International Journal of Structural and Civil Engineering Research Vol. 8, No. 3, August 2019 Effect of Rice Husk Ash on Compressive Strength of Concrete R. R. Singh Civil Engineering Department, PEC, Chandigarh, India Email: rrs837angwlmp@gmail.com Damandeep Singh Structures, Civil Engineering Department, PEC, Chandigarh, India Email: gilldaman391@gmail.com Abstract—Over the past decades concrete technology has entered the broad areas of research to enhance the properties and performance of concrete. Moreover there is the introduction of the new types of concrete such as selfcompacting concrete (SCC), high strength concrete (HSC) or ultra-high strength concrete (UHSC). Now these types of concrete are being widely used in the world and they require the high cement binder. So high cement content means high loss to environment as in the manufacturing of one tonne of cement, about 1 tonne of CO2 is emitted. So it is necessary to reduce usage of cement by introducing new supplementary cementitious materials which are the byproducts of industries to reduce debris. Rice Husk Ash is one of these. The potential of rice husk ash as a cement replacement or addition material is well established. A review of literature urges the need for optimizing the replacement level or additionof RHA in concrete for improved compressive strength at optimum water binder ratio. This paper discusses the improved compressive strength of RHA- High strength concrete at optimized conditions. A Mechanism The following reaction that will takes place in Rice husk ask concrete When silicon burnt in the presence of Oxygen will form silica. Due to hydration of cement there will be formation of CSH gel and Calcium hydroxide. But Calcium hydroxide is soluble product and unstable in concrete. The highly reactive silica reacts with Calcium hydroxide that will lead to form again CSH (gel) which will leads to get higher strength than that of ordinary concrete. Index Terms—compressive strength, concrete, RHA, High Strength Concrete (HSC), replacement, addition II. A I. ConcreteMaterials Concrete mixtures to be examined were made in the laboratory using the following materials: cement, RHA, Super plasticizer, coarse aggregates and fine aggregates. INTRODUCTION The rice husk ash is one of the by product which is released from paddy. RHA generally referred to an agricultural by-product of burning husk under controlled temperature of below 800 °C. Rice husk ash (RHA) is now accepted as a highly reactive pozzolanic material with silicon dioxide (Si02) more than 85% .The usage of rice husk ash in concrete leads to development of high strength concrete and also reduces the self weight of the structure. Less requirement of cement means less emission of result in reduction in green house gas emission. By continuous research on properties of rice husk ash, the results shows that it contain high silica content which is more than 90%, it reduces shrinkage cracks and leads to increase the strength of concrete. B Rice Husk Ash RHA was obtained from burning rice husk in a Ferro cement furnace in the laboratory, and later ground using a Los Angeles machine for 5000 cycles. The fineness of RHA retained using a 45 micrometer sieve and its specific gravity were 18.5% and 2.05 respectively. The surface was 25250 m2/kg. C Cement Locally produced ordinary Portland cement (OPC) was used. It has a specific gravity and specific surface of 3.11 and of 3200 m2/kg respectively. Manuscript received February 1, 2019; revised May 30, 2019. © 2019 Int. J. Struct. Civ. Eng. Res. doi: 10.18178/ijscer.8.3.223-226 MATERIALS 223 International Journal of Structural and Civil Engineering Research Vol. 8, No. 3, August 2019 TABLE I. CHEMICAL COMPOSITION OF OPC AND RHA Oxides % Materials Sio2 Al2O3 Fe2O3 MgO Na2O K2O P2O5 CaO MnO OPC 20.99 6.19 3.86 0.20 0.17 0.60 0.05 65.96 0.06 RHA 88.82 0.46 0.67 0.44 0.12 2.91 1.00 0.67 0.08 Mixture proportioning for all the mixes was based on the Indian Standards. Using the codal provisions, the control concrete containing superplasticizer (SpOPC) was designed with water to cementitious (w/cm)ratio of 0.27 and cement content of 537 kg/m3.The coarse aggregate content forthis and subsequent mixes was fixed at 1055 kg/m3. A total of 6 series of "RHA addition'' and"RHA replacement" mixtures were cast to evaluate the effects of method ofincorporating of RHA on properties of fresh and hardened concrete. RHA was"added" or ''replaced" at 5%, 10% and 15% of the cement content. The property of fresh concrete investigated was Workability designed to produce slump in the range of 200-250 mm. The compressive strength of concrete samples was tested at 1, 3, 7, 28 and 180 days of water curing. The optimum mixes of the RHA "addition"and ''replacement" were selected for further investigating the compressive strength(150 mm cube). D Superplasticizer The new generation of polycarboxylic ether