| Abstract:
In this study, the effect of nano gel wollastonite dosage in three level (0, 5 and 10 percent per dry by weight of the cement) and the mixture ratios of lingocellulosic material to cement in three level (10: 90, 20: 80 and 30: 70) on physical, mechanical, microscopic and biological properties of composite made from rice straw fibers-cement was investigated. Three replicates for each treatment and 27 experimental boards were manufactured. Specimens were prepared according to DIN-EN634 standard test methods to measure mechanical and physical properties. Mechanical and physical properties including static bending strength, modulus of elasticity, internal r bonding(IB), water absorption after 2 and 24 hours immersion in water, density and decay resistant (weight loss ) were measured. Micro-structural properties of composites were evaluated by SEM images. The results showed that, bending strength, modulus of elasticity, internal bonding and density were significantly increased with increasing Nano gel wollastonite. Also, with increasing Nano gel wollastonite, dimensional stability and decay resistance were increased in comparison with the control sample. Results of scanning electron microscopy showed that the calcium hydroxide formed hydrated calcium silicate gel (C-S-H gel) after addition the Nano gel wollastonite. SEM images showed that the micro-structure of the boards was improved by increasing the nano-wollastonite content.
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