Enhancing the dynamic splitting tensile performance of ultra-high performance concrete using waste tyre steel fibres

Abstract

The application of waste fibres in ultra-high performance concrete (UHPC) would reduce the total material cost of UHPC, but it is still unclear whether industrial fibres can be replaced by waste tyre fibres in terms of the impact resistance. In the present work, a series of experiments were performed to figure out the influence of waste tyre steel fibre (WF) content (i.e., 1.0 %, 2.0 %, 3.0 % and 4.0 %) on the workability, compressive strength, elastic modulus, flexural strength and dynamic splitting performance of UHPC, in comparison with plain UHPC containing 2.0 % industrial straight steel fibre (IF). The results reveal that the slump of UHPC is reduced with the increasing WF fibre content, but the flexural and static splitting strengths of UHPC are improved by up to 31.0 % and 24.7 %, respectively, within the measured WF content. Moreover, the dynamic splitting strength and dissipation energy of UHPC are promoted when the WF content is lower than 3.0 %, while an opposite trend takes place as the content of WF reaches 4.0 %. Additionally, the dynamic increase factor of WF reinforced UHPC shows higher sensitivity to strain rate than UHPC containing 2.0 % IF throughout the strain rate range of 2.0 s−1–6.5 s−1. The optimal WF content of UHPC can be regarded as 3.0 % considering the overall static strengths, dynamic splitting behaviour, as well as economic and ecological impact.