Mahafuzur Islam Mondal Leon¹, Md. Rashedul Haque^1,, Afrin Sultana Tisha¹, Imtiaz Shoad¹

The possibility to reuse and recycle agricultural garbage as a building material has been displayed in a diversity of applications. This research is an investigational study that was made on the influence of using Rice Husk Ash (RHA) and Wheat Straw Ash (WSA) as a partial substitution of cement in the concrete mixture. The RHA and WSA have been chosen combined for this research due to their easy availability and their cementitious properties. The objective of this research was to minimize the utilization of large quantities of cement, evaluate the compressive strength of concrete, and compare it with control concrete. RHA and WSA carried a large amount of formless silica that can be a customary partial replacement of ordinary Portland cement in concrete. The cylindrical specimens (100 mm × 200 mm) were made for this research as a partial substitution of 0%, 5%, 10%, 15%, and 20% by volume of an equal amount of RHA and WSA with constant water/cement ratio as 0.45. In this research, the unit weight of concrete, compressive, splitting tensile and flexural strength, and water absorption tests were performed at different percentages of replacement and different curing periods such as 7 and 28 days. The optimum compressive strength was given a 15% substitution of cement by RHA and WSA. After that the compressive, splitting tensile, and flexural strength of concrete was decreased with increasing ordinary Portland cement replacement with RHA and WSA. The unit weight of concrete has been decreased, and water absorption has been increased with increasing ordinary Portland cement replacement with RHA and WSA.

Rice Husk Ash (RHA), Wheat Straw Ash (WSA), Water-cement ratio, Unit weight, Compressive strength, Water absorption