EFFECT OF STEEL FIBERS ON FRESH AND HARDENEDPROPERTIES OF SELF COMPACTING CONCRETE A SEMINAR REPORT Submitted by N. SIVA RAMA KRISHNA Roll No: 141519 In partial fulfillment of seminar for the award of the degree Of MASTER OF TECHNOLOGY IN ENGINEERING STRUCTURES Under The Guidance of Dr. S. Venkateswara Rao Assistant Professor in Civil Engineering Department NATIONAL INSTITUTE OF TECHNOLOGY WARANGAL-506004 1 NATIONAL INSTITUTE OF TECHNOLOGY WARANGAL-506004 CERTIFICATE This is certified that N. Venkateswara Rao Assistant professor Department of Civil Engineering 2 . Warangal during academic year 2015-2016 under my supervision. Dr. S. SIVA RAMA KRISHNA has submitted the seminar report on “EFFECT OF STEEL FIBERS ON FRESH AND HARDENED PROPERTIES OF SELF COMPACTING CONCRETE” in the partial fulfillment of the 2nd semester M. To the best of my knowledge the seminar report submitted by him have not been submitted to any university or institute for the award of any degree.Tech course in Engineering Structures as prescribed by the National Institute of Technology. Sai Nitish and Mr.Tech. Assistant Professor in Department of Civil Engineering. Warangal for their support during this seminar work. His help. Finally I express my gratitude to my parents for supporting me in every walk of life. National Institute of Technology.ACKNOWLEDGEMENTS I deeply indebted to my guide Dr. Engineering Structures National Institute of Technology. NIT. NIT Warangal who helped in this course of seminar. N. motivation and constant encouragement throughout the course of this seminar work. advice and guidance have been a constant source of inspiration to us throughout the seminar course. I also thankful to all the faculty members of Civil Engineering Department. Warangal for his invaluable guidance. S. Warangal 3 . Praveen research scholars in department of civil engineering. I will remain thankful to Mr. Siva Rama Krishna M. Venkateswara Rao. filling ability and segregation resistance of the fresh concrete.ABSTRACT Self-compacting concrete (SCC) is an innovative concrete that is able to flow under its own weight. tensile strength and split tensile strength are compared. due to which it will offer little resistance to cracking which leads to sudden failure of the structure.However. and improve several hardened properties such as tensile strength. energy absorption capacity etc. elastic modulus. Steel fibers acts as a bridge to retard their cracks propagation. Hardened properties of concrete such as compressive strength. 4 . J-ring and V-funnel tests were conducted for evaluating the fluidity. addition of fibers to fresh concrete results in a loss of workability. In this seminar the properties of plain self-compacting concrete and selfcompacting concrete with steel fibers is studied... completely filling formwork and achieving full compaction without vibration. With the increase of strength of concrete brittle ness of concrete increases. Slump flow. toughness. 3 Preparation and Casting of specimens 4.4 Results and Discussions 4.3 Indian scenario of SCC CHAPTER-2 LITERATURE REVIEW CHAPTER-3 EFNARC SPECIFICATIONS FOR SCC CHAPTER-4 REVIEW OF JOURNAL PAPER 4.5 Conclusions REFERENCES 5 .1 General 1.2 Advantages of Self Compacting Concrete 1.2 Mix proportions 4.1 Materials 4.CONTENTS CHAPTER-1 INTRODUCTON 1. but also by resistance to segregation between coarse aggregate and mortar when the concrete flows through the confined zone of reinforcing bars. is known to be brittle and can easily crack under low levels of tensile force. In this seminar addition of fly ash and steel fibers effect on fresh and hardened properties selfcompacting concrete is presented.CHAPTER-1 INTRODUCTION 1. toughness. It is used to facilitate and ensure proper filling and good structural performance of restricted areas and heavily reinforced structural members [2]. flexural strength and impact strength of concrete may increase significantly. can be overcome by the inclusion of fibers [3]. the energy absorption capacity. 