NIT Surathkal Terrabind Review

EXPERIMENTAL INVESTIGATION ON BLACKCOTTON SOIL TREATED WITH TERRABIND CHEMICAL AND FLY ASH by VIJETHA R.V Register No.: 11TS27F THESIS SUBMITTED FOR THE AWARD OF THE DEGREE OF MASTER OF TECHNOLOGY in TRANSPORTATION SYSTEM ENGINEERING DEPARTMENT OF CIVIL ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY KARNATAKA SURATHKAL, P.O. SRINIVASNAGAR - 575 025 MANGALORE, INDIA JULY 2013 National Institute of Technology Karnataka, Surathkal DECLARATION by the M.Tech Student I hereby declare that the Report of the P.G. Project Work entitled “EXPERIMENTAL INVESTIGATION ON BLACK COTTON SOIL TREATED WITH TERRABIND CHEMICAL AND FLY ASH” which is being submitted to the National Institute of Technology Karnataka Surathkal, in partial fulfilment of the requirements for the award of the Degree of Master of Technology in the Department of Civil Engineering, is a bonafide report of the work carried out by me. The material contained in this Report has not been submitted to any University or Institution for the award of any degree. 11TS27F VIJETHA R.V (Register Number, Name & Signature of the Student) Department of Civil Engineering Place: NITK, SURATHKAL Date: ACKNOWLEDGEMENT I avail myself of this opportunity to express my gratitude and regards for Dr. A. U. Ravi Shankar, Professor, Department of Civil Engineering, who has been both the inspiration and the instrument for the success of the entire project. I thank him for his able and timely guidance throughout. It gives me great pleasure to acknowledge Ms. Lekha B.M, Phd Scholar, Department of Civil Engineering, who has supported and guided me at every stage of the project. I also express my extreme gratitude towards Mr. Samir Das Gupta, Terra Nova Technologies, for providing, Terrabind chemical for my present study. I am deeply indebted to all the faculty members of the Department of civil engineering for their knowledgeable advice and encouragement throughout the course of the study. I sincerely acknowledge the valuable help rendered by Mr. Sadhanand and Mr. Yatish and all other non-teaching staff of the Department of Civil Engineering, NITK. Finally, I would like to thank my family and friends for their support. It would have been impossible for me to accomplish this study without their support. Vijetha R.V specific gravity. Hence. Destructive results caused by this soil have been reported in many countries. Swelling of soil stabilized with Terrabind and fly ash (FA) has reduced by 100%. Triaxial compression test has been determined for untreated and treated soil. Swelling properties have been determined by conducting free swell index test and swell pressure test. Chemical stabilization is one of the effective methods that can be used to stabilize these soils. consistency limits have been determined and engineering properties like MDD. From the experimental results it was observed that consistency limits and dry density improved marginally. Durability of the soil is studied by conducting wet-dry cycle test and freeze. OMC. laboratory studies has been carried-out to investigate the influence of chemical called Terrabind on BC soil and further the influence on BC when Terrabind is added in combination with fly ash (FA) is investigated. . Fatigue test has been conducted to determine the fatigue life of untreated and treated BC soil. There have been many methods available for controlling the expansive nature of black cotton soil. Percentage weight loss was less than 14% for 12th cycle of freezethaw. Further chemical analysis was conducted to determine the chemical composition of untreated and treated soil. Black cotton soil abundantly found in Gadag district of North Karnataka. Basic geotechnical properties like grain size distribution. are susceptible to detrimental volumetric changes.thaw cycle test. Unconfined compressive strength. with changes in moisture. . Soil stabilized with Terrabind and FA has showed better results compared to soil stabilized with Terrabind. which shows that the stabilized soil has become durable. in the present work.ABSTRACT Black cotton soil (BC) is one among the problematic soil that has a high potential for shrinking or swelling due to change in moisture content. CBR. unconfined compressive strength and unsoaked CBR has increased enormously. Swelling has reduced to a great extent. Soaked CBR has not increased much. 5 PRINCIPLES OF SOIL STABILIZATION 4 1.6.4 STABILIZATION TECHNIQUES 14 .8 OBJECTIVES OF PRESENT INVESTIGATION 9 1.1The science behind reacting clay soil with Terrabind 6 1.4 USES OF STABILIZATION 4 1.6 STABILIZATION USING TERRABIND CHEMICAL 5 1.0 LITERATURE REVIEW 10 11 2.2 Terrabind and Fly Ash (FA) 7 1.7 NEED OF PRESENT INVESTIGATION 9 1.6.3 Terrabind chemical constituents 7 1.1 GENERAL 11 2.3 BLACK COTTON SOIL 13 2.CONTENTS Declaration Certificate Acknowledgement Abstract Contents List of figures List of tables List of Abbreviations 1.2 ROLE OF SUBGRADE 2 1.1 GENERAL 1 1.0 INTRODUCTION 1 1.3 SOIL STABILIZATION 3 1.6.9 SCOPE OF WORK 2.2 IDENTIFICATION AND CLASSIFICATION OF SWELLING SOILS 11 2. 8 DURABILITY STUDIES 25 2.2.1 Mechanical stabilization 14 2.2.5.2 pH OF SOIL BY ELECTROMETRIC METHOD 27 3.5.1 GENERAL 3.2 Quick Lime/Hydrated Lime 17 2.3 CONDUCTIVITY OF SOIL BY ELECTROMETRIC METHOD 28 3.6 REVIEWS ON RESEARCH FINDINGS ON STABILIZATION OF SOIL USING TRADITIONAL ADMIXTURES 19 2.3 Fly ash 18 2.4 SILICA CONTENT IN SOIL BY GRAVIMETRIC METHOD 29 3.5.8 Ca AND Mg OXIDE IN SOIL BY TITRIMETRIC METHOD 33 3.5 IRON OXIDE (Fe2O3) IN SOIL BY COLORIMETRIC METHOD 30 3.7 REVIEWS ON RESEARCH FINDINGS ON STABILIZATION OF SOIL USING NON TRADITIONAL ADMIXTURES 22 2.1 GENERAL 37 4.6 R2O3 (Al2O3 + Fe2O3) IN SOIL BY GRAVIMETRIC METHOD 31 3.4.1 Portland Cement 17 2.9 SUMMARY 26 3.5 TYPES OF STABILIZERS 17 2.0 CHEMICAL ANALYSIS 3.1.0 MATERIALS AND METHODOLOGY 37 4.2 Chemical stabilization 15 2.1SOIL SPECIMEN 27 27 27 3.2 MATERIALS USED 37 4.7 CHLORIDE CONTENT IN SOIL BY ARGENTOMETRIC METHOD 32 3.9 CHEMICAL ANALYSIS RESULTS ON UNTREATED AND TREATED SOIL 36 4.1 Soil 37 .4. 4 Class C Fly ash 38 4.9 Swell pressure 45 4.3.4.3.2.9 Fatigue 61 .2 Compaction test results 53 5.11 Fatigue test 45 47 5.3.4 Compaction tests 41 4.10 Durability 4.3.6 Free swell index 58 5.3 Application of Terrabind to BC Soil 38 4.7 Swell pressure 58 5.7 Triaxial compression test 43 4.3.2 TESTS ON BASIC PROPERTIES OF BLACK COTTON SOIL 50 5.8 Free swell index 44 4.3.3.3 TESTS CONDUCTED ON SOIL 40 4.2 Grain size analysis test 40 4.5 Unconfined Compression Test 42 4.1 Specific Gravity test 40 4.2.2.3.3.3.2.4 CBR test results 56 5.3 RESULTS OF TESTS PERFORMED ON BC SOIL TREATED WITH TERRABIND CHEMICAL AND TERRABIND+ FLY 51 5.3.3 Consistency limits test 40 4.3.3.3 Unconfined compression test results 54 5.1 Plasticity Characteristics 51 5.3.2.3.3.5 Terrabind dosage 39 4.3.5 Triaxial test 57 5.1 GENERAL 50 5.3.3.2 Terrabind 38 4.0 RESULTS AND DISCUSSIONS 50 5.8 Durability 59 5.6 California Bearing Ratio Test 42 4. 4: variation of maximum dry density of treated soil for different curing 54 5.7: Variation of Soaked CBR of treated soil for different curing period 57 5.6: Triaxial compression testing setup 44 4.9: Samples prepared for freeze-thaw & wet-dry cycle test 47 4.5: Determination of CBR 43 4.10: Schematic Diagram of Accelerated Fatigue Load Test Set-up 48 5.1: Black cotton soil 37 4.6.8: Samples prepared for freeze-thaw & wet-dry cycle test 47 4.5: Variation of UCS of treated soil for different curing period 55 5.2: Casagrande apparatus for determination of liquid limit 41 4.0 CONCLUSIONS 63 6.3: Samples prepared for the determination of plastic limit 41 4.3: variation of Plasticity index of treated soil for different curing period 53 5.7: Free swell index setup 45 4.1: variation of liquid limit of treated soil for different curing period 52 5.8: Graphical representation of freeze-thaw cycles for untreated and treated BC soil 61 .4: UCS Samples 42 4.2: variation of Plastic limit of treated soil for different curing period 53 5.1: Distribution of black cotton soil in India 14 4.6: Variation of Unsoaked CBR of treated soil for different curing period 57 5.1 SCOPE FOR FUTURE STUDIES REFERENCES 65 66 LIST OF FIGURES Fig No. Description Page No 2. 9: Freeze and thaw test results of untreated and treated BC soil 60 5.1 Physical properties of Terrabind 8 2.10: Fatigue test results of untreated BC soil 61 5.7: FSI test results of untreated and treated soil for different curing period 58 5.2: Variation of LL.6: Triaxial test results of untreated and treated soil for different curing periods 58 5.12: Fatigue test results of soil treated with Terrabind and Fly ash 62 . PL and PI of untreated and treated soil 52 5.3: MDD and OMC of untreated and treated soil for different curing period 54 5.1 Classification of swelling soils as per (IS: 1498) 13 3.1: Results of basic soil properties of untreated black cotton soil 50 5. Description Page No 1.LIST OF TABLES Table No.4: UCS results of untreated and treated soil for different curing period 55 5.8: Swell pressure test results of untreated and treated BC soil 59 5.1: Physical properties of FA 39 5.11: Fatigue test results of soil treated with Terrabind 62 5.5: CBR test results of untreated and treated soil for different curing period 56 5.1: Chemical composition of untreated and treated BC soil 36 4. transport systems are among the various factors affecting the quality of life. about 65% of freight and 80% passenger traffic is carried by the roads. The growth of the population has created a need for better and economical vehicular operation which requires good highways having proper geometric design. rail. and water. in India. Average growth of the number of vehicles has been around 10. (Chen 1975). convenience and safety are provided to the travelling public. embankments. Hence roadways are the lifeline of our country and the development of road infrastructure has played a very important role in faster development of the Indian economy. 1 . as per the National Highways Authority of India. Problematic soil such as expansive soil is normally encountered in foundation engineering designs for highways. About 33% of villages in India still do not have all-weather road and remains cut-off during monsoon.CHAPTER 1 INTRODUCTION 1. air. lack of transportation infrastructure and regulatory controls are jointly impacting economic development. pavement condition and maintenance. Mobility is provided by the transportation infrastructure and this has a huge impact on the development and welfare of the population. backfills etc. Expansive soil are normally found in semi-arid regions of tropical and moderate climate zones and are abundant. like road. Moreover. Rural areas have very poor access. In several countries.6 million vehicles). where the annual evaporation exceeds the precipitation and can be found anywhere in the world. retaining walls. The highways have to be maintained so that comfort. Hence only roads are considered in this project.1 GENERAL Mobility is fundamental to economic and social activities of any country. in many countries road networks cater to the majority of transportation needs. though only about 2% of the road network is covered by these roads. For example. Though there are several modes of transport. The National Highways carry about 40% of total road traffic.16% per annum over recent years (The Automobile industry in India is rapidly growing with an annual production of over 2. The Pavement structure consists of a relatively thin wearing surface constructed over a base course and a sub-base course. and permanency of strength. Destructive results caused by this type of soil have been reported in many countries. national and state highways in the North Karnataka are facing problem due to early distress in the pavement due to the poor strength of soil under wet condition. Hence. Sub-grade is the major component of a pavement. it is necessary to have a proper diagnostic study of the soil to be used as sub grade. 1. A sub grade performance generally depends on two interrelated characteristics: Load bearing capacity: The sub grade should be capable of withstanding oncoming loads. ease and permanency of compaction. The performance of the pavement is dependent on the type and properties of the sub-grade soil. which rests upon an in-situ sub-grade. 2 . A sub grade that can support a high amount of loading without excessive deformation is considered good.2 ROLE OF SUB GRADE The Sub-grade refers to the in-situ soil on which the stresses from the overlying roadway will be distributed. and soil type. Rural roads. The Sub-base or Sub-base course and the base or base course materials are stress distributing layer components of a pavement structure. Various techniques are used for stabilization of sub-grade soil. economical flexible pavement structures requires sub-grade materials with good engineering properties. moisture content.Expansive soil is one among the problematic soil that has a high potential for shrinking or swelling due to change of moisture content. The sub-grade should possess desirable properties to extend the service life of the roadway section and to reduce the required thickness of the flexible pavement structure. The wearing surface is primarily asphalt/concrete. drainage. These desirable properties include strength. The properties of all the pavement structure layers are considered in the design of the flexible pavement system. They notified that the construction of long lasting. This load bearing capacity is often affected by degree of compaction. Volume changes: Soil may undergo volume change when exposed to excessive moisture or freezing conditions. A cement material or a chemical is added to a natural soil for the purpose of stabilization. Hence. chemical or biological method or any combination of such methods employed to improve certain properties of natural soil to make it serve adequately for an intended engineering purpose. In other words. improve construction techniques to achieve economy in construction cost. the search for new materials and improved techniques to process the local materials for better performance has received an increased impetus. the best option is to modify the properties of the soil so that it 3 . The process may include the blending of soil to achieve a desired gradation or mixing of commercially available additives that may alter the gradation. stabilization includes compaction. Some clay soil shrink and swell depending upon their moisture content. Commonly used materials are fast depleting and this has led to an increase in the cost of construction.3 SOIL STABILIZATION Stabilization is the process of blending and mixing materials with a soil to improve certain properties of the soil. The different uses of soil pose different requirements of mechanical strength and resistance to environmental forces. controlling method to be used for the stabilization. while soil with excessive fines may be susceptible to frost heave in freezing areas. There is an urgent need to identify new materials. The decreasing availability and increasing cost of construction materials and uncertain economic climates force engineers to consider more economical methods for building roads. Soil stabilization is the collective term used to denote any physical. or act as a binder for cementation of the soil. drainage and many other such processes. When poor quality soil is available at the construction site. 1. the most common application being in the construction of road and air-field pavements. texture or plasticity. where the main objective is to increase the strength or stabilization of soil and to reduce the construction cost by making best use of locally available materials. Stabilization is being used for a variety of engineering works. preconsolidation. 