Study on PVA fiber surface modification for strain-hardening cementitious composites (PVA-SHCC)

摘要

A new class of high-performance fiber reinforced cementitious composite, namely Engineered Cementitious Composites (ECC) reinforced with Polyvinyl alcohol (PVA) fibers, is characterized by strain-hardening, multiple-cracking and tight crack width. Due to the high cost of imported PVA fibers, the practical applications of ECC are limited, especially in China. In the present study, different oiling agents are utilized to modify the local PVA fiber surface. A direct single fiber pull-out method was utilized to study the interfacial behavior after fiber surface treatment. The composite flexural performance was studied using a three-point bending test. Different flexural parameters such as first-cracking and post-cracking strength, first-cracking toughness and post-cracking toughness, ultimate load and toughness indices were determined from the load-deflection curves. The oil treatments have proven effective in modifying the fiber-matrix interface with the reduced chemical debonding energy (G(d)) values of 50%-85% in comparison to untreated PVA fiber. Chemical debonding energy as low as 2.8 J/m(2) and frictional bond strength (tau(0)) 1.8 Mpa have been observed. Flexural strength varies between 4.5 Mpa and 8.2 Mpa depending on the oiling treatment. The oiling treatments have shown increased toughness values and toughness index up to 160 by using 2% volume of fibers. With most of the treated fibers have shown strain-hardening performance, presenting possible potential of utilizing Chinese PVA fiber in the design of cost-effective strain-hardening cementitious material. (C) 2018 Published by Elsevier Ltd.