Properties of Rice Straw Cementitious Composite

Utilization of rice straw as a building material is the main aim of this work. The study is divided into four divisions; study the effect of treatments on the constituents and tensile properties of rice straw, hydration of rice straw with Portland cement, development of high content fly ash cementitious binder, and determination physical and mechanical properties of straw fly ash cementitious binder composites. Treating rice straw with 1% NaOH solution, it is classified as a filler or reinforcement for cementitious building materials. Whereas, the addition of 6% CaCl2 to the mixture improves the compatibility due to the decrease of the inhibitor effect of soluble materials. An acceleration of the cement hydration process can be observed. On the other hand, optimum curing temperature will be given during the first 24 hours at 85oC for all the studied systems. Fly ash -calcium hydroxide- gypsum- cement mixture with 70%:3.5%:7%:19.5% weight ratio results in the highest compressive strength (50 MPa at 28 days). According to compressive strength and flexural strength data, rice straw cementitious mixture could be classified as carrying material for making bricks with straw content up to 10 %.