Toughness evaluation of ultra-high toughness cementitious composite specimens with different depths

摘要

Ultra-high toughness cementitious composite (UHTCC), which is a kind of high-performance fibre-reinforced cementitious composite, is characterised by tensile strain hardening behaviour and remarkable toughness capacity. The current study presents a toughness estimation of UHTCC beams of different depths under four-point bending. An improved method, based on ASTM C 1609 and JCI-SF 4, is used to evaluate the toughness capacity. In this method, an equivalent deflection transformation relationship between different depths of samples is introduced to ensure that toughness comparison is conducted at similar deformation states. Two toughness evaluation indices at equivalent controlling deflection are adopted. One is the new proposed toughness index T_v, which represents the energy dissipation per unit volume in the plastic hinge region, and the other is the traditional flexural strength parameter. Theoretical analysis and experimental results both indicate that the proposed toughness index T_v is independent of depth for strain hardening cementitious composite, which can be considered as an intrinsic material property.