钢纤维形状及掺量对超高性能混凝土力学性能的影响

Influence of steel fiber shape and dosage on mechanical properties of ultra-high performance concrete

对比研究了钢纤维形状及掺量对超高性能混凝土(UHPC)工作性能及力学性能的影响,并通过SEM分析研究其演化机理。结果表明:随钢纤维掺量的增加,UHPC的工作性能变差,且端勾型钢纤维对工作性能劣化最明显。当钢纤维掺量为1.5%~2.5%时,端勾型和长直线型钢纤维UHPC的抗压、抗折及劈裂抗拉强度较高;当钢纤维掺量超过1.0%后,UHPC的拉压比会出现大幅提高,折压比相对提高不明显;当钢纤维掺量为1.5%~2.0%时,短直线型钢纤维UHPC的力学性能和工作性能最佳。SEM分析发现,钢纤维在基体中错向连续搭接分布,形成三维网状结构,能够阻止宏观裂缝的产生和微裂纹的发展,使UHPC表现出良好的力学性能。

The influence of steel fiber shape and volume fraction on the working perfomance and mechanical properties of ultra-high performance concrete(UHPC) was comparatively researched,and SEM method was used to reveal its evolution mechanism.The results show that with the gradual increase of steel fiber content,the working performance of UHPC gradually deteriorates,and the end hook steel fiber has the most significant effect on the deterioration of working performance.When the volume fraction of steel fibers is 1.5%~2.5%,the compressive strength,flexural strength,and splitting tensile strength of end hook type and long straight line type steel fiber UHPC are the best..When the volume fraction of steel fibers is 1.5%~2.0%,the mechanical and working properties of short linear steel fiber UHPC are the best.Through SEM analysis,it was found that steel fibers are distributed in a staggered and continuous manner in the matrix,easily forming a three-dimensional network structure,which can prevent the generation of macroscopic cracks and the development of microcracks,and enable UHPC to exhibit good mechanical properties.