钢纤维特性及成型方式对UHPC弯曲性能的影响

Effect of steel fiber characteristics and molding method on bending properties of UHPC

为研究钢纤维特性及试件成型方式对超高性能混凝土(UHPC)弯曲性能的影响,本文对该材料进行四点弯曲试验,设计变化参数分别为钢纤维长径比、体积掺率、形状以及试件成型方式。结果表明:1)当钢纤维长径比由37提高至65时,UHPC峰值韧性比提高52.47%,峰后韧性先降低后提高;2)UHPC初裂荷载、峰值荷载和弯曲韧性均随钢纤维掺率的提高而提高;3)相比搅拌法成型UHPC,渗浆法成型UHPC峰值韧性下降24.32%~35.78%;4)与端钩形钢纤维增强UHPC相比,弧形钢纤维增强UHPC的峰值荷载和弯曲韧性均下降;5)可以从能量比与强度比角度评价UHPC在挠曲硬化段和软化段的弯曲韧性。本文成果可为UHPC的广泛应用提供一定的借鉴。

In order to study the influence of steel fiber characteristics and specimen forming method on the bending properties of ultra-high performance concrete(UHPC),a four-point bending test is carried out,and the design parameters are steel fiber length-diameter ratio,volume fraction,shape and specimen forming method.The results show that:1)The length-diameter ratio of steel fiber is increased from 37 to 65,the peak toughness ratio of UHPC is increased by 52.47%,and the post-peak toughness is decreased first and then increased;2)The initial crack load,peak load and bending toughness of UHPC all are increased with the increase of steel fiber content;3)Compared with UHPC by stirring method,the peak toughness of UHPC molded by slurry method is decreased by 24.32%~35.78%;4)Compared with the end hook steel fiber reinforced UHPC,the peak load and bending toughness of the arc steel fiber reinforced UHPC are decreased;5)The flexural toughness of UHPC in flexural hardening and softening sections can be evaluated from the perspective of energy ratio and strength ratio.The results can provide some references for the wide application of UHPC.