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M.tech thesis

Following are some suggestions for future research. As GFRSCC technology is now being adopted in many countries throughout the world, in the absence of suitable
standardized test methods it is necessary to examine the existing test methods and identify or, when necessary, develop test methods suitable for acceptance as International Standards. Such test methods have to be capable of a rapid and reliable assessment of key
properties of fresh SCC on a construction site. At the same time, the testing equipment should be reliable, easily portable and inexpensive. The test procedure should be carried out by a single operator and the test results have to be interpreted with a minimum of training. Also, the results have to define and specify different GFRSCC mixes. One primary application of these test methods would be in verification of compliance on sites and in concrete production plants, if self- compacting concrete could be manufactured in large quantities..

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M.tech thesis

  1. 1. STUDY ON THE STRESS-STRAIN BEHAVIOUR OF HIGH STRENGTH GLASS FIBRE REINFORCED SELF-COMPACTING CONCRETE UNDER AXIAL COMPRESSION WITH & WITHOUT CONFINEMENT A DISSERTATION SUBMITTD IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF Master of Technology in Structural Engineering By B.VENKATARAJU (06014D2023) DEPARTMENT OF CIVIL ENGINEERING JNTUH COLLEGE OF ENGINEERING, KUKATPALLY HYDERABAD – 500085, AP, INDIA (AUTONOMOUS) MARCH – 2011
  2. 2. STUDY ON THE STRESS-STRAIN BEHAVIOUR OF HIGH STRENGTH GLASS FIBRE REINFORCED SELF-COMPACTING CONCRETE UNDER AXIAL COMPRESSION WITH & WITHOUT CONFINEMENT A DISSERTATION SUBMITTD IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF Master of Technology in Structural Engineering By B.VENKATARAJU (06014D2023) Under the guidance of Dr.M.V.SESHAGIRI RAO DEPARTMENT OF CIVIL ENGINEERING JNTUH COLLEGE OF ENGINEERING, KUKATPALLY HYDERABAD – 500085, AP, INDIA (AUTONOMOUS) MARCH – 2011
  3. 3. DEPARTMENT OF CIVIL ENGINEERING JNTUH COLLEGE OF ENGINEERING, KUKATPALLY HYDERABAD– 500085, AP, INDIA. CERTIFIACTE This is to certify that the dissertation work entitled “Study On The Stress- Strain Behaviour Of High Strength Glass Fibre Reinforced Self-Compacting Concrete Under Axial Compression With & Without Confinement” that is being submitted by B.VenkataRaju, HT No: 06014D2023 in partial fulfillment for the award of M.Tech in “Structural Engineering” to the Department of Civil Engineering, JNTUH College of Engineering, KUKATPALLY, Hyderabad, is a record of bonafide work carried out by him under my guidance and supervision. Signature of Head Project Guide Dr. P.SRINIVASA RAO Dr.M.V.SESHAGIRI RAO, Professor and Head of the Proffesor of Civil Engineering Deparment of Civil Engineering Dept. of Civil Engineering JNTUHCE, Hyderabad-85 JNTUHCE, Hyderabad-85 i
  4. 4. DECLARATION BY THE CANDIDATE I, B.VenkataRaju, bearing HT. No: 06014D2023 hereby declare that the report of the Post Graduate Thesis work entitled “Study On The Stress-Strain Behaviour Of High Strength Glass Fibre Reinforced Self-Compacting Concrete Under Axial Compression With & Without Confinement”, which is being submitted to the JNTUH College of Engineering, Kukatpally, in partial fulfillment of the requirements for the award of the Degree of Master of Technology in Structural Engineering., 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 or diploma. Place: JNTUHCE, Kukatpally, Hyderabad Date: ii B.VENKATARAJU H.T.No: 06014D2023 Ph: +919177263599 Ph: +919440904158 e-mail: bvraju1766@gmail.com Department of Civil Engineering, JNTUHCE, Hyderabad.
  5. 5. Dedicated to DEAR and NEAR ONES iii
  6. 6. ACKNOWLEDGEMENT I sincerely thank my advisor Dr. M.V.SESHAGIRI RAO, Professor in Civil Engineering for his guidance, suggestions, and continuous support throughout my Project. I greatly appreciate all the support that he has been given to me, both on this thesis and during the entire period in which I have been working for him. My profound thanks to Dr. P.SRINIVASA RAO, Professor and Head of the Department of the Civil Engineering, JNTU College of Engineering from for his valuable suggestions and help is carryout this dissertation work. For the assistance and help he provided as being my co-advisor here at JNT University and also during my Project work. I express my sincere gratitude to Dr. N.V.RAMANA RAO, Principal & professor, JNTUH College of Engineering for his constant encouragement during the project work. The support and help provided by him good self during this work is invaluable. I would like to thank Smt. P.SRI LAKSHMI, Assistant professor of Civil Engineering, JNTUH College of Engineering, for sparing her valuable time in clarifying my doubts during my project work. I would like to thank M/s Grasim Industries Limited, manufactures of Ultra tech cement for extended co-operation in free supply of cement for research purpose to conduct this project work. I also acknowledge the sincere and untiring efforts of Engr.Devaraj who assisted me during all stages of my experiments and also helped me in preparing the experimental set-up utilized in this study. Thanks are due to the laboratory personnel for their substantial assistance in the experimental work Finally, my special thanks to all my professors & friends, who rendered valuable help. I had taken, which helped me complete my Master’s Degree in Technology. (B.VENKATA RAJU) M.Tech (Structural Engineering) Department of Civil Engineering JNTUHCE, Hyderabad-85 iv
  7. 7. ABSTRACT A self-compacting concrete (SCC) is the one that can be placed in the form and can go through obstructions by its own weight and without the need of vibration. Since its first development in Japan in 1988, SCC has gained wider acceptance in Japan, Europe and USA due to its inherent distinct advantages. Although there are visible signs of its gradual acceptance in the Middle East through its limited use in construction, Saudi Arabia has yet to explore the feasibility and applicability of SCC in new construction. The contributing factors to this reluctance appear to be lack of any supportive evidence of its suitability with local marginal aggregates and the harsh environmental conditions. Concrete is a vital ingredient in infrastructure development with its versatile and extensive applications. It is the most widely used construction material because of its mouldability into any required structural form and shape due to its fluid behaviour at early ages. However, there is a limit to the fluid behaviour of normal fresh concrete. Thorough compaction, using vibration, is normally essential for achieving the required strength and durability of concrete. Inadequate compaction of concrete results in large number of voids, affecting performance and long-term durability of structures. Self-compacting concrete (SCC) provides a solution to these problems. As the use of concrete becomes more widespread the specifications of concrete like durability, quality, and compactness of concrete becomes more important. Self -Compacting Concrete is recently developed concept in which the ingredients of the concrete mix are proportioned in such a way that it can flow under its own weight to completely fill the formwork and passes through the congested reinforcement without segregation and self consolidate without any mechanical vibration. Self – Compacting Concrete (SCC) is a very fluid concreter and a homogeneous mixture that solves most of the problems related to ordinary concrete. This specification helps the execution of construction components under high compression of reinforcement. In this work an attempt has been made to study Stress – Strain behaviour of Glass fibre Self–Compacting Concrete under confined and unconfined states with different percentages of confinement (in the form of hoops). Since the confinement provided by lateral circular-hoop reinforcement, is a reaction to the lateral expansion of concrete, lateral reinforcement becomes effective only after considerable deformation in the axial v
  8. 8. direction. Complete Stress – Strain behaviour has been presented and an empirical equation based on rational polynomial is proposed to predict the stress – strain behaviour of such concrete under compression. The proposed empirical equation shows good correlation with the experimental results. There is an improvement in the Compressive Strength, Secant modulus and this is due to the addition of the glass – fibres to the Self- Compacting concrete and also confinement in the form of hoops in Self-Compacting Concrete mix. Key words: Glass-fibre, Reinforced Self – Compacting Concrete, 6mm diameter Mild steel, admixtures, Stress – Strain behaviour, A single Polynomial empirical equation. vi
  9. 9. TABLE OF CONTENTS Certificate ……...………………………………….…………………………………….. i Declaration by the Candidate …………….…………………………………………….. ii Acknowledgement …………………………………………………………………..…. iv Abstract ………………………………………………...………………………………...v Table of Contents …......................................................................................................... vii List of Figures …………………………………………………………………………. xvi List of Tables ……………………………………………………………………...…….xix Notations and Abbreviations ………………………………………………………........xxi CHAPTER 1: INTRODUCTION………………………………………………….1-37 1.0 . Introduction to Self-Compacting Concrete ......………………..…………………….1 1.0.1. Advantages and disadvantages of Self-Compacting Concrete……………1 1.0.2.Definition and Properties of Self-Compacting Concrete…………………....3 1.1. Historical Development of Self-Compacting Concrete……………….…..………....4 1.2. World-wide Current Situation of Self-Compacting Concrete …………………...…...5 1.2.1. Japan………………………………………………………………………...6 1.2.2. Europe ……………………………………………………………………...8 1.2.3. European Development …………………………………….……….….....10 1.2.4. Scandinavia ………………………………………………….…………….12 1.2.5. France ……………………………………………………………………..12 1.2.6. Germany …………………………………………………………………..13 1.2.7. Belgium …………………………………………………………………...13 1.2.8. Spain ………………………………………………………………………14 1.2.9. Holland ……………………………………………………………………14 1.2.10. Switzer Land …………………………………………………………….14 1.2.11. Italy ………………………………………………………………………14 1.2.12. Other European countries ………………………………………………..15 1.2.13. UK Development ………………………………………………………...15 1.2.14. Academic Institutions ……………………………………………………16 vii
