Effect of Sand Size on Mechanical Performance of Cement-Based Composite Containing PVA Fibers and Nano-SiO2

Both finer sand and nanoparticles have a filler effect on mechanical performance of cement-based composite. In this paper, the influence of sand size in mechanical performance of cement-based composites, containing polyvinyl alcohol fiber (PVA) and nano-SiO2 (NS), was investigated. The studied mechanical performance, included compressive, flexural, tensile strength, and fracture toughness. A 0.9% volumetric percentage of PVA and a 2% NS mass content were used to make cement-based composites with a 0.38 w/b. Silica sand with four sand size ranges (380-830 mu m, 212-380 mu m, 120-212 mu m and 75-120 mu m) was adopted as fine aggregate. The 28-day curing was conducted for all specimens under 20 degrees C and 95% humidity. It is concluded that the finer sand decreased workability and mechanical strength of PVA-reinforced composites containing NS. However, this reduction was very limited for the sand particles less than 380 mu m. The ultimate tensile stain, fracture toughness, and energy were decreased as sand size declined. In addition, the fracture performance of the composites was greatly dependent on fracture energy.