Impact of PVA fiber as fine aggregate replacement in alkali-activated fly ash on flow rate, mechanical properties and drying shrinkage

This study focuses to discuss the performance of alkali-activated mortar (AAM) reinforced by Polyvinyl Alcohol (PVA) fiber as a replacement of fine aggregate. Drying shrinkage is a major problem of alkali-activated mortar (AAM). Therefore, in order to reduce shrinkage and improve the performance of the mortar; the Polyvinyl Alcohol (PVA) fiber was introduced to replace the fine aggregate. An experimental test, including flow rate, compressive strength, modulus elasticity, poison's ratio, flexural strength and rate of drying shrinkage, was performed to investigate the performance of AAM with various percentage of PVA fiber. Based on the test, it was obtained that the utilization of PVA fiber as a fine aggregate replacement shows a slight decrease in the flow rate compared to plain AAM. The density of PVA AAM reinforced-fiber of five mixtures is almost similar to plain AAM with the differences lower than 2%. The use of PVA at levels ranging from 0% to 2%, with a level increment of 0.5% by volume, as fine aggregate replacement increased compressive strength, but decreased flexural strength. The replacement of fine aggregate with a certain value of PVA, which are 0.5% by volume, reduces the drying shrinkage of mortar. However, adding PVA more 0.5% by volume to the mortar increases the drying shrinkage.