  10. 10. 1.2.15. Concrete Producers ……………………………………………………...16 1.2.16. Admixture suppliers ……………………………………………………..17 1.2.17. Consultants ………………………………………………………………17 1.2.18. Contractors ………………………………………………………………18 1.2.19. UK Precasters ……………………………………………………………18 1.2.20. Seminars and events ……………………………………………………..18 1.2.21. The Future ……………………………………………………………….17 1.3. Motive for Development of Self-Compacting Concrete ……………………………21 1.4. Construction Issues …………………………………………………………………22 1.5. Applications of Self-Compacting Concrete ………………………………………...22 1.6. Existing Tests for Fresh SCC Mixes ………………………………………………..25 1.6.1. Filling ability..…………….……………………………………………....25 1.6.2. Passing ability.………….…….….………………………………….....…25 1.6.3. Resistance to segregation...……………………………………………….25 1.6.4. U-type test...……………………………………………………………....25 1.6.5. Slump Flow test...………………………………………………………....26 1.6.6. L-Box test ………..…………………………………………………….…26 1.6.7. Orimet test...……………………………………………………………....27 1.6.8. V-funnel test...……………………………………………………….……27 1.6.9. Slump Flow/J-Ring combination test………………………………...…...28 1.6.10. Orimet/J-Ring combination test.……...……………………………...….28 1.6.11. GTM Segregation test...……………………………………………..…..29 1.7. Development of Prototype ……………………………………………………….....29 1.8. Scope and Objectives of Investigation …………………...…………...…………….30 1.8.1. Models of the Specimens ……………….………………..……………….32 1.8.2. Advantages of Reinforced Structures …………… ……………………….33 1.8.3. Investigations on Self-Compacting Concrete……………………………...34 1.8.4. Mix-design method ……………………….………………………..…......34 1.8.5. Evaluation method for materials ……………………………………….…34 1.9. Acceptance Test at Job Site ………………………………………………………....35 1.10. New structural design and construction systems …………………………………..36 viii
  11. 11. CHAPTER 2: LITERATURE REVIEW…………………….................................38-86 2.0 General …………………………………...………………….……………………...38 2.1 Previous Research Work on Self-Compacting Concrete ……….…...………………38 2.1.1 Hajime Okamura ……………………………………..….………………39 2.1.2 Kazumasa Ozawa ……………………………………..…………………41 2.1.3 Subramanian and Chattopadhyay ………………………..………………41 2.1.4. Khayat et al ……………………………………………….……………..43 2.1.5. Dehn et al. ……………………….……………………….……………...44 2.1.6. Kuroiwa ………………………………………………….………………45 2.1.7 Ferraris et al………………………………………………...…………….46 2.1.8 Anirwan Senu Guptha et al[2006] ……………………………………….49 2.1.9. ACI committee report No.226 [1987]…………………………..……......49 2.1.10. Gibbs, [1999] ………………………………………………….…………50 2.1.11. Manu Santhanam,[2008] ……………………………………..……...50 2.1.12. Hemant Sood[3] Et Al, [2009] …………………………………..………50 2.1.13. Kazim Turk[3] Et Al, [2007] ……………………………………...……..50 2.1.14. Srinivasa Rao.P, [2008] ……………………………………………...…..51 2.2 Constituent Materials for SCC ………………………………………………………51 2.2.1. Powder (Mixture of Portland cement and Filler)………………………...51 2.2.1.1 Cement …………………………………………………………..51 2.2.1.2 Filler ……………………………………………………………..52 2.2.2 Aggregates …………………………………………………………………54 2.2.3 Admixtures ………………………………………………………………...56 2.2.4 Ranges of the quantities of the Constituent Materials for SCC …………...57 2.3 Hardened Properties of SCC ………………………………………………………...58 2.3.1 Compressive, Tensile, and Bond Strength ………………………………...58 2.3.2 Modulus of Elasticity ……………………………………………………...59 2.3.3 Shrinkage and Creep ………………………………………………………59 2.3.4. Durability…………………………………………………………………...60 2.3.5 Water Absorption and Initial Surface Absorption ………………………...63 2.3.6 Water Permeability ………………………………………………………..63 2.3.7 Rapid Chloride Permeability ………………………………………………64 ix
  12. 12. 2.4. Influence of Admixtures on Concrete Properties …………………………………...65 2.5. Mineral Admixtures ………………………………………………………………...65 2.6 Blast Furnace Slag ………………………...……………………………………..…..65 2.7 Fly Ash …………………………………………...………………………………….67 2.8 Silica Fume …………………………………...………………………………….…..69 2.9 Chemical Admixtures ……………………………………………………………..…71 2.10 Superplasticizers ..…………………………………...……………………………...72 2.11 Viscosity Modifiers ..……………………………………………………………….75 2.12 Bonding between Aggregate and Cement Paste ………………….………………..78 2.13 Examples of Self-Compacting Concrete Applications ………………………….….80 2.14 Criteria………………………………………………………………………………..82 2.14.1 Guidelines in Japan…………………………………………………………82 2.14.2 Guidelines in Europe……………………………………………………......83 CHAPTER 3: SELF-COMPACTING CONCRETE COMPOSITION…..........87-103 3.0 Introduction….…………………………………………………....………………….87 3.1 Portland Cement ………………………………………………………..……………88 3.2 Aggregates ……………………………………………………………….…………..92 3.3 Blast Furnace Slag ………………………………………………………..………….92 3.4 Fly Ash ………………………………………………………………………………93 3.5 Silica Fume ……………………………………………………………….………….96 3.6 Superplasticizers …………………………………………………………..…………97 3.7 Viscosity-Modifying Admixtures ……………………………………...…...……….99 3.8 Fibres …………………...……………………………………………….………….100 3.8.1. The effect of fibres on workability………………………………………101 3.8.2. Maximum fibre content…………………………………………………..101 3.9 Concrete Mix and Tests ………………………………………………………...….102 CHAPTER 4: DESIGN OF A SUITABLE SCC MIX…….…………………104-121 4.0. Materials for Self-Compacting Concrete ………………………………………….104 4.0.1. Cement ………………………………..…………………………..……..104 4.0.2. Aggregates ………………………………………………..……………..104 x
  13. 13. 4.0.2.1. Fine aggregate .......……………………………………….……104 4.0.2.2. Coarse aggregate ………………………………………………104 4.0.3. Admixtures ………………………………………………………….…...104 4.0.3.1. Mineral Admixtures ………………………………………..….104 4.0.3.2. Fly ash …………………………………………………………………106 4.0.3.2.1. Advantages of Fly ash ……………………………….106 4.0.3.2.2 Environmental Protection …………………………….107 4.0.3.2.3. Areas of usage of Fly ash ……………………………107 4.0.3.2.4. Chemical Admixtures ………………………………..108 4.0.4. Superplasticizer ………………………………………………………...109 4.0.4.1. Advantages of Superplasticizer ………………………………..109 4.0.4.2. Dosage ………………………………………………………..109 4.0.5. Viscosity modifying Agent (VMA) ………………………………….….109 4.0.5.1. Advantages ………………………………………………….…111 4.0.5.2. Dosage …………………………………………………………111 4.0.6. Water ……………………………………………………….……………111 4.1. Mix Design ……………………………………………………………….………..112 4.1.1. Mix Design Principles.…...……………………………..…..…..………..113 4.1.2. General requirements in the Mix Design ……………………………..…114 4.1.2.1. A high volume of paste ………………………….…….…..…..114 4.1.2.2. A high volume of fine particles (<80m) ………………..…..…114 4.1.2.3. A high dosage of super plasticizer ………………………….…114 4.1.2.4. The possible use of viscous agent (water retainer) ……….…...114 4.1.2.5. A low volume of core segregate ………………………….…...115 4.1.3. Mix Design ………………………………………………………..……..115 4.1.4. Various procedures for Mix Design …………………………………..…117 4.2. By EFNARC Guidelines …………………………………………………………..119 4.2.1. Guidelines to find reasons of Faulty mixes ……………………..……….119 4.2.2. Mix Design and Trial Proportion …………………………………..……120 CHAPTER 5: QUALITY ASPECTS OF SELF -COMPACTING CONCRETE ……………………………………………………. 122-143 5.0. Test Methods ………………………………………………………………....……122 xi
  14. 14. 5.0.1. Introduction …….……………………………………………..…………122 5.0.2. Slump Flow Test / and T50 cm test ……………………………………...123 5.0.2.1. Assessment of test ………………………………………….….123 5.0.2.2. Equipment ………………………………………………...…...123 5.0.2.3. Procedure …………………………………………………....…124 5.0.2.4. Interpretation of results ……………………………………......125 5.0.3. V funnel test ……………………………………………………………..125 5.0.3.1. Introduction ….…………… ………………………………......125 5.0.3.2. Assessment of test …..………………………… ……….…..…125 5.0.3.3. Equipment ………………………………………… ….……....126 5.0.3.4. Procedure of flow time ………………………………..…….....126 5.0.3.5. Procedure for flow time at T 5 minutes ……………..…………127 5.0.3.6. Interpretation of results …………………………….....……….127 5.0.4. L –Box test method ……………………………………………...………128 5.0.4.1. Introduction ………….……….………………...………..…….128 5.0.4.2. Assessment of test ………………………….……………..…...128 5.0.4.3. Equipments …………………………………..………………...129 5.0.4.4. Procedure …………………………….………..…………….…130 5.0.4.5. Interpretation of results ………………………...…………..….130 5.1. Case Studies Overseas ………………………………………………..……..……..130 5.1.1. Shark and Pengium Aquariums at the Oceanopole MarineParkinBrest. …………………………………………...…..……..130 5.1.1.1 Main project description ……………………………….....…….130 5.1.1.2. Why SCC was used …………………………………..….…….131 5.1.1.3. Project requirements …………………………………..…...…..131 5.1.2.Basement for Research and Development building in Tokyo, Japan ….....131 5.1.2.1. Main project description ……………………………………...131 5.1.2.2. Why SCC was used ……………………………………………131 5.1.3. Pipe screen for a Tail Tunnel at the Meinrad Leinert Square,Zurich, Switzerland...…………………………………………...131 5.1.3.1. Main project requirements ……………………………….....…131 5.1.3.2. Why SCC was used ……………………………………………132 xii
  15. 15. 5.1.4. Modular hotel room units by old castle Precast Rehoboth, MA (USA) ………………………………………………….132 5.1.4.1. Main project description………………………………...……...132 5.1.4.2. Why SCC was used ……………………………………….…...132 5.1.5. Case study in land ……………………………………………...…….….132 5.2. Requirements of Self-Compacting Concrete ...…………………………...……….133 5.2.1.Application area …………………………………………………..……………...133 5.2.2. Requirements ……………………………………………………..….…133 5.2.2.1. Filling Ability …………………………………………….……133 5.2.2.2. Passing Ability ………………………………………….……..134 5.2.2.3. Resistance to Segregation ………………………………...……134 5.3. Workability criteria for the fresh SCC ………………………………………….....136 5.4. Complexities Involved In Making SCC ………………………………………...…137 5.5. Limitations of SCC ……………………………………………………...………...138 5.6. Advantages of SCC ………………………………………………………………..138 5.6.1. Some Architectural Advantages of SCC Include ……………………....139 5.7. Economic Impact of Self-Compacting Concrete In Precast …………..…………...140 5.7.1. Applications ………………………………………………..……..…...142 5.8. Perfomance …………………………….…………………………………………..142 CHAPTER 6: EXPERIMENTAL PROCEDURES..……………………..........144-181 6.0. General……………………………………………………………………………..144 6.1. Introduction ………………………………………………………………………..144 6.2. Research Significance ……………………………………………………………..145 6.3. Experimental Program ……………………………………………………………..145 6.4. Materials Used …………………………………………………………..…………145 6.4.1. Cement …………………………………………………...…….………..145 6.4.2. Fine aggregate ………………………………………………….………..146 6.4.3. Coarse aggregate ………………………………………………..……….146 6.4.4. Mineral Admixtures ……………………………………………..………147 6.1.4.1. Fly ash …………………………………………………………147 xiii
  16. 16. 6.4.5. Chemical Admixture ……………………………………………..……...147 6.4.6. Viscosity Modifying Agent ……………………………………….……..148 6.4.7. Glass Fibres ……………………………………………………….……..148 6.1.7.1. Effect of Glass fibre on Bleeding ………………………………...148 6.1.8. Water ……………………………………………………………….……149 6.5. Mix Proportion ………………………………………………………………..…...149 6.5.1. Trail Mixes ………………………………………………………….…...149 6.6. Development of Glass Fiber Reinforced Self Compacting Concrete(GFRSCC)….150 6.7. Workability…………………………………………………………………………151 6.8. Testing of SCC in Fresh State.………………………………………………….….151 6.9. Specimen Preparation …………………………………………………………...…151 6.10.Casting ...……………………………………………………………………….….152 6.11.Curing ………………………………………………………………………....…..152 6.12.Compressive Strength ………………………………………………...………..…152 6.13. Tests of GFRSCC With and Without Confinement in Hardened State …….……153 6.14. Failure mode of Test Specimen in Compression …………………………..…….154 6.15. Comparison with Conventional Concrete to GFRSCC ...………………………...156 6.15.1. Conventional Concrete ………………………………………………....156 6.15.2. Glass Fibre Reinforced Self Compacting Concrete (GFRSCC) ….........156 6.16. Development of Analytical Stress-Strain models for GFRSCC with & without Confinement ……………………………………………………………………157 6.16.1. Effect of fiber on Ultimate strength and strain …………………………157 6.16.2. Relationship between Fiber Index, stress ratio and strain ratio ………...158 6.16.3. Ductility factor Vs Fiber Index ………………………………………...160 6.16.4. Non Dimensionalised stress – strain curve …………………………….161 6.16.5. Model caluculations for Normalised stress – Normalised Strain curve of GFRSCC (0.798% Confinement)………………………………………162 6.17. Experimental Results ……………………………………………………………..165 6.17.1. Stress-Strain values of Cylinder without confinement (M50 grade GFRSCC)…………………………………………………………….…165 6.17.2. Stress-Strain values of Cylinder with 0.798% confinement (M50 grade GFRSCC)……………………………………………………….………168 xiv
