Mechanical Properties of Polyvinyl Alcohol Fiber-Reinforced Concrete Composite Containing Fly Ash and Nano-SiO2

In this study, the influence of polyvinyl alcohol (PVA) fibers and nano-SiO2 particles on the mechanical properties of concrete composites containing 15% fly ash was assessed. Portland cement was replaced by nano-SiO2 particles at different levels (1%, 3%, 5% and 7% by weight). PVA fibers were added to the concrete composite containing 5% nano-SiO2 and 15% fly ash at different concentrations (0.05%, 0.10%, 0.15%, and 0.2% by volume). The binder content of all concrete mixes was 500 kg/m(3), with a water-to-binder (w/b) ratio of 0.36. Slump and slump flow tests were used to evaluate the workability of the fresh concrete mixtures. The mechanical properties of the concrete mixes were assessed by testing the compressive and flexural strength and the compressive and flexural modulus of elasticity. The results showed that the workability of the fresh concrete composite decreased with increases in the nano-SiO2 and PVA fiber content. When the nano-SiO2 dosage was below 5%, the compressive and flexural elastic modulus and compressive and flexural strength increased with increases in the nano-SiO2 dosage. However, these values decreased when the nano-SiO2 dosage was increased from 5% to 7%. The mechanical properties of the concrete composite containing nano-SiO2 were improved greatly by PVA fibers. The reinforcement of PVA fibers on the flexural and compressive strength of the concrete composite (fiber volume dosage <0.15%) became more and more obvious as the fiber dosage increased. A small volume fraction (<0.1%) of PVA fibers increased the flexural and compressive modulus of elasticity while there was a decreasing trend in both elastic moduli when the fiber content increased from 0.1% to 0.2%.