混杂直钢纤维超高性能混凝土的力学性能和裂缝扩展行为研究

Study on the Mechanical Properties and Crack Propagation Behavior of Hybrid Ultra-high Performance Concrete with Straight Steel Fiber

为了更好的掌握混杂直钢纤维超高性能混凝土的力学性能和裂缝扩展行为,提高混凝土质量。研究了不同长度直钢纤维混杂超高性能混凝土的抗压强度、弯曲性能和韧性变化规律,并采用数字图像相关技术分析了其裂缝扩展行为。结果表明:长纤维和中纤维的组合更有利于增强UHPC的力学性能,但长纤维掺入量过大会导致试件韧性下降;短、中纤维混杂试件的应变区较为集中,宏观裂纹扩展方向也较为单一,而中、长纤维混杂易导致微裂纹出现多个分支,应变区和宏观裂纹形态也更加复杂。研究成果为超高性能混凝土质量控制提供有益借鉴。

In order to better understand the mechanical properties and crack propagation behavior of hybrid straight steel fiber ultra-high performance concrete,and improve the quality of concrete.the changes in compressive strength,bending performance,and toughness of ultra-high performance concrete mixed with different lengths of straight steel fibers were studied,and the crack propagation behavior was analyzed using digital image correlation technology.The results indicate that the combination of long fibers and medium fibers is more conducive to enhancing the mechanical properties of UHPC,but the excessive addition of long fibers can lead to a decrease in the toughness of the specimens;The strain zone of short and medium fiber hybrid specimens is relatively concentrated,and the macroscopic crack propagation direction is also relatively single.However,the mixture of medium and long fibers can easily lead to multiple branches of microcracks,and the strain zone and macroscopic crack morphology are also more complex.The research results provide useful references for quality control of ultra-high performance concrete.