高强ECC受火（高温）后的残余力学性能、爆裂机理及其改善措施

ECC所展现出的高延性、超高韧性、微裂缝控制特性和耐久性，使其可满足下一代基础设施的要求，极具应用前景。为了适应现代经济发展的需求，满足超大跨径桥梁、超高层建筑等混凝土结构的设计要求，研发出更高强度、更高延性的ECC材料已成为世界性的研究热点。但是在遭受火灾（高温）时，高强ECC中的聚合物纤维发生熔融，导致其力学性能大幅下降，而且极易发生爆裂，引发人们对其在建筑结构中使用安全性的担忧。鉴于此，本项目以高强ECC的抗火性能为研究目标。首先，基于微观力学理论，从多个尺度层面揭示高强ECC在火灾（高温）后的力学性能劣化规律与机理；其次，借助现代先进测试技术与理论分析，探明高强ECC的高温爆裂发生机理；最后，参照高强混凝土高温抗爆的研究经验，结合高强ECC的自身特性，对其高温性能改善技术进行探索。本项目的顺利开展将丰富ECC火灾安全领域的理论体系，为高强ECC结构的工程实践提供理论依据和指导原则。

ECC exhibits high ductility, ultra-high toughness, micro-cracking behavior, and durability, which allow it to satisfy the requirements of next-generation infrastructures, and subsequently, shows great perspective in practical applications. To meet the needs of modern economic, and satisfy the design requirements for mega bridge/buildings, the development of ECC possessing high strength and high ductility has become the research hotspot worldwide. However, the melting of polymer fibers under fire or high temperature is likelihood to cause a significant deterioration in the mechanical performance of ECC, and simultaneously along with a severely explosive spalling, which raises the safety concerns of buildings as it is applied in structural elements. Therefore, this proposal puts a special emphasis on the performance of high strength ECC under fire. Firstly, the residue mechanical performance of high strength ECC and mechanism relates its deterioration after fire exposure are revealed from the perspective of multiple-scales based on micro-mechanics theory. Secondly, the mechanism about the occurrence of explosive spalling in high strength ECC under fire is clarified relying on the advanced testing technology and theoretical analysis. In final, combined the characteristics of high strength ECC, the improvement measures to its performance under fire is explored with referring to the research experiences in the field of high strength concrete. The research achievements will enrich the theoretical system of ECC in the field of fire safety, and provide the theoretical guidance for the application of high strength ECC in building structures.