Split Tensile Strengths of Concrete Incorporating Rice Husk Ash and SawDust Ash (original) (raw)

2016, Journal of Multidisciplinary Engineering Science and Technology (JMEST) ISSN: 2458-9403 Vol. 3 Issue 7

This work investigated the split tensile strengths of concrete containing rice husk ash (RHA) and saw dust ash (SDA). RHA and SDA were obtained from open air calcination. Ordinary Portland cement (OPC) was partially replaced with each of RHA, SDA, and RHA-SDA at 5%, 10%, and 15%. Nine concrete cylinders of dimensions 150×300mm were produced using 100% OPC. Eighty one concrete cylinders also of dimensions 150×300mm were similarly produced for each of the percentage replacement of OPC with RHA, SDA, and RHA-SDA, making a total of 252 concrete cylinders. The concrete cylinders were cured by immersion and tested for split tensile strength at 28, 90, and 150 days. Models were developed to predict the tensile strengths of concrete containing RHA and SDA as binary and ternary blends with OPC at varying percentage replacements and curing ages. The split tensile strength decreased with increasing percentage replacements of OPC with RHA, SDA, and RHA-SDA. At 28 days of curing, values of 0.86N/mm 2 , 0.78N/mm 2 , and 0.70N/mm 2 were obtained at 5%, 10%, and 15% replacements of OPC with RHA respectively. Values of 0.77N/mm 2 and 0.58N/mm 2 were obtained at 5% and 10% replacements of OPC with SDA respectively. Values of 0.82N/mm 2 and 0.64N/mm 2 were obtained at 5% and 10% replacements of OPC with RHA-SDA respectively. Split tensile strengths of concrete with RHA, SDA, and RHA-SDA were lower at early age of curing but improved at later ages. For 5% replacement of OPC with RHA values of 1.42N/mm 2 and 1.85N/mm 2 were obtained at 90 and 150 days of curing respectively. For 5% replacement of OPC with SDA values of 1.28N/mm 2 and 1.65N/mm 2 were obtained at 90 and 150 days of curing respectively. For 5% replacement of OPC with RHA-SDA values of 1.35N/mm 2 and 1.66N/mm 2 were obtained at 90 and 150 days of curing respectively. Values for the control were 1.34N/mm 2 and 1.61N/mm 2 at 90 and 150 days of curing respectively. Thus, based on split tensile strength values, concrete produced with 5% to 15% replacement of OPC with RHA and 5% to 10% replacement of OPC with RHA-SDA could be used in reinforced and unreinforced concrete works where time of loading is not critical. The models developed were tested and found to be adequate for predicting split tensile strengths of binary and ternary blended OPC-RHA-SDA cement concretes.