Properties of poly(vinyl alcohol) fiber reinforced high-performance organic aggregate concrete

Poly(vinyl butyral) (PVB) has many special engineering aggregate properties such as super lightweight, physical toughness, adhesion to a variety of surfaces and energy-absorbing characteristics. Poly(vinyl alcohol) (PVA) fiber has some very attractive characteristics, such as good bonding to cementitious matrix, high strength, high modulus and low gravity. Previous studies show that PVB and PVA contain hydroxyl groups which have the potential to form hydrogen bonds between molecules or within different parts of a single molecule. This special feature provides remarkable changes in the surface bond strength, not only between the aggregate and the matrix, but also between the fiber reinforcement and the matrix and aggregates. This study focuses on the development of a lightweight high-performance cementitious composite material which is reinforced with Poly(vinyl alcohol) (PVA) fiber and contains Poly(vinyl butyral) (PVB) as the sole aggregate. Static mechanical properties such as compressive and flexural strengths are investigated. Special properties such as fracture toughness and impact resistance are also evaluated. PVB composite produces low average density but high compressive strength. The addition of PVA fiber improves flexural ductility, fracture toughness, and impact resistance with fiber volume fractions. In general, the increase in fracture toughness was found to be linear with increasing fiber volume fraction, whereas the increase associated with the impact resistance was non-linear. Comparisons are made with a lightweight concrete having equal density, and a normal-weight concrete. Two models based on fiber bridging mechanics and the rule of mixtures are developed to characterize fracture toughness and impact resistance respectively. Good correlations are obtained for the materials tested when experimental results are compared to those predicted by the developed model.