钢-PVA混杂纤维UHPC的弯曲性能试验研究

Experimental study on bending performance of steel-PVA hybrid fiber reinforced UHPC

通过四点弯曲试验研究了钢纤维和PVA纤维混掺比例对超高性能混凝土(UHPC)弯曲性能的影响,利用数字图像相关(DIC)技术分析了UHPC的裂缝发展规律。结果表明:在混杂纤维总掺量(2.0%)不变的情况下,随着PVA纤维掺量的增加,UHPC的抗弯强度下降,峰值挠度基本先增大后减小,裂缝数量先增大后减小,裂缝分布均匀性先提升后降低;总体上,混杂纤维UHPC的弯曲性能比单掺钢纤维UHPC的弯曲性能好,钢纤维和PVA纤维混掺时的最佳掺量分别为1.6%和0.4%,此时,UHPC的抗弯强度降幅仅为1.99%,但峰值挠度、裂缝数量显著提高,裂缝分布均匀性明显提升。

The influence of the mixing ratio of steel fiber and PVA fiber on the bending performance of Ultra-High Performance Concrete(UHPC)was studied through the four point bending test,and the crack development pattern of UHPC was analyzed by using Digital Image Correlation(DIC)method.The results show that,when the total content of hybrid fibers(2.0%)remains unchanged,with the increase of PVA fiber content,the bending strength of UHPC decreases,the peak deflection basically increases and then decreases,the number of cracks first increases and then decreases,and the uniformity of crack distribution first improves and then decreases.Overall,the bending performance of hybrid fiber reinforced UHPC is better than that of UHPC with steel fiber,and the optimal mixing ratio of steel fiber and PVA fiber is 1.6%and 0.4%.At this time,the bending strength of UHPC decreases by only 1.99%,but the peak deflection and number of cracks significantly increase,and the uniformity of crack distribution significantly improves.