应变硬化水泥基材料组合结构的力学性能研究

水泥基材料自身的低强、高脆性是引起开裂的主要原因,裂缝的形成和开展也加速了混凝土结构耐久性的劣化.在水泥基材料中引入高强高弹的聚乙烯醇纤维能够显著改善脆性,使其具有准应变硬化和多缝开裂特性.通过四点弯曲试验,研究养护条件(标养、水养)、基体的厚度和龄期对应变硬化水泥基材料组合结构的力学性能的影响.结果表明,标准养护优于水养,基体养护24h后浇筑砂浆有利于界面粘结和整体结构性能的发展,且20mm SHCC-砂浆组合试件的准应变硬化和多缝开展更显著,结构延性大幅度提高.此外,采用组合结构形式有利于应变硬化水泥基材料的推广应用.

Research on the mechanical performance of specimen combinating strain-hardening cementitious composites and mortar

Low strength and high brittleness are the dominant reason for the cracking of cementitious composites.The durability of concrete structure will be deteriorated with the forming and spread of cracks.Applying PVA fiber with high strength and modulus into cementitious composite can significantly improve the toughness,which behavior in a unique performance of pseudo-strain-hardening and multiple cracking.Four-point bending test was carried out to investigate the mechanical performance of specimen combinating SHCC and mortar with different curing(standard curing,water curing),thickness and age.The results indicate that the standard curing is better than water curing,the interfacial bonding and integral property of the composite structure was significantly enhanced by the technics of casting mortar after the SHCC substrate casted for 24h and the structure with 20mm specimen cambinating SHCC and mortar substrate behavior in more notable pseudo-strain-hardening and multiple cracking.Furthermore,the composite structure will put the practical application of SHCC forward.