Self Compacting Concrete - 2018
- 1. Self Compacting Concrete L D College of Engineering Ahmedabad A presentation for UltraTech – Rising Star A presentation by:- Het Modi Drashti Shah Garima Lodha Under the guidance of : Prof P I Modi Prof Tarachandani Prof D K Oza 1
- 2. Table of content: • Genesis • Introduction to Self Compacting Concrete (SCC) • Modifications in constituents for concreting • Site visit • Application of SCC • Comparative study b/w normally vibrated concrete and SCC • Why has SCC not been standardized? • Future Scope • References 2
- 3. Introduction The need for very fluid concrete has been existing for a long time. In earlier times, this always had to be done with a high increase of the water content. The results were poor stability of the concrete because of insufficient cohesion. Segregation and bleeding caused very low concrete quality. Hence SCC – Self compacting concrete is revolutionary development in Concrete World. 3
- 4. Genesis 1983 • Labor crisis in Japan and concern for durability of concrete structures 1986 • Basic concept of SCC by Prof H. Okamura of Tokyo University 1988 • First prototype for field experiments and implementation 2002 • EFNARC published 1st European Guideline for SCC 4
- 5. Dr. (prof.) Hajime Okamura • Hailed as Father of SCC Technology • Currently President of Kochi University of Technology • CAMET/ACI award for outstanding contribution in development of self compacting high performance concrete, 1995 5
- 6. 6 Volume of SCC cast in Japan
- 7. Self Compacting Concrete • According to European guidelines by EFNARC : “Concrete that is able to flow and consolidate under its own weight, completely fill the formwork even in the presence of dense reinforcement, whilst maintaining homogeneity and without the need for any additional compaction” • According to Japan Society for Civil Engineers (JSCE): “Self-compacting high-performance concrete is a high performance concrete that can be compacted into every corner of a formwork, purely by means of its own weight and without the need for vibrating compaction” NOTE: SCC has not been mentioned in IS codes 7
- 8. SCC and conventional concrete along the common scale for workability Source: Self compacting Concrete in Japan by Masahiro OUCHI Associate Professor, Kochi University of Technology, Japan.8
- 9. A concrete mix may be classified as self compacting if it has the following characteristics : • Filling ability • Passing ability • Segregation Resistance Aspects of SCC: 9
- 10. Additional aspects of SCC are: • Pumpability • Finishability • Self-levelling 10
- 11. Modifications in constituents for concreting 11
- 12. • Mixing Water: • Water quality must be established on the same line as that for using reinforced concrete or prestressed concrete. • Cement: • All cements conforming to standards can be used • C₃A content is the main factor in the control of the fluidity of cement pastes • Portland cement with a C₃A content of less than 5%, such as low heat Portland cement and moderate heat Portland cement, is very useful for the production of self compacting concrete. 12
- 13. • Aggregates: Aggregates should be from the same source such that all their properties (water absorption, moisture content etc.) are same. Coarse Aggregates Size<20mm Desirable 10-12 mm Should be cubical or rounded Fine Aggregates Affect the properties of SCC more potently as opposed to Coarse Fine aggregates should be well graded (preferably blended sands) Moisture content should be closely monitored (bulking) 13
- 14. • Additions: Additions are used to improve and maintain the cohesion and segregation resistance. Also, the addition will regulate the cement content in order to reduce the heat of hydration and thermal shrinkage. 14
- 15. • Mineral fillers: • Mineral fillers are widely used specially ground limestone (CaCo₃) Limestone powder is regarded as a non-binder however it improves the fluidity of concrete and prevents the segregation of high flowable concrete 15
- 16. • Fly ash : • Increases cohesion • Reduces sensitivity to changes in water content (hence prevents bleeding and segregation) • Makes the concrete dense and impervious • Reduces the cement content in concrete 16
