Rice husk ash and sewage sludge ash as sustainable replacement material for concrete

Abstract The development of supplementary cementitious materials (SCMs) has become essential in the advancement of low-cost construction materials for production of self-sufficient housing especially in developing countries. The use of these SCMs as admixtures not only improves concrete properties but protects and conserves the environment by saving energy and natural resources. Thus, studies have been conducted to find the suitability of combination of sewage sludge ash and rice husk ash to replace cement partially in conventional concrete. The effects on the nature of concrete exhibited mechanical properties of concrete such as compressive strength from a combination of sewage sludge ash and rice husk ash at different proportions. Sewage sludge ash (SSA) and rice husk ash (RHA) are used as partial replacement of cement for 10%, 20%, 30%, 40% and 50% in the concrete. The samples had been tested with compressive test to compare with normal concrete (OPC). There was an increment compressive strength of concrete at 10% amount replacement SSA and RHA, but the compressive strength declined when the amount replacement SSA and RHA are developing more than 10%. In addition, the concrete also showed increasing of compressive strength within the additional curing period, which was 7 days, 14 days and 28 days.