地聚物混凝土材料和构件的高温性