热-力耦合路径下再生保温混凝土的劣化行为与细观损伤演变机制

Recycled aggregate thermal insulation concrete (RATIC) can realize the recycling of resources, and improve the effect of building energy saving. Research on damage process in high temperature of RATIC is the core of its high temperature resistant. In this study, mortar substrate is enhanced by fiber reinforced and light aggregate is modified, which was designed to improve its high temperature resistance by optimizing the material composition and microstructure characteristics of RATIC. The multiscale study of macro-fine-micro is carried out to study the damage causes mechanism of RATIC under the thermomechanical coupling way systemically and further clarify the mesoscopic reason for degradation of RATIC. The research on building mesoscopic model for high temperature damage of RATIC is carried out to reveal the influence law of microcrack development caused by deformation mismatch among multicomponent and thermo induced degradation of material performance on the macroscopic mechanical behavior of RATIC, analyse the damage evolution behavior at high temperature of RATIC, build the damage prediction model based on damage variables. It provides theoretical basis for the optimization and fire resistance design of RATIC to meet the development needs of building energy conservation, solid waste circulation and structural integration.

再生保温混凝土可以实现资源的循环利用，并提高建筑的节能效果，该混凝土的高温损伤研究是该类型混凝土结构耐高温研究的核心和前沿问题。本研究对轻骨料进行改性并对砂浆基体进行纤维增强，旨在通过优化再生保温混凝土的材料成分和微结构特征提升其耐高温性能。开展宏-细-微多尺度研究，对热力耦合途径下再生保温混凝土的损伤成因机理进行系统研究，进一步明确温度-力共同作用下再生保温混凝土劣化的细观成因；开展构建再生保温混凝土高温损伤的细观模型工作，揭示多组分间变形不协调引发的微裂缝发展和材料性能的热致退化等因素对再生保温混凝土宏观力学行为的影响规律，解析再生保温混凝土的高温损伤演化规律，建立基于损伤变量的损伤预测模型。为该混凝土的材料优化和耐火设计提供理论依据，以适应建筑节能、固废循环与结构一体化的发展需求。

火灾是最频繁，最具破坏性的灾难之一。火灾的发生会导致混凝土材料微细观结构的损伤劣化，体现在水化物分解、孔隙结构粗化、热开裂、水汽压力升高诱致开裂等，继而导致材料宏观力学性能及耐久性的下降，最终威胁人民群众生命财产安全。因而，混凝土的物理力学性能劣化和损伤的渐进性演化也是国内外关注的重大科技问题。再生保温混凝土是以无机保温材料玻化微珠作为轻骨料的新型再生混凝土，兼具隔热与承重双重功能。近年来，再生保温混凝土作为轻质高强的耐高温结构混凝土受到广泛关注。因此，本课题对在温度/载荷等多因素耦合环境下再生保温混凝土物理力学性能、微结构劣化以及高温损伤演化规律进行了跨尺度研究，基于多种现代测试技术对退化过程进行动态捕捉和追踪，通过构建损伤变量对再生保温混凝土损伤在可测空间进行转化，开展微细观损伤和开裂过程的观测和定量分析，明确了热力耦合途径下再生保温混凝土细观结构损伤动态演化机制，揭示了再生保温混凝土力学性能退化与其微观结构之间的定量关联，考虑再生骨料原生损伤及混凝土细观累积损伤，建立了再生保温混凝土跨尺度热损伤计算模型，对热致混凝土损伤演化进行较为全面准确的评估。本研究为再生保温混凝土高温性能预测提供参考，对再生保温混凝土设计优化与工程应用具有重要意义。