  17. 17. 6.17.3. Stress-Strain values of Cylinder with 1.062% confinement (M50 grade GFRSCC)………………………………………………………….……171 6.17.4. Stress-Strain values of Cylinder with 1.327% confinement (M50 grade GFRSCC)………………………………………………………….……174 6.17.5. Stress-Strain values of Cylinder with 1.591% confinement (M50 grade GFRSCC)………………………………………………………….……177 CHAPTER 7: DISCUSSIONS OF THE TEST RESULTS...…..……………....182-188 7.0. Discussions ………………………………………………………………………...182 7.1. Characteristics of GFRSCC Mixes in Hardened State …………………………….183 7.1.1. Compressive Strength ……………………………………………...……183 7.1.2. Modulus of elasticity ……………….……………………………………183 7.1.3. Secant Modulus ………………………………………………………….183 7.1.4. Stress-Strain behaviour with & without confinement……………………184 7.1.5. Energy absorption capacity (Toughness) ………………………………..185 7.1.6. Ductility ………………………………………………………………….186 7.1.7. Analytical expressions.…………………………………………………...186 CHAPTER 8: CONCLUSIONS AND RECOMMENDATIONS……………..189-205 8.0. Conclusions ………………………………………………………………………..189 8.1 Recommendations for Future Research ………………………………………….192 BIBLIOGRAPHY ………………………………………………………………194 APPENDIX A …………………………………………………………………..200 VITA ……………………………………………………………………………205 xv
  18. 18. LIST OF FIGURES Figure No. Title. Page No. 1.0 Excellent finish of a neat cement SCC…………………………………………………..2 1.1. Necessity of Self-Compacting Concrete (Ouchi and Hibino, 2000) ………………..21 1.2. Rational construction system proposed by Ozawa (Ouchi et al., 1996) ………..….22 1.3 Annual production of SCC in Japan Total production of ready-mixed concrete in Japan in 19997 is 67,620×1,000 m ………………………………………………..…23 1.4 Anchorage 4A of Akashi-Kaikyo Bridge …………………………………………...24 1.5 U-type test (Ouchi and Hibino, 2000) ……………………………………………….26 1.6 V-funnel (Dietz and Ma, 2000) ……………………………………………………...27 1.7 Slump Flow/J-Ring combination test (Kosmatka et al., 2002) ……………………...28 1.8. Cylinder without any confinement …………………...……………………………..32 1.9. Cylinder with confinement ………………………………………………………….32 1.10 Rational acceptance test at job site for self-compacting concrete (Ouchi and Hibino, 2000) .......……………………………………………..………………..36 1.11 Anchorage of Akashi-Kaikyo Bridge, Japan (Ouchi and Hibino, 2000) …………..37 2.1. Small pipes used as obstacles in formwork (Okamura, 1997) ...……………………39 2.2 Effect of super plasticizer on viscosity (Okamura, 1997)……………………………40 2.3 Compressive strength of SCC with and without HPMC (Subramanian and Chattopadhyay, 2002) ……………………………………………………………..43 2.4 Pullout specimen (Dehn et al., 2000) ………………………………………………..45 2.5 Viscosity –Yield stress and the workability box (Ferraris et al., 1999) ……………..48 2.6 Rational mix-design method for self-compacting concrete (Ouchi et al., 1996) ……74 2.7 Anchorage of Akashi-Kaikyo Bridge, Japan (Ouchi and Hibino, 2000) ……………81 2.8 Sandwich structure applied to immersed tunnel in Kobe, Japan (Ozawa, 1989) ……82 3.1 Materials used in regular concrete and self-compacting concrete by absolute volume (Kosmatka et al., 2002) …………………………...…………..88 3.2. Microstructural development in Portland cement pastes (Mindess et al., 2003) …...90 3.3 SEM micrograph of fly ash particles (Kosmatka et al., 2002) ………………………94 xvi
  19. 19. Figure No. Title. Page No. 3.4 Effect of microsilica in densifying the concrete mix - comparison between conventional and microsilica concretes (St John, 1998) …………………………….97 3.5 Effect of superplasticizer on cement: (a) Cement and water; (b) Cement, water, and superplasticizer (Ramachandran, 1984) ………………………...……….98 3.6 Dispersing action of water-reducing admixtures: (a) flocculated paste; (b) dispersed paste (Mindess et al., 2003) …………………………………………...99 4.1. Mix design flow chart ……………………………..……………………………...114 5.1. Showing the apparatus of Slump Flow and slump flow in (a) & (b) respectively....123 5.2. Showing the apparatus of V-funnel test ……………...………………...………….126 5.3. L-Box Apparatus …………………………………………………………………..129 5.4. Showing the performance of Conventional Concrete & SCC in (a) and (b) respectively …………………………………………………………………………143 6.1 Casted cylinder specimen tested UTM …………………………………………….155 6.2 Casted cube specimen under tested under Compression testing machine………….155 6.3. Cracks being visible on the test specimen ………………………………………....156 6.4. Typical Stress-Strain behaviour of (M50 grade GFRSCC) with and without confinement at 28 days………………………………………………………....157 6.5. Stress ratio (fu/f') Vs Fiber Index…………………………………………………..159 6.6. Strain ratio (єu/є) Vs Fiber Index …………………………………………………159 6.7. Fiber Index Vs Ductility Factor …………………………………………………...160 6.8. Normalised Stress – Normalised Strain…………………………………………….161 6.9. Stress-Strain behaviour of GFRSCC without confinement………………………..167 6.10. Normalized Stress-Strain Curve of GFRSCC without Confinement……………..167 6.11. Stress-Strain behaviour of GFRSCC (0.798% Confinement)………………….....170 6.12. Normalized Stress-Strain Curve of GFRSCC (0.798% Confinement)………..….170 6.13. Stress-Strain behaviour of GFRSCC (1.062% Confinement) ………………..…..173 6.14. Normalized Stress-Strain Curve of GFRSCC (1.062% Confinement)………..….173 6.15. Stress-Strain behaviour of GFRSCC (1.327% Confinement) ……………..176 6.16. Normalized Stress-Strain Curve of GFRSCC (1.327% Confinement)…………...176 xvii
  20. 20. 6.17 Stress-Strain behaviour of GFRSCC (1.591% Confinement) …………………….179 6.18. Normalized Stress-Strain Curve of GFRSCC (1.591% Confinement)………….. 179 6.19. % of Different confinements Vs % of Improvement of compressive Strength…..180 7.1. Typical Stress-strain behavior of GFRSCC with and without confinement ………182 7.2 Graphical representation of increase in strength, Specific Toughness with different confinements …………………………………………..…………...187 7.3 Graphical representation of increase in strength, Energy Absorption (% increase) with different confinements ………………………………………….188 7.4 Graphical representation of increase in strength, ductility (% increase) with different confinements ………………………………………….188 xviii
  21. 21. LIST OF TABLES Table No. Title. Page No. 1.1. SCC Guide line and specification development in Europe as of September 2001 (Based up on a paper by Dingenouts ………………………………9 2.1. Chemical composition and Physical characteristics of Super-pozz® (SeedatandDijkema, 2000)…………………………………………….……………..52 2.2 Assessment of Concrete Permeability according to Water Penetration Depth(TheConcreteSociety, 1987)……………………………………………….….63 2.3 Relationship between charge passed and chloride permeability (ASTM C-1202-94)………………………………………………………………….65 3.1 Typical composition of ordinary Portland cement (Mindess et al., 2003) …………..88 3.2: Concrete composition, dry materials……………………………………………….103 4.1. Typical Properties of Glenium-2 ………………………………………………..…119 4.2. Mix composition as per EFNARC guidelines ……………………………………..110 5.1. List of methods for workable properties of SCC ………………………………….135 5.2 Workability properties of SCC and alternative methods …………………………..136 5.3 Acceptance criteria for SCC as per EFNARC guide lines …………………………136 6.1. Physical properties of Cement ……………………………………………………..146 6.2. Chemical compositions of Cement as per manufacturers test report ...……………146 6.3 Physical characteristics of VTPS fly ash …………………………………………...147 6.4 Chemical composition of VTPS fly ash ……………………………………………147 6.5. Properties of Selected Glass Fibres ………………………………………………..148 6.6. Details of Mix proportion for SCC M50 grade ……………………………………150 6.7 Quantities per m3 of the final mix arrived for GFRSCC M50 grade …………….…150 6.8. Fresh properties of GFRSCC ……………………………………………………...151 6.9. Hardened properties of GFRSCC with & without Confinement at 28days (Cylinder) ……………………………………………………………….153 6.10 Compressive strength of Cubes tested at 28 days (without Confinement) ……….154 6.11. Peak Stress and Peak Strain values of M50 grade GFRSCC with different confinement variation …………………………………………………………..158 xix
  22. 22. Table No. Title. Page No. 6.12 Stress-Strain values of Cylinder without confinement (M50 gradeGFRSCC) ………………………….................................................165 6.13 Stress-Strain values of Cylinder with 0.798% confinement (M50 gradeGFRSCC) ………………………………. ……………………...168 6.14 Stress-Strain values of Cylinder with 1.062% confinement (M50 gradeGFRSCC) ………………………………………………………....171 6.15 Stress-Strain values of Cylinder with 1.327% confinement (M50 gradeGFRSCC) …………………..………………………………………174 6.16 Stress-Strain values of Cylinder with 1.591% confinement (M50 gradeGFRSCC) …………………..……………………………………....177 6.17. Peak stress values and strain values corresponding to peak stress ……………….180 6.18 Stress Strain Equations for Different Confinements of M50 Grade GFRSCC..……………………………………………….............181 7.1 Secant Modulus of GFRSCC ……………………………………………….…….184 7.2 Constants A1, B1 values for Ascending & Descending Portions ……………...…..185 7.3 Young’s Modulus of Elasticity, Energy absorption and ductility values For GFRSCC with and without confinement reinforcement ………………………185 8.1. Peak stress and Peak strain for Different confinements of GFRSCC ...…………...192 xx
  23. 23. NOTATIONS AND ABBREVIATIONS EASEC East-Asia Structural Engineering Construction ECC Engineering Construction and Contracts ITZ Transition Zone Interfacial LNG Liquid Nitrogen Gas μm Micrometer (micron) RILEM International Union of Laboratories and Experts in Construction Materials, Systems and Structures SEM Scanning Electron Microscope TC Technical Committee W/C Water to Cement Ratio WSM Workability of Fresh Special Concrete Mixes Fi Fibre Index Ec Young’s Modulus, N/mm² E ant sec Secant Modulus, N/mm²  Strain f Stress in N/mm² fu Ultimate Stress, N/mm² u Strain corresponding to ultimate stress fu/f’ Stress Ratio ; єu/є’ Strain Ratio GF SCCp GFSCC without confinement GFR 0.798 SCC GFRSCC with 0.798% confinement GFR 1.062 SCC GFRSCC with 1.062% confinement GFR 1.327 SCC GFRSCC with 1.327% confinement GFR 1.591 SCC GFRSCC with 1.591% confinement 3R Three rings, 6mm diameter 4R Four rings, 6mm diameter 5R Five rings, 6mm diameter 6R Six rings, 6mm diameter xxi