superplasticizer, Glenium 51, having a specific gravity and solid content of 1.09-1.10 and 34%-36% respectively was used. E Coarse Aggregates The coarse aggregate was crushed granite of 20 mm maximum size. Its specific gravity and water absorption were 2 .63 and 0.71% respectively. F Fine Aggregates Fine aggregate used was mining sand conforming to zone 1 of BS 410. Its specific gravity, water absorption and fineness modulus were 2.53, 3.36% and 4.53 respectively. III. MIXTURE PROPORTION AND TESTS TABLE II. MIX PRO PORTIONS Mix Sp(%) SLUMP(mm) WATER(kg) OPC(kg) RHA(kg) CA(kg) FA(kg) SpOPC 1 220 140 537 - 1055 669 RHA5A 1 240 152 537 26.9 1055 619 RHA10A 1 225 160 537 53.7 1055 657 RHA15A 1 200 167 537 80.6 1055 516 RHA5R 1 225 145 510 26.9 1055 657 RHA10R 1.1 200 145 486 53.7 1055 645 RHA15R 1.1 220 145 456 80.6 1055 636 IV. ''replacement" on the strength property of HSC are discussed below: 1) Effect of RHA "Addition" From Table 3, it is noted that for theRHA addition series, the optimum strength resulted from 10% addition of RHA, similar to that found previously. Compared to the control SpOPC, except for 15% RHA content. All RHA mixes exhibited superior strength at 180 days. 2) Effect of RHA "Replacement" of Cement For RHA replacement mixes, the highest strength was achieved at 5% cement replacement. At 1 0% replacement, strength of 80 N/mm2 was still achievable. Increasing the RHA content further, decreases the strength significantly. Previous research indicatedthat the optimum replacement of cement by RHA for optimum strength was about I0% to 20%. RESULTS AND DISCUSSIONS A Workability The measured slump values of all the mixes are given in Table 2. It isapparent that varying amounts of water between 145 kg and 167 kg andSuperplasticizer (Sp) between 0.9-1.0percent of cement content was needed tomaintain workability of concrete in the range of 200250 mm. In general, forsimilar workability, Sp dosage for RHA addition mixes was lower than thereplacement series. B Effect of RHA on Compressive Strength The compressive strength for various concrete mixes is presented inTable 3. The effects of method of incorporation of RHA.i.e. by "addition'' orcement © 2019 Int. J. Struct. Civ. Eng. Res. 224 International Journal of Structural and Civil Engineering Research Vol. 8, No. 3, August 2019 TABLE III. COMPRESSIVE STRENGTH OF HSC Compressive Strength (N/mm2 ) Mix 1d 3d 7d 28d 128d SpOPC 44.5 60.6 69 83 87.4 RHA5A 40 65 72 86.3 101.6 RHA10A 39 61.9 73.3 87.3 103.5 RHA15A 29 52 72.1 83 100.1 RHA5R 43.9 67.4 77.6 87.8 102.6 RHA10R 39.1 58.1 73.6 86.2 100.2 RHA15R 25 48 64.4 77.6 94.4 120 100 1d 80 3d 60 7d 40 28d 20 128d 0 SpOPC RHA5A RHA10A RHA15A Graph 1 – Results showing compressive strength with addition of RHA 100 80 1d 60 3d 40 7d 20 28d 0 SpOPC RHA5R RHA10R RHA15R Graph 2 – Results showing compressive strength with replacement of RHA V. REFERENCES CONCLUSION [1]. V. M. Malhotra and P. K. Mehta, “Advances in concrete technology,” Pozzolanic and Cementitious Materials, vol. 1, 1996. [2]. Basha, A. Mohamed, and A. S. Muntohar, “Effect of the cementrice husk ash on the Plasticity and compaction of soil,” Electronic Journal of Geotechnical Engineering, vol. 8, 2003. [3]. H. B. Mahmud, “Rice husk ash as a cement replacement material in concrete - The Malaysian Experience,” in Proc., the 4t 1 JSPVCC Seminar on Integrated Engineering, Kyoto, Japan, 1992, pp. 280-285. [4]. D. G. Nair. K. S. Jagadish, A. Fraaij, “Reactive pozzolanas from rice husk ash: An alternative to cement for rural housing,” Cement and Concrete Research, vol. 36, pp. 1062-1071, 2006. [5]. G. Giaccio, G. R. Sensale, and R. Zerbino, “Failure mechanism of normal and high strength concrete with rice husk ash,” Cement and Concrete Composites, vol. 29, pp. 566-574, 2007. Irrespective of method of inclusion or percentage of RHA. Theworkability of concrete of200 to 250 mm slump can be obtained with Sp dosage of less than 1.2 % of total cementitious content. The optimum "addition'' or “replacement'' level of RHA to produce optimum strength is 10% and 5%respectively. Both RHA concrete mixtures when subjected to water curing conditions were able to achieve compressive strength of 80 N/mm2at 28 days. Concrete containing 10% RHA "addition" was able to attain 100N/mm2 at 180 days. © 2019 Int. J. Struct. Civ. Eng. Res. 225 International Journal of Structural and Civil Engineering Research Vol. 8, No. 3, August 2019 [6]. M. A. Ahmadi, O Alidoust, I. Sadrinejad, and M Nayeri, “Development of mechanical properties of self compacting concrete containing rice husk ash,” World Academy of Science, Engineering and Technology, vol. 34, 2007. [7]. G. A. Habeeb and M. M. Fayyad, “Rice husk ash concrete: the effect of rha average particle size on mechanical properties and drying shrinkage,” Australian Journal of Basic and Applied Sciences, vol. 3, no. 3, pp. 1616-1622, 2009. © 2019 Int. J. Struct. Civ. Eng. Res. 226