Effect of unprocessed rice husk ash as a cementitious material in concrete
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Effect of unprocessed rice husk ash as a cementitious material in concrete

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Effect of unprocessed rice husk ash as a cementitious material in concrete Document Transcript

  • 1. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME240EFFECT OF UNPROCESSED RICE HUSK ASH AS A CEMENTITIOUSMATERIAL IN CONCRETE(A COMPARISON WITH SILICA FUME)Mohammad Qamruddin1, Prof.L.G.Kalurkar21Master of Civil Structures, Civil Engineering, Faculty of Engineering, Jawaharlal NehruEngineering College Aurangabad2Professor at Jawaharlal Nehru Engineering College Aurangabad Dr.Babasaheb AmbedkarMarathwada University, Aurangabad,431001, MaharashtraABSTRACTFast depleting natural resources, huge consumption of energy, and environmentalhazards involved in the production of cement has inspired for searching the substitution byother material with similar material, especially in developing countries. Rice husk ash(RHA), an agricultural waste, is classified as “a highly active pozzolan” because it contains avery high amount of amorphous silica and a large surface area. The objective of the study isto investigate the mechanical properties of concrete with different replacement levels ofordinary Portland cement by rice husk ash and silica fume individually and in combination.The cylinders (150mmdia x 300mmheight) were cast. The splitting tensile strength at 7daysand 28 days have been obtained with normal curing regime. For RHA a maximum increase insplitting tensile strength was 10% whereas for silica fume it was 17% compared with nominalmix when used individually. Combination of RHA and silica fume did not show any excitingresults.Keywords: Rice husk ash, Silica fume, cementitious material, concrete.INTERNATIONAL JOURNAL OF CIVIL ENGINEERING ANDTECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 4, Issue 2, March - April (2013), pp. 240-245© IAEME: www.iaeme.com/ijciet.aspJournal Impact Factor (2013): 5.3277 (Calculated by GISI)www.jifactor.comIJCIET© IAEME
  • 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME2411. INTRODUCTIONWith growing environmental consciousness at all levels of society, the pollution andhealth hazards especially associated with the concrete and cements industries, is comingunder intense scrutiny from environmentalists and the governments. The developed countriesare farther ahead in tackling the problem by using industrial and agricultural wastes in theirindustries. These industrial and agricultural wastes are mostly the by-products of oil and coalburning by-products, slag, rice husk ash, bagasse, fly ash, cement dust, stone crusher dust,marble dust, brick dust, sewer sludge, glass, tires, etc. Million tons of these waste materialsare abundantly available and discarded every year in the world. They pose environmentalproblems like air pollution and leaching of hazardous and toxic chemicals (arsenic, beryllium,boron, cadmium, chromium, chromium(VI), cobalt, lead, manganese, mercury, molybdenum,selenium, strontium, thallium, and vanadium, along with dioxins and polycyclic aromatichydrocarbon compounds, etc.) when dumped in landfills, quarries, rivers and oceans [1,2].Consequently air and water pollution have been inextricably linked to environmentalproblems and climate change. The production of cement (key binding component ofconcrete) is costly, consumes high energy, depletes natural resources and emits huge amounts0of greenhouse gases (1 ton of cement production emits approximately 1 ton of CO2).Consequently, environmental degradation, serious pollution and health hazards associatedwith cement and concrete industries.Rice Husk is one of the waste materials in the rice growing regions. This not onlymakes the purposeful utilization of agricultural waste but it will also reduce the consumptionof energy used in the production of cement. Therefore Rice Husk is an agro based productwhich can be used as a substitute of cement without sacrificing the strength and durability.Generally the Rice Husk Ash is used while burning the raw clay bricks in the Brick Kilns.Till recently it is also used in Hotels for cooking but now it is replaced by LPG Gas. SinceRice Husk has negligible protein