PVA纤维增强水泥基复合材料热处理后的力学性能

为了促进聚乙烯醇(PVA)纤维增强水泥基复合材料(PVA-ECC)在热环境工程领域中的应用,通过狗骨试件拉伸试验,研究了高粉煤灰掺量的PVA-ECC热处理后的力学性能变化;采用单纤维抗拉试验、单纤维拔出试验以及单裂缝拉伸试验研究了PVA-ECC性能提升的机制。结果表明:在不高于200℃的热处理后,PVA-ECC仍能实现多裂缝开裂,相比20℃,50、100、200℃热处理后的PVA-ECC复合材料的拉伸力学性能提高,其幅度为100℃> 50℃> 200℃;纤维强度不是PVA-ECC抗拉性能变化的控制因素,适当的温度处理提高了纤维与基体的化学黏结力和摩擦力,从而提高了纤维的桥接作用和裂缝的余能,进而提高了PVA-ECC的抗拉性能和摩擦耗能能力。PVA-ECC性能变化的机制分析为PVA-ECC工程设计提供了良好的理论基础。 

Mechanical properties of PVA fiber reinforced engineered cementitious composites after thermal treatment

In order to promote the engineering application of polyvinyl alcohol (PVA) fiber reinforced engineered cementitious composites (PVA-ECC) in thermal environment, mechanical property change of PVA-ECC with high-volume of fly ash after thermal treatment was investigated through dogbone specimen tensile test. The single fiber tensile test, single fiber pullout test and single crack tensile test were conducted to explore the performance improvement mechanism of PVA-ECC. The results indicate that PVA-ECC can keep its characteristic of multiple-cracking after thermal treatment by no more than 200℃. Compared to 20℃, tensile mechanical properties are significantly improved after being treated at 50, 100, 200℃, and the rule is: 100℃> 50℃> 200℃.The fiber strength is not a controlled factor for the change of PVA-ECC tensile properties, and a proper thermal treatment enhances chemical bond and frictional bond between fiber and matrix, and thus increases bridge stress and crack complementary energy, which result in the improvements of tensile properties and friction energy dissipation capacity for PVA-ECC. The mechanism analysis of PVA-ECC performance variation provides a sound theoretical basis for PVA-ECC engineering design.