1. In wet weather. These types of soil quality improvement are referred to as soil modification. 2. reduction of plasticity index or swelling potential. and increases in durability and strength. Thickness reduction: The strength and stiffness of a soil layer can be improved through the use of additives to permit a reduction in design thickness of the stabilized material compared with an unstabilized or unbound material. have also been used. The design thickness strength. Soil improvement by mechanical or chemical means is widely adopted. Since the nature and properties of natural soil vary widely. stabilization may also be used to provide a working platform for construction operations. a number of chemical additives. stability. Each layer must resist shearing. and durability requirements of a base or sub base course can be reduced if further analysis indicates suitability. the ability of that layer to distribute the load over a greater area is generally increased so that a reduction in the required thickness of the soil and surface layers may be permitted. In order to stabilize soil for improving strength and durability. 4 . Quality Improvement: The most common improvements achieved through stabilization include better soil gradation. an appropriate stabilization technique has to be adopted for a particular situation after considering the soil properties. This has led to the development of soil stabilization techniques. Densification of soil by decreasing the air voids.5 PRINCIPLES OF SOIL STABILIZATION The principles of soil stabilization are: 1. both inorganic and organic. As the quality of a soil layer is increased. avoid excessive deflections that cause fatigue cracking within the layer or in overlying layers.4 USES OF STABILIZATION Pavement design is based on the premise that minimum specified structural quality will be achieved for each layer of material in the pavement system. Increasing the compaction using well graded soil mass. and prevent excessive permanent deformation through densification.meets the pavement design requirements. 1. Effective utilization of locally available soil and other suitable stabilizing agents.150%. The process of soil stabilization is useful in the following applications. Reducing the adsorbed water layer of clay particle to achieve maximum compaction. The reaction of Terrabind with clay soil creates a permanent reaction in the molecular structure of clay soil particles rendering reduced swell potential. load bearing) of soil and crushed macadam road base designs by 25% .3. greater compaction. Increasing the bearing capacity of foundation soil. 5. 1. Improving the durability and life span of the structures under adverse moisture and stress conditions. Controlling the grading of soil and aggregates in the construction of bases and Sub bases of the highway and airfields. Improving the natural ground for the construction of highways and airfields. 4. Increasing the shear strength of soil. Reducing the permeability of soil. Designing the soil mix for intended stability and durability values. 1. 6. The needs for soil stabilization in the present scenario are 1. 3. 5 . Environment friendly procedures to encourage the use of industrial wastages to reduce the cost of construction of roads. 3. Limited financial resources make it difficult to provide a complete network road network system using conventional method of construction. 2. cohesion. 4. Terrabind will improve engineering properties (compaction.6 STABILIZATION USING TERRABIND CHEMICAL The need to replace clay soil in the embankment/ sub grade layer is eliminated/ reduced with Terrabind treatment. 2. load bearing and soil particle cohesiveness. Terrabind alters the very molecular structure thus the characteristics of the soil clatter permanently. World over. road developers can reduce pavement thickness. Terrabind breaks down the capillary action of soil particles thus reducing the moisture retentive nature of most expansive soil. Terrabind attacks the clay lattice of the soil which alters the ionic charge in clay and creates a chemical bond between the clay particles. 4.1 The science behind reacting clay soil with Terrabind 1. More effective than lime in high sulphate soil (lime reaction in such soil leads to volume expansion leading 6 . thereby increasing particulate attraction and decreasing voids resulting in increased material density and hardness while maintaining flexibility. lower initial construction costs. The interaction of its components activates and binds the naturally occurring mineral cements in soil together to form a material analogous to most sedimentary rocks. this stabilization technology has proved its capability. 2. Lower life cycle costs and minimize human error while increasing road base strength and durability when compared to their planned design mix.Conventional soil stabilization techniques involve chemicals molecules attaching to clay soil grains. However. Terra Nova technologies manufactures the same technology in India at a lower cost. these chemicals molecules get washed away with rising ground water.6. 6. improve logistical efficiency. 5. 1. Terrabind reduces shrink and swell by forming a chemical and physical bond between the clay particles that resist water absorption. This allows the moisture content of the soil to stabilize which reduces the movement of the soil. Terrabind distributes the mineral ions evenly throughout the mixture. With terrabind. 3. greater layer density and reduced voids. This results in reduced shrink and swell of soil particles. Lignins provide the required tensile and compressive strength for trees to grow vertically without being drawn to the ground. Terrabind formulation consists of a proprietary combination of lignosulphonates (that contain calcium hydroxide) and organic lignins that allow for polymeric binding between soil grains.6. 3. 2.6.2 Terrabind and Fly Ash (FA) Terrabind in combination with Fly ash is highly recommended for use in combination with Terrabind. The process of mechanical mixing of the electrolyte emulsion and lignins in Terrabind and with soil activates aluminosilicates present in soil that catalyses the absorption of mineral ions resulting in strong polymeric binding. The electrolyte emulsion also stabilizes the moisture level resulting in reduced soil particle movement. 1. Break down capillary action responsible for water retention (swell/shrink). 7 . Alter the ionic exchange responsible for water attraction in soil molecules. Electrolyte emulsion: The electrolyte emulsion attacks the clay lattice of soil by altering the ionic charge in clay and breaking down the capillary action of clay soil particles thus reducing the ability for soil particles to attract and retain moisture. Activate aluminosilicates within soil to increase particle binding and layer density.1. The science behind Terrabind’s formulation focuses on creating three primary changes in soil molecules. 5%-10% fly ash (Class C) by weight of soil is an ideal range. Lignins and lignosulphonates: Lignin is the active chemical compound responsible for binding cells and fibres in trees and plants. Terrabind has a catalyst effect when combined in clay soil with fly ash.3 Terrabind chemical constituents Terrabind is an advanced proprietary electrolyte lignin emulsion and a highly concentrated liquid chemical. 1. the properties of emulsions allows for greater workability of the materials with lesser moisture thus resulting in a more uniform mix and greater absorption of cementitous components with soil molecules. Additionally.1 shows the physical properties of Terrabind chemical.sulfurous Color Dark Amber Toxicity See Cautions Wetting Ability Excellent Detergency None Foaming None Emulsification None Phosphates None Storage 2 Years Cold Stability Excellent Flash Point None Boiling Point 182 degrees C Solubility in Water Complete Specific Gravity 1. 8 .7 Ph 1 Weight per gallon 14. Table 1. Table1.1 Physical properties of Terrabind Description Properties Form Liquid Odor Sharp.The addition of cementitous binders (lime/fly ash/cement) with Terrabind treatment of soil further strengthens soil because Terabind catalyses the activation of aluminosilicates in soil along with the calcium hydroxide present in cementitous binders.19 lb. stabilization is a must to prevent destruction of structures built on it. Terrabind is one such chemical manufactured by Terra Nova technologies for the first time in India. and bitumen) which require large amounts of stabilizers to stabilize soil thus leading to higher costs. polymers and so on as soil stabilizers due to expansion in manufacturing capacity. terrabind is used to stabilize this soil to prove its capability. Limited laboratory experiments are performed to determine if these products improve the material properties of soil and if they offers superior mechanical properties compared to other types of stabilization for which comprehensive laboratory and field performance already exists. Although there are variety of chemicals available in the market. Thus we need to investigate the stabilization mechanism of some of the commercially available chemical based products to better understand their potential value for road construction. ammonium chloride. this stabilization technology has proved its capability.7 NEED OF PRESENT INVESTIGATION In recent years. low cost. laboratory investigation has been conducted by stabilizing the soil with Terrabind chemical. The process has not been subjected to a rigorous technical investigation and is presently carried out using empirical guidelines based on experience. The liquid limit and plasticity index are very high (>50 and >30 respectively) and to improve these properties.8 OBJECTIVES OF PRESENT INVESTIGATION The investigation is carried out on black cotton soil (expansive soil). Since black cotton soil is one of the problematic soils.1. Portland cement. This soil is having very poor geotechnical properties. 1. World over. which is a major type of soil available in Northern Karnataka. It becomes therefore important to perform a research study that can give required scientific support to the use of Terrabind as soil stabilizer. only limited research has been performed on effectiveness of use of these 9 . potassium compounds. enzymes. and relatively wide applicability compared to standard stabilizers (hydrated lime. In order to overcome the high shrinkage and swelling properties of this soil. more attention has been given to the use of various non-traditional chemicals such as sulfonated oils. Swell pressure test and free swell index test is conducted on treated and untreated soil to determine the improvements in swelling properties of treated soil. 4) To determine the durability of the treated and untreated BC soil. fatigue test has been conducted under different load condition and its performance at different curing period is studied. BC soil obtained from Gadag district situated in North Karnataka is used for the study. Further freeze-thaw and wet-dry test is performed to determine the durability of the stabilized soil.9 SCOPE OF WORK To meet the above mentioned objectives. The performance of Terrabind treated soil is investigated for different curing period. Chemical composition of soil is determined by performing various laboratory chemical tests. 1. 10 . 3) To Study the fatigue behavior of stabilized soil under repeated load condition. 6) To determine the chemical composition of untreated and treated soil. soil is blended with commercially available chemical called Terrabind and further Terrabind + fly ash combination is also tried on the soil and its strength properties were determined. To find the variation in strength properties. Proper investigation is very much essential to determine the potential of Terrabind in improving the geotechnical properties of soil. Objectives of the present investigation are: 1) The general objective of this investigation is to study the engineering properties of black cotton soil treated with a Terrabind Stabilizer. 5) To study the swelling characteristics of treated soil.chemicals as stabilizing agent. To study the performance of soil (untreated and treated) under repeated load condition. Laboratory experiments are performed to evaluate the geotechnical properties of the soil. The influence of applying this stabilizer has been examined via various laboratory tests. 