钢纤维-橡胶/混凝土抗剪性能试验

抗剪强度和剪切韧性是反映构件在复合受力状态下承载能力及耗能能力的重要指标。为研究钢纤维(SF)-橡胶/混凝土的剪切性能，设计了14组SF-橡胶/混凝土试件，通过双面剪切试验，研究了SF体积分数掺量、橡胶掺量和水胶比对SF-橡胶/混凝土试件的抗剪性能及剪切破坏形态的影响。研究表明:SF的桥联作用及其与橡胶颗粒的协同作用可显著改善混凝土的抗剪性能。SF对SF-橡胶/混凝土试件的抗剪性能起主导作用，SF-橡胶/混凝土试件的抗剪强度、峰值变形及剪切韧性相比普通混凝土及橡胶/混凝土试件均显著提高，且增幅随SF掺量的增加而增大，剪切破坏呈现出明显的延性特征。当SF体积分数为1.5vol%时，橡胶掺量(等体积取代砂取代率)为10%的SF-橡胶/混凝土试件的抗剪强度、峰值变形相比橡胶/混凝土分别提高了78%、63%。橡胶对SF-橡胶/混凝土试件的抗剪性能也起到辅助作用，SF-橡胶/混凝土试件的剪切韧性及延性相比SF/混凝土试件进一步增加。采用水胶比优化设计后，随着橡胶掺量的增加，SF-橡胶/混凝土的抗剪强度、峰值变形及峰值前剪切韧性可基本保持不变，而峰值后韧性指标进一步增加，增幅可高达96%。根据试验结果，考虑橡胶及SF掺量的影响提出了SF-橡胶/混凝土的抗剪强度计算式。 

Experimental study on shear behavior of steel fiber-rubber/concrete

Shear strength and toughness are important indices for evaluating load-resisting capacity and energy absorption of members under complex loading conditions. In order to study the shear-resisting capacity of high-strength steel fiber(SF)-rubber/concrete, 14 sets of SF-rubber/concrete specimens were designed for double-shear experiments, in which influence of parameters including SF volume fraction, rubber volume substation and water to binder ratio on the shear-resisting behavior and failure modes of SF-rubber/concrete were investigated. Research results show that the bridging action of SF and its positive synergy with rubber particles in SF-rubber/concrete can significantly improve the shear-resisting behavior of concrete. SF play a dominant role in shear-resisting behavior of SF-rubber/concrete specimens. The shear strength, deformation at peak load and shear toughness of SF-rubber/concrete specimens are significantly higher than the plain concrete and rubberized concrete specimens, which increase with the SF volume fraction, and the shear failure mode of SF-rubber/concrete is obviously ductile. When the SF volume fraction is 1.5vol% and the rubber content (volume substitution of sand) is 10%, the shear strength and deformation at peak load of SF-rubber/concrete specimens are 78% and 63% respectively, higher than those of the rubber concrete. Rubber particles also help to improve the shear-resisting behavior of SF-rubber/concrete. The shear toughness and ductility of SF-rubber/concrete are further increased compared with SF reinforced concrete. With the increase of rubber content, the shear strength, peak deformation and pre-peak shear toughness of SF-rubber/concrete can be unchanged after using the optimized water-binder ratio, while the post-peak toughness index can be further increased by 96%. Based on the test results, shear strength formula of SF-rubber/concrete was established considering the influence of SF volume fraction and rubber substitution.