6 .1 GENERAL Self-compacting concrete (SCC) is considered as a concrete which can be placed and compacted under its self-weight with little or no vibration without segregation or bleeding. But workability of the concrete decreases [4]. Okamura at Ouchi University. SCC. The self-compactibility achieved not only by high deformability of paste or mortar. This inherent shortcoming. Okamura and Ozawa have employed the following methods to achieve self-compactibility: Figure 1: Methods for achieving self-compactibility [1]. which limits the application of this material. like any other concrete. (1) Limited aggregate content (2) Low water-powder ratio (3) Use of super plasticizer SCC was conceptualized in 1986 by Prof. Japan [1]. With addition of steel fibers. 1. Improved durability of the concrete Enhanced productivity Improved surface finish Enhancement in the flow ability Faster construction time Improvement of working environment Higher resistance to segregation Greater freedom in the design of complex geometries Easier to place Increased consumption of industrial waste products such as fly ash Improving the filling capacity of highly congested structural members Reduction in labor cost 1. 7 . This offers following advantages over conventional concrete [13]. Kaiga and Rajasthan Atomic Power Project.2 Advantages of Self compacting Concrete Self-compacting concrete (SCC) is one of the very latest developments in concrete technology. Laboratory studies conducted at SERC Chennai.3 Indian Scenario of SCC In India. the development of concrete possessing self-compacting properties is still very much in its initial stages. does not require to be vibrated to achieve full compaction. The SCC as the name suggests. It is boon to the construction industry. SCC was used by Nuclear Power Corporation of India Ltd at Tarapur. Over the past couple of years. Some pioneering efforts have been made in Delhi Metro Project. Indian Institute of Technology at Madras and Roorkee have given enough inputs and confidence to adopt SCC in India [12]. few attempts were made using European Guidelines for testing SCC in the laboratories and in the field. There are many organization/academic institutions/cement companies in India who are working hard in the laboratory and field for the advancement and use of SCC in structures to minimize carbon emission and making cost effective construction product [11]. 8 .5%. Mustafa Sahmaran. self-compacting ability and other desired SCC properties. I. the mechanical properties. Moreover. V-funnel. L-flow.5% to 4%. Although results obtained from some of the mixes exceeded the upper limits suggested by EFNARC. the flexural strength of the concrete having Waving Steel Fibres (WSF) was higher than that of concrete with Flat Steel Fibres (FSF) and Hook Ended Steel Fibres (HESF) at the same volume fractions of steel up to the limit. as well as type and dosage of super plasticizer to be used are the major factors influencing the properties of SCC. Addition of silica fume. and the results indicated that the proposed method could be used to produce successfully SCC of high quality [5]. metakaolin and fly ash into concrete were 2. 2.5%. In general. The increase is up 3. Slump flow. Ubox and compressive strength tests were carried out to examine the performance of SCC. and the paste of binders was then filled into the voids of aggregates to ensure that the concrete thus obtained has flow ability. V-funnel. all mixes had good flow ability and possessed self-compaction characteristics [15]. It is found that flexural strength is most probably depends on amount of volume fraction than that of type of fiber [14]. fly ash. The flexural strength increases significantly due to the addition of steel fibres compared with normal concrete. the amount of aggregates required was determined which is affected by packing factor (PF). Kung-Chung Hsu and His-Wen Chai (2001) proposed a new mix design method for selfcompacting concrete. So optimum fiber content is 3. and J-ring tests are performed to assess workability. namely the compressive and tensile strengths. First. metakaolin and steel fibers. They used three types of steel fibers such as wave steel fibers (WSF). Hook ended steel fibers (HESF) and flat steel fibers (FSF) with changing volume fraction of steel fibers from 0.5% and 10% by weight of cement content respectively. The amount of aggregates. Alperen Yurtseven. binders and mixing water. Ozgur Yaman (2005) studied the hybrid fiber reinforced self-compacting concrete.5% volume