碳纤维编织网增强超高韧性水泥基复合材料弯曲性能的试验研究

短纤维增强超高韧性水泥基复合材料(Engineered Cementitious Composites,通常称为ECC材料)可以将传统水泥基材料在抗拉荷载下单一裂纹的宏观开裂模式转化为多条细密裂缝的微观开裂模式,其极限拉伸应变可达2%甚至达6%,具有典型的应变硬化特性、显著的韧性特征和优良的耐久性能。纤维编织网增强混凝土(Textile Reinforced Concrete,简称TRC)同样是一种新型的纤维增强水泥基复合材料,在这种复合材料结构中,直接将纤维粗纱沿混凝土结构中的应力主向连续布置,纤维对基体的增强效果得到了显著提高。采用纤维编织网与PVA短纤维相结合研究开发新型混凝土结构防裂新技术,结合PVA短纤维增强ECC和纤维编织网两种材料的优点,可以获得更为优良的抗裂和控制裂缝的能力,从而极大程度地提高混凝土结构的耐久性和使用寿命。通过四点弯曲试验,研究纤维编织网表面处理方法、水胶比、PVA纤维掺量对此种复合材料裂缝控制能力和承载能力的影响,并与TRC的弯曲性能作了比较。

An experimental study on the flexural properties of carbon textile reinforced ECC

It is well know n that the failure mode of traditional cementitious composite components under tensile loading exhibits a macro single crack pattern.Engineered Cementitious Composites(ECC)typically possess strain hardening property,prominent toughness and superior durability,and the failure pattern of ECC components involves multiple fine cracks under tensile loading even at ultimate tensile strain.Textile reinforced concrete(TRC) is a new type of continuous long fiber reinforced cementitious composites.Rovings are placed along the direction of principal stress so that the reinforcing effect can be significantly enhanced.In order to develope new type of anti- cracking technique for concrete structures,a new cementitious composite reinforced by a combination of carbon textile and short-cut PVA fiber was proposed,and four-point bending experiments of specimens were performed.The experimental results show that crack resistance and control can be achieved when both carbon textile and short-cut PVA fiber are combined as reinforcements.Accordingly,the durability and service life of concrete structures would be greatly enhanced due to combining the advantages of both ECC and TRC.Comparing with TRC,the influences of the surface treatment of textile,water-binder ratio and volume content of PVA fiber on the crack resistance and bearing capacity of the new material were also investigated.