  24. 24. CHAPTER 1 Introduction
  25. 25. CHAPTER 1 Introduction 1.0. Introduction to Self-Compacting Concrete Development of self-compacting concrete (SCC) is a desirable achievement in the construction industry in order to overcome problems associated with cast-in-place concrete. Self-compacting concrete is not affected by the skills of workers, the shape and amount of reinforcing bars or the arrangement of a structure and, due to its high-fluidity and resistance to segregation it can be pumped longer distances (Bartos, 2000). The concept of self-compacting concrete was proposed in 1986 by professor Hajime Okamura (1997), but the prototype was first developed in 1988 in Japan, by professor Ozawa (1989) at the University of Tokyo. Self-compacting concrete was developed at that time to improve the durability of concrete structures. Since then, various investigations have been carried out and SCC has been used in practical structures in Japan, mainly by large construction companies. Investigations for establishing a rational mix-design method and self-compactability testing methods have been carried out from the viewpoint of making it a standard concrete. Self-compacting concrete is cast so that no additional inner or outer vibration is necessary for the compaction. It flows like “honey” and has a very smooth surface level after placing. With regard to its composition, self-compacting concrete consists of the same components as conventionally vibrated concrete, which are cement, aggregates, and water, with the addition of chemical and mineral admixtures in different proportions (see Chapter 3). Usually, the chemical admixtures used are high-range water reducers (superplasticizers) and viscosity-modifying agents, which change the rheological properties of concrete. Mineral admixtures are used as an extra fine material, besides cement, and in some cases, they replace cement. In this study, the cement content was partially replaced with mineral admixtures, e.g. fly ash, slag cement, and silica fume, admixtures that improve the flowing and strengthening characteristics of the concrete. 1.0.1 Advantages and disadvantages of Self-Compacting Concrete Compared to NVC, SCC possesses enhanced qualities, and its use improves productivity and working conditions (De Schutter et al., 2008; The Concrete Society and BRE, 2005). 1
  26. 26. Because compaction is eliminated, the internal segregation between solid particles and the surrounding liquid is avoided which results in less porous transition zones between paste and aggregate and a more even colour of the concrete (RILEM TC 174 SCC, 2000). Improved strength, durability and finish of SCC can therefore be anticipated. Very good finish effect is shown in Figure 1.0, a pure cement SCC placed in a steel mould, demoulded 24hours after casting. The surface is so smooth and dense that it can reflect light. Figure 1.0 Excellent finish of a neat cement SCC For much concrete construction, the structural performance is improved by increasing reinforcement volumes, limiting cracking by using smaller bar diameters and using complex formwork, all of which increase the difficulty of compaction (Okamura and Ouchi, 2003a; RILEM TC 174 SCC, 2000). SCC meets the above developments by making casting homogeneous concrete in congested structures possible; it also improves efficiency and effectiveness on site by reducing the construction time and labour cost. SCC also improves the workplace environment by reducing noise pollution and eliminating the health problems related to the use of vibration equipment such as ‘white fingers’ and deafness (RILEM TC 174 SCC, 2000). SCC is therefore called ‘the quiet revolution in concrete construction’ (The Concrete Society and BRE, 2005). As a result, the precast concrete products industry has become the biggest user of SCC in Europe (Skarendahl, 2003). SCC requires higher powder and admixture (particularly superplasticisers) contents than NVC and so the material cost is higher (The Concrete Society and BRE, 2005). It was reported that in most cases, the cost increase ranged from 20% to 60% compared to similar 2
  27. 27. grade NVC (Nehdi et al., 2004; Ozawa, 2001). However, in very large structures, increased material cost by using SCC was outweighed by savings in labour costs and construction time (Billberg, 1999). The benefits of SCC were fully displayed in a composite sandwich system, which involves casting SCC and NVC in layers within the same structural elements (Okamura and Ouchi, 2003a; Ouchi, 2001; Ozawa, 2001). The increased content of powder and admixture also leads to higher sensitivity (i.e. reduced robustness) of SCC to material variation than that of NVC; thus greater care with quality control is required (Walraven, 1998). 1.0.2 Definition and Properties of Self-Compacting Concrete It is important at this stage to define SCC and its characteristics. Literally, self-compacting characteristics are related to the fresh properties. The definitions of SCC given in the literature vary, a most common one is that‘ a concrete that is able to flow under its own weight and completely fill the form work, whilemaintaining homogeneity even in the presence of congested reinforcement, and then consolidating without the need for vibrating compaction’ (The Concrete Society and BRE, 2005). SCC has three essential fresh properties: filling ability, passing ability and segregation resistance Testing-SCC, 2005; The Concrete Society and BRE, 2005). Filling ability is the characteristic of SCC to flow under its own weight and to completely fill the formwork. Passing ability is the characteristic of SCC to flow through and around obstacles such as reinforcement and narrow spaces without blocking. Segregation resistance is the characteristic of SCC to remain homogeneous during and after transporting and placing. It is passing ability that distinguishes SCC from other high consistence concrete (Domone, 2000). Additional properties, such as robustness and consistence retention, are also important in applications of SCC. Robustness refers to the ability of SCC to retain its fresh property when the quality and quantity of constituent materials and the environmental conditions change. Consistence retention refers to the period of duration of the fresh properties. 3
  28. 28. A number of commonly used tests are subsequently described for evaluating the fresh properties. There is no difference in test methods for hardened properties (strength, stiffness, and durability etc.) between SCC and NVC. Both fresh and hardened properties are key to the successful application of SCC. SCC therefore can be designed by fresh or hardened requirements. 1.1 Historical Development of Self-Compacting Concrete Self-compacting concrete, in principle, is not new. Special applications such as underwater concreting have always required concrete, which could be placed without the need for compaction (Bartos, 2000). In such circumstances vibration was simply impossible. Early self-compacting concretes relied on very high contents of cement paste and, once superplasticizers became available, they were added in the concrete mixes. The mixes required specialized and well-controlled placing methods in order to avoid segregation, and the high contents of cement paste made them prone to shrinkage. The overall costs were very high and applications remained very limited. The introduction of “modern” self-leveling concrete or self-compacting concrete (SCC) is associated with the drive towards better quality concrete pursued in Japan around 1983, where the lack of uniform and complete compaction had been identified as the primary factor responsible for poor performance of concrete structures (Dehn et al., 2000). Due to the fact that there were no practical means by which full compaction of concrete on a site was ever to be fully guaranteed, the focus therefore turned onto the elimination of the need to compact, by vibration or any other means. This led to the development of the first practicable SCC by researchers Okamura and Ozawa, around 1986, at the University of Tokyo and the large Japanese contractors (e.g. Kajima Co., Maeda Co., Taisei Group Co., etc.) quickly took up the idea. The contractors used their large in-house research and development facilities to develop their own SCC technologies. Each company developed their own mix designs and trained their own staff to act as technicians for testing on sites their SCC mixes. A very important aspect was that each of the large contractors also developed their own testing devices and test methods (Bartos, 2000). In the early 1990’s there was only a limited public knowledge about SCC, mainly in the Japanese language. The fundamental and practical know-how was kept secret by the large corporations to maintain commercial advantage. 4
  29. 29. The SCCs were used under trade names, such as the NVC (Non-vibrated concrete) of Kajima Co., SQC (Super quality concrete) of Maeda Co. or the Biocrete (Taisei Co.). Simultaneously with the Japanese developments in the SCC area, research and development continued in mix-design and placing of underwater concrete where new admixtures were producing SCC mixes with performance matching that of the Japanese SCC concrete (e.g. University of Paisley / Scotland, University of Sherbrooke / Canada) (Ferraris, 1999). 1.2. World-wide Current Situation of Self-Compacting Concrete Self-compacting concrete has already been used in several countries. In Japan, major construction projects included the use of SCC in the late ’90s. Today, in Japan, efforts are being made to free SCC of the “special concrete” label and integrate it into day-to-day concrete industry production (Okamura, 1997). Currently, the percentage of self-compacting concrete in annual product of ready-mixed concrete (RMC), as well as precast concrete (PC), in Japan is around 1.2% and 0.5% of concrete products. In the United States, the precast industry is also leading SCC technology implementation through the Precast/Prestressed Concrete Institute (PCI) which has done some research on the use of SCC in precast/prestressed concretes starting with 1999 (Bartos, 2000). It is estimated that the daily production of SCC in the precast/prestressed industry in the United States will be 128000 m3 in the first quarter of 2011 (around 1% of the annual ready-mix concrete). Furthermore, several state departments of transportation in the United States (23 according to a recent survey) (Bartos, 2000)are already involved in the study of SCC. With such a high level of interest from the construction industry, as well as manufacturers of this new concrete, the use of SCC should grow at a tremendous rate in the next few years in the United States. However, even if it is made from the same constituents the industry has used for years, the whole process, from mix design to placing practices, including quality control procedures, needs to be reviewed and adapted in order for this new technology to be applied properly. Research regarding the self-compacting concrete was also carried out in Canada, few years after the concept was introduced in Japan. Institute for Research in Construction, Canadian Precast/Prestressed Concrete Institute, CONMET-ICON, and ISIS are some of the bodies which studied various aspects of the new technology. 5
