Prediction of Optimal Dosage of Rice Husk Ash in Blended Cement for Production of Hollow Sandcrete Blocks Using Response Surface Methodology

Abstract

Rice Husk Ash (RHA) is a supplementary cementing material which is obtained through the combustion of rice husk. It is capable of replacing Portland Limestone Cement (PLC) up to 30%, depending on its degree of pozzolanic activity but it is deficient in early age strength development. Based on this, this study predicted the optimum replacement content of PLC with RHA for production of Hollow Sandcrete Blocks (HSB) using Response Surface Methodology (RSM) at 90 days curing age of the HSB. HSB of sizes 450 x 225 x 225 mm, and 450 x 150 x 225 mm were produced using mix ratio 1:6 and 1:8, respectively. A total number of two hundred and eighty-eight blocks were produced and the properties (Density, Compressive Strength (CS), Water Absorption Capacity and Abrasion) of the HSB were subjected to Analysis of Variance (ANOVA). The ANOVA of the models of the chosen variables (RHA fi neness and contents) indicate a signifi cant level at p < 0.0001 (which is lesser than 0.05) for all the responses (Density, CS, WAC and Abrasion). For sustainable use of RHA as substitute of PLC in HSB, 34% RHA content was predicted by the response surface methodology model.