In this paper an experimental study was made on the effects of using Rice Straw Ash (RSA) &
Wheat Straw Ash (WSA) as partial replacements of cement in mortar. The objects were to produce
Nano Silica (NS) form RSA & WSA as agricultural wastes by using chemical acids. Then, control
specimens with Ordinary Portland Cement (OPC) was made and in other specimen’s cement were
replaced with 5%, 10%, 15% and 20% of RS & WS ashes by weight of cement. The workability
was measured by the slump test. The pulse velocity and the sorptivity were also computed. The
compressive and tensile strengths were also estimated. Experimental result showed that it was
feasible to produce silica from WSA by chemical activation method. Also, the highest compressive
strength, tensile strength and sorptivity noticed at 15% WSA