  30. 30. The introduction of the SCC in Europe is largely connected with the activities of the international association RILEM, France, particularly of its Technical Committee TC145-WSM on “Workability of Fresh Special Concrete Mixes” (Dhir and Dyer, 1999). The TC145-WSM was founded in 1992 and immediately attracted expert memberships from all over the world. The aim was to look at the production stage of a number of “special” concretes and identify workability parameters and other characteristics of the mixes in their fresh state that governed the reliable and economical achievement of the “special” or “high-performance” parameters the concretes offered. As the importance of the SCC became widely recognized, other European countries, Germany, Sweden, UK, Denmark, Netherlands, Norway, Finland, etc., have decided to keep up with the developments in this area. For example, in Sweden, the SCC market share was at five percent in RMC and PC in 2010, and was expected to double in 2012. Housing and tunneling, as well as bridge construction for the Swedish National Road Administration were the main areas of use for SCC. In the Netherlands and Germany, the precast industry is mainly driving the development of SCC, with an expected eight percent of market share in 2012 in Netherlands. Today, self-compacting concrete is being studied worldwide, with papers presented at almost every concrete-related conference, but until now - year 2003 - there is no universally adopted standardized test method for evaluation of self-compactability of this concrete. Currently, the use of self-compacting concrete is being rapidly adopted in many countries. The use of self-compacting concrete should overcome concrete placement problems associated with the concrete construction industry. However, there still is a need for conducting more research and development work for the measurement and standardization of the methods for the evaluation of the self-compacting characteristics of SCC. 1.2.1. Japan SCC was first developed in Japan in 1988 in order to achieve more durable concrete structures by improving the quality achieved in the construction process and the placed material. The removal of the need for compaction of the concrete reduced the potential for durability defects due to inadequate compaction (e.g. honeycombing). 6
  31. 31. The use of SCC was also found to offer economic, social and environmental benefits over traditional vibrated concrete construction. These benefits included faster construction and the elimination of noise due to vibration. One of the main drivers for the development of the technology was the reduction in the number of skilled site operatives that the Japanese construction industry was experiencing in the 1980s. The use of SCC meant that less skilled labour was required for the placing and finishing of the concrete. SCC was developed from the existing technology used for high workability and underwater concretes, where additional cohesiveness is required. The first research publications that looked into the principles required for SCC were from Japan around 1989 to 1991. These studies concentrated upon high-performance and super-workable concretes and their fresh properties such as filling capacity, flowability and resistance to segregation. The first significant publication in which ‘modern’ SCC was identified is thought to be a paper from the University of Tokyo by Ozawa et al. in 1992. The term ‘self-compacting concrete’ is not used within the paper, although a high-performance concrete was produced which possessed all the essential properties of a self-compacting concrete mix. In the following few years many research papers were published on concretes such as super-workable, self-consolidating, highly-workable, self-placeable and highly-fluidised concretes, all of which had similar properties to what we now know as SCC. These were mainly papers on work into the mix design of what would become ‘SCC’ and its associated fresh properties. In 1993, research papers were beginning to be published of case studies on the use of these early forms of ‘SCC’ in actual applications. One of the first published references utilising the term ‘self-compacting’ was in Japan in 1995. After the development of this prototype SCC, intensive research began in many places in Japan, especially within the research institutes of large construction companies, and as a result, SCC has now been used in many practical applications. The first significant international workshop dedicated to the material was held at Kochi University of Technology, Japan in August 1998. The majority of these papers 7
  32. 32. focused upon the development of SCC in different countries, including research and development into mix design models, mix constituents and rheology. In April 1997, the Japanese Society of Civil Engineers (JSCE) set up a research subcommittee with the aim of establishing recommendations for the practical application of SCC. This was subsequently published in English in August 1999. The 2nd International Symposium on SCC was organized by the University of Tokyo in October 2001. A total of 74 papers plus two keynote and four invited speakers from 20 countries were included. Since the 1st International Workshop had concentrated mainly upon mix design and rheology, the 2nd International Symposium concentrated more on the long-term durability and life-cycle cost of SCC. A conference was recently held in Japan in October 2002 on Concrete Structures in the 21st Century, which contained six papers on SCC, including four from Japan. These papers illustrated that the basic technology of the material in Japan is relatively well understood and that the majority of current efforts in research and development are concentrated on taking this knowledge further into new applications such as composite structures and sheet piling 1.2.2. Europe In the second half of the 1990s, interest and use of SCC spread from Japan to other countries, including Europe. Some of the first research work to be published from Europe was at an International RILEM (International Union of Testing and Research Laboratories of Materials and Structures) Conference in London in 1996. Papers were presented on the design of SCC by University College London, and a mix-design model by the Swedish Cement and Concrete Research Institute (CBI). A Technical Committee (TC 174-SCC) was set up by RILEM in 1997 with the objective of gathering, analysing and presenting a review of the technology of SCC, as well as looking for unified views on testing and evaluation. Seventeen full members and three corresponding members covering ten countries on four continents took part in the work and a state-of-the-art report was published in 2000. 8
  33. 33. Sweden was the first country in Europe to begin development of SCC, and in 1993 the CBI organised a seminar in Sweden for contractors and producers, leading to a project aimed at studying SCC for housing. As part of this project, large numbers of half-scale house walls were cast using SCCs which were made with different filler materials. The work from this project contributed to the first European project on SCC which began in January 1997 and was completed in 2000. The main goal of this Brite-EuRam project (BRPR-CT96-0366) was to develop a new vibration-free production system to lower the overall cost of in-situ-cast concrete construction. The first part concerned the development of SCC with or without steel fibres and the second part dealt with full-scale experiments in civil engineering and housing. This project included partners from several European countries, including the UK. Parallel to this Brite-EuRam project, CBI continued work together with the Swedish National Roads Authority (SNRA) into SCC for bridge casting. Laboratory investigations, pre-qualifying tests, half-scale trials and finally full-scale trials were all completed. The first of three bridges wholly cast in SCC was completed in January 1998 and is thought to be the first bridge cast with this material outside of Japan. This work also showed that the hardened properties of SCC are superior to conventional concrete, including compressive strength, frost resistance, permeability and reinforcement bond strength. This is thought to be mainly due to both the increased cementitious content generally used and the denser interfacial transition zone between the aggregate and the paste of SCCs. Studies also showed that total bridge building costs can be reduced by as much as 5–15% when using SCC compared with conventional concrete. An earlier report on the same work was also published by the SNRA. This report concluded that as well as reducing overall bridge costs, using SCC has the potential to reduce the energy consumption and emission of greenhouse gases by 20–30% due to the reduced resources required in the construction process and the enhanced durability of the resultant concrete. However, it does not take into account the likely increased cement content used to make the SCC and the additional energy required for its production. 9
  34. 34. The first major event dedicated to SCC in Europe was the 1st International RILEM Symposium on SCC in Stockholm in 1999. The papers included 23 from Asia, 38 from Europe, five from North America and one from Australia. The symposium attracted 340 participants from 35 countries, which is a ratio of 5 to 1 of participants to papers, indicating the increasing interest in the material in Europe. 1.2.3. European Development Development and use of SCC began to quickly spread from Sweden to other Scandinavian countries at the end of the 1990s. The concrete industry in countries such as France and the Netherlands have also recently been developing and using the material, with countries such as Germany and the UK progressing closely behind. All of these countries have now used SCC in both in situ and precast applications. Countries such as Greece and the Eastern European countries are still mainly conducting research and development or are at the initial site trial stage. Two European-wide research projects are currently under way in the field of SCC. 1. Following the completion of the European-wide SCC Brite- EuRam project in 2000, it was clear that the remaining fundamental obstacle to the material’s wider use in Europe was the absence of suitable test methods to identify its three key properties (i.e. passing ability, filling ability and resistance to segregation). The EU therefore agreed to support an additional three-year project from 2001 to 2004 through its Growth programme (Growth Project GRD2- 2000-30024) to develop test methods for SCC and to prepare the way for European standardisation. The project involves twelve European partners and is led by the University of Paisley, Scotland. 2. A RILEM committee was also formed in September 2000 to focus on assembling relevant existing knowledge on various aspects on the casting of SCC. The committee aims to build further on the work of RILEM TC 174-SCC mentioned in the previous section and the objective is to find links between the fundamental basic mechanisms of SCC and the current practical experience regarding SCC. The knowledge will be further developed through technical discussions and a workshop and will result in a report on the existing available knowledge on the casting of SCC. 10
