高韧性纤维水泥基复合材料抗压强度及荷载-位移对比分析

Comparative Analysis of Strength and Load-displacement Curve for High Toughness Fiberreinforced Cement Composites

高韧性纤维水泥基复合材料能够有效改善水泥基材料存在的脆性高、韧性差等缺陷,其在建筑工程领域尤其是城市更新体系中的应用日趋广泛。本文对聚乙烯醇纤维、改性聚丙烯纤维和超高分子量聚乙烯纤维这3种高韧性纤维水泥基复合材料不同龄期的抗压强度、最大荷载、最大荷载对应位移、等效弯曲强度和等效弯曲韧性进行了对比分析研究,结果表明:3种高韧性纤维水泥基复合材料不同龄期的抗压强度、最大荷载、最大荷载对应位移和弯曲韧性的主要影响因素为纤维的分散性、纤维与胶凝材料结合力(结合力影响了纤维的拔出效应和拉伸效应相互作用情况)以及纤维抗拉强度、断裂伸长率和弹性模量,通过计算高韧性纤维水泥基复合材料不同龄期的荷载-位移情况,得出等效弯曲性能的大小排序为:高分子聚乙烯纤维水泥基复合材料>改性聚丙烯纤维水泥基复合材料>聚乙烯醇纤维水泥基复合材料。

High toughness fiber-reinforced cement-based composites have effectively improved the high brittleness and poor toughness of cement-based materials,and their application is becoming more and more widespread in the field of civil engineering,especially in urban renewal systems.This paper compares the compressive strength,maximum load,displacement corresponding to maximum load,equivalent bending strength,and equivalent bending toughness of three types of high toughness fiber cement-based composites at different ages:polyvinyl alcohol fiber,modified polypropylene fiber,and ultra-high molecular weight polyethylene fiber.The results show that the main factors affecting the compressive strength,maximum load,displacement corresponding to maximum load,and bending toughness of the three types of high toughness fiber cement-based composites at different ages are:the dispersion of fibers,the bonding strength between fibers and cementitious materials(bonding strength affects the interaction between the pullout effect and stretching effect of fibers),as well as the tensile strength,breaking elongation rate,and elastic modulus of fibers.According to the calculation of the load-displacement behavior of the three types of high toughness fiber cement-based composites at different ages,the equivalent bending performance is in the following order:cement-based composite with high molecular weight polyethylene fiber>cement-based composite with modified polypropylene fiber>cement-based composite with polyvinyl alcohol fiber.