2) To study the suitability of the commercial stabilizer for stabilizing BC soil. (Warren and Kirby 2004). by consolidating under load and by changing volumetrically along with seasonal moisture variation. From clay minerals by the presence of montomorillonite. structural elements.CHAPTER 2 LITERATURE REVIEW 2. Expansive soil can be found on almost all the continents on the Earth.Therefore. Movement is usually in an uneven pattern and of such a magnitude to cause extensive damage to the structures resting on them.1 GENERAL For centuries humankind has wondered at the instability of earth materials.2 IDENTIFICATION AND CLASSIFICATION OF SWELLING SOILS For identification of swelling soils. and work towards better quality control and quality assurance for their application. pavements. Clay minerals can be known by microscopic examination. the expansiveness 11 . especially expansive soil. and architectural features. 2. we need to do more to develop our knowledge of proven methods to deal with expansive soil. The results are usually excessive deflections and differential movements resulting in damage to foundation systems. One day they are dry and hard. some laboratory tests are available. Expansive soil has a high potential for shrinking or swelling due to change of moisture content. support research for further improvement of these methods. In a significant number of cases the structures become unusable or uninhabitable. the lack of appropriate improvements sometimes results in volumetric changes that are responsible for billions of dollars of damage each year. Even when efforts are made to improve these soils. Destructive results caused by this type of soil have been reported in many countries. X-ray diffraction and differential thermal analysis. and the next day wet and soft. The primary problem that arises with regard to expansive soil is that deformations are significantly greater than the elastic deformations and they cannot be predicted by the classical elastic or plastic theory. Expansive soil has always presented problems for lightly loaded structures. free swell index (Sridharan and Prakash 2000) . Potentially expansive soils are usually recognized in the field by their fissured or shattered condition.The following table gives the various criteria proposed for classifying expansive soils. Another simple way of finding out expansiveness in laboratory is free-swell test. then the soil is of high swelling capacity. Soil having free swell values as low as 100% may exhibit considerable volume change. together pointers to swelling characteristic of the soil for large clay content. and should be viewed with caution. Where soils is having free swell values below 50% seldom exhibit appreciable volume changes. It is reported that good grade high swelling commercial Bentonite will have a free swell values 1200% to 2000%. vigorous swelling may occur by upward heaving of soil or structure by the development of large swelling pressure. A liquid limit and plasticity index. when wetted under light loading. plasticity index. The potential expansion or potential swell or the degree of expansion is a convenient term used to classify expansive soils from which soil engineers ascertain how good or bad the potentially expansive soils are. The free swell test should be combined with the properties of the soil. That of greatest importance is difference between field soil moisture content at the time the construction is under taken and the equilibrium moisture content that will finally be achieved under the conditions associated with the complicated structure. Also the shrinkage limit can be used to estimating the swell potential of a soil. or obvious structural damage caused by such soils to existing buildings. If the equilibrium moisture content is considerable and higher than field moisture content. Weather a soil with high swelling potential will actually exhibit swelling characteristics depends on several factors. 12 . Many criteria are available to identify and characterize expansive soils.of the soil can be judged. A low shrinkage limit would show that a soil could have volume change at low moisture content. such as liquid limit. But these limits are considerably influenced by the local climatic conditions (Holtez and Gibbs 1956). even under very light loadings. Karnataka. some calcium carbonate. cracking and unevenness. As a result of wetting and drying process. Madhya Pradesh. during rains the stone has a tendency to sink into the soft subgrade. Because of the extensive occurrence of this soil. Black cotton soil occurs mostly in the central and western parts and covers an area of about 5. Tamil Nadu and Uttar Pradesh as shown in the Fig. These soils have presented serious problems to vehicular traffic during the rainy season as the natural subgrade soil becomes wet and sticky. large tracts are covered by expansive soil known as black cotton soil. They are predominantly rich in montmorillonitic clays of high base exchange capacity which generally ranges from 50 to 70 equiv/100g.Table 2. Black cotton soil has a high percentage of clay minerals and iron oxide. 2012). Cracks measuring 70 mm wide and over 1 m deep have been observed and may extend up to 3m or more in case of high deposits . 13 . 2. and so soft that its bearing capacity becomes almost nil.1. it is not economically feasible to replace it by a better subgrade material.3 BLACK COTTON SOIL In India. The major area of their occurrence is the south Vindhyachal range covering almost the entire Deccan Plateau (Muthyalu et al. Andhra Pradesh. in the form of settlement. vertical movement takes place in the soil mass.1 Classification of swelling soils as per (IS: 1498) Degree of expansion Low Medium High Very high L. Deposits of BC soil in the field show a general pattern of cracks during the dry season of the year. which extends over the states of Maharashtra. heavy depression.4 lakh square kilometers and thus form about 20% of the total area of India. All these movements lead to failure of pavement. and a low organic content. Even when stone boulders are laid as pavement over the natural subgrade soil.L (%) 20-35 35-50 50-70 70-90 P.I (%) < 12 12-23 23-32 > 32 FSI (%) < 50 50-100 100-200 > 200 Degree of severity Non critical Marginal Critical Severe 2. 1 Mechanical stabilization Mechanical soil stabilization refers to either compaction or the introduction of fibrous and other non-biodegradable reinforcement to the soil.1: Distribution of black cotton soil in India 2. Chemical stabilization 2.4 STABILIZATION TECHNIQUES Broadly.Figure 2. 1. although it is common to use both mechanical and 14 . Mechanical stabilization 2. soil stabilization takes the following forms. This practice does not require chemical change of the soil.4. There are several methods used to achieve mechanical stabilization: Compaction: Compaction typically employs a heavy weight to increase soil density by applying pressure from above. the cost of transportation. moisture conditions and soil permeability. and boulders.2 Chemical Stabilization One method of improving the engineering properties of soil is by adding chemicals or other materials to improve the existing soil. Operators of the machine must be careful not to over compact the soil.4. Addition of graded aggregate materials: A common method of improving the engineering characteristics of a soil is to add certain aggregates that lend desirable attributes to the soil. increasing its density to meet engineering requirements. the role of the stabilizing (binding) agent in the treatment process is either reinforcing of the bounds between the particles or filling of the pore spaces. Machines are used for this purpose. such as increased strength or decreased plasticity. This technique is generally cost effective: for example. Soil Reinforcement: Soil problems are sometimes remedied by utilizing engineered or non-engineered mechanical solutions. for too much pressure can result in crushed aggregates that lose their engineering properties. This method provides material economy. calcium chloride. It includes mixing or injecting additives such as lime. sodium silicate. Larger aggregates. cement. are often employed where additional mass and rigidity can prevent unwanted soil migration or improve load-bearing properties. 2.chemical means to achieve specified stabilization. improves support capabilities of the sub grade. large soil compactors with vibrating steel drums efficiently apply pressure to the soil. and furnishes a working platform for the remaining structure. bituminous materials and resinous materials with or in the soil to increase stability of the soil. Geo-textiles and engineered plastic mesh are designed to trap soil and help control erosion. and processing of a 15 . stones. such as gravel. Generally. meaning that the additive reacts with or changes the chemical properties of the soil. larger quantities of additive are used. and plasticity. An understanding of the use of the additive(s). An understanding of and means of incorporating (mixing) the additive. 2. In general. in order to properly implement this technique. and how they interact with the surrounding environment. thereby upgrading its engineering properties. 4. improperly incorporating the additive into the soil can have devastating results on the success of the project. 16 . Additives can also be chemical. An understanding of the type(s) of soil and their characteristics on site. So. meaning that upon addition to the parent soil their own load-bearing properties bolster the engineering characteristics of the parent soil. After the additive has been mixed with soil. Placing the wrong kind or wrong amount of additive or. but does not provide the designer with a significant increase in soil strength and durability. 5. spreading and compaction are achieved by conventional means. 3.stabilizing agent or additive such as soil cement or lime to treat an in-place soil 1material will probably be more economical than importing aggregate for the same thickness base course. smaller amounts of additives are required when it is simply desired to modify soil properties such as gradation. An understanding of how the resulting engineered soil will perform. an engineer must have: 1. Soil modification refers to the chemical stabilization process that results in improvements of some properties of the soil for improved constructability. how they react with the soil type and other additives. workability. The selection of the type and the determination of the percentage of the additive to be used are dependent upon the soil classification and the degree of improvement in soil quality desired. A clear idea of desired result. Additives can be mechanical. When it is desired to improve the strength and durability significantly. Nontraditional stabilizers (sulfonated oils. Not all stabilizers work for all soil types. Traditional stabilizers (hydrated lime. polymers. increase the soil density or neutralize the harmful effects of a substance in the soil. Generally.2. Portland cement. moderately fine. ammonium chloride. Nearly all types of soil can benefit from the strength gained by cement stabilization. alter the effect of moisture. 2. potassium compounds. In clay soil. 2. 17 . By breaking up the clay into small sized particles. enzymes. and fine-graded clay soil. Experience has shown that lime will react well with medium. However. Following are the most commonly used traditional stabilizers and their applications: 2. stabilizer may be used to act as a binder.the amount of cement used will dictate whether modification or stabilization has occurred. it becomes more rigid. It also increases the strength and workability of the soil.1 Portland Cement Portland cement is a mechanical additive that can be used for soil modification (to improve soil quality) or soil stabilization (to convert the soil to a solid cement mass). and fly ash).5.2 Quick Lime/Hydrated Lime Lime is a chemical additive that has been utilized as a stabilizing agent in soil for centuries. It is very important to achieve proper gradation while applying lime to clay soil. and so on). and reduces the soil ability to swell. the main benefit from lime stabilization is the reduction of the soil plasticity: by reducing the soil water content. the best results have occurred when used with well-graded fines that possess enough fines to produce a floating matrix. and a single stabilizer will perform quite differently with different soil types. you allow the lime to introduce homogenously and properly react with the clay. These may be divided into two groups: 1.5.5 TYPES OF STABILIZERS A variety of stabilizers are available in the market. and cement like mass. Fly ash is a pozzolan.3 Fly ash Coal burning electric utilities annually produce million tons of fly ash as a waste byproduct and the environmentally acceptable disposal of this material has become an increasing concern. By bonding the soil grains together. 18 . One of the most promising approaches in this area is use of fly ash as a replacement to the conventional weak earth material will solve two problems with one effort i.5. Efforts have always been made by the researchers to make pertinent use of fly ash in road constructions in the localities which exists in the vicinity of thermal power stations. Fly ash can be mixed with lime and water to stabilize granular materials with few fines. Fly ash and other ash such as bottom ash and boiler ash have been widely used in application with source. Fly-ash reduces the potential of a plastic soil to undergo volumetric expansion by a physical cementing mechanism. The factors that most readily influence the quality and reactivity of fly ashes are the source of the coal. Also.e. is a by-product of the combustion of coal. soil particle movements are restricted. a chemical additive consisting mainly of silicon and aluminum compounds. 2012). producing a hard. providing adequate support for pavements and improving working conditions where undesirable soil are encountered. Fly ash controls shrink. the efficiency of the burning operation and the collection and storage method of the ash (Pankaj et al. 2012) Fly ash. It has been successfully used with granular and fine grained materials to improve soil characteristics. elimination of solid waste problem on one hand and provision of a needed construction material on other. the degree of pulverization of coal. (Koteswara et al.swell by cementing the soil grading together much like a Portland cement bonds aggregates together to make concrete.2. this will help in achieving sustainable development of natural resources. which cannot be evaluated by the plasticity index. Its role in the stabilization process is to act as a pozzolan and/or as a filler product to reduce air void. eliminates surface pumping or rutting and extends the life of pavement structure. as well as the presence of water trapped within the clay clusters (Chew et al. and Laser diffractometric measurement. In general. it consists of blending lime with cohesive soils or mixing Portland cement with non-cohesive soils. This technique is widely used in road rehabilitation or in reprocessing of road base materials for increasing life of the structure. widely used to improve their shear strength as well as stiffness. SEM. require improvement in their properties before using them as construction material. having low shear strength and low stiffness. 