  35. 35. A specification and guideline document has recently been produced by EFNARC (European Federation of Producers and Contractors of Specialist Products for Structures) which aims to provide a framework for the design and use of high-quality SCC in Europe based on the latest research findings combined with field experience. It is probably the first European guidance document to be universally available, and is freely available on the internet. It is intended that the document be updated as SCC technology evolves and advances. Most of the major European countries are currently in the process of developing guidelines or specifications for the use of SCC. Table 1 shows a snapshot of the current stage in the development of SCC guidelines or specifications for each of the European countries listed. Table 1.0 SCC Guide line and specification development in Europe as of September 2001 (Based up on a paper by Dingenouts Country Guideline Organization Acceptance Phase Publication Date Austria n/a Draft 2002 Denmark n/a Draft in preparation n/a Europe EFNARC Guideline 2002 Finland n/a Draft 2003 France AFGC Industry recommendation 2000 Germany Annex to DIN 1045 For comment 2003 For comment 2003 Italy Annex to EN 206 In preparation 2002 BRL1801 Approval n/a Netherlands TC73/04 Accepted 2001 Norway Norwegian Concrete Society Accepted 2002 Sweden Swedish Concrete Assoc. (SCA) Accepted 2002 11
  36. 36. 1.2.4. Scandinavia As described earlier, Sweden was at the forefront of the development of SCC outside Japan and it is estimated that SCC now accounts for approximately 7–10% of the Swedish ready-mix market, up from approximately 3% in 2000. Currently, the CBI, four universities and the government in Sweden are all conducting research into SCC. SCC is often used in Sweden today by contractors such as NCC on a commercial basis. NCC and other Swedish contractors are also conducting research into SCC, both internally and with other companies and universities/institutes. The Swedish Concrete Association (SCA) has also recently published recommendations for the use of SCC. The volume of SCC produced in Norway has increased from approximately 0·5% (or 12 000 m3) of total concrete volume in 2000 to approximately 1·2% (or 29 500 m3) in 2001. A Norwegian guideline for the production and use of the material was issued in late 2001 and an English translation has recently been completed. SCC is used in Finland only to a limited degree, although companies such as Lohja Rudus and Parma Betonila each have experience from approximately 10–20 construction sites. There is also a national project on the practical aspects of SCC led by the Technical University of Helsinki (HUT) and VTT which began in 2001 and will finish in 2003. No SCC standardisation as yet exists. Universities in Denmark, such as the DTU (Technical University of Denmark), have also recently undertaken research into SCC, as well as holding training courses on SCC. The first project investigating SCC in Iceland was from 1996 to 1999 and was a collaboration between the Icelandic Building Research Institute (IBRI) and an Icelandic ready-mix concrete company, Steypusto¨ UNKNOWN SYMBOL 240 FONT¼Times New Roman in H. F., which showed that it was possible to cast SCC in Iceland with Icelandic materials. IBRI continue to conduct research into SCC and they are hosting the 3rd International Symposium on SCC in August 2003. 1.2.5. France France is quite active in the research and development of SCC. A national research project on SCC called BAP (Be´tons auto-plac¸ants) is currently ongoing. French recommendations for the use of the material were established in July 2000 and are used as reference on construction sites. 12
  37. 37. The Lafarge Group have conducted a large amount of research and development at their Laboratoire Central de Recherches (LCR) at L’Isle d’Abeau, near Lyon. Their progress in the development of SCC is approximately two years ahead of the position in the UK. They have spent approximately £2 million on researching and developing the material internationally and currently produce approximately 50,000 m3/annum of SCC, with this volume increasing almost exponentially at present. The Lafarge Group wanted to validate the assumption that using SCC generates an overall cost saving. They therefore worked with a contractor to simultaneously construct two identical apartment buildings in Nanterre, France. Conventional concrete methods were used for one building and for the second building the construction process was adapted to utilize SCC materials and processes. The building constructed using SCC materials and processes was completed 2·5 months before the conventionally constructed building and with an overall project cost saving of 21·4%. 1.2.6.. Germany In Germany, SCC requires technical approval before it can be used on site. The current DIN standards do not allow this type of concrete to be used because the consistency and the fines content do not comply with the standard. Therefore, the DIBt (German Institute of Technical Approvals in Berlin) requires suitability tests from a third-party laboratory, usually universities, who then issue an official approval. Many contractors have obtained approvals and are constructing with SCC. At least six different universities and research establishments in Germany are also conducting research into SCC. The University of Stuttgart is also involved with the current European-wide SCC test methods project (Growth GRD2-2000- 30024). 1.2.7. Belgium A Belgian national contact group on SCC exists chaired by Professor De Schutter of the University of Ghent. This group of universities, contractors, suppliers and other interested parties meet several times a year to discuss SCC development in Belgium. Several national research projects on SCC are also currently under way, funded mainly by the National Fund for Scientific Research, Flanders, and other interested parties. These projects are investigating the transport of potentially aggressive media in SCC, the spalling behaviour of SCC and the integration of SCC into the building industry. 13
  38. 38. 1.2.8. Spain SCC production is just beginning in Spain, but the first structures have already been constructed in Malaga, Valencia and Madrid. The current problem is that SCC is not included in the basic Spanish regulations for concrete, and so care has to taken and its use fully justified. Instituto Eduardo Torroja de Ciencias de la Construccio´n (CSIC) is leading the standardisation group for SCC in the Spanish National Standardisation Agency (AENOR). The target is to issue some Spanish standards on SCC by the end of 2002. They are also collaborating with other Spanish research groups such as UPC (Universitat Polite`cnica de Catalunya) in Barcelona 1.2.9. Holland The precast concrete industry in the Netherlands first became interested in SCC in 1998. A project was begun to develop SCC precast applications by the Belton Group, an association of 24 precasters, which is a subsidiary of BFBN (Association of the Dutch Concrete and Precasting Industry). Although the Belton project was formally completed in December 1999, intensive collaboration in SCC is still continuing. In 2002 a total volume of 2,50,000 m3of precast SCC is expected to be produced and approximately 30 companies have been certified for the production of SCC pre-cast elements. Guidelines for ready-mix SCC are finished and are expected to be approved by the end of 2002, at which point the certification of ready-mix plants can begin. Currently, ready-mix SCC is being used, but mainly for demonstration projects. 1.2.10. Switzerland SCC currently accounts for approximately 1% of the ready-mix concrete market in Switzerland and the material has largely been developed by trial and error. The use of SCC is currently not limited by Swiss standards because the standards apply to performance and not the composition of concrete. Research into SCC has been conducted at the Swiss Federal Institute of Technology (ETH) in Zurich and at the EMPA (Swiss Federal Institute for Materials Testing and Research) in Du¨bendorf. 1.2.11. Italy In Italy the majority of SCC applications are in the precast market, although SCC has been used for in situ applications. The Italian Standards Institute has just completed a 14
  39. 39. document on SCC, which is now being considered as a Standard (as an annex to EN 206- 1). The Italian Ready-Mixed Concrete Producers Association is also preparing guidelines on SCC. 1.2.12. Other European countries Other countries in Europe such as the Czech Republic and Greece are also beginning to research and construct with SCC. A bridge abutment and an experimental tunnel lining have both been cast with SCC in Prague and a trial was held for the use of SCC in the 2·5 km cable-stayed bridge over the Corinthian Gulf in Greece. 1.2.13. UK Development Until about four years ago, interest in SCC in the UK was largely confined to research studies at Paisley University and University College London (UCL). There has, however, been a rapid increase in interest from UK industry in the last three years. Two of the first site applications were in 2000 for the Midsummer Place shopping centre extension in Milton Keynes and the Millennium Point project in Birmingham. The Concrete Society in the UK formed a working party early in 1999 consisting of 18 experts from universities, suppliers, producers, designers and contractors with the aim to maintain a watching brief on the impact and uptake of SCC in the UK. They have recently produced both an information sheet and Part 1 of a Current Practice Sheet. The Part 1 report deals with materials, properties, production and placing of SCC. At the time of writing, Part 2, which will cover production, placing and optimisation of the construction process, was 90% complete. A three-year research project into SCC in the UK is also currently being conducted by the Building Research Establishment’s (BRE) Centre for Concrete Construction. This work is funded by the UK Department of Trade and Industry’s (DTI’s) Construction Industry Directorate. The aim of the project is to encourage the wider use of SCC by the UK construction industry, and to demonstrate the economic, social and environmental advantages it offers over traditional vibrated concrete construction. The work involves consulting with UK industry on its perceptions of SCC, researching the production of SCC mixes suited to industry needs and disseminating this and additional information through demonstration events and the publication of case studies and guidance material. 15