fraction only beyond this fraction flexural strength is decreasing. Slump flow.CHAPTER-2 LITERATURE REVIEW Nan Su. and the ultrasonic pulse velocities of hybrid fiber reinforced-SCC mixtures are also determined at various ages. Vinayak and Mangulkar (2013) investigated the flexural strength of self-compacting concrete specimen produced by silica fume. In which two different types of steel fibers (straight and hooked) with different aspect ratio used. It was observed that it is possible to achieve self-compaction with considerable fiber inclusion (60 kg/m3). the property of self compactibility is maintained. indirect tensile test and flexural test. Decrease in workability is small with the addition of steel fibers in the range of 40-80 kg/m3. S. as well as the comparison on the effects of different type and aspect ratio of fibers to the self-compacted concrete. and flexure strength of self-compacting concrete. They concluded that with increasing fiber fraction rheological parameters are increasing.Safan.75% and 1. Maximum compressive strength is observed at 3% fiber content beyond that increment is marginal. This investigation was carried out using several tests. respectively. The fibers they used are polypropylene fibers and steel fibers. Rathi (2012) aimed to determine and do the comparative study of the properties of concrete containing no fibers and concrete with fibers.0% of the cement content. 50) with 2. including compressive strength. which included workability tests of SCC. Different steel fibers (crimped. And also found that bleeding of fresh concrete is decreased due to addition of fibers. Beyond this volume fraction of steel fibers workability is decreasing more amount due to uneven distribution of fibers. the counterpart specimens contain fibers failed in a ductile manner. Bhalchandra and Amit Bajirao (2012) Aimed to study the mechanical performance of plain SCC and SFRSCC (Steel Fiber Reinforced Self Compacting Concrete) by varying the different volume fractions of steel fibers. Finally they found that compressive strength is increasing with increasing fiber content. compressive test.97% over plain SCC [6].Ponikiewski and Golaszewski (2013) studied the effect of different type of steel fibers on rheological properties. The investigation shows that it is possible to achieve self-compaction with different types of steel fiber with different aspect ratio [10]. The plain SCC specimens failed suddenly in flexure and impact. S. Workability is found out by conducting slum flow test. 9 . and failure was accompanied by several cracks [8]. Sable and K. By using two point workability test they found the rheological parameters yield stress and plastic viscosity. An experimental investigation on the mechanical properties. straight and hook ended) were used at different aspect ratio (80. T50cm. Flexural strength increase is 34. They concluded that Polypropylene fibers have more impact resistance compared to steel fibers. flexural strength and impact strength of fiber reinforced selfcompacting concrete was performed. The results of the investigation showed that: the optimum dosage of steel and polypropylene fiber was 0.Etman and Kasem (2014) Studied the effect of different fibers on the fresh and hardened properties was studied.5% volume fraction in making the concrete. compressive strength. They used the mineral admixture of fly ash. Kamal. Load deflection curves are plotted from them we came to know that energy absorption capacity is increasing with addition of increasing fiber content [7].A. Many different test methods have been developed in attempts to characterize the properties of SCC. Filling ability Passing ability Segregation resistance Filling ability: The ability of SCC to flow into and fill completely all spaces within the formwork. List of some test methods for different parameters of SCC are shown in Table 1. Typical acceptance criteria for Self-compacting Concrete with a maximum aggregate size up to 20 mm are shown in Table 2. under its own weight. 