2011) . A lot of studies have been carried out regarding stabilization of soil treated with fly ash. cement. The effectiveness of using various percentages of high calcium fly ash and cement in stabilising fine-grained clayey soil has been studied by conducting uniaxial 19 .2. The microstructure of cement-treated marine clay has been investigated using XRD. (Tastan et al.Chemical stabilization for these soils is a popular method. the designer can have advantage of strength and stiffness. Many studies have been carried out regarding stabilization of soil using various traditional stabilizers like lime. used to decrease the potential for local shear failure of subgrade. It also results in the increase of stiffness and thus. These mechanisms are the production of hydrated lime by the hydration reaction which causes flocculation of the illite clay particles.6 REVIEWS ON RESEARCH FINDINGS ON STABILIZATION OF SOIL USING TRADITIONAL ADMIXTURES The weak subgrade of cohesive soils. Results indicate that the magnitude of changes in the properties and behavior of cement-treated marine clay is due to the interaction of four underlying microstructural mechanisms. 2004). Soils are either treated only with fly ash or are used in combination with any other stabilizer. surface deposition and shallow infilling by cementitious products on clay clusters. Following are the few reviews of literature on stabilization of soil using traditional stabilizers. preferential attack of the calcium ions on kaolinite rather than on illite in the pozzolanic reaction. fly ash etc. Chemical stabilization. Some of the studies reviewed in this paper are as follows. 80. 9 11. grain size distribution. 3. 60. 8. 5. thereafter.. 12.e. Further analysis of Pavement structures for construction traffic and for operating traffic incorporating subgrades improved by in situ stabilisation with fly ash and cement were made which showed very good results compared to conventional flexible pavements without improved subgrades (Kolias et al.e. 2012) evaluated BC soil properties by adding different quantities of Lime and fly ash (% by weight). addition of fly ash and RHA reduces the PI and specific gravity of the soil.e. 6. linear shrinkage. In terms of material cost. and 90 % and the results were evaluated. while these values decrease with addition of fly ash. The FSI value and SP decreased with increase in fly ash content. UCS and CBR values were increased indicating the improvement in the strength properties of the stabilized soil (Laxmikant et al. 13.compression. (Pankaj et al. 20. 40. 2011). 10. at 0. Similarly BC soil stabilized by adding different percentages of fly ash (i. compaction characteristics. and 15%) were subjected to various laboratory studies. the use of less costly fly ash can reduce the required amount of lime The geo-engineering properties such as Atterberg limits. Results indicate that. The moisture and density curves indicate that addition of RHA results in an increase in OMC and decrease in MDD. It was observed that PI of clay-fly ash mixes decreased with increase in fly ash content i.. the same decreases with further increase in fly ash content. addition of fly ash made expansive soil less plastic and increased its workability by colloidal reaction and changing its grain size. 2005). The result showed that the use of Lime and fly ash increases the CBR values. This shows 20 . UCS of clay-fly ash mixes were found to be maximum at 20% fly ash content and thereafter it reduced with further increase in fly ash content. It was concluded that thickness of pavement can be decreased by 66% as the CBR value was increased considerably after stabilization and in combination. in indirect (splitting) tension and flexure and 90-day soaked CBR test. the admixtures are beneficial for lower plasticity and higher silt content soil. UCS and CBR of highly plastic commercial clay were stabilized using different proportion of fly ash i. OMC reduced with increase in fly ash content but the MDD increased upto an fly ash content of 20%.e. swelling pressure. and 15%) and Rice Husk Ash (RHA) (i. that there exists an optimum fly ash content that gives better compressive strength. volcanic ash and their combinations have been evaluated through Atterberg limits.60% by adding 12% of mill scale (Murthy et al. standard proctor compaction. It was found that the unconfined compressive strength of organic soil can be increased using fly ash. The durability properties of 14 stabilized soil mixtures were also investigated by studying the influence of water immersion on strength. 2012). 2012) conducted a laboratory studies to stabilize BC soil using Cement kiln dust (CKD) as an admixture with and without adding polymer fibers. Soil organic content is a detrimental characteristic for stabilization. Similarly (Tastan et al. The permeability value of BC soil increased manifolds by increasing the percentage of mill scale and the plasticity of the BC soil was decreased from 35. The pozzolonic effect appears to diminish as the water content decreases. (Rao et al. a waste product found in metal industry which mainly contains iron oxide was treated with BC soil in varying proportions and its mechanical properties were evaluated. water absorbtivity and drying shrinkage. Mill scale. The CBR value of BC soil mixed with 15% mill scale was increased by three times that of plain BC soil. tested under un-soaked conditions. Resilient moduli of the soil showed significant improvement. splitting tensile strength.71% to 30. Clayey soil stabilized using various dosages of cement kiln dust. Increase in organic content of soil indicates that strength of the soil–fly ash mixture decreases exponentially. strength characteristics and decreases the plasticity. It was also observed that the CBR values of clay-fly ash mixes. modulus of elasticity and CBR tests. 2011) studied the effectiveness of fly ash in the stabilization of organic soil and the factors that are likely to affect the degree of stabilization. Developed stabilized soil mixtures showed satisfactory strength and durability (Hossain and Mol 2011). UCS. and the reduction in water content is due to the addition of fly ash. This study 21 . showed peaks at 20% and 80% fly ash content (Bidula 2012). It was found that mixing mill scale in varying proportions increases the permeability of the soil. It was observed that strength and stiffness are attributed primarily to cementing caused by pozzolanic reactions. Many by-products other than fly ash have been used in the stabilization of various soils and its effectiveness has been reported and discussed. where as plastic limit was increased by 41%. The nature of soil stabilization dictates that products may be soil-specific and/or environment-sensitive. These products were divided into 7 categories: salts. The rapid evolution of existing products and introduction of new stabilizers further complicate the process of defining the performance characteristics of the various nontraditional soil stabilization additives. and fly ash. little independent research has been documented pertaining to the use of nontraditional stabilization additives. but perform poorly when applied to dissimilar materials in a different environment. By addition of CKD the LL and PI of the mixture was decreased by 23 % and 57% respectively. and tree resins. In other words. and superior durability compared to traditional stabilization additives. A review of the literature indicates that there has been a large quantity of research completed regarding the application of traditional stabilization additives such as lime. The CBR value was increased significantly even for soaked CBR tests. The shear strength parameters of clay soil significantly increased upon admixture stabilization and admixture with fiber treatment. reduced cure times. It was observed that the UCS of Clay soil increased by 7 times with admixture stabilization and 9 times for admixture with fiber modification with respect to plain samples. little research has been completed to distinguish between products that deliver enhanced performance and those that do not. A large quantity of advertisements. pamphlets. acids. Many of these stabilizers are advertised as requiring lower material quantities. Unfortunately.7 REVIEWS ON RESEARCH FINDINGS ON STABILIZATION OF SOIL USING NON TRADITIONAL ADMIXTURES Nontraditional stabilization additives have become increasingly available for commercial and military applications. higher material strengths.revealed that the fiber reinforcement improves the soil properties in terms of improved stress-strain patterns and progressive failure in place of quick post peak failure of plain samples. 2. lignosulfonates. petroleum emulsions. some products may work well in specific soil types in a given environment. most of the information disclosed 22 . enzymes. However. Unfortunately. cement. and videos has been distributed testifying to the benefits of a particular stabilization additive. polymers. The results also indicated that the strength of soil-cement is increased considerably by adding acrylic resin as an additive material. the increase in shear strength is a function of curing time and amount of resin.7%). 1991) tested a poorly graded clay-silt by treating it with several organic additives of which the two-part epoxy system bisphenol A/epichlorohydrin resin plus a polyamide hardener showed the best dry CBR results.68 gm/cc) of the standard specimen. Experimental results indicated that in-situ precipitation of lime in the soil by sequential mixing of CaCl2 and NaOH solutions with expansive soil developed strong lime modification and soil-lime pozzolanic reactions. Both limemodification reactions and well developed crystalline cementation products (formed by lime-soil pozzolanic reactions) contributed to the marked increase in the 23 .cm (density= 1. cm reported by earlier workers using UF and other modified phenol formaldehyde resins. (Gopal and Singh 1983) studied the effectiveness of urea-formaldehyde (UF) and its copolymers when treated with dune sand. 2011) investigated the soil-cement mixture by adding different percentage of acrylic resin to improve the engineering properties of the soil for construction.in these media is subjective and nontraditional engineering properties are poorly documented. (Estabragh et al.3%) and sand (90. catalyst (0. The results showed that by increasing the cement content in the soil-cement mixture. made by a novel technique using this resin (9%). reduced the plasticity index and increased the unconfined compressive strength of the expansive clay cured for 24 hours. The lime modification reactions together with the poorly developed cementation products controlled the swelling potential. MDD increases and OMC decreases in compaction tests. was higher than the strengths ranging from 11. (Majebi et al. It was observed that for given cement content. Compressive strength tests on soil-cement showed that the increase in strength depends on the cement content and the curing time.3 to 105 kg/sq. It was found that the maximum unconfined compressive strength of 165 kg/sq. (Thyagaraj 2012) made an attempt to study the precipitation of lime in the soil by successive mixing of CaCl2 and NaOH solutions with the expansive soil in two different sequences. Following are the few reviews of literature on stabilization of soil using nontraditional stabilizers. Increase in fibre content caused an increase in strength and shrinkage potential but brought on the reduction of swelling potential and increase in curing duration improved the unconfined compressive strength and shear strength parameters of the stabilized soil significantly.5%. Following are some of reviews based on improvement in swelling properties of soil. Atterberg limits.05%. (Cai et al.unconfined compressive strength of the expansive soil that were cured for periods of 7-21 days.15%.e. and 10% by mass) (bentonite) by means of swell potential and strength. effectively.e. (Manchikanti et al. cohesion and angle of internal friction of the clayey soil and it led to a reduction of swelling and shrinkage potential. There was a valuable decrease in liquid limit and plasticity index of the treated soil which indicated that gypsum can be used as a stabilizing agent for expansive clay soil. and curing period of 7 days was accepted as a cure time for optimum improvement in this study. FSI and UCS tests were performed on treated and untreated samples. 2006) worked on reducing the brittleness of soil stabilized by lime only by mixing the soil with a newly proposed mixture of polypropylene fibre. 0. 0. It was found that the most important change quickly occurred in the first week. Nine groups of treated soil specimens were prepared and tested at three different percentages of fibre content (i. Appropriate curing time for optimum improvement was determined by obtaining the swell percent variation with cure time up to 2 months using the considered maximum gypsum content (10% by mass) for the mixture. (Bose et al. 2009) studied the performance expansive soil when treated with different percentages of gypsum (2. 8% by weight of the parent soil). 7. Some of the soil stabilization studies were based on improvement in strength properties only and few papers have investigated on both strength and the swelling properties of soil. It was observed that increase in lime content resulted in an initial increase followed by a slight decrease in unconfined compressive strength. 5%.25% by weight of the parent soil) and three different percentages of lime (i. 2%.5%. after a curing period of 7 days. 0. 