Contribution of steel fiber on the dynamic tensile properties of hybrid fiber ultra high toughness cementitious composites using Brazilian test

A series of quasi-static and dynamic Brazilian tests were conducted in this study to investigate the influence of steel fiber (SF) on the dynamic tensile behavior of hybrid fiber ultra-high toughness cementitious composites (UHTCCs). Four different kinds of hybrid fiber UHTCCs were prepared with different SF content, but the polyvinyl alcohol (PVA) fiber content remained as 2%. Under quasi-static tensile loading, the composites with 0.5% SF exhibited the highest energy dissipation approximately 2.9 times that of the composites with 1.5% SF. However, the composites with 1.5% SF was recommended to resist the dynamic tensile loading with the highest dynamic tensile strength and energy dissipation among the four composites. The increase in SF content improved the dynamic tensile strength and energy dissipation of hybrid fiber UHTCC, and their contribution was influenced by the strain rate. Based on the high speed image investigation, the crack velocity in the UHTCC increased with the strain rate, which led to the strain rate effect on the various micromechanical parameters of the fiber tension and pullout. By comparing the dynamic tensile behavior of hybrid fiber UHTCC and ultra-high performance concrete (UHPC), it was found that the dynamic energy dissipation of UHTCC were similar with that of UHPC under the same impact loading, although their dynamic tensile strength was 59%-73% of UHPC. (C) 2020 Elsevier Ltd. All rights reserved.