content, it is not useful for animal feeding. Rice Husk Ash isobtained from burning of Rice Husk, which is the by-product of rice milling. It is estimatedthat 1,000 kg of rice grain produce 200 kg of Rice Husk; after Rice Husk is burnt, about 20percent of the Rice Husk or 40 kg would become RHA. Rice Husk Ash contains as much as80-85% silica which is highly reactive, depending upon the temperature of incineration. Dueto relative high water demand, the lime Rice Husk Ash cement developed lower compressivestrengths. However, the strength characteristics are considered adequate for general masonrywork. The water demand for normal consistency tends to increase with increasing Ashcontent of the blended cements. However, this can be corrected by application of certainwater reducing admixtures. The investigations as outlined above point towards encouragingtrend. Normally fly Ash may be used for partially replacing cement to the extent of about25% of cement. Reactions that take place in the preparation of Rice Husk Ash concrete are;Silicon burnt in the presence of Oxygen gives Silica.Si + O2 SiO2C3S (Cement) + H2O CSH + Ca (OH) 2
  • 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME242The highly reactive silica reacts with Calcium hydroxide released during the hydration ofcement, resulting in the formation of Calcium Silicates responsible for strength.SiO2 + Ca (OH)2 CSH + SiO2Mehta, P.K., (1) has conducted investigations on Portland Rice Husk Ash cements up to50% of Ash showed higher compressive strength than the control Portland cement even at asearly as 3 days. Mehta, and Pirtz (2) in a concrete mixture, when 30% Rice Husk Ash byweight of the total cementing material was present, the 7 days and the 28 days compressivestrengths were higher. Subba Rao.et.al (3) studied the reaction product of lime and silicatefrom Rice Husk Ash and showed that it is Calcium Silicate Hydrate (C-S-H) which accountsfor the strength of lime Rice Husk Ash cements.2. MATERIAL PROPERTIES INVESTIGATED FOR THIS RESEARCHTable 1:- Material Properties1 Nominal Max.Size of coarse aggregate 20 mm2 Slump range (Medium) 50-75 mm IS 10262-2009(Pg.02)3 Finness Modulus Of Fine Aggregate 2.88 Confirming to zone II (IS 383-1970)4 Finness Modulus Of Steel Slagaggregate2.86 Confirming to zone II (IS 383-1970)5 Finness Modulus Of Coarse Aggregate 5.12 Confirming to zone II (IS 383-1970)6 Specific Gravity Of Fine Aggregate 2.657 Specific Gravity Of Steel Slag aggregate 2.678 Specific Gravity Of Coarse Aggregate 2.759 Specific Gravity Of Cement 3.1510 Water Absorption of fine aggregates 4.7 %11 Water Absorption of coarse aggregates 1.65 %
  • 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME2433. CHEMICAL COMPOSITION AND PHYSICAL PROPERTIES OF RICE HUSKASH USED IN THE STUDYTable 2:- Chemical Composition of rice husk ash:Constituent SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O K2OPercentage ( % ) 94.84 0.39 0.54 1.32 0.40 0.01 0.11 1.45Table 3:- Physical Properties of rice husk ashPhysical Properties Steel SlagColour GreyAppearance Amorphousspecific gravity 2.173.1 RHA characteristicsA residual RHA obtained from open filed burning from local resource was used. Thematerial was carefully homogenised packed to enhance the transport to the laboratory.Grinded RHA (GRHA): after drying and homogenization process the RHA was ground in alaboratory ball mill by one hour for optimization. The size and shape of the natural rice huskash particles make difficult the development of pozzolanic reactions and the water demandstrongly increases. The GRHA was passed through IS 90 micron sieve and this was used forthe research. Adopting an adequate sequence for concrete mixing process, where the RHAand the coarse aggregates are mixed during a certain time and after that the rest of componentmaterials are incorporated, the RHA characteristics can be improved. Table 2 and 3 presentssome chemical composition of the ash and the physical characteristics.4. EXPERIMENTAL PROGRAMMaterials used in this study were OPC 53 grade cement confirming to IS 8112 andfine aggregate and coarse aggregate confirming to IS 383-1970.The cement and aggregatewere tested to fulfill the IS requirements.Rice husk ash was replaced with cement as 10%, 15%, 20% and 25%, similarly silicafume was also replaced with cement in different batches with percentage replacementsas10%, 15%, 20% and 25%. In the third step rice husk ash and silica fume were replaced incombination asRice husk ash and silica fume were replaced according to following table
