Some Properties of HIGH-VOLUME FLY ASH CONCRETE

1. Some Properties of HIGH-VOLUME FLY ASH CONCRETE By PROF. ARUN KUMAR CHAKRABORTY Associate Professor Department of Civil Engineering Bengal Engineering and Science University Shibpur; Howrah – 711 103; West Bengal

2. INTRODUCTION • Fly ash, a principal byproduct of coal burning power plants, is an industrial waste product containing large amounts of silica, alumina and small amount of unburned carbon, which pollutes environment. This fly ash has real disposal problems, and should hence be utilized effectively for various purposes. • Fly ash, being primarily pozzolanic, can actually replace a percentage of the Portland cement, to produce a stronger, more durable and more environment friendly concrete. • The cement production process releases a lot of carbon-di-oxide in atmosphere, which is the primary green house gas that causes global warming. Hence replacement of a considerable portion of cement by fly ash, can make a major contribution toward solving the global warming problem.

3. Fly Ash Concrete: In commercial practice, the dosage of fly ash is limited to 15%-30% by mass of the total cementitious material, which has a beneficial effect on the workability and cost economy of concrete but for improved durability against sulfate attack, alkali-silica expansion, and thermal cracking, larger amounts of fly ash, are necessary. • High-Volume Fly Ash Concrete: • According to some researchers, more than 30% fly ash by mass (equivalent as 50% by volume) of the cementitious material may be considered enough to classify the mixtures as High-Volume Fly Ash (HVFA) concrete. • It is possible to produce sustainable, high performance concrete mixtures with 50% or more cement replacement by fly ash.

4. Behaviour of High Volume Fly Ash in Concrete: • It is generally observed that a higher substitution of Portland cement by fly ash reduces the water requirement for obtaining a given workability, mainly due to three mechanisms: • Fly ash gets absorbed on the surface of oppositely charged cement particles and prevent them from flocculation, releasing large amounts of water, thereby reducing the water-demand for a given workability. • The spherical shape and the smooth surface of fly ash particles help to reduce the interparticle friction and thus facilitate mobility. • Due to its lower density and higher volume per unit mass, fly ash is a more efficient void-filler than Portland cement.

5. Applications of High-Volume Fly Ash Concrete: • HVFA system has proven to be an economical construction material. Several applications of HVFA concrete in structures, and pavements have been reported all over the world. • Few information are available on long term properties and durability aspects of HVFA concrete, particularly, in India, where there is a lot of variation in quality and properties of fly ash. • A detailed study is hence necessary to reveal these aspects before prescribing the High Volume Fly Ash Technology in practical application considering the availability of local materials and climatic condition in our country.

6. EXPERIMENTAL PROGRAM MATERIALS USED: • Detailed properties of cement and fly ash is given in Table 1. • Detailed properties of Coarse and Fine aggregates are shown in Table 2. • Conplast SP430 manufactured by M/S Fosroc India Ltd. Bangalore, has been used as a superplasticizer (conforming to ASTM C 494 type F) and Pidicrete CF-21 manufactured by Pidilite Industries has been used as normal plasticizer (ASTM Type A). TYPES OF CONCRETE MIXES: • Detailed mix proportions are given in tables T3.1, T3.2, T3.3, T3.4, T3.5 and T3.6.

7. Table1: Physical Properties and Chemical Analysis of the Materials used

8. Table2: Grading of Coarse and Fine Aggregate

9. Table T3.1: Mix Proportion and Fresh Properties of different M20 concrete mixes having cementitious material content 350 Kg/m3 made with O.P.C

10. Table T3.2: Mix Proportion and Fresh Properties of different M40 concrete mixes having cementitious material content 400 Kg/m3 made with O.P.C

11. Table T3.3: Mix Proportion and Fresh Properties of different M60 concrete mixes having cementitious material content 450 Kg/m3 made with O.P.C

12. Table T3.4: Mix Proportion and Fresh Properties of different M20 concrete mixes having cementitious material content 350 Kg/m3 made with P.P.C

13. Table T3.5: Mix Proportion and Fresh Properties of different M40 concrete mixes having cementitious material content 400 Kg/m3 made with P.P.C

14. Table T3.6: Mix Proportion and Fresh Properties of different M60 concrete mixes having cementitious material content 450 Kg/m3 made with P.P.C

15. TYPES OF TESTS ON CONCRETE SAMPLES: • Compressive strength at 28days, 91days, 180 days and 365 days as per IS 516:1959. • Flexural strengths at 28, 91 and 365 days as per IS516: 1959. • Splitting tensile strengths at 28, 91 and 365 days as per IS 5816: 1999. • Abrasion test at 56 and 365 days as per IS 1237: 1980. • Water Permeability at 56 and 365 days as per DIN1048 part V. • Rebound Hammer Test and Ultra Sonic Pulse Velocity Test as per IS 13311: 1992 Part I & II.

16. COMPRESSIVE STRENGTH VS % FLYASH FOR M20 CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 350 KG/M3 MADE WITH O.P.C. & P.P.C. O.P.C. P.P.C.

17. COMPRESSIVE STRENGTH vs % FLYASH FOR M40 CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 400 KG/M3 MADE WITH O.P.C. & P.P.C. O.P.C. P.P.C.

18. O.P.C. P.P.C. COMPRESSIVE STRENGTH vs % FLYASH FOR M60 CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 450 KG/M3 MADE WITH O.P.C. & P.P.C.

19. Comparison of Compressive Strength of M20 Concrete having cementitious material content 350 Kg/m3 using O.P.C & P.P.C. for different % of Fly Ash 28 Days 91 Days

20. Comparison of Compressive Strength of Concrete having cementitious material content 350 Kg/m3 using O.P.C & P.P.C. for different % of Fly Ash. 180 Days 365 Days

21. Comparison of Compressive Strength of M40 Concrete having cementitious material content 400 Kg/m3 using O.P.C & P.P.C. for different % of Fly Ash. 28 Days 91 Days

22. Comparison of Compressive Strength of Concrete having cementitious material content 400 Kg/m3 using O.P.C & P.P.C. for different % of Fly Ash. 180 Days 365 Days

23. Comparison of Compressive Strength of M60 Concrete having cementitious material content 450 Kg/m3 using O.P.C & P.P.C. for different % of Fly Ash. 28 Days 91 Days

24. Comparison of Compressive Strength of Concrete having cementitious material content 450 Kg/m3 using O.P.C & P.P.C. for different % of Fly Ash. 180 Days 365 Days

25. O.P.C. P.P.C. SPLITTING TENSILE STRENGTH VS % FLYASH FOR M20 CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 350 KG/M3 MADE WITH O.P.C. & P.P.C.

26. O.P.C. P.P.C. SPLITTING TENSILE STRENGTH VS % FLYASH FOR M40 CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 400 KG/M3 MADE WITH O.P.C. & P.P.C.

27. SPLITTING TENSILE STRENGTH VS % FLYASH FOR M60 CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 450 KG/M3 MADE WITH O.P.C. & P.P.C. O.P.C. P.P.C.

28. Comparison of 28 Days Split Tensile Strength of Concrete having different cementitious material content using O.P.C & P.P.C. for different % of Fly Ash. 350 Kg/m3 400 Kg/m3 450 Kg/m3

29. Comparison of 91 Days Split Tensile Strength of Concrete having different cementitious material content using O.P.C & P.P.C. for different % of Fly Ash. 350 Kg/m3 400 Kg/m3 450 Kg/m3

30. Comparison of 365 Days Split Tensile Strength of Concrete having different cementitious material content using O.P.C & P.P.C. for different % of Fly Ash. 350 Kg/m3 400 Kg/m3 450 Kg/m3

31. FLEXURAL STRENGTH VS % FLY ASH FOR CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 350 KG/M3 MADE WITH O.P.C. & P.P.C. O.P.C. P.P.C.

32. FLEXURAL STRENGTH VS % FLY ASH FOR CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 400 KG/M3 MADE WITH O.P.C. & P.P.C. O.P.C. P.P.C.

33. FLEXURAL STRENGTH VS % FLY ASH FOR CONCRETE HAVING CEMENTITIOUS MATERIAL CONTENT 450 KG/M3 MADE WITH O.P.C. & P.P.C. O.P.C. P.P.C.

34. Comparison of 28 Days Flexural Strength of Concrete having different cementitious material content using O.P.C & P.P.C. for different % of Fly Ash. 350 Kg/m3 400 Kg/m3 450 Kg/m3

35. Comparison of 91 Days Flexural Strength of Concrete having different cementitious material content using O.P.C & P.P.C. for different % of Fly Ash. 350 Kg/m3 400 Kg/m3 450 Kg/m3

36. Comparison of 365 Days Flexural Strength of Concrete having different cementitious material content using O.P.C & P.P.C. for different % of Fly Ash. 350 Kg/m3 400 Kg/m3 450 Kg/m3

37. Change in Compressive Strength (with respect to 28 days) of Concrete made with O.P.C. and P.P.C having cementitious material content 350 Kg/m3 for different % of Fly Ash due to various exposures. P.P.C. O.P.C.

38. Change in Compressive Strength (with respect to 28 days) of Concrete made with O.P.C. and P.P.C having cementitious material content 400 Kg/m3 for different % of Fly Ash due to various exposures. O.P.C. P.P.C.

39. Change in Compressive Strength (with respect to 28 days) of Concrete made with O.P.C. and P.P.C having cementitious material content 450 Kg/m3 for different % of Fly Ash due to various exposures. O.P.C. P.P.C.

40. Depth of Carbonation for Concrete made with O.P.C. and P.P.C. having different cementitious material content for different percentages of Fly Ash after 365 days exposure in air. 350 Kg/m3 Procedure 450 Kg/m3 400 Kg/m3

41. Abrasion Thickness of Concrete made with O.P.C. and P.P.C. having cementitious material content 350 kg/m3 for different percentages of Fly Ash at early and later ages P.P.C. O.P.C.

42. Abrasion Thickness of Concrete made with O.P.C. and P.P.C. having cementitious material content 400 kg/m3 for different percentages of Fly Ash at early and later ages P.P.C. O.P.C.

43. Abrasion Thickness of Concrete made with O.P.C. and P.P.C. having cementitious material content 450 kg/m3 for different percentages of Fly Ash at early and later ages P.P.C. O.P.C.

44. WATER PERMEABILITY OF CONCRETE FOR DIFFERENT PERCENTAGES OF FLY ASH AT 365 DAYS. 350 Kg/m3 350 Kg/m3 O.P.C P.P.C 400 Kg/m3 400 Kg/m3

45. CONCLUSION • For similar cementitious material content and similar range of slump, the use of fly ash (0 to 50 %) decreased the water-to-cementitious-material ratio in general. • The long term strength of the concrete containing fly ash is higher than that of control concrete without fly ash. • Abrasion resistance of fly ash concrete is less than corresponding samples without fly ash both at early and longer ages, in general. The loss of thickness due to abrasion increases with percentage of fly ash in concrete. • The fly ash concrete shows lower water permeability compared to that of control concrete. • The depth of carbonation is increased with the increase in percentage replacement of fly ash in concrete.

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