Impact resilience of multiscale fibre reinforced composites

Abstract

This research considered cementitious composites reinforced with macroscale, microscale and nanoscale fibres. Ten test groups including a combination of the multiscale fibres (steel fibres, polyvinyl alcohol (PVA) fibres and carbon nanofibres (CNFs)) were studied. An experimental programme was developed to determine the compressive, tensile and flexural strength as well as impact toughness. This multiscale fibre reinforcement (steel, PVA and CNFs) in normal concrete mixes for practical applications led to a tenfold increase in impact resilience, based on a small-scale repeated impact test performed in this study, and also considerably enhanced the tensile strength of the cementitious composites. On the other hand, cementitious composites singly reinforced with nanoscale CNFs in normal concrete mixes including coarse and fine aggregates showed negligible improvements in impact toughness and tensile strength. Three-point bending tests on reinforced concrete beam specimens showed that the macroscale structural performance of the concrete members was enhanced with the addition of multiscale fibres. The toughness or energy absorption capability increased by 29%. It is therefore concluded that multiscale fibre reinforcement, including CNFs, has the potential to reduce the projectile–target collision force due to increased ductility of the concrete members and to alleviate concrete spalling resulting from projectile penetration on account of increased toughness.