2011) conducted field studies on expansive soil subgrades by treating it with KCl. 5%. CaCl2 and FeCl3 because of their ready 24 . it was concluded that FeCl 3 is the best treatment to reduce the heave. Moreover.treated with respect to the untreated test track and the time taken to attain the maximum heave for FeCl3-treated test track is nearly one-half. they can be applied to the ground in the form of electrolyte solution. These variations resulting from freeze– thaw (F-T) and wet–dry (W-D) actions. After each cycle the swell potential and swell pressure were measured. (Homoud et al. or a combination of these actions. 43%. is still not fully explored and additional studies are needed (Little et al. 2005). Results showed that there was reduction in maximum heave by 22%. during the last few decades increased emphasis has been placed by transportation agencies and researchers to better understand the behavior of stabilized aggregate bases and subgrade soil under freeze–thaw and W-D cycles. It was observed that FeCl3 –treated test track showed the best performance. have been presented in a number of previous studies. From the test results. better than the other treatments. For this purpose six expansive soils were obtained from various locations in Irbid (a city in northern Jordan). As the number of 25 . CaCl2-treated.8 DURABILITY STUDIES Variations in climatic conditions have been recognized by pavement engineers as a major factor affecting pavement performance. respectively for KCl-treated. The influence of such actions on a pavement structure indicates possible changes in the engineering properties of associated pavement materials. 30%. among others. of the time taken by the untreated test track to attain its maximum heave. 2005). however. Furthermore it was noted that the first cycle causes the most reduction in swelling potential. 1995) investigated the effect of cyclic wetting and drying on the expansive characteristics of clays. Importance of climatic conditions has also been emphasized by AASHTO (2005) and by (Little et al. To this end.dissolvability in water and supply of adequate cations for ready cation exchange. Specifically. FeCl3. This research area. Results of heave recorded from the untreated and treated test tracks were compared. several studies have been undertaken to evaluate the performance of pavement materials under these actions. 2. The experimental data indicated that upon repeated wetting and drying the soil showed sign of fatigue after every cycle resulting in decreased swelling ability. This inevitably caused a reduction in swelling characteristics.9 SUMMARY From the above literature reviews it can be observed that the soil stabilized using both traditional and nontraditional stabilizers have given good results. It has been observed that most of the papers have concentrated on improvement in strength parameters and very less study has been made on improvements in swelling properties of soil which is one of the important properties of expansive soils and very fewer studies have been made on durability of stabilized soil. It is also observed that in many papers FA used in combination with other stabilizers have given better results compared to the use of only one stabilizer. Improvement in strength. Admixtures like locally available industrial wastes. This led to lower structural element orientation due to the integration of structure along the bedding resulting in correspondingly lower water absorption thus reducing swelling ability.cycles increases additional reduction was observed until an equilibrium state is reached. Scanning electron micrographs clearly showed a continuous rearrangement of particles during cyclic wetting and drying. Limited efforts are made to use of nontraditional liquid stabilizers to stabilize the soil. 2. Cyclic wetting and drying results in particle aggregation as demonstrated by the reduction in clay content and plasticity (LL and PI) between the initial and final cycles. Taking all this in note the following study is based on stabilizing BC soil which is one of the problematic expansive soils found abundantly in North Karnataka region by a liquid stabilizer called Terrabind and later Terrabind is used in combination with FA. 26 . by products etc have given good results. Traditional stabilizers are usually required in large quantity and are uneconomical compared to nontraditional stabilizers. changes in swelling properties and durability of the treated soil is studied and discussed. 3. The solution is stirred again immediately before testing 4. 27 . 30 gms of soil sample prepared as per IS: 2720 (part-1) is taken in a 100 ml beaker.2 pH OF SOIL BY ELECTROMETRIC METHOD Procedure 1.All aggregation of particles is broken down so that the soil sieved on 425 IS sieve retains only discrete particles. 75 ml of distilled water is added to it and stirred for few seconds. 3. The pH meter is calibrated by means of the standard buffer solution following the procedure recommended by the manufacturer.This chapter briefly describes the procedure of various laboratory chemical tests conducted on soil samples. Three readings of the pH of the soil suspension are taken with brief stirring in between each reading. 2. The electrode is first washed with distilled water dried with help of an ordinary filter paper and then immersed in the soil specimen. 3. 5. Then the beaker is covered with a cover glass and allowed to stand for one hour with occasional stirring.1 SOIL SPECIMEN The soil sample received from the field is prepared in accordance with IS: 2720 (part 1) – 1983.CHAPTER 3 CHEMICAL ANALYSIS 3.1 GENERAL Chemical analysis has been performed on untreated and treated soil sample to determine its composition. The tests are conducted as per IS 2720 (Part-26). 6.1. Buffer solution pH 9. Calibration of the pH meter is checked with one of the standard buffer solutions. 3. pH meter directly provided the pH values. 28 . 8. 6. 75 ml of distilled water is added to it and the suspension is stirred for a few seconds.the suspension is stirred again immediately before testing. Buffer solution pH 4. 2.9.0 (at 250c) -5.106 gms of potassium hydrogen phthalate dissolved in distilled water and diluted to 500ml with distilled water. 4.7. 9. Two or three readings of the pH of the soil suspension are made with brief stirring in between each reading.3 CONDUCTIVITY OF SOIL BY ELECTROMETRIC METHOD Buffer solutions: following buffer solutions are used for the test. The electrode is washed with distilled water dried with help of an orginary filter paper and then immersed in the soil specimen. 30 gms of soil prepared as per IS: 2720 (part-1) is taken in a 100 ml beaker. Procedure 1.54 gms of sodium tetraborate (borax) dissolved in distilled water and diluted to 500 ml. 2. 3. The beaker is then be covered with a cover glass and allowed to stand for one hour with occasional stirring . 1.2 (at 250c) . 5. The pH readings of the soil suspension are taken when a constant value is reached and the electrode is removed from the suspension immediately and washed with distilled water. The pH meter is calibrated by means of the standard buffer solution following the procedure recommended by the manufacturer. 8. 3. Procedure 1. The whole mass is allowed to evaporate to dryness by keeping it on a hotplate till whole of the hydrochloric acid disappeared.7. 6. Then the electrode is removed from the suspension immediately and washed with distilled water. Further 10 ml of distilled water and 10 ml of concentrated hydrochloric acid (HCl) is added to it and is mixed with the help of glass rod till it dissolves. The residue is baked in oven for 01 hour and then allowed to cool. 4. About 10 ml of distilled water and 10 ml of concentrated hydrochloric acid (HCl) is added to the beaker and is mixed and grounded with a glass rod to dissolve. The solution is later filtered through Whatman filter paper no. The solution is then heated to boiling and after one minute it is removed from flame and 20 ml of hot distilled water is added. 3. 2. it is then cooled and weighed. The pH readings of the soil suspension are taken when a constant value is reached. i. 29 . 7. 9. The crucible was placed in a Bunsun Burner for 25 minutes and ignited at a temperature of 80 to 1000c. About one gram of the dried soil sample accurately weighed is taken in a 500 ml beaker. 9. The crucible is then removed from Bunsun Burner. 42 and the whole of silica along with filter paper is placed in a preweighed crucible. In calibration of the pH meter is again checked with one of the standard buffer solutions.4 SILICA CONTENT IN SOIL BY GRAVIMETRIC METHOD Reagents: The following Reagents are used for the test. Concentrated Hydrochloric acid (HCl). pH meter directly provides the conductivity values. 5. 8. 30 . Concentrated Hydrochloric acid. 5 ml of 5% potassium thiocyanate and 4 ml of 4N HCl are added and the solution is made to 100 ml with distilled water.20 ml of concentrated HCl + distilled water is added to make it 100 ml of solution.required 33. 11. iii. For 4N of 100 ml solution -. Solutions i..5 IRON OXIDE (Fe2O3) IN SOIL BY COLORIMETRIC METHOD Reagents: The following Reagents shall are used for the test. 4N Hydrochloric acid (4N HCl) For 1N of 1000 ml solution -. Potassium thiocyanate. = 1000 mgs) 3. 2. Procedure 1. filtrate is used for the calculation of R2O3 (Al2O3+Fe2O3) by making the volume up to 100 ml in a 100 ml Nessler’s tube Calculations % silica oxide (SiO2) = (w3/w) x 100 Where. The weight of the silica is calculated by subtracting the empty weight of the crucible. 5% Potassium thiocyanate 5 gms of Potassium thiocyanate is added into a 100 ml beaker and distilled water is added to make 100 ml of solution ii.required 83 ml of concentrated HCl + distilled water is added to make it 1000 ml of solution. i. Ammonium Chloride (NH4Cl). The passing of Whatman filter paper 42 i. 50 ml of distilled water is added to Nessler’s tube of 100 ml capacity. W3 = Weight of SiO2 (in mgs) W = Weight of soil sample taken (in mgs) (1 gm. ii.10.e. Dilute ammonia --. Readings are recorded as Fe in mg/lt for 5 mg of soil and Fe2O3 is calculated for 100 mg of soil. 2.mg / Lt Fe 100 mg of soil ---------------------.-.-.add 50 ml Ammonia and make it to 100 ml with distilled water.4297 X x 1. Rosolic acid solution (few drops) or Methyle red indicator (2 drops) iii.05 ml / 100 ml -------------.6 R2O3 (Al2O3 + Fe2O3) IN SOIL BY GRAVIMETRIC METHOD Reagents: The following Reagents are used for the test. Half of the filtrate (50 ml from collected 100 ml in Nessler’s tube) is taken for estimation of R2O3 (Al2O3 + Fe2O3) Aluminium and Iron oxide.3. 31 . After calibration 10 ml sample is taken in a Cuvette and placed in spectrometer.50 mg of soil / 100 ml -------------- 5 mg of soil / 1000 ml (1Lt) 5 mg of soil -----------------------. 4.x 100 / 5 = X mg as Fe For Fe2O3 multiplied by constant 1.4297 = Y % Fe2O3 3. i. The Spectrometer is caliberated and set to method no. About 0. 900.0.05 ml of filtrate is added to the nessler’s tube of 100 ml solution to get light red colour. Calculations: 1000 mg of soil taken / 100 ml 100 ml / 1000 mg 1 ml / 10 mg -------------. 5. Procedure 1. ii. To the first 50 ml filtrate about 4 gms of ammonium chloride (NH4Cl) and two drops of methyle red is added and heated to boiling and is removed from the flame after one minute.0. Ammonium Chloride (NH4Cl). Dilute ammonia is added to the solution until the precipitation starts and the solution is filtered through Whatman no 42 filter paper. 4. Silver nitrate (Ag No3) ii. Potassium Chromate (5%) Solutions i.50 gm = 500 mg) 3.7 CHLORIDE CONTENT IN SOIL BY ARGENTOMETRIC METHOD Reagents: The following Reagents are used for the test. i. W3 = Weight of R2O3 obtained (in mg) W = Weight of soil sample taken (in mg) (0.3.0141N) 2. Then the solution is filtered and diluted to 100 ml with distilled water. ii. The total weight of (Al2O3 + Fe2O3) is obtained by subtracting from the final weight.395 gms of Silver Nitrate (AgNO3) is dissolved in distilled water and diluted to 1000 ml. the weight of the empty crucible. Standard Silver Nitrate solution (0. 6.silver nitrateis added to the solution until a definite red precipitate is formed and is allowed to stand for 12 hours. Calculations % R2O3 = (w3/w) x100 Where. The final weight of the crucible is noted. 5. The precipitates along with the filter paper is then placed in a weighed crucible and the crucible is ignited in the Bunsun Burner or (Muffle furnace) or any other suitable arrangements. Potassium Chromate (5%) 5 gms (K2Cr O4) Potassium Chromate is dissolved in distilled water . 32 . 5.D.] 33 .D. iii. The volume of standard silver nitrate solution (0. iv. Ammonium Chloride (NH4Cl). 3.A) Solutions i. Ethylenediaminetetraacetate dehydrate (tetra acetic acid disodium salt E.0 with concentrated Ammonium Hydroxide (NH4OH) and the final volume is made to 1000 ml (1 ltr. The suspension is then filtered through Whatman No.. ii. 6. Magnesium salt of E.8 CALCIUM AND MAGNESIUM OXIDE IN SOIL BY TITRIMETRIC METHOD Reagents: The following Reagents are used for the test. Ammonium Acetate solution [57 ml of glacial acetic acid is diluted to 800 ml with distilled water & then neutralized to pH 7. Later 25 ml of soil solution is taken and 10 drops of Potassium Chromate (5%) indicator is added till light yellow colour develops. Sodium hydroxide (NaOH) vi. i.0141N) in ml is recorded when the colour changes from yellow to brick red colour.A. Glacial acetic acid. Murexide vii.T. v. 2.). 1:4 soil suspension is prepared i. 4. Concentrated Ammonium hydroxide (NH4OH).e.Procedure 1.0141N) solution. The sample is titrated using Standard Silver Nitrate Titrant (0. 3. 50 filter paper using Buchner funnel and vaccum pump. 25 gms of soil is taken in 100 ml of aerated distilled water and is shaked for about one hour. The suspension is heated in a hot plate up to boiling and is removed from the flame and allowed to cool down.T. 0 with conc.(1-hydroxy -2 napthylazo) -5-nitro-2-naphthol-4 – sulfonic acid: no 203 in the colorindex.723 gms analytical reagent-grade disodium EDTA dehydrate is weighed. Erichrome Black T indicator Sodium salt of 1. also called (ethylenedimitrilo) tetraacetic acid disodium salt (EDTA) and dissolved in distilled water and diluted to 1000 ml. and 0.25 gm magnesium salt of EDTA is added and diluted to 250 ml with distilled water. 