Bending resistance of PVA fiber reinforced cementitious composites containing nano-SiO2

Abstract In this study, the effects of polyvinyl alcohol (PVA) fiber content and nano-SiO₂ (NS) on bending resistance of cementitious composites were investigated including bending strength and toughness. PVA fiber contents from 0.6% to 1.5% were added in the composites. The NS contents was 0% and 2% by mass. The water to binder ratio (w/b) was 0.38 for all composites. The specimens were cured for 28 days under 20^∘C and relative humidity of 95% before bending test. The results show that the bending strength was improved with PVA fiber content increasing and the maximum bending strength was obtained at PVA fiber content of 1.5%. Although PVA fiber increased bending resistance regardless of NS addition, the optimal content was 1.2%. When the fiber content was less than 1.2%, the bending resistance of cementitious composites increased with fiber content. However, the toughness began to decrease as PVA fiber content increased from 1.2 % to 1.5%.2% NS addition decreased both bending strength and toughness due to the fact that NS was prone to self-desiccation and flock together, resulting in micro crack and strength loss.