 10 7 100 100 25 22 19 16 13 31 28 25 22 19 16 Report -24 -30 -36 0 -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 -6 -12 -18 -24 -30 Austroads 2012 — 70 — . Notice that often the same test is run on different simulated binder ages. The PG specification (e. Test Temp.00 kPa Test Temp @ 10 rad/s. Minimum. 1. oC o 230 135 46 52 58 64 ROLLING THIN FILM OVEN RESIDUE (T 240) Mass Loss. No matter what the desired PG binder specification.g. oC f 1. oC Physical Hardening Creep Stiffness. oCa Minimum Pavement Design Temperature. 2. if the average 7-day maximum pavement design temperature is greater than 52 °C but less than 58 °C then you should use the ‘< 58’ column. For instance. 3 Pa*s. For instance. TP 5: o d 100 (110) 100 (110) 100 (110) G*sinδf. except the conditioning time is extended to 24 hours ± 10 minutes at 10 °C above the minimum performance temperature. The PAV aging temperature is based on simulated climatic conditions and is one of three temperatures 90 °C. Austroads 2012 — 71 — . The tests run on the binder are listed in the left-hand column. or by following the procedures as outlined in MP 2 and PP 28.Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members Performance Grade Average 7-day Maximum Pavement Design Temperature. except in desert climates. TP 5:c G*/sinδf. G*/sinδ = high temperature stiffness and G*/sinδ = intermediate temperature stiffness. 1. oC Dynamic Shear. 7 AASHTO T48-06–2006. TP 3 Determine the critical cracking temperature as described in PP 42 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31 28 Report 0 0 -6 -12 -18 -24 -30 -6 -12 -18 -24 -30 0 0 -6 -12 -18 -24 -6 -12 -18 -24 0 0 -6 -12 -18 -24 -6 -12 -18 -24 a b c d e f Pavement temperatures are estimated from air temperatures using an algorithm contained in the LTPP Bind program. TP 1 Determine the critical cracking temperature as described in PP 42 Direct Tension. Test Temp. The PAV aging temperature is 100 °C for PG 58. Maximum. where it is 110 °C. TP 5: G*/sinδf. ‘Flash Point Temp. (1994). C Dynamic Shear. The 24-hour stiffness and m – value are reported for information purposes only. Physical hardening – TP 1 is performed on a set of asphalt beams according to Section 12. ASTM D 4402:b Maximum. oC 1. measurement of the viscosity of the original asphalt binder may be used to supplement dynamic shear measurements of G*/sinδ at test temperatures where the asphalt is a Newtonian fluid. Minimum ( C) Viscosity. 90 °C or 110 °C.20 kPa Test Temp @ 10 rad/s. For instance.and above. 5000 kPa Test Temp @ 10 rad/s. Maximum.00 kPa Test Temp @ 10 rad/s. Standard method of test for flash and fire points by Cleveland open cup. oCa Minimum Pavement Design Temperature. They are not necessarily listed by their common names but the applicable AASHTO test procedure is listed. 3 Pa*s. oC o 230 135 70 76 82 ROLLING THIN FILM OVEN RESIDUE (T 240) Mass Loss. 2. T 48. Minimum (°C)’ means that the flash point is measured according to AASHTO T 48-06 and that the value in the adjacent column represents the minimum allowable in degrees Centigrade. percent Dynamic Shear. For quality control of unmodified asphalt binder production. T 48 7. Source: Kennedy et al. Minimum. This requirement may be waived at the discretion of the specifying agency if the supplier warrants that the asphalt binder can be adequately pumped and mixed at temperatures that meet all applicable safety standards.00 70 76 82 PRESSURE AGING VESSEL RESIDUE (PP 1) PAV Aging Temperature. oC Physical Hardeninge Creep Stiffness. may be provided by the specifying agency. Minimum. C o a PG 70 PG 76 PG 82 10 16 22 28 34 40 10 16 22 28 34 10 16 22 28 34 < 70 < 76 < 82 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34 ORIGINAL BINDER Flash Point Temp. . hotmix asphalt. 76. laboratory. demonstration trial.INFORMATION RETRIEVAL Austroads. Sydney. state-of-the-art review. validation/implementation trial Abstract: This report presents a review of field trials of WMA technologies conducted in various countries in the world. A number of recommendations are made as a result of the review. 2012. AP-T215-12 Keywords: warm mix asphalt. with the emphasis on performance differences between WMA and conventional HMA and the identification of field performance data that could be used to complement the Austroads WMA evaluation field trials for Australian road conditions. A4. development trial. Review of Overseas Trials of Warm Mix Asphalt Pavements and Current Usage by Austroads Members.