钢纤维对超高性能混凝土抗弯力学性能的影响

为研究长、短钢纤维对超高性能混凝土（UHPC）受弯力学性能的影响，设计并制作了13组标准养护条件下的UHPC试件，其中3组为掺单一型短钢纤维，其他组均为掺混杂型钢纤维，对其进行立方体抗压及四点抗折试验。结果表明：对于掺加单一型短钢纤维的钢纤维/UHPC，钢纤维体积掺量为5vol%时，抗折强度最大，为19.98 MPa，继续增加钢纤维掺量，抗折强度反而降低；掺混杂型钢纤维的UHPC比单一型的抗折强度高，并且当长、短钢纤维体积掺量分别为2vol%和1vol%时，抗折强度达到最大，为23.55 MPa；钢纤维/UHPC的抗弯力学性能主要受长纤维的影响，短纤维影响较小；长纤维掺量对钢纤维/UHPC的抗折强度、延性以及抗弯韧性有一定影响，但是主要取决于长、短纤维的搭配，长、短纤维体积掺量最优搭配为2vol%和1vol%。

Effect of steel fibers on the flexural response of ultra-high performance concrete

In order to investigate the effect of short and long steel fibers on the flexural response of ultra high performance concrete(UHPC), 3 groups of mono-fiber and 10 groups of hybrid-fiber reinforced UHPCs were designed and cubic compression test and four points bending test were performed. Test results show that:for mono-fiber reinforced UHPC, the highest bending stress is 19.98 MPa with a fiber volume content of 5vol% and the bending stress decreases if more fibers are added. For hybrid-fiber reinforced UHPC, bending stress is higher than the mono-fiber reinforced UHPC, the highest bending stress is 23.55 MPa with a fiber volume content of 2vol% and 1vol% for long and short steel fibers, respectively. The flexural response of steel fiber/UHPC is dominantly affected by the volume content of long fibers rather than that of short fibers. The mechanical performance such as bending strength, ductility and flexural toughness are not simply affected by the volume content of long fibers, the balance of volume contents between long and short steel fibers is very critical, the optimal result tested in this experiment is the group of 2vol% and 1vol% for long and short fibers, respectively.