Abstract

This paper discusses the experimental results of tests carried out on the flexural properties of various fibre-reinforced concretes at low volume fractions of fibres upto 0.5%. The flexural properties, namely flexural strength, toughness, and ductility, were measured using four point bending tests on beam specimens. Compared to reference concrete without fibres, fibre addition was seen to enhance the pre-peak as well as post-peak region of the load-deflection curve significantly. The best flexural performance was obtained at the highest volume fraction of 0.5%. At this volume fraction, flexural toughness and ductility of hybrid fibre concretes (incorporating a blend of steel and non-metallic fibres) were comparable to steel fibre concretes. Increased fibre availability in the hybrid fibre systems (due to the lower densities of non-metallic fibres), in addition to the ability of non-metallic fibres of bridging smaller micro cracks, are suggested as the reasons for the enhancement in flexural properties.

Key words: Micro cracking, silica fume, fibre reinforcement, toughness.