Mechanical performance of Strain-Hardening Cementitious Composites (SHCC) with hybrid polyvinyl alcohol and steel fibers

Recently, hybridizing fibers with distinct properties in cementitious materials has gained much attention due to their advantage over single-type fiber reinforcements. However, for Strain-Hardening Cementitious Composites (SHCC), most existing studies only compared hybrid-fiber SHCC (HySHCC) with conventional concrete or introduced additional steel fibers into mono-fiber SHCC, rather than keeping the total fiber dosage constant to show the positive synergetic effect. This study aims to explore the benefits of using hybrid steel/polyvinyl alcohol (PVA) fibers in SHCC with a fixed total fiber dosage of 2.5 vol% by evaluating the mechanical, economic and environmental potentials. The mechanical performance of HySHCC was comprehensively tested under compression, tension, static three-point bending and cyclic four-point bending. The crack pattern under uniaxial tension was digitally captured, and the static three-point bending performance was numerically simulated using a finite element method. While HySHCC generally showed slightly lower ultimate tensile strain and higher environmental impacts than PVA-SHCC, the crack control ability, compressive strength, modulus of elasticity and flexural toughness were superior. The findings of this study offer a new insight on the design and selection of fiber-reinforced cementitious composites for structural applications.