Stress–strain behaviour of hybrid-fibre engineered cementitious composite in compression

Targeting the balance between high strength and toughness of engineered cementitious composite (ECC), polyvinyl alcohol (PVA)-steel hybrid-fibre-reinforced engineered cementitious composites were developed in this study. Cylindrical specimens were tested under uniaxial compression to investigate the stress–strain behaviour of hybrid-fibre composites with particular focus on the impact of matrix strength and steel fibre content. The experimental results indicated that the mechanical properties of hybrid-fibre systems were improved with increasing content of steel fibre, and this enhancement became more and more pronounced with increasing matrix strength. The impact of additional steel fibre on compressive parameters, such as compressive strength, strain corresponding to peak stress, elastic modulus and toughness index, were also strongly influenced by the matrix strength. Positive responses due to steel fibre were reduced with decreasing matrix strength, and even transformed into a negative effect in a low-strength matrix. When considering both high strength and toughness, a moderate amount of steel fibres was favourable. Furthermore, a simple analytical model especially for hybrid-fibre-reinforced ECC was proposed to give satisfactory predictions of the complete stress–strain behaviour. It is expected that this model can be used as a first approximation for non-linear analysis of ECC structures.