Effect of fiber length and surface characteristics on the mechanical properties of cementitious composites

Abstract

A disadvantage of conventional concrete is its low flexural strength and ductility in tension. Cracks form when the tensile strength of conventional concrete, which is limited, is exceeded due to various actions (loads, restrained shrinkage, temperature variation, chemical reactivity) accentuating the effects of carbonation and chloride-induced corrosion of concrete and reinforcement, thereby compromising the residual service life and strength of concrete members. Addition of fibers to enhance the flexural capacity of structural materials through crack control is an ancient idea that is now spearheading novel developments in the area of high-performance cementitious materials. Currently, the state of the art is focused on the use of synthetic fibers in self-consolidating, fine-aggregate cementitious mixes that demonstrate strain hardening properties in tension, outstanding crack control and improved durability performance. This paper deals with experimental characterization of the performance of a material of this class, reinforced with PVA fibers (polyvinyl alcohol with original hydrophilic surface properties). Parameter of study is the length of the fibers as well as the fiber surface properties which are chemically modified through pertinent surfactants. The parametric study compares the mechanical response of FRC to that of plain (unreinforced) cementitious material of the same composition, through tests of material samples in uniaxial compression, extension, splitting and flexure.