1.50 gm magnesium salt of EDTA is added and diluted to 100 ml distilled water] iii. iv.3.5 ml of glacial acetic acid is diluted to 400 ml with DW & then neutralized to pH 7. also called (ethylenedimitrilo) tetraacetic acid disodium salt (EDTA) and dissolved in distilled water and diluted to 500 ml. NH4OH and the final volume is made to 500 ml] ii. 0.20 ml of conc. Sodium hydroxide solution (1N) 4 gms of sodium hydroxide pallets is dissolved in 100 ml of distilled water vi. Ammonium hydroxide (NH4OH). v. Murexide 34 .01M) For 1000 ml titrant.] For 100 ml Buffer solution [6.76 gms ammonium chloride (NH4Cl) is dissolved in 57. Ammonium hydroxide (NH4OH).8615 gm analytical reagent-grade disodium EDTA dehydrate is weighed . Buffer solution For 250 ml Buffer solution [16. Standard EDTA titrant ( 0. 1.50 gm dye is dissolved in 100g of triethanolamine or ethylene glycol monomethyl ether.90 gms ammonium chloride (NH4Cl) is dissolved in 143 ml of conc.[28. 2 drops per 50 ml solution is added for titration. For 500 ml titrant. 5. The suspension is stirred and kept overnight and later the water sample is collected from the solution. 6. 6. 100 ml of sample from solution is taken in a conical flask and 1 ml of Buffer solution and 3 drops of Erichrome Black T indicator is added to get light yellow colour. Concentration of magnesium oxide is determined following the EDTA method. Measure the concentration Magnesium oxide. 35 .Procedure for the estimation magnesium oxide 1. 7. About 50 gms of the dried sample accurately weighed is taken in a 500 ml beaker and about 100 ml of Ammonium acetate solution is added. The concentration of calcium oxide is determined following the EDTA method. 4. 100 ml of sample is taken from the solution in a conical flask and 2 ml of Sodium hydroxide solution and 1 pinch Murexide is added and sample changes to light yellow colour. 4. 5. 7. The sample is titrated using EDTA titrant. 3. Volume of EDTA solution is recorded when colour changes from light yellow to light pink or green or blue. 3. The suspension is stirred and kept overnight and later the water sample is collected from the solution. Procedure for Estimation of Calcium oxide 1. Measure the concentration of Calcium oxide. The sample is titrated using EDTA titrant. 2. About 50 gms of the dried sample accurately weighed is taken in a 500 ml beaker and 100 ml of Ammonium acetate solution is added directly to it. Volume of EDTA solution is recorded when colour changes from light yellow to light pink or green or blue. 2. 012 0. It can be observed that there is an increase in SiO2. chloride and sulphate content in treated soil when compared with untreated soil.085 0.89 14. Since a clear trend is not observed. the changes in composition of soil before and after treating with Terrabind and FA cannot be explained clearly.43 1.1: Chemical composition of untreated and treated BC soil Oxides (%) SiO2 R2O3 Fe2O3 Al2O3 Chloride Sulphate CaO MgO pH Conductivity (millisiemens/cm) TDS(PPm) LOI BC BC+Terrabind BC+Terrabind+FA 57.11 0.67 1.29 58.75 8.13 12.3.5 8.12 58.052 0.015 8. MgO.091 0.17 188 14. Table 3.17 0.9 CHEMICAL ANALYSIS RESULTS ON UNTREATED AND TREATED BC SOIL Table 3.16 186 - 36 1.017 0.22 187 - .025 0.45 10.22 6.016 0.05 9.1 shows the chemical composition of untreated and treated BC soil. CaO content and pH value and decrease in Fe2O3.08 2.18 8.013 0.22 8.04 0.0045 0.71 2. All the tests are performed as per the relevant codes. Changes in their properties are studied by blending the soil sample with Terrabind chemical and FA.2 MATERIALS USED 4. Experiments are conducted to determine the geotechnical and engineering properties of the soil.CHAPTER 4 MATERIALS AND METHODOLOGY 4.1 GENERAL This chapter deals with details of experimental investigation carried out on Black cotton soil.1 Soil Black cotton soil which is abundantly available in Gadag district (North Karnataka) is used for the investigation.2. 4. The collected sample is first air dried and then oven dried before using it for the tests. The soil sample is obtained from a depth of 2 meter below the ground surface.1: Black cotton soil 37 . Figure 4. Terrabind alters the properties of road base materials (soil/ aggregate) at a molecular level thus rendering greater compaction. a chemical called Terrabind manufactured by Terra nova technologies is used to stabilize the soil. Raichur. Sieve analysis results showed that the fly ash size ranges below 45µ. Terrabind is initially diluted in OMC of soil (obtained after conducted heavy compaction test on untreated soil) and then the Terrabind water solution is mixed with the soil homogenously and the treated soil is allowed to mature for 20 minutes prior to test. FA properties are determined before using it for treating the soil. specific gravity are also determined.4. load bearing and cohesiveness.2. India. Terrabind has a catalyst effect when combined in clay soil with fly ash.3 Application of Terrabind to BC Soil As per the company specification 1ml of Terrabind is sufficient for every 3 kg of soil. 4. 5%-10% fly ash (Class C) by weight of soil is an ideal range. Terrabind is a revolutionary advanced lignosulphonate liquid ionic organic compound for the purpose of soil stabilization.2. A weighed sample of fly ash is separated through a nest of sieves for determination of particle size distribution. It is available in the liquid concentration and is to be mixed with water in specified proportion before mixing with the soil as per the company specification.Other engineering properties like moisture content. The FA used in the project is provided by Thermal power station. Karnataka.following table shows the physical properties of FA used for the study.2. 6% by weight of soil of FA was used in the present study.2 Terrabind In the present study. Terra Nova Technologies is the first company to manufacture this technology in India. The same concentration is applied in this work. 4. The treated soil is kept in incubators to maintain the OMC of soil throughout the test.4 Class C Fly ash Terrabind and Fly ash is highly recommended for use in combination with Terrabind combination for higher strength sub grade. 38 . 2kg. i. Therefore for 30 Kg soil.69 litres of water. amount of Terrabind =30/3=10ml.5% 5. Amount of Terrabind: 1ml for 3Kg. MDD of soil: 17.31% 4. Soil taken: 30Kg 2. MDD of soil: 17.5) +2%]*20/100= 2. Soil taken: 20Kg 2.Table 4. OMC of soil: 16. 39 . Water to be added= [(16.31-7. Therefore for 20 Kg soil. For Soil and Terrabind: 1. Natural moisture content: 7. 7.7 g/cc 3.5 Terrabind dosage: 1ml for every 3kg soil.16 0. 6.1: Physical properties of FA Properties Specific gravity Water content(%) Loss on Ignition(%) Size Test values 1.66ml.2. Water to be added= [(16. OMC of soil: 16. amount of Terrabind =20/3=6. Natural moisture content: 6% 5. 6% of 20kg= 1. Amount of Terrabind: 1ml for 3Kg.29 litres of water. Terrabind and FA: 1.975 0. 6.31% 4.31-6) +2%]*30/100= 3. FA content= 6% by weight of soil.7 g/cc 3.43 < 45 µ 4. Soil.e. The various tests conducted are given below. Three trials are conducted and the average value is reported.3 Consistency limits test Liquid limit (LL) and plastic limit (PL) of the soil are determined as per the procedure available in IS: 2720 (part 5)-1985. Atterberg’s limits tests 4. Fatigue test 4. Grain size analysis test 3. Swell pressure 10. The test results are depicted in Table 5. “Determination of specific gravity of fine grained soils”. Standard 40 .3.1. Treated soils are tested at different curing periods. Compaction tests 5. 4. Unconfined compressive strength test 6.3 TESTS CONDUCTED ON SOIL Soil samples collected from site are tested for their geotechnical properties and strength characteristics.3.1. The test is conducted as per IS 2720 (part4) 1985. Durability test 11. Triaxial compression test 8. 4. The tests are conducted on treated and untreated soil.1 Specific Gravity test Specific gravity test is performed on untreated soil using Standard test equipment and procedure available as per IS: 2720 (part 3)-1980. The sedimentation analysis is done by hydrometer method using sodium hexa metaphosphate as the dispersing agent.3. Free swell index 9.2 Grain size analysis test Sieve analysis and sedimentation analysis tests are conducted on untreated soil to determine the grain size distribution. The results are tabulated in Table 5. Specific gravity test 2. California Bearing Ratio test 7. 1.4. 3. Figure 4.4 Compaction tests Compaction test is conducted to determine the maximum dry density and optimum moisture content of treated and untreated soil using Standard test equipment and procedure available in IS: 2720 (part 7)-1980. 4.Casagrande’s apparatus is used to find out LL.”Determination of water content –Dry density Relation using Light compaction” for light compaction and IS: 2720 (part 8)- 41 . Figure 4.1.2: Casagrande apparatus for determination of liquid limit.3: Samples prepared for the determination of plastic limit. The consistency limits of untreated soil samples are tabulated in Table: 5. Results of tests on untreated soil smaple are tabulated in Table 5.4: UCS Samples 4. Three identical soil specimens are tested for each curing period and the average of three are reported. Results of tests on untreated soil smaple are tabulated in Table 5. 7 and 28 days curing. 42 . Untreated soil is tested for soaked and unsoaked condition for both light and heavy compaction densities.6 California Bearing Ratio Test CBR test is conducted using Standard test equipment and procedure available in IS: 2720 (part 16)-1979.1. For untreated soil samples. UCS tests are conducted for both light and heavy compaction densities.Dry Density Relation using Heavy Compaction” for heavy compaction. 4. “Laboratory Determination of CBR”. “Determination of Unconfined Compression Strength”. “Determination of water content .3.5 Unconfined Compression Strength test Unconfined compression test are performed using Standard test equipment and procedure available as per IS: 2720 (part 10)-1973.1983. Figure 4. whereas treated soil specimens are tested only for heavy compaction density values.1. The tests are conducted on treated soil specimens for 1.3. treated soil is tested only for heavy compaction density for soaked and unsoaked condition. The tests are conducted using standard equipments and procedure available as per IS: 2720 (Part 11)-1971. “Determination of shear parameters by triaxial test”.Whereas. Results of tests on untreated soil smaple are tabulated in Table 5.1.5: Determination of CBR 4.3.7 Triaxial compression test Tri axial compression test is performed to determine the shear strength parameters (C and Ø) of soil at consolidated undrained condition for treated and untreated soil specimens. Figure 4. 43 . and Vk= the volume of soil specimen read from the graduated cylinder containing kerosene. The procedure involves in taking two oven dried soil samples (passing through 425μ IS sieve).6: Triaxial compression testing setup 4. The final volume of soil is read after 24hours to calculate free swell index.8 Free swell index The free swell index test is conducted to determine the amount of swelling in treated and untreated soil. Vd= the volume of soil specimen read from the graduated cylinder containing distilled water. The free swell index of the soil shall be calculated as follows: Free swell index.Figure 4. The procedure followed is as per IS: 2720 (part-10)-1977. 44 . Water is filled in one cylinder and kerosene (non-polar liquid) in the other cylinder up to 100ml mark.3. 10g each which are placed separately in two 100ml graduated soil sample. percent = ((Vd-Vk)/Vk)*100 Where. Both treated and untreated soil is tested to determine its swell pressure.9 Swell pressure Swell pressure of treated and untreated soil is determined using swell pressure apparatus. Durability of stabilized 45 . The swell test apparatus is designed to determine the swelling pressure developed by expansive soil specimens moulded to desired densities at known moisture contents when soaked in water. The maximum load indicated on the proving ring in kilograms divided by the area of the specimen gives the swelling pressure in kg/cm2. Treated soils are tested after 7 and 28 days of curing.Figure 4.the test is conducted as per IS: 2720(part 11)-1977. on coming into contact with water.7: Free swell index setup 4. is transferred to a load measuring proving ring through a perforated swell plate and a load transfer bar. 4.10 Durability Durability can be defined as the ability of a material to retain its stability and integrity over years of exposure to the destructive forces of weathering.3.3. The load applied to restrain the change in volume caused by the expansive nature of the soil. The data are used to calculate the volume and moisture changes of the soil specimens. This procedure is repeated until the specimens have gone through 12 cycles of freezing and thawing. The specimens are brushed parallel. the specimens are kept in a moisture room for 22 h. Wet and dry cycle: The durability test for wet and dry cycle is performed in accordance with ASTM D559 (ASTM 1994). Freeze and thaw cycle: Durability test procedure for freeze and thaw is followed according to S. weighed and measured after each cycle to obtain soil cement losses. in which. A. Then the specimens are dried at 110°C for 48 hours and their final weight is taken. This test gives the percent mass loss of samples after 12 wet-dry or freeze-thaw cycles.7°C and 100% humidity. Shihata and Z. A. after the 7 days of curing. the specimens are placed in water-saturated felt pads and stood on carriers in a freezer at a temperature not higher than -10°C for 22 h. Triplicate sets of samples of compacted chemical treated soil are prepared and tested for its durability using. After that the specimens are weighed. Briefly.soil is essential in defining the final mixture because it serves as an indicator of its resistance to the destructive forces of environment. On removal. specimens are dried to a constant weight at a temperature of 110°C and weighed to determine the oven-dry weight of the specimens. Baghdadi (2001). this test consisted of exposing the soil–cement specimens to 12 cycles and each cycle consisted of wetting the specimen by submerging it in water at room temperature (25 +1. 