10 . Passing ability: The ability of SCC to flow through tight openings such as spaces between steel reinforcing bars without segregation and blocking. Similarly no single method has been found which characterizes all the relevant workability aspects so each mix design should be tested by more than one test method for the different workability parameters [13].CHAPTER-3 EFNARC SPECIFICATIONS FOR SCC A concrete mix can only be classified as Self Compacting Concrete if the following three characteristics are fulfilled. So far no single method or combination of methods has achieved universal approval and most of them have their adherents. Segregation resistance: The ability of SCC to remain homogeneous in composition during transport and placing. Table 1: List of test methods for workability properties of SCC [13] Table 2: Acceptance criteria for Self-compacting Concrete [13] 11 . Rathi [10].1 Materials 4.3 Coarse Aggregate: Crushed granite aggregate with a maximum size of 12mm having the specific gravity value of 2.70 and fineness modulus of 6.806 are used as fine aggregate.1. the water absorption of 0. 12 .1%.5 Chemical Admixtures: A polycarboxylic type super plasticizer (SP) is used in all concrete mixtures with 1% dosage of weight of cement. Its dosage is 0. 4. The initial and final setting times were found as 74minutes and 385 minutes respectively. The objective of their study is to determine and do the comparative study of the properties of concrete containing no fibers and concrete with fibers. The loose and compacted bulk density values of sand are 1600 and 1688 kg/m3 respectively. 4. Standard consistency of cement was 30%. In addition to the SP. 4. a viscosity modifying admixture (VMA) is also used.4 Fly Ash: Fly ash used with the product name “Pozzocrete60” which available in 30 kg bags.15. The specific gravity of the cement is 3.1. It satisfies all the requirements of the IS 3812: 1981.1.CHAPTER-4 REVIEW OF JOURNAL PAPER This is the research done by S. as well as the comparison on the effects of different type and aspect ratio of fibers to the self-compacted concrete. Sable and K. 4.2 Fine Aggregate: The specific gravity of 2.1.013 are used as coarse aggregate.75 and fineness modulus of 2.1. The loose and compacted bulk density values of coarse aggregates are 1437 and 1526 kg/m3 respectively. the water absorption of 1. 4.5% of weight of cement.4%.1 Cement: The cement used in this experimental work is 53 grade Ordinary Portland Cement which is confining to IS 12269-1987. CR 50/30 4.81 149. Table 3 Mix Proportions [10] S. 13 .484 203.6 Fiber: The main variables used in the study are three different types of steel fibers i.306 1 0. After 24hrs of casting.916 737. The mix proportions are shown in Table 3.49 903.916 737.5 80/60 3. crimped type steel fiber(CR). 0 0 498.5 80 348.484 203.484 203.3 Preparation and Casting of specimens The concrete cubes of size 150*150 are casted to find out the compressive strength.5 % constant dosages of fibers are used by weight of cement.5 2.484 203.81 149. 300 mm height are casted to evaluate split strength of specimens.916 737.306 1 0.1.4.81 149.916 737.306 1 0.49 903. straight type steel fiber(SF) with two values of aspect ratios (80 and 50). SF 80/130 5.5 50 348.306 1 0.916 737.5 50 348. SF 50/80 6. HK 50/30 4.3 0 903.484 203.5 50 348.2 Mix Proportions The grade of the concrete produced is M30. 4.484 203. 30% of the fly ash is replaced with cement.49 903.49 903. Seven different types of the concrete mixes are made with 2.49 903.306 1 0.5%constant dosage of fibers by weight of cement. demoulded the specimens and kept in the specimens in curing pond. The cylinders with size 150mm diameter. hook ended steel fiber (HK).306 1 0. The beams of 100*100*500 mm size are prepared to find out flexural strength.e. 2. HK 80 348.916 737.81 149.81 149.NO Type Aspect Cement Fly ash of ratio (kg/m3) Fine Coarse Water SP (kg/m3) Aggregate Aggregate (kg/m3) (%) fiber (kg/m3) (kg/m3) VMA (%) 1. 30 10. The results of slump flow and V-funnel tests are shown in Table 4. Table 4: Slump flow and V-funnel test results [10] Slump flow S.00 12.02 2 HK 80/60 80 660 4.89-5 sec which are within the limits specified by the EFNARC.59 16. V-funnel flow time is in the range of 7. U-box and J-ring are conducted.2-12. Expect two mixes HK 80/60 and SF 80/130 all other mixes satisfied the EFNARC specifications.56 3 HK 50/30 50 690 4.39 6 CR 50/30 50 705 4. The slump flow is used to assess the horizontal free flow when there is no restriction to the flow. L-box and U-box are for the evaluation of passing ability and J-ring test for stability evaluation.4 Results and Discussion 4.30 12. V-funnel.89 7.10 10.21.50 From the table 4 we can observe that slump flow diameter is in the range of 660-715mm and T50cm is 2.20 9. L-box.1 Fresh Properties of SCC In order to find out the fresh characteristics of Self compacting concrete the tests like slump flow.70 11.23 13.10 8. U-box and J-ring are shown in Table 5. 