  40. 40. 1.2.14. Academic institutions The leading academic institution in the UK with regard to SCC is the Advanced Concrete and Masonry Centre at the University of Paisley. This team is led by Professor Bartos and also includes John Gibbs and Dr Mohammed Sonebi. They were key members of the original Brite-EuRam project (BRPR-CT96- 0366) mentioned in the previous section and are leading the current European-wide project on test methods. In addition, Professor Bartos is Chairman and John Gibbs the Secretary of the Concrete Society Working Party on SCC. Paisley University also began an 18-month Government-funded research project in December 2001 aimed at reducing the cost of SCC and encouraging its use in general construction. As mentioned earlier, the other academic institution in the UK with a history of research into SCC is University College London (UCL). The work into SCC is being coordinated by Dr Peter Domone, who is also a member of the Concrete Society Working Party on SCC. UCL is also involved with the European-wide project on the testing of SCC. Dundee University’s Concrete Technology Unit has also recently begun a three-year research project investigating the formwork pressures generated by SCCs and other specialist concretes. This project will determine if the current CIRIA formwork pressure recommendations are applicable to current new materials and types of concrete such as SCC, and if not, safe design pressures will be established. 1.2.15. Concrete producers RMC Ready-mix Ltd is the UK’s leading supplier of ready-mixed concrete. The company has been undertaking development work on SCC since 1998 with the aim of producing mix design criteria for materials local to any of their 325 batching plants throughout the UK. It was originally thought that the material would be a niche product, but RMC is now concentrating upon developing more economical mixes to enable the material to be more universally used. This development is targeted at customer needs in terms of the application, strength requirement and other technical factors that may be specified. 16
  41. 41. Lafarge Aggregates Ltd have been conducting research and development into SCC in France for several years, and it is now available at each of their plants in the UK. Lafarge produce their own family of admixtures especially for the production of SCC, called Agilia. These products are fully developed and are all currently available and Lafarge see the next step as getting these existing products accepted and used by the market. Tarmac Topmix Ltd first began researching and developing SCC in 1998 and first started using it at their precast factory at Tallington in 1999. The first ready-mixed SCC was supplied in 2000 and the eventual aim is to make it available at all plants in the country. 1.2.16. Admixture suppliers Sika Ltd launched Sika ViscoCrete in the UK in 1998, which was the first admixture on the UK market specifically for producing SCC. Six different types are available and it can be used with either retarders or accelerators. Other admixture manufactures have now followed this lead. MBT and Grace. Construction Products both produce admixtures for the UK SCC market, including superplasticisers, viscosity-modifying admixtures and specialist admixtures for precast applications. The ready-mix companies RMC and Lafarge produce their own admixtures for SCC. 1.2.17. Consultants Consultants in the UK do not generally undertake any concrete research or development directly, but do sometimes sponsor or collaborate in research projects at universities and research organisations. Mott MacDonald have an established track record with the development of specifications and guidance notes for SCC and are a member of the Concrete Society Working Party on SCC. They have also worked closely with ready-mix suppliers and contractors to use the material on a variety of projects throughout the UK. However, many UK consultants are cautious when specifying SCC due to the lack of existing guidance, standards and test methods and the lack of an established track record for the material. 17
  42. 42. 1.2.18. Contractors Contractors in the UK generally rely upon the ready-mix supplier for any expertise in SCC mix design. However, knowledge and appreciation of the material among contractors is slowly increasing as the use of SCC becomes more widespread. John Doyle Construction are probably the leading contractor in the UK in the use of SCC and are involved in several research and development projects such as the European SCC test methods project and the project on formwork pressures at Dundee University. They have used the material several times in the UK in actual applications such as column encasement and basements, although its use is still job-specific. Site trials are always conducted before SCC is used in the intended structure. Other contractors have used SCC in the UK but its use is still job-specific, often to solve a problem during construction such as congested reinforcement. 1.2.19. UK precasters Aarsleff Piling’s Balderton premises claim to be the UK’s first user of SCC in precast pile production. An SCC mix was developed in partnership with RMC with a compressive strength of 26–28 MPa at only 16 hours. At nine days the 50 MPa mark had been passed and the piles could be driven. Aarsleff have also won a £4·25 million contract to supply and install approximately 3000 precast concrete piles for the Channel Tunnel Rail Link. SCC was used for these piles and casting began in June 2002 with installation beginning the following month. Tarmac Precast Concrete Ltd are also now using SCC at their three UK precast plants. SCC currently accounts for approximately 65% of bespoke production at their Tallington plant and their long-term objective is to convert fully to SCC when economics and practicalities allow Current contracts are for prison units, double-T beams and columns. Trent Concrete Ltd in Nottingham has been experimenting with SCC for the last two years and production using the material first began in August 2002. 1.2.20. Seminars and events The SCI (Society of Chemical Industry) held a seminar on SCC in January 2001 in London. Approximately 60 delegates attended and the speakers were the main 18
  43. 43. practitioners of SCC in the UK from the areas of research (Professor P. Bartos), design (Dr N. Henderson), ready-mix (R. Gaimster) and contracting (P. Goring). This meeting was one of the first events in the UK to begin to introduce the material to members of the construction industry who had no experience or knowledge of SCC. A demonstration and international workshop on SCC, lasting a total of two and a half days, was held at the Advanced Concrete and Masonry Centre at Paisley University in May/ June, 2001. The event was attended by 70 delegates from eleven countries and helped raise the awareness and knowledge of the material in Scotland and the rest of the UK.Four demonstration events on SCC around the UK have also recently been held by BRE’s Centre for Concrete Construction as part of their DTI-funded project on SCC, which combined practical demonstrations with presentations by industry experts on SCC. The events were aimed at people in the industry with little or no knowledge of the material, with more than 140 people attending the four events 1.2.21. The Future From its origins in Japan in the late 1980s, research, development and use of SCC has spread steadily throughout the world. Approximately 7–10% of the Swedish ready-mix market is now SCC and research is being conducted in virtually every country in Europe. National working groups on the material now exist in some form in most countries in Europe, with the majority of them working towards producing some form of guidance on the use of SCC. Large amounts of research and development are now also being conducted in Canada and the USA at places such as the University of Sherbrooke and the University´ Laval. The first North American conference on SCC was held in November 2002 by Northwestern University. American concrete organisations such as the American Concrete Institute (ACI), American Society for Testing and Materials (ASTM) and PCI (Precast/Prestressed Concrete Institute) have all recently formed committees to produce guidelines, standards and specifications for SCC. The material is slowly gaining acceptance in this huge market and already it is estimated that approximately 4,000–5,000 m3 is used per day in precast applications in 19
  44. 44. North America. Nearly 1,00,000 m3 of ready-mixed SCC has also so far been used in North America. Countries such as Argentina, Australia and New Zealand are also all now beginning to conduct research and development work into SCC, with more countries sure to follow. A third International Symposium on SCC is being held in Iceland in August 2003, where much of the research and development work presently under way will be presented. The main barrier to the increased use of SCC in the UK and Europe seems to be the lack of experience of the process, and the lack of published guidance, codes and specifications. This situation will improve, however, as experience and knowledge increases and each country begins to produce its own guidance and specifications. Precasters are currently the overwhelming users of SCC in the UK, in Europe and in the USA. This is partly due to them owning and operating the on-site batching plant, and so they are able to take full advantage of all the potential benefits of SCC. They can also minimise or control the potential disadvantages of the material (such as inconsistency of supply and site acceptance). In the countries where SCC has been adopted relatively quickly, such as Japan and Sweden, the ready-mix concrete producers are owned or operated by the contractors, therefore the increased material costs can be directly offset by savings in the construction process, in a similar way to precast production. Although SCC is not expected to ever completely replace conventionally vibrated concrete, the use of the material in both the precast and ready-mix markets in the UK, Europe and the rest of the world is expected to continue to increase. The main drivers for this increase in use are expected to include 1. An increase in the experience of both producers, contractors, designers and clients. 2. An increase in available guidance on the production, design and use of SCC. 3. A decrease in the unit cost of the material as technology and experience improves. 4. The demand from clients for a higher-quality finished product. 5. The decrease in skilled labour available in many countries for both the placing and finishing of concrete. 20