46 . After the 12 cycles.5°C) for 5 h after moist curing at 21 + 1. and drying for 42 h at a temperature of 71°C. moisture changes and volume changes (swelling and shrinkage). For this purpose the laboratory experiments are conducted in a fatigue testing apparatus and the specimens are subjected to number of repeated loads. To investigate fatigue behavior of terrabind stabilized soils.9: Samples prepared for freeze-thaw and wet-dry cycle test 4. specimens are exposed to the repeated loading in the laboratory.Figure 4.11 Fatigue test Fatigue life is the number of load cycles corresponding to the failure of the specimen under repeated loading or number of loading. The 47 .3.8: Samples prepared for freeze-thaw & wet-dry cycle test Figure 4. amount of load etc. Bangalore. The main components of the test set-up are: I. Loading system including loading frame and load sensing device ii. Data Acquisition system Figure 4.number of loading cycles varied depending upon curing period.10: Schematic Diagram of Accelerated Fatigue Load Test Set-up 48 . A cylindrical specimen of length to diameter ratio of 2 is used and the treated soil samples are tested for 7 and 28 days curing. a) Specimen Preparation and curing The type of specimen tested for fatigue capacity of the Terrabind stabilized specimen is similar to the one tested for their unconfined compression test. This section describes the methodology adopted for this purpose. The equipment is procured from SPANTROICS. The Fatigue test equipment that is capable of applying the repeated loads at a frequency 0 to 12 Hz is used in the present investigation. Control system including function generator iii. at the selected stress level and frequency) is continued till the failure of the test specimen.  In the control unit through the dedicated software. The load cell is brought in contact with the specimen surface. the selected loading stress level.  The failure pattern of the test specimen is noted down manually. For this propose the following testing procedure is adopted  The Cylindrical specimen is mounted on the loading frame and the Deflection sensing transducers (LVDT) are set to read the deformation of the specimen.e.c) Testing Procedure All the fatigue loading tests are conducted on cylindrical specimens using a fatigue testing equipment. frequency of loading and the type of wave form are fed in to the loading device  The loading system and the data acquisition system is switched on simultaneously and the process of fatigue load application on the test specimen is initiated  The repeated loading. 49 . at the designated excitation level (i. 1: Results of basic soil properties of untreated BC soil.1. For such soil improvement in the strength is achieved by chemical stabilization by converting the soil into a rigid or granular mass. But important exception occurs when compaction gives rise to excess pore pressure.0 3 Consistency limits (%) Liquid Limit 64 Plastic Limit 31 Plasticity Index 33 50 . 5.0 Clay 15. the particles of which are sufficiently strong bound to resist the external pressure. Property Values 1 Specific gravity 2.0 2 Sand 26. Increase in the soil solid volume occupation either by heavy compaction and /or by other mechanical methods always increases the soil strength. SL No. and discussed.1 GENERAL One of the important properties of soil that need to be improved through the addition of admixtures is its strength. In this chapter the results obtained from various tests conducted on untreated soil and treated with Terrabind Stabilizer and combination of terrabind and class CFA has been reported.CHAPTER 5 RESULTS AND DISCUSSIONS 5.0 Silt 54.5 Grain size distribution (%) Gravel 5. Table 5.2 TESTS ON BASIC PROPERTIES OF BLACK COTTON SOIL The results of tests on basic soil properties of BC soil are tabulated in Table 5. compared. S Standard Compaction a) OMC condition b) Soaked condition I.19 268. There is a slight increase in plastic limit with increase in curing time for both the combination.3 CH 16.S standard Compaction a) MDD.20 20. Terrabind and BC. γdmax (kN/m3) b) OMC (%) I. 5.45% 152. 51 .C CBR Value (%) I.89% 28.7 16. γdmax (kN/m3) b) O.45 17.S Standard Compaction I.31% 25. In case of soil treated with Terrabind.S modified Compaction a) MDD. PL has increased by 6% and PI has reduced by 49% for 28 days curing period. LL has reduced by 11%.3.27 RESULTS OF TESTS PERFORMED ON BC SOIL TREATED WITH TERRABIND CHEMICAL AND TERRABIND. Terrabind and FA).4 IS Soil Classification Engineering Properties 5 6 7 I.1 Plasticity Characteristics Table 5.04% 0.2 shows the variation in consistency limits of blended soil for different curing period. plastic limit has increased by 9% and plasticity index has reduced by 30% for 28 days curing period and in case of soil stabilized with Terrabind and FA liquid limit has reduced by 22%.17% 0. From the table it is been observed that there is a gradual and slight decrease in liquid limit and plasticity index with curing days for both the combinations (BC.S Modified Compaction a) OMC condition b) Soaked condition UCS (kN/m2) I. It is also observed that soil stabilized using Terrabind and fly ash has showed better results compared to soil stabilized only with terrabind.S Modified Compaction 5. FA.M. 1.1: variation of liquid limit of treated soil for different curing period. 5.3 shows the graphical representation of variation of liquid limit. 52 .2: Variation of consistency limits of untreated and treated soil for different curing period. 5. Table 5. plastic limit and plasticity index respectively for different curing periods. Figure 5.2.From the results obtained it is clear that the chemical improves the consistency limits of soil and the chemical is more effective when FA is added. Property BC soil LL PL PI 64 31 33 BC+ Terrabind BC+ Terrabind+ FA 1 Day 7 Days 28 Days 1 Day 7 Days 28 Days 60 58 57 55 51 50 33 34 34 29 28 33 27 24 23 26 23 17 62 60 58 Liquid limit(%) 56 TERRABIND 54 52 TERRABIND + FLYASH 50 48 46 44 1 7 Curing period in days 28 Figure5. 5. It can be observed that there is very slight increase in dry density of treated soil.3.40 35 30 Plastic limit(%) 25 TERRABIND 20 15 TERRABIND+ FLY ASH 10 5 0 1 7 28 Curing period in days Figure 5. It can also be observed that dry density increased with increase in curing time and OMC reduced with increase in curing days.5 KN/m3 and 18. Soil stabilized with Terrabind and fly ash has showed better results compared to soil stabilized with Terrabind.8 KN/m3 for soil 53 .3: variation of Plasticity index of treated soil for different curing period.2 Compaction test results Following table shows the IS modified compaction results of treated and untreated soil. 30 Plasticity index 25 20 TERRABIND 15 TERRABIND+ FLY ASH 10 5 0 1 7 28 Curing period in days Figure 5. MDD of soil stabilized with Terrabind for 28 days curing is 18.2: variation of Plastic limit of treated soil for different curing period. 7 17.3. BC soil 1 Day 7 Days 28 Days BC+ Terrabind+ FA 1 7 28 Day Days Days 17.S modified Compaction a) MDD (KN/m3) 18.75 1.9 1. Variation of dry density of treated soil with respect to different curing periods is graphically represented in Fig.C (%) Dry density (KN/ m3) I.8 TERRA BIND + FLYASH 1. Increase in dry density might be due to the Activation of aluminosilicates within soil particles which results in alteration of the ionic exchange responsible for water attraction in soil molecules.29 16.31 16.31 16.7 16. Freeze and Thaw. UCS.3: MDD and OMC of untreated and treated soil for different curing period. Table 5.3 Unconfined compression test results Based on Heavy compaction test results (MDD and OMC).9 18.7 0 7 Curing period in days 28 Figure 5.85 TERRA BIND 1. UCS tests for untreated and treated soil samples were carried out and the test results are presented in the Table 54 .7 17. Swell pressure.0 18.31 16.4. 5.4: variation of maximum dry density of treated soil for different curing period.8 1.11 BC+ Terrabind Property b) O.25 16.5 17. Fatigue. 5.M.21 16. These results were further used for the preparation soil samples for other tests which include CBR.stabilized with Terrabind and fly ash. 5. The strength of soil stabilized with Terrabind (1203 KN/m2) was more compared to soil stabilized with Terrabind and fly ash (971.54 890. From the results it is observed that the strength of soil treated with terrabind has increased by 80% and soil treated with Terrabind and fly ash has increased by 73%.37 971.25 UNCONFINED COMPRESSIVE STRENGTH Strength( KN/m2 ) 1400 1200 1000 TERRA BIND 800 600 TERRA BIND + FLYASH 400 200 0 0 7 28 Curing days Figure 5.23 BC+ Terrabind+ FA 1 Day 7 Days 28 Days 1203. 5.68 792. Variation of unconfined compressive strength of treated soil with respect to different curing periods is graphically represented in Fig.5. Results showed increase in strength with increase in curing time for both the combinations. 55 .5: Variation of unconfined compressive strength of treated soil for different curing period.4.98 743.25 KN/m2).4: Unconfined compressive strength results of untreated and treated soil for different curing period. This enormous increase in strength is due to Terrabind chemical reaction with the clay lattice of the soil which alters the ionic charge in clay and creates a chemical bond between the clay particles. Table 5. BC+ Terrabind Property BC soil UCS 1 Day 268 7 Days 28 Days 414. 55 56 . But in case of soaked condition there is not much increase in CBR.3% and 2.25 40.3 1. It can be observed from the table that the CBR of treated soil at unsoaked condition has increased enormously for both the combinations.34 2.4 CBR test results The results of the CBR tests are tabulated in Table 5.66 Soaked condition 1. Soil stabilized with Terrabind and fly ash has showed better results because addition of cementitous materials like fly ash.09 40.the maximum CBR at soaked condition for 28 days curing period is 2.67 1.5.5. BC+ Terrabind Property CBR Value (%) BC soil 1 Day BC+ Terrabind+ FA 7 Days 28 Days 1 Day 7Days 28 Days Unsoaked condition 28.3.5: CBR test results of untreated and treated soil for different curing period.04 0.69 47.6 and 5. Table 5. From the results obtained it is clear that the chemical improves the unsoaked CBR of soil to a great extent and is more effective when fly ash is added. The unsoaked CBR of soil has increased by 31% and 48% for soil treated with Terrabind and Terrabind+ fly ash respectively.57 2. further strengthens soil because Terabind catalyses the activation of aluminosilicates in soil along with the calcium hydroxide present in cementitous binders . 5.7 for unsoaked and soaked tests respectively.Variation of CBR values with respect to different curing periods are graphically represented in Fig.12 1.4 48.17 33.74 53.55% respectively for soil stabilized using Terrabind and Terrabind+ fly ash. 5.6: Variation of Unsoaked CBR of treated soil for different curing period.2 0 0 7 Curing days 28 Figure 5.4 0.3.maximum cohesion was found to 320 KN/m2 and 350 KN/m2 for soil stabilized with Terrabind and 57 . CBR( SOAKED) 1.8 1.6.6 0. Table shows the variation in cohesion and angle of friction of untreated and treated soil.4 1.5 Triaxial test: Results of Triaxial compression test have been presented in the table 5.7: Variation of Soaked CBR of treated soil for different curing period.CBR ( UNSOAKED ) STRENGTH ( KN/ m2) 60 50 40 TERRA BIND 30 TERRA BIND + FLYASH 20 10 0 0 7 28 CURING DAYS Figure 5.2 TERRA BIND 1 0.it can be observed that cohesion has increased gradually with increase in curing days and angle of failure has also increased with increase in curing days.6 Strength(KN/m2) 1.8 TERRA BIND + FLYASH 0. 72 KN/m2 and 35.33 0 5. This shows that the chemical is very effective in reducing the swelling properties of BC soil. Table 5.3.12 58 . Property BC soil BC+ Terrabind BC+ Terrabind+ FA 1 Day 7 Days 28 Days 1 Day 7 Days 28 Days FSI (%) 50 8.7 Swell pressure Results of swell pressure test have been presented in the table 5. Swell pressure of treated soil was determined after 7 days curing and the swell pressure was found to be 36.33 8. Table 5.6 Free swell index: Results of Free swell index test have been presented in the table 5.8.5: Triaxial compression test results of untreated and treated soil for different curing period BC+ Terrabind BC+ Terrabind+ FA BC soil 1 Day 7 Days 28 Days 1 Day 7 Days 28 Days Property Cohesion ( c ) KN/m2 Angle of failure(Ф) in degrees 90 38 45 160 45 320 54 120 35 230 35 350 36 35 5.3. Swell pressure of treated soil is found to be 49.7: Free swell index test results of untreated and treated soil for different curing period. the swelling was reduced by 83% and 100% for soil stabilized with Terrabind and Terrabind+ fly ash respectively.33 8.33 8.5 KN/m2.33 8. It is observed from the results that the swelling property of black cotton soil has reduced greatly after stabilizing the soil with Terrabind and with the addition of flyash the swelling has reduced to zero with time.7. When free swell index test was conducted after 28 days.Terrabind+FA respectively and angle of failure was found to be 54° and 36° for soil stabilized with Terrabind and Terrabind+FA respectively. 1% for untreated soil.8: Swell pressure test results of untreated and treated BC soil.9 and results of soil treated with Terrabind and Terrabind+FA have been presented in table 5.81%. 4. Table 5.10. Soil Mix Untreated soil Soil +Terrabind Soil +Terrabind+ Flyash Swell Pressure (KN/m2 ) 49. Percentage loss in weight after the last cycle of freez and thaw (12th cycle) was found to be 8.12 5. the samples couldn’t withstand and samples got collapsed within a fraction of seconds. Thus we can say the stabilized soil has increased its durability as the percentage weight loss has reduced by 46% and 59 .11 respectively.72 35.8 shows the results of swell pressure test of untreated and treated soil. soil treated with Terrabind and Terrabind + FA respectively.8 Durability: Wet and Dry method When the samples were immersed in water for the first cycle of wetting. Swell pressure was reduced by 26 % and 29% respectively for soil stabilized with Terrabind and Terrabind+ fly ash respectively.495 36. and 5. Table 5.KN/m2 respectively for soil stabilized with Terrabind and Terrabind+ fly ash respectively. The reduction in swell pressure is due to the action of electrolytic emulsions presents in Terrabind that attacks the clay lattice of soil by altering the ionic charge in clay and breaking down the capillary action of clay soil particles thus reducing the ability for soil particles to attract and retain moisture. From the table we can observe that in most cases percentage loss in weight is more for thawing. Tables show the percentage loss in weight after each cycle. Freeze and thaw test Results of freeze and thaw test on untreated have been presented in table 5.3.75% and 4. 