14 at .20 15. The test results of L-box.4.4. No Type of fiber V-funnel test Aspect ratio Flow Diameter of T50cm(sec) Flow time time flow (mm) (Sec) T5min (Sec) 1 0 0 715 2.21 5 SF 50/30 50 700 4.34 4 SF 80/130 80 670 5.90 12. We can conclude that the two mixes are having high viscosity.59 and V-funnel flow at T5min is 9.02-16. 4.96 6.18 6 CR 50/30 24. No Compressive Strength Split tensile Flexural (MPa) strength Strength Type of Fiber 7 Days 28 Days (MPa) (MPa) 1 0 23.858 30 6 5 SF 50/30 50 0. The variation of compressive strength. 4.821 27 7 3 HK 50/30 50 0. split tensile strength and flexural strength are conducted on the hardened specimens of SCC.57 42.58 5.82 4.60 5. U-box and J-ring in the range of 0.2 Hardened properties of SCC The tests like compressive strength.92 3 HK 50/30 24. figure 3 and figure 4 respectively.60 4.948.02 40.39 32.66 43. Table 6: Results of Compressive strength.68 5.63 15 .00 7.59 6.70 46.58 5 SF 50/30 23.948 10 2 2 HK 80/60 80 0. 10-30mm and 2-7 sec respectively.890 13 3 4 SF 80/130 80 0. split tensile strength and flexural strength shown in figure 2.Table 5: The results of L-box.85 5.898 12 4 The results of the L-box. No Type of fiber Aspect ratio L-box U-box J-ring (h2/h1) ratio H1-H2 (mm) H1-H2 (mm) 1 0 0 0.890 26 4 6 CR 50/30 50 0. U-box and J-ring tests [10] S.97 4 SF 80/130 27.20 4.11 36. The results are shown in Table 6.821-0.93 5. Split tensile strength and Flexural strength at 28 days [10] S. The results are within the limits of EFNARC specifications of SCC.98 2 HK 80/60 29.50 3. HK 80/60 Shows maximum strength. the results shows that addition of fibers increases the split tensile strength. the compressive strength of HK 80/60 if more compared to all other fibers. For the same aspect ratio 50. 16 . For the same aspect ratio with different fibers HK 50 having more split tensile strength than CR 50 and SF 50. HK fibers shows more strength and SF shows lowest strength. Split tensile strength (MPa) 8 Split tensile strength 7 6 5 4 Split tensile strength (MPa) 3 2 1 0 0 HK 80/60 HK 50/30 SF 80/130 SF 50/30 CR 50/30 Type of fiber Figure 3: Split tensile strength at 28 days From figure 3.Compressive strength at 28 days Compressive Strength (MPa) 50 45 40 35 30 25 20 Compressive Strength 15 (MPa) 10 5 0 0 HK 80/60 HK 50/30 SF 80/130 SF 50/30 CR 50/30 Type of fiber Figure 2: Compressive strength at 28 days From Figure 2. The flexural strength of SF fibers is lower than other two types of fibers. With increasing aspect ratio viscosity of the concrete increases which will leads to decrease the ability to flow.5 Conclusions It is possible to achieve self-compaction with the addition of different steel fibers with different aspect ratios. it is obvious that the hook end and crimped fiber have good bond and anchorage in the matrix resulting in more strength. It is observed that for the same aspect ratio the hook ended fiber shows improvement in all properties of concrete as compared to the crimped & straight fiber. 17 .98 to 6. Flexural strength is reduced in the same type of fiber when aspect ratio is lowered.89MPa and Flexural strength ranges from 4. The straight fibers have less strength as compared with hook end and crimped fibers because of their shape. Split tensile strength ranges from 3. Due to the shape.50 to 46. Aspect ratio 80 haven’t satisfied the V-funnel test results specified by the EFNARC. The maximum percentage increase is 28. The SCC developed compressive strengths ranging from 32. All mixes are having good flowing ability.Flexural Strength (MPa) 8 Flexural Strength 7 6 5 4 Flexural Strength (MPa) 3 2 1 0 0 HK 80/60 HK 50/30 SF 80/130 SF 50/30 CR 50/30 Type of fiber Figure 4: Flexural strength at 28 days From figure 4.03%.92MPa at the end of 28 days. 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