Trade-off between strength and ductility of random discontinuous fiber reinforced cementitious composites

Abstract

It is well known that fiber reinforcement is an effective way of improving toughness of brittle materials. However, it is less clear how fiber reinforcement (particularly for random discontinuous fibers) can contribute to strength and ductility enhancement of the composites. In this paper, we address this issue from a micromechanics point of view. The conditions for multiple cracking, which is the mechanism of pseudo ductility, are briefly reviewed in terms of micromechanical parameters such as fiber aspect ratio, matrix toughness, and interfacial bond strength. Special attention is given to examining competing effect of these microparameters on composite strength and ductility. Experimental results of direct tensile tests of several random discontinuous fiber-reinforced high strength concretes and OPC paste are presented and discussed in light of recent advancements in pseudo strain-hardening theory.