4 7.7 4.7 3.69 151.1 4.93 151.0 2.62 151.9 3.2 150.89 157.5 3.94 151.00 154.6 3.0 4.4 1.9 146.94 151.9 5.3 4.2 149.7 3.3 8.75 151. Figure 5.38 155.2 146. of Cycles 1 2 3 4 5 6 7 8 9 10 11 12 Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw Freeze Thaw BC Soil + Terrabind + FA % % weight weight weigh (gm) loss t loss 0.1 4.1 4.81 151.3 8.6 3.00 152.7 3.0 8.90 157.0 152.56 152.7 7.1 0.3 3.9 2.0 4.2 2.5 3.12 151.1 5.19 154.2 3.9: Freeze and thaw test results of untreated and treated BC soil. Table 5.65 156.56 151.00 151.8 shows the graphical representation of freeze and thaw cycles for untreated and treated BC soil.13 155.7 4.6 7.62 150.3 8.6 149.7 147.3 148.7 9.2 148.44 151.7 7.53% for soil treated with Terrabind and Terrabind + FA respectively.06 151.3 3.5 148.1 7.1 147.9 4.8 153.7 0.3 7.6 3.12 151.9 4.1 BC Soil + Terrabind % weight weight weight (gm) (gm) loss 160.06 157.00 154.2 3.12 151.00 151.8 2.81 153.12 151.0 5.5 60 .69 151.38 156.68 151.95 156.1 8.4 8.0 3.0 4.13 154.4 3.5 149.8 3.5 3.7 5.0 8.12 152.50 151. BC Soil No.8 148.3 7.0 6.12 151.0 4.7 147.3 9.1 5.81 152.3 3.7 3.7 3.3 149.24 151.81 152.62 153.75 151.7 2.5 148.4 148.0 8.0 3.51 155.8 2.2 145.81 153.7 151.9 147.75 154.94 153.0 148.8 148.6 9.4 3.6 2.1 1.3 8.82 155.31 160.0 4. 14. 5.10 9 8 7 6 BC 5 BC+TERRA 4 BC+TERRA+FA 3 2 1 0 1 2 3 4 5 6 7 8 9 10 11 12 Figure 5.3. When 2/3rd of UCS strength was applied the no of cycles for untreated. It can also be observed that number of cycles also depend on amount of stress applied.13. 13365. Number of cycles has reduced with increase in applied stress. and 18560 respectively for soil specimens cured for 28 days. UCS(31.65 50 16 66. and 5.33 10. soil treated with Terrabind and soil treated with Terrabind and FA was found to be 3798.12 and results of soil treated with Terrabind and Terrabind+ FA have been presented in table 5.10: Fatigue test results of untreated BC soil. Table 5.9 Fatigue Test Results of fatigue test on untreated samples have been presented in table 5.99Kg) % of UCS Applied strength stress(Kg) 33.33 61 Fatigue life(No of cycles) 8422 6612 3798 .66 21.8: Graphical representation of freeze-thaw cycles for untreated and treated BC soil. From the tables we can observe that number of cycles has increased greatly for treated soil and number of cycles has increased with increase in curing period. 33 50 66.33 50 66.66 62 Applied stress(Kg) 35.12: Fatigue test results of soil treated with Terrabind and Fly ash.33 50 66.66 33.91 98. Curing period UCS (Kg) Total UCS strength(Kg) 7 days 93.49 57.11: Fatigue test results of soil treated with Terrabind.65 38.17 46.61 28 days 147.97 28 days 115.41 49.66 33.81 % of UCS strength 33.Table 5.1 Fatigue life(No of cycles) 20119 18715 16318 23450 20570 18560 .6 UCS (Kg) % of UCS strength 33.66 Applied stress(Kg) 31.29 52.54 Fatigue life(No of cycles) 15589 12567 10415 20449 16780 13365 Table 5.99 70. Curing period Total UCS strength(Kg) 7 days 105.22 73.81 62.33 50 66.8 77. PL =31%. The improvement in UCS value is very much encouraging. The strength of soil stabilized with Terrabind (1203 KN/m2) is more compared to strength of soil stabilized with Terrabind + FA (971. Amount of clay content plays a major role in the variation of consistency limits.25% and 16. PI has reduced from 26 % for one day curing to 17% for 28 days curing period. “classification of swelling soils”. Untreated soil shows LL=64%. and PI =33%. PI has reduced from 27% for one day curing to 23% for 28 days curing period.31% to 16. Increase in dry density may be due to the activation of aluminosilicates within soil particles which results in alteration of the ionic exchange responsible for water attraction in soil molecules.11% for soil stabilized with Terrabind and Terrabind + FA for 28 days curing period respectively.CHAPTER 6 CONCLUSIONS The following conclusions are drawn from the experimental study 1. 2. For soil stabilized with Terrabind+FA. Since the tested soil contains only 15% of clay. MDD increased from 17. Improvement in dry density of treated soil is marginal. there is no much improvement in Atterberg’s limits.5 KN/m3 and 18. It was also found that as the curing period increases the UCS value also increases.8 KN/m3 for soil stabilized with Terrabind and Terrabind + FA respectively for 28 days curing period. This tendency may be due to effective cation exchange 63 . There is no significant increase in the consistency limits for the chemical treated BC soil. As per IS:1498.7 KN/m3 to 18. Terrabind chemical is found to be effective in increasing the UCS value. the degree of expansion with respect to LL has reduced from high to medium for soil stabilized with Terrabind and FA and with respect to PI degree of expansion has reduced from very high to medium for soil stabilized with Terrabind as well as for soil stabilized with Terrabind and FA. For soil stabilized with Terrabind. 3. OMC was reduced from 16.25 KN/m2). process which generally takes longer period. This enormous increase in strength is due to Terrabind chemical reaction with the clay lattice of the soil which alters the ionic charge in clay and creates a chemical bond between the clay particles. 4. CBR value of treated soil at unsoaked condition increases enormously for both the combinations. The unsoaked CBR value of soil increases from 28.17% for untreated soil to 40.69% and 53.66% for soil stabilized with Terrabind and soil stabilized with Terrabind+FA for 28 days curing respectively. From the results obtained it is clear that the chemical improves the CBR value of the unsoaked soil to a great extent and it is more effective when FA is added to it. Soil stabilized with Terrabind+FA shows better results due to the addition of cementitous materials like FA which strengthens the soil further. Terrabind catalyses the activation of aluminosilicates in soil along with the calcium hydroxide presents in cementitous binders, but in case of soaked condition there is not much increase in CBR. The maximum CBR at soaked condition for 28 days curing period for soil stabilized using Terrabind and Terrabind+FA is 2.3% and 2.55% respectively. 5. From Free Swell Index (FSI) test it was observed that swelling property of BC soil has reduced greatly after stabilizing the soil with Terrabind and with the addition of FA the swelling has reduced to zero with longer curing time. When FSI test was conducted after 28 days, the swelling has reduced by 83% and 100% for soil stabilized with Terrabind and Terrabind+FA respectively. This shows that the chemical is very effective in reducing the swelling properties of BC soil and is found to be more effective when FA is added. As per IS: 1498 “classification of swelling soils”, the degree of expansion with respect to FSI has reduced from medium to low. 6. Swell pressure test results showed that Swell pressure reduced from 49.5 KN/m 2 to 36.72 KN/m2 and 35.12 KN/m2 for soil stabilized with Terrabind and Terrabind+ FA tested after 7 days of curing. Swell pressure was reduced by 26% and 29% for soil stabilized with Terrabind and Terrabind+ FA respectively. The reduction in swell 64 pressure is due to the action of electrolytic emulsions presents in Terrabind that attacks the clay lattice of soil by altering the ionic charge in clay and breaking down the capillary action of clay soil particles thus reducing the ability for soil particles to attract and retain moisture. This shows that the chemical is very effective in reducing the swelling properties of BC soil and is found to be more effective when fly ash is added. 7. From freeze and thaw test it has been observed that the percentage loss in weight after the last cycle of freezing and thawing (12th cycle) is 8.81%, 4.75% and 4.1% for untreated soil, soil treated with Terrabind and soil treated with Terrabind + FA respectively. As per AASHTO, percentage weight loss should be within 14 %. Thus we can say that the stabilized soil is durable. 8. The fatigue analysis conducted based on the UCS test results indicate that the fatigue life has increased greatly after stabilizing the soil. Soil specimen mix prepared with Terrabind and Terrabind + FA exhibited reasonably good fatigue life. 9. Chemical test results on untreated and treated BC soil shows an increase in SiO2, CaO content and pH value and decrease in Fe2O3, MgO, chloride and sulphate content for treated soil when compared with untreated soil. Since a clear trend is not observed, the changes in chemical composition of treated and untreated soil cannot be explained clearly. 6.1 SCOPE FOR FUTURE STUDIES 1. The present study can be extended by adding different proportions of FA with Terrabind. 2. Since a clear trend was not observed in chemical tests of treated and untreated soil, further investigation can be done to understand the effect of chemicals on soil composition. 3. Since Terrabind has given good results on treating it with BC soil, field studies can be conducted 65 REFERENCES Bose, B. (2012). "Geo-Engineering Properties of Expansive Soil Stabilized with Fly Ash." EJGE 17. Cai, Y., Shi,B., Charles, W.W. and Chao, S.T. (2006). “Effect of polypropylene fibre and lime admixture on engineering properties of clayey soil.” Engineering Geology , Elsevier publications., 230–240. Chen, F.H. (1975). “Foundations on Expansive Soils.” Elsevier publications., 120130. Chew, H.S., Kamruzzaman, H.M. and Lee, F.H. (2004). “Physicochemical and engineering behavior of cement treated clays.” journal of geotechnical and geoenvironmental engineering. Estabragh, A., Beytolahpour, I. and Javadi, A. (2011). “Effect of Resin on the Strength of Soil-Cement Mixture.” J. Mater. Civ. Eng., 23(7), 969–976. Gopal, R. and Singh, J. (1983).“Chemical stabilisation of sand, comparative studies on urea-formaldehyde resins as dune sand stabiliser and effect of compaction on strength.” Indian Society of Desert Technology., 13-19. IS: 2720 (part 3)-1980, “Determination of specific gravity, Section-1 Fine grained soils.” Bureau of Indian Standards, New Delhi. IS 2720 (Part 5)-1985. “Determination of Liquid and Plastic limit” Bureau of Indian Standards , New Delhi. 66 Hossain. Basma. H. I. New Delhi. and Gibbs. New Delhi. “Engineering properties of expansive clays.A. and Mol . “Determination of Unconfined Compression Strength” Bureau of Indian Standards . A.I.A.J. 64-663.”Journal of geotechnical engineering. Holtz. IS: 2720 (part 16)-1979.”determination of Free Swell index of soils” Bureau of Indian Standards . “Determination of water content .” Elsevier publications. (1956). (2011). “Determination of shear parameters by triaxial test” Bureau of Indian Standards . IS: 2720 (part-10)-1977. New Delhi. “ Some engineering properties of stabilized clayey soils incorporating natural pozzolans and industrial wastes. and Bashabsheh. M. New Delhi. “Laboratory Determination of CBR” Bureau of Indian Standards .L. “cyclic swelling behavior of clays..I. A. IS: 2720 (Part 11)-1971. 25. K.G.121. New Delhi.. IS: 2720 (part 10)-1973.. IS: 2720 (part-11)-1977.(1995). 67 . Husein. W.” ASCE.”determination of Swelling pressure of soils” Bureau of Indian Standards . New Delhi..Dry Density Relation using Heavy Compaction” Bureau of Indian Standards .IS: 2720 (part 8)-1983.M. Homoud. “Comparison of Fly Ash and Rice Husk Ash Stabilized Black Cotton Soil. 02. R.” Indian geotechnical society. E. “Study on performance of chemically stabilized expansive soil. 27. (2005). (2012). D.L.. D. (2012). K. Y. (1991). 4. poorly graded soil system.” National Lime Association Kendall Publishing Company. (2011). and Jones. P. and Raju. S.” International Journal of Advances in Engineering & Technology. “Field investigation of heave of chemicallystabilised expansive soil subgrades. “ Stabilisation of clayey soils with high calcium fly ash and cement. Muthyalu. Y.. 42-45. 68 . R. Manchikanti. and Blessingstone. V. 3. and Karahalios.” International Journal of Engineering and Technology. 139-148. 4.. (2012).Tripathi. Ramu. V. (2012).A.. “Stabilization of expansive soil using mill scale.. and Raju. 4. Little.K. Smith . P. Kasselouri. A. Koteswara.R.” International Journal of Engineering Science and Technology. Laxmikant. T... and Singh. “Handbook for Stabilization of Pavement Subgrades and Base Courses with Lime. (2005). “Epoxy-resin-based chemical stabilization of a fine. Grissom. W.”Elsevier publications.” International Journal of Earth Sciences and Engineering .. S. S.E. Majebi..K. Murthy.V.” Transportation Research Record. Kolluru.N.Kolias..S. 2. “Effect of Fiber on FlyAsh Stabilized Sub Grade Layer Thickness. A.. “Expansive clay soil a wide spread and costly geohazard. S... “http://terranovatechnologies. “ Stabilization of Organic Soils with Fly Ash.B. Engrs. (2012). M. Nagrale. and Aydilek. E. Sridharan. A. (2012). (2011). K. Sai. (2000). U. 69 . and Kirby.com/. (2004). R. Edil . Rao.” Geostra. Tastan.D. and Salini...S.”Journal of Materials in Civil Engineering. Rao. S. T. P.S. Terra Nova Technologies. K. A. 4. Nangare. Instn . (2012).” Geotech. K.” Thyagaraj. 235-240. Geoinstitute of ohe American Society of Civil Engineers.D. “Classification procedures for expansive soils. Engng..T. Civ.. Satishkumar. Geotech.. Benson. and Prakash.Pankaj.” International Journal of Engineering and Innovative Technology.P. “Laboratory studies on stabilization of an expansive soil by lime precipitation technique.. 819-833.. T..M.” International Journal of Engineering Science and Technology (IJEST). 1. R. Geoenviron.” Proc. and Blessingstone. 5. Warren. T. “Stabilisation of Black Cotton Soil Using Admixtures. Nalawade. ASCE publication.. En. V. “Performance of recron-3s fiber with cement kiln dust in expansive soils.M. K. and Chavhan.W. C. (2011).