  45. 45. 1.3 Motive for Development of Self-Compacting Concrete The motive for development of self-compacting concrete was the social problem on durability of concrete structures that arose around 1983 in Japan. Due to a gradual reduction in the number of skilled workers in Japan's construction industry, a similar reduction in the quality of construction work took place. As a result of this fact, one solution for the achievement of durable concrete structures independent of the quality of construction work was the employment of self-compacting concrete, which could be compacted into every corner of a formwork, purely by means of its own weight (Figure 1.1). Studies to develop self-compacting concrete, including a fundamental study on the workability of concrete, were carried out by researchers Ozawa and Maekawa (Bartos, 2000) at the University of Tokyo. Decreasing in the future Figure 1.1 Necessity of Self-Compacting Concrete (Ouchi and Hibino, 2000). During their studies, they found that the main cause of the poor durability performances of Japanese concrete in structures was the inadequate consolidation of the concrete in the casting operations. By developing concrete that self-consolidates, they eliminated the main cause for the poor durability performance of the concrete. By 1988, the concept was developed and ready for the first real-scale tests and at the same time the first prototype of self-compacting concrete was completed using materials already on the market. The prototype performed satisfactorily with regard to drying and hardening shrinkage, heat of hydration, denseness after hardening, and other properties and was named “High Performance Concrete.” At almost the same time, “High Performance Concrete” was defined as a concrete with high durability due to low water-cement ratio by professor Aitcin (Ouchi et al., 21 Skill of workers Self-Compacting Concrete Durable concrete structures
  46. 46. 1996). Since then, the term high performance concrete has been used around the world to refer to high durability concrete. Therefore, Okamura (1997) has changed the term for the proposed concrete to “Self-Compacting High Performance Concrete.” 1.4 Construction Issues By employing self-compacting concrete, the cost of chemical and mineral admixtures is compensated by the elimination of vibrating compaction and work done to level the surface of the normal concrete (Khayat et al., 1997). However, the total cost for a certain construction cannot always be reduced, because conventional concrete is used in a greater percentage than self-compacting concrete. SCC can greatly improve construction systems previously based on conventional concrete requiring vibrating compaction. Vibration compaction, which can easily cause segregation, has been an obstacle to the rationalization of construction work. Once this obstacle has been eliminated, concrete construction could be rationalized and a new construction system, including formwork, reinforcement, support and structural design, could be developed (Figure 1.2). 1.2 Rational construction system proposed by Ozawa (Ouchi et al., 1996). 1.5 Applications of Self-Compacting Concrete Since the development of the prototype of self-compacting concrete in 1988, the use of self-compacting concrete in actual structures has gradually increased. The main reasons for the employment of self-compacting concrete can be summarized as follows: 22
  47. 47. 1. To shorten construction period 2. To assure compaction in the structure: especially in confined zones where vibrating Compaction is difficult 3. To eliminate noise due to vibration: effective especially at concrete products plants 300 200 100 0 1990 91 92 93 94 95 96 97 Fig. 1.3 Annual production of SCC in Japan Total production of ready-mixed concrete in Japan in 1997 is 67,620×1,000 m That means the current condition of self-compacting concrete is a “special concrete” rather than standard concrete. Currently, the percentage of self-compacting concrete in annual product of ready-mixed concrete in Japan is around 0.1% (Fig. 1.3). A typical application example of Self-compacting concrete is the two anchorages of Akashi-Kaikyo (Straits) Bridge opened in April 1998, a suspension bridge with the longest span in the world (1,991 meters) (Fig. 1.4). The volume of the cast concrete in the two anchorages amounted to 2,90,000 m³. A new construction system, which makes full use of the performance of self-compacting concrete, was introduced for this. The concrete was mixed at the batcher plant beside the site, and was the pumped out of the plant. It was transported 200 meters through pipes to the casting site, where the pipes were arranged in rows 3 to 5 meters apart. The concrete was cast from gate valves located at 5 meter intervals along the pipes. These valves were automatically controlled so that a surface 23
  48. 48. level of the cast concrete could be maintained. In the final analysis, the use of self-compacting concrete shortened the anchorage construction period by 20%, from 2.5 to 2 years. Fig. 1.4 Anchorage 4A of Akashi-Kaikyo Bridge Self-compacting concrete was used for the wall of a large LNG tank belonging to the Osaka Gas Company, whose concrete casting was completed in June 1998.The volume of the self-compacting concrete used in the tank amounted to 12,000 m³. The adoption of self-compacting concrete means that 1. The number of lots decreases from 14 to 10, as the height of one lot of concrete casting was increased. 2. The number of concrete workers was reduced from 150 to 50. 3. The construction period of the structure decreased from 22 months to18 months. Self-compacting concrete is often employed in concrete products to eliminate the noise of vibration. This improves the working environment at plants and makes it possible for concrete product plants to be located in the urban area. The annual production of concrete products using self-compacting concrete exceeded 2,00,000 tons in 1996. 24
  49. 49. 1.6 Existing Tests for Fresh SCC Mixes Fresh SCC must possess at required levels the following key properties: 1.6.1. Filling ability: This is the ability of the SCC to flow into all spaces within the formwork under its own weight. 1.6.2. Passing ability: This is the ability of the SCC to flow through tight openings such as spaces between steel reinforcing bars, under its own weight. 1.6.3. Resistance to segregation: The SCC must meet the required levels of properties A & B whilst its composition remains uniform throughout the process of transport and placing. Many tests have been used in successful applications of SCC. However, in all the projects the SCC was produced and placed by an experienced contractor whose staff has been trained and acquired experience with interpretation of a different group of tests. In other cases, the construction was preceded by full-scale trials in which a number, often excessive, of specific tests was used (Ouchi et al., 1996). The same tests were later used on the site itself. Below is a brief summary of the more common tests currently used for assessment of fresh SCC. 1.6.4 U-type test: Of the many testing methods used for evaluating self-compactability, the U-type test (Figure 1.5) proposed by the Taisei group is the most appropriate, due to the small amount of concrete used, compared to others (Ferraris, 1999). In this test, the degree of compactability can be indicated by the height that the concrete reaches after flowing through obstacles. Concrete with the filling height of over 300 mm can be judged as self-compacting. Some companies consider the concrete self-compacting if the filling height is more than 85% of the maximum height possible. 25
  50. 50. >300mm Figure 1.5 U-type test (Ouchi and Hibino, 2000). 1.6.5. Slump Flow test: The basic equipment used is the same as for the conventional Slump test. The test method differs from the conventional one by the fact that the concrete sample placed into the mold is not rodded and when the slump cone is removed the sample collapses (Ferraris, 1999). The diameter of the spread of the sample is measured, i.e. a horizontal distance is determined as opposed to the vertical distance in the conventional Slump test. The Slump Flow test can give an indication as to the consistency, filling ability and workability of SCC. The SCC is assumed of having a good filling ability and consistency if the diameter of the spread reaches values between 650mm to 800mm. 1.6.6. L-Box test: This method uses a test apparatus comprising of a vertical section and a horizontal trough into which the concrete is allowed to flow on the release of a trap door from the vertical section passing through reinforcing bars placed at the intersection of the two areas of the apparatus (Dietz and Ma, 2000). The time that it takes the concrete to flow a distance of 200mm (T-20) and 400mm (T-40) into the horizontal section is measured, as is the height of the concrete at both ends of the apparatus (H1 & H2). The L-Box test can give an indication as to the filling ability and passing ability. 26
  51. 51. 1.6.7. Orimet test: The test is based on the principle of an orifice rheometer applied to fresh concrete (Bartos, 2000). The test involves recording of time that it takes for a concrete sample to flow out from a vertical casting pipe through an interchangeable orifice attached at its lower end. The shorter the Flow-Time, the higher is the filling ability of the fresh mix. The Orimet test also shows potential as a means of assessment of resistance to segregation on a site. 1.6.8. V-funnel test: Viscosity of the self-compacting concrete is obtained by using a V-funnel apparatus, which has certain dimensions (Figure 1.6), in order for a given amount of concrete to pass through an orifice (Dietz and Ma, 2000). The amount of concrete needed is 12 liters and the maximum aggregate diameter is 20 mm. The time for the amount of concrete to flow through the orifice is being measured. If the concrete starts moving through the orifice, it means that the stress is higher than the yield stress; therefore, this test measures a value that is related to the viscosity. If the concrete does not move, it shows that the yield stress is greater than the weight of the volume used. An equivalent test using smaller funnels (side of only 5 mm) is used for cement paste as an empirical test to determine the effect of chemical admixtures on the flow of cement pastes. Figure 1.6V-funnel (Dietz and Ma, 2000). 27

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