Establishment of fiber factor for rheological and mechanical performance of polyvinyl alcohol (PVA) fiber reinforced mortar

Abstract

In this paper, two types of polyvinyl alcohol (PVA) fibers with three kinds of aspect ratios were added to reinforce mortar. Rheological properties, density loss, ultrasonic pulse velocity (UPV), compressive strength and flexural strength were evaluated and the relationship between system viscosity and fiber volume fraction was developed based on a simplified two-phase system of fiber reinforced cementitious composites (FRCCs). In addition, the rheological and hardened properties of 29 PVA-FRCCs groups were divided into three grades by two specific fiber factors (FF) values that were associated with fiber content, i.e. critical fiber factor Fc and dense fiber factor Fd (Fc < Fd). When the FF is lower than Fc = 100, the fibers have insignificant effect on rheological properties and exerts some damage on the matrix. When the FF exceeds Fd = 400, a large amount of fibers formed clusters and almost deteriorate the rheological and hardened properties of mortar. When the value of FF is between Fc = 100 and Fd = 400, the content of fibers is proposed to produce desirable PVA-FRCCs with proper rheological properties and excellent mechanical properties. Conclusively, it is found that rheological properties can significantly affect the hardened properties of PVA-FRCCs by means of variation in fiber dispersion and microstructure. The obtained values of Fc and Fd assisted in determination of fiber content for mix design proportion. The optimum PVA fiber type as well as aspect ratio were proposed in each region, which would help for design of PVA-FRCCs with favorable rheological and hardened properties in practical applications.