- 17. • Silica fumes: • high fineness and spherical shape of silica fume results in good cohesion and improved resistance to segregation • Contributes to strength by creating dense packing and acting as pore filler • Vulnerable to plastic shrinkage cracking Used at Palais Royal, Shri Ram Mills, Mumbai 17
- 18. • Ground Granulated Blast Furnace Slag : • Reduces Heat of hydration • Pore filler • Reduces W/C ratio Source: Concrete Technology by M.S. Shetty 18
- 20. Concrete viscosity can be reduced Reduces water content up to 30% Good dispersing agents and hence allow the usage of silica, fly ash etc Workability characteristics such as pumpability, compactability, finishibility is improved Changes in concrete performance by pumping are small SUPERPLASTICIZER 20
- 21. Effect of high dosage of superplasticizer 21
- 22. • Viscosity Modifying Agent: • Makes SCC more robust • Reduces sensitivity towards variations in proportions Note: they should not be regarded as a way of avoiding the need of a good mix design 22
- 23. Addition of excess of VMA 23
- 24. • Limited aggregate content • Low water to powder (cement) ratio • Use of superplasticizer (HRWRA: High Range Water Reducing Admixture) Methods of achieving SCC 24
- 25. Typical range of SCC mix composition as given in EFNARC 25
- 26. Modifications required in Manufacturing Process of SCC: 26
- 27. Step1-Batching and Proportioning: • During Storage of aggregates, following precautions should be taken: • Cross-contamination of different type and size of aggregate should be prevented • Protected from weather to minimize surface moisture fluctuation and fine movement • Adequate storage capacity should be available 27
- 28. Step-2 Mixing • Longer time is needed to achieve complete mixing of SCC • ‘ball’ formation of constituent material(due to free fall) should be prevented 28
- 29. Step-3 Transportation Transportation should be such that concreting is continuous and should be within the consistent retention time 29
- 30. Step 4- Placing • SCC gives a mirror copy of the formwork. Hence, if care is not taken, SCC shows up any deficiencies in the formwork material • Limit of vertical free fall distance to 5 meter • Limit of permissible distance of horizontal flow from point of discharge • SCC allows novel methods of placing concrete including pumping bottom up 30
- 31. Step 5&6 – Compacting and Finishing • SCC is capable of achieving both self compacting and self finishing • Use of vibrators will affect the balance of SCC and will usually lead to significant segregation • Light vibration can be used if the need arises • If air is trapped • If there is break in placing process 31
- 32. Step 7 - Curing • SCC tends to dry faster, and is vulnerable to plastic shrinkage cracking. • Hence early curing should be commenced as early as possible. 32
- 33. Site Visit : Nuvoco Vistas’ (Lafarge) RMC Plant • Location: Nuvoco Vistas operating RMC plant, B/H Sanghi Cement Godown, Sarkhej Sanathal Road, Ahmedabad • Date of visit: 7/02/2018 • Objective: To analyze various properties of SCC and making of mix design • Quality Control Incharge: Mr. Dhiren Patel 33
- 34. • Can retain it’s workability for 4 hours without any change. • w/c ratio : 0.3 • Admixture used: HWRA and VMA (.6% weight of binder) • Cement – OPC 53 • Concrete – M 25 34
- 35. Fresh SCC 35
- 36. Test Methods 36
- 38. Slump Flow Test Property Tested: Flowing Ability 38
- 39. 39
- 40. V-Funnel Test V-Funnel Test @ T5 minutes Property tested: viscosity Property tested: segregation resistance 40
- 41. L-Box Property tested: Passing ability 41
- 42. U-Box Property tested: Passing ability 42
- 43. Typical acceptance criteria for various SCC test Source: EFNARC guidelines 43
- 44. Cube Casting: 44
- 45. Concrete cubes exhibited self levelling and self finishing 45
- 48. Problems associated with mass concreting and how SCC solves them.. High heat of Hydration Cold joints Congested Reinforcement 48
- 49. Delhi Metro SCC was used at about 40 different places and upto the volume of 10,000 metre cube Used in rotary dome and column casting 49
- 50. Palais Royale, Mumbai • India’s first residential building to use SCC • World’s deepest girder of 9m made via SCC • SCC of grade M-80 was used 50
- 51. Rapid -Monolithic -Disaster Proof (RMD) Technology 51
- 52. ensures absolutely no joints (monolithic) between the elements with great surface finish all the elements are cast together 52 What is RMD Technology??
