Workability and compressive strength of concrete containing binary cement, mixed fines, and superplasticizer

Abstract

Growing awareness about the influence of buildings on the environment has resulted in a need for more ecologically friendly buildings made of inexpensive but longlasting construction materials. Experimental findings on the workability and strength qualities of concrete produced by partial substitution of sand with lateritic soil at various percentage replacement levels of cement with Rice Husk Ash (RHA) up to 15% are presented herein. The chemical analysis of RHA and lateritic soil, as well as the consistency and setting times of OPC and OPC/RHA pastes were conducted. They were all found to be within the limits specified by appropriate standards. Slump values for all concrete mixtures reduced with increase in the replacement level of cement with rice husk ash (RHA), with and without the inclusion of superplasticizer. However, for mixtures without superplasticizer, up till 10% replacement of cement with RHA, slump increased with increase in sand replacement with laterite up to 20% and started fluctuating for laterite levels beyond 20%. For mixes with superplasticizer, slump rose for laterite levels up to 10% and fluctuation set in thereafter. The results also revealed that at all ages and for all investigated levels of sand replacement with laterite, the compressive strength of concrete attained its highest value at 95% OPC with 5% RHA. Furthermore, this highest value of the compressive strength is substantially the same with that of the 0%RHA with 0%laterite reference concrete. The findings of this research will be of benefit to concrete professionals interested in the inclusion of laterite and RHA to achieve greenness, sustainability, and cost-effectiveness in concrete.