  • 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME244Table 4:-Batch Cement(%) RHA(%) Silica fume(%)1 100 0 02 90 10 03 85 15 04 80 20 05 75 25 06 90 0 107 85 0 158 80 0 209 75 0 2510 90 5 511 85 7.5 7.512 80 10 1013 75 12.5 12.514 75 15 1015 70 20 1016 65 25 10Designed concrete mix of M-20 grade having mix proportion 1:1.90:2.96 with w/c ratio 0.5same for different percentages of rice husk ash and silica fume were used.The concrete ingredients namely, cement and coarse aggregates and rice husk ash and silicafume according to batches were first mixed in the dry state and water was added last.Cylinders of size 150mm diameter x 300mm length for split tensile strength, Cubes of size150x150x150 mm for compressive strength were cast replacing rice husk ash and silica fumeby weight of cement.All the samples were watered cured for 7 days and 28 days. For each batch of RHA and silicafume percentage replacement 6 specimens were cast. Details of the experimentalinvestigation of effect of different percentages replacement of fine aggregate by steel slag aregiven elsewhere.4.1 Testing Programme4.1.1 Compressive StrengthThe cube specimen was placed in the machine, of 1000kN capacity. The load wasapplied at a rate of approximately 140 kg/sq.cm/min until the resistance of the specimen tothe increasing load can be sustained. Results are presented in Tables 5 and 6.4.1.2 Splitting Tensile StrengthThe cylinder specimen was placed horizontally in the centering with packing skip orloading pieces carefully positioned along the top and bottom of the plane of loading of thespecimen. The load was applied without shock and increased continuously at a nominal ratewithin the range 1.2 N/mm2/min to 2.4 N/mm2/min until failure the specimen. The maximumload applied was recorded at failure.
  • 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME245TEST RESULTS FOR SPLITTING TENSILE STRENGTH4. DISCUSSIONS ON TEST RESULTS4.1 Splitting tensile Strength of ConcreteAs the replacement level increases there is increase in splitting tensile strength at 28days age of strength. The maximum splitting tensile strength for the replacement with RHAand silica fume individually was 4.54 and 4.78 respectively. An increase of 14% and 20%was observed for RHA and silica fume individually. RHA and silica fume in combinationshowed a decreasing trend of strength.
  • 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME2465. CONCLUSIONS1. Replacement of cement with Rice Husk Ash leads to increase in the compressive strengthat 14% at 15% replacement.2. Optimum replacement level for silica fume was found to be 20% where 17% increase insplitting tensile strength is observed.3. The strength achieved for the replacement of combination of RHA and SF was even lessthan the nominal mix but cannot be authenticated due to less number of tests.REFERENCES[1] P.K.Mehta, “Properties of Blended Cements Made from Rice Husk Ash”, ACIJournal/September 1977 pp. 440-442.[2] P.K.Mehta and D.Pritz, “Use of Rice Husk Ash to Reduce Temp in HSC”,Journal/February 1978 pp. 60-63.[3] James, J., Subba rao .M., “Reactive of Rice Husk Ash”, Cement and Concrete Research,Vol.16, 1986.[4] Rahman M.N., “Curing of RHA Mix sand concrete blocks”, International Journal ofStructures, Vol. 8, No.1, 1988.[5] Seshagiri Rao M.V., Chankravarthi R.K., Narasimha Murthy, “Rice Husk Ash BlendCement” National Seminar on “Recent Advances in Civil Engg. With Special. Reference toBuilding Industry”, JNTU College of Engg. & Tech., Hyderabad1992.[6] K. Sasiekalaa and R. Malathy, “Flexural Performance of Ferrocement LaminatesContaining Silicafume and Fly Ash Reinforced With Chicken Mesh”, International Journal ofCivil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 130 - 143,ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.[7] Raju Sathish Kumar, Janardhana Maganti and Darga Kumar Nandyala, “Rice Husk AshStabilized Compressed Earth Block-A Sustainable Construction Building Material – AReview”, International Journal of Civil Engineering & Technology (IJCIET), Volume 3,Issue 1, 2012, pp. 1 - 14, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.