Influence of using agro-waste as a partial replacement in cement on the compressive strength of concrete – A statistical approach

•Utilization of agro-waste as a substitute in cement to reduce landfill problems.•The best-fit statistical model identified for predicting compressive strength of concrete.•DOE and RHA has good pozzolanic reaction to be used as a cementitious material. Recent efforts in sustainable infrastructure development have focused on using industrial wastes to enhance the mechanical properties of concrete. A majority of the relevant research has aimed at using industrial wastes as a replacement material in cement. Hence, in this study relatively new agro-industrial wastes, namely spent bleach earth (SBE) and de-oiled Earth (DOE), were used in combination with rice husk ash (RHA) as substitute in cement. Cement was partly replaced with different percentages of SBE, DOE, and RHA, individually and in combination, to form binary and ternary blended binders. The percentage of waste in cement was varied from 0% to 20% in increments of 2.5%. The ratio of fine to coarse aggregate was maintained constant at 40:60 for the concrete mixtures. The results indicated the partial replacement of cement by 5% SBE, 7.5% DOE and 7.5% RHA individually increased the compressive strength of concrete. A furture increase in the replacement percentage resulted in gradual decrease in the compressive strength. Furthermore, the combined influence of the aforementioned pozzolanic wastes was examined by using ternary blends comprising concrete SBE and DOE; concrete SBE and RHA; as well as concrete DOE and RHA. The relation between the compressive strength at 7 and 28 days for different levels of replacements indicated that the compressive strength increased when a 2.5% concentration of the aforementioned three combinations was added to cement. Prediction analysis was conducted using the regression and artificial neural network (ANN) methods. The R2 values obtained with the regression and ANN methods were 0.6561 and 0.9673 for 7 days and 0.6441 & 0.9636 for 28 days respectively.