Optimization of PVA fiber dosage for improved mechanical properties of engineered cementitious composites

Abstract This paper presents experimental investigation on optimizing polyvinyl alcohol (PVA) fiber dosage in engineered cementitious composites (ECC) designed for M-30 and M-40 concrete grades. The study examined workability, compressive, tensile, flexural, shear, and impact strengths across ECC mixes with different PVA fiber contents varying from 0 to 2.5 % by volume with an interval of 0.5 %. Increase in PVA fiber content reduces the workability and is mainly due to fiber entanglement and increased internal friction within the mix. Addition of PVA fiber improves all the mechanical properties up to an optimal content of 1.5 % by volume. At this optimal dosage, compressive, flexural, split tensile and shear strength increased by 3.9 & 4.5 %, 94.2 & 109.5 %, 91.6 & 98.9 %, 140.9 & 157.7 % for M-30 and M-40 grade concrete respectively. Impact strength results showed that number of blows for final failure increased by 174 & 165 times for M-30 & M-40 grades respectively compared to control mix. Results indicate that addition of fiber improves mechanical properties significantly up to an optimal dosage of 1.5 % by volume, beyond which workability decreases and strength gains remains same or slightly decrease due to fiber clustering.