混杂钢纤维增强超高性能水泥基材料力学性能分析

采用平直型超细钢纤维与压痕型中长钢纤维混杂,系统研究了混杂比例对超高性能水泥基复合材料(UHPCC)流动性能、力学行为的影响,以及纤维外形对界面粘结力的影响.研究表明,随压痕型钢纤维掺入量增加,新拌浆体的流动度下降;在纤维体积率一定时,2种纤维等比例混杂,材料的抗压、拉伸、弯曲强度与弯曲韧性等力学性能为最佳;当水胶比固定时,压痕钢纤维与基体界面粘结力大于平直型超细钢纤维.试验还表明,2种纤维混杂在不同结构、不同尺度和不同时间层次对抑制裂缝的生成和扩展分别发挥作用,两者协同作用使材料总体力学性能显著提升.

Mechanical behaviors of hybrid steel fiber reinforced ultra-high performance cementitious composites

An experimental program was carried out to investigate the influence of hybrid fibers(straight steel fiber with smaller diameter and indented steel fiber with lager diameter)on the fluidity and mechanical behaviors of ultra-high performance fiber reinforced cementitious composites(UHPFRCC).The results show that the fluidity of fresh UHPFRCC pastes decreases with the addition of indented fibers at same water-to-binder ratio.The mechanical properties,namely,compressive strength,tensile strength,bending strength and toughness are improved more effectively by hybrid steel fibers as the volume fraction of both fibers are the same.Meanwhile,the cohesive strength between matrix and the crimped fiber is higher than that between matrix and straight fiber at given water-to-binder ratio.The results also suggest that the higher properties of UHPFRCC could be achieved as the multiscale cracks at different ages are resisted by hybrid steel fibers with different diameters and geometrical shapes,provided the volume fraction of hybrid fibers is optimized.