- 53. Rajiv Gandhi Housing Corporation, Karnataka Project completion time: 7 days Technology Support: UltraTech Cement Limited, Unit -UltraTech Concrete 53
- 54. Comparative study b/w normally vibrated concrete(NVC) and SCC 54
- 55. Property Comparison As observed in trials at Structural Engineering research Centre (SERC) Chennai Grade – M70 55
- 56. COMPARISON OF COST ANALYSIS BETWEEN SELF COMPACTING CONCRETE AND NORMAL VIBRATED CONCRETE by Krishna Murthy (as published in IJCIET in 2014) Cost Comparison 56
- 57. Cost reduction factors: • Higher speed of placing • Reduced machine/ equipment cost • Possible higher concrete quality and durability • Reduced manpower • Reduced finishing/ repair work 57
- 58. Why has SCC not been standardized yet? • It is a fairly new concept (1983) in the concrete domain, with it’s entry happening in India in the year 2004 only • No specific mix design exists for SCC, with each mix being designed differently to cater to the construction needs. • There is no particular limit at which we can differentiate between NVC and SCC • However, with the ongoing research we do expect the standardization of SCC 58
- 59. Future Scope • The use of SCC has been gaining momentum and the SCC market is expected to grow by 5.7% annually ( for UK as estimated by designbuilding.org). • Use of rice husk, and similar additives in SCC is being experimented in order to reduce the concrete manufacturing cost. • SCC gives flexibility to both the engineers as well as the architects to design and construct complicated structures, without having to compromise on quality and durability. • With the increasing population, the need for high rise buildings would be inevitable which in turn would make SCC a necessity. • ACI has already published journals regarding SCC and we expect both, BIS and ACI to standardize SCC in near future. 59
- 60. References • Papers and Guidelines: • Japan Society of Civil Engineers “Recommendation for Mix Design of Fresh Concrete and Construction Placement related Performance of Evaluation” 2007 • The European Guidelines for Self-Compacting Concrete in accordance with BIBM, CEMBUREA, ERMCO, EFCA and EFNARC • Okamura, H. and Ouchi, M. “Self-compacting high performance concrete” Journal of Advanced Concrete Technology of Japan Concrete Institute • “Self-compacting concrete: modern concrete and admixture technology” by R Beissel, Sika AG, Switzerland H Lim, Sika Pte. Ltd. , Singapore • Masahiro OUCHI Associate Professor, Kochi University of Technology, Japan “Self- compacting concrete in japan” • EN codes 60
- 61. • Websites: • www.constructionworld.in • www.designbuilding.uk • https://www.ultratechcement.com/common/images/downloads/brochures/Ult raTech_Concrete_Freeflow.pdf • www.Lafarge.com.en • www.Vvpedulink.ac.in • https://www.omicsonline.org/open-access/selfcompacted-concrete-mix-design- and-its-comparison-with-conventional-concrete-m40-2165-784X-1000176.pdf • https://www.researchgate.net/publication/291284968_A_cost- reduction_of_self-compacting_concrete_incorporating_raw_rice_husk_ash 61
- 62. “ 25 years ago no one in concrete construction industry could ever imagine creating and placing concrete mixes that would achieve in place compressive strengths as high as 120 MPa…. …. however structures today have attained strength as high as 130 MPa – are testaments to the benefits of Sillica Fume technology in Concrete construction” -- Michael Shydlowski, President, Master Builder 62