1. THE EFFECT OF RICE HUSK ASH ON STRENGTH AND PERMEABILITY OF CONCRETE
2. Introduction The production of cement is costly, consumes high energy, depletes natural resources and emits huge amounts of greenhouse gases (1 ton of cement production emits approximately 1 ton of CO2). Consequently, environmental degradation, pollution and health hazards problems associated with cement industries, have come under scrutiny. So, now a days many people are trying to use industrial and agricultural wastes in concrete. These wastes otherwise pose several environmental problems.
3. Objectives To investigate compressive strength properties of concrete containing different percentage of Rice Husk Ash To investigate the permeability properties of concrete containing different percentage of Rice Husk Ash To determine the optimal replacement of cement with Rice Husk Ash, by comparing the results of compressive strength and permeability tests.
4. Methodology (Detail of Tests) Name of test Size of specimen (mm) No. of mix No. of specimen for each mix Total no. of specimen Compressive strength test 15015015 0 4 (0%, 15%, 25%, 35%) 6 (3-7 Days, 3-28 Days) 24 Permeability Test 150x150x150 4 (0%, 15%, 25%, 35%) 6 (3-7 Days, 3-28 Days) 24
5. All the specimen were cast with M25 mix The specimen were taken out from the mould after 24 hours and cured for 7/28 days. Specimen of cubes were tested for Compressive Strength and Coefficient of Permeability and the final results were analysed to find the optimal percentage replacement of cement with Rice Husk Ash (RHA) Methodology
6. Material used in the experimental investigation Cement Water Coarse Sand Rice Husk Ash Coarse Aggregate
7. Continue.. Ordinary Portland Cement of grade 43 (source J.K Cement) Rice Husk Ash used in the study has been obtained from NK Enterprises, Singhania House, Jharsuguda, Orissa, India Water- Tap water was used in concrete masonry
8. Rice Husk Ash OPC Fine Aggregates Coarse Aggregates
9. Rice Husk Ash Rice husk is one of the main agricultural residues obtained from the outer covering of rice grains during the milling process. Rice Husk Ash is obtained from burning of Rice Husk, which is the by-product of rice milling. It is estimated that 1,000 kg of rice grain produce 200 kg of Rice Husk after burn. The rice husk ash had no useful application and had usually been dumped into water streams and caused pollution until it was known to be a useful mineral admixture for concrete.
10. Standard Consistency of the cement paste = 29.5 Initial setting time of cement = 115min Final setting time of cement = 220min Specific gravity of cement = 3.38 Test on cement Fineness modulus of fine aggregates =2.50 Specific gravity of fine aggregates= 2.65 Test on fine aggregates Specific gravity of coarse aggregates= 2.61 Fineness modulus of coarse aggregates =7.68 Test on coarse aggregates
11. Mix Design for M25 Grade Concrete Table of final mix proportion (Wt. in Kg)/m3 concrete Cement Fine Aggregat e Coarse Aggregat e Water Cement ratio 1 1.3 2.9 0.45
12. Preparation, casting and curing of concrete cubes
13. Testing Methods Compressive strength test Cube failure after compression test Compression testing machine
14. Permeability Permeability of concrete generally refers to the rate at which water or other aggressive substance (sulphates, chlorides ions, etc.) can penetrate concrete. Low permeability of concrete to moisture and gas is the first line of defence against: frost damage, acid attack, sulphate attack, corrosion of steel embedment and reinforcements, carbonation, alkali-aggregate reaction, and efflorescence.
15. Methods For Testing Permeability (IS 3085:1965) Constant flow Method Darcys law has been used to determine the co-efficient of permeability. The equation used is Ks= Where, Ks - Coefficient of saturated permeability (m/s) Q - Volume of flow rate (m3/s) A -Cross-sectional area (m2) L -Specimen thickness in the direction of flow (m)
16. Permeability test Permeability apparatus Permeability mould Water reservoir and pressure controler Air Chamber
17. Continue Permeability test Set-Up (Schematic)Typical Details of Permeability Cell
18. Sealing of specimen (1) Filling pieces of jute rope (2) Filling mixture of lac & wax (3) Filling Epoxy injection grout (4) Applying Sikadur 31 compound(Epoxy Grou
19. Leakage testing & Running the test Fill the water reservoir and apply the desired pressure (10 Kg/cm2) and note the initial gauge reading. After steady state of flow is reached, put the empty beaker below the mould and note the time and pressure on the gauge Note the discharge passed in a particular time interval and at an average pressure on gauge. From the Darcy's law find the coefficient of permeability.
20. Result and Discussion Type of Mix RHA (Kg) OPC (Kg) Compressive Strength (MPa) Average Compressive Strength (MPa) Percentage Improvement w.r.t. M0 Mix M0 (0%) 19.84 21.24 20.56 20.55 ---- M1 (15%) 24.40 24.91 25.46 24.92 17.54 M2 (25%) 24.76 21.05 21.50 22.44 8.42 M3 (35%) 19.00 18.10 17.16 18.08 -13.66 Values of Compressive Strength (7-days curing)
21. Continue Type of Mix RHA (%) Compression Strength (MPa) Average Strength (MPa) Ratio of RHAC/OPC Percentage Improvement w.r.t. OPC M0 0% 33.41 31.23 30.30 31.64 ---- ---- M1 15% 34.26 34.56 35.00 34.61 1.09 8.58 M2 25% 33.35 33.20 31.80 32.78 1.03 3.47 M3 35% 30.20 29.78 28.98 29.65 0.93 -6.71 Values of Compressive Strength (28-days curing)
22. Compressive Strength of different mixes (7 & 28 days) 20.55 24.92 22.44 18.08 31.64 34.61 32.78 29.65 0 5 10 15 20 25 30 35 40 M0 M1 M2 M3 CompressiveStrength(MPa) Concrete Mix 7 days 28 days
23. Permeability test results Mix Sample Discharge Q (ml) Time T (Hrs) Head of water H (m) Co-efficient of permeability, K(m/sec) X 10-12 Avg. K(m/sec) X 10-12 M0 16 18 18 68.67 71.12 23.97 26.04 25.01 M1 12 14 18 73.58 76.03 16.78 18.94 17.86 M2 7 10 18 66.22 78.48 10.88 13.11 12.00 M3 15 16 18 68.67 73.58 22.47 22.37 22.42 Values of coefficient of permeability for 7-days water curing
24. Coefficient of permeability of RHAC at 7-days water curing 25.01 17.86 12 22.42 0 5 10 15 20 25 30 M0 M1 M2 M3 CoefficientofPermeability(10-12m/s) Concrete Mix
25. Continue Mix Sample Discharge Q (ml) Time T (Hrs) Head of water H (m) Co-efficient of permeability, K(m/sec) X 10-12 Avg. K(m/sec) X 10-12 M0 8 10 18 63.77 63.77 12.91 16.13 14.52 M1 6 7 18 68.67 71.12 8.99 10.13 9.56 M2 4 4 18 73.58 71.12 5.6 5.77 5.69 M3 9 8 18 66.22 68.67 13.98 12.0 13.00 Values of coefficient of permeability for 28-days water curing
26. Coefficient of permeability of RHAC at 28-days water curing 14.52 9.56 5.69 13 0 2 4 6 8 10 12 14 16 M0 M1 M2 M3 CoefficientofPermeability(10-12m/s) Concrete Mix
27. Coefficient of Permeability of all mixes at both 7 and 28-days water curing 25.01 17.86 12 22.42 14.52 9.56 5.69 13 0 5 10 15 20 25 30 M0 M1 M2 M3 CoefficientofPermeability(10-12m/s) Concrete Mixes 7 days 28 days
28. Permeability of concrete is influenced primarily by following factors: The nature of the hardened cement paste Porosity and interconnectivity of pores in the cement paste and micro-cracks in the concrete. w/c ratio Degree of hydration The degree of compaction The type and quantity of constituent materials. (fine cement tends to reduce permeability, well graded aggregate tends to decrease permeability)
29. Conclusions The coefficient of permeability of RHAC is significantly lower than that of OPC for all percent changes. The coefficient of permeability of RHAC decreases for 15 % & 25 % replacement but it starts increasing at 35% replacement for cement. The permeability of OPC and RHAC decreases with increase in curing period of samples. The addition of RHA had a significant effect on the compressive strength of concrete. Compressive strength of concrete increases with the addition of RHA upto a certain level, after which it decreases. Optimal cement replacement level (by RHA) is 25%, for which the compressive strength is maximum.
30. Continue. The compressive strength is maximum at 15% replacement and then it starts decreasing for both 7 and 28 days cured specimens. With 25% replacement the compressive strength of cubes is nearly equal but slightly above then the OPC mix concrete specimens, but at 35% replacement the strength is less then the OPC mix for both 7 and 28 days cubes. The compressive strength of OPC & RHAC increases with increase in curing period of samples. The permeability of all mixes decreases with increase in compressive strength as compared to control concrete mix accept at 25% replacement.
31. Continue. The results obtained from this study indicates that up to 25% of RHA could be advantageously blended with cement without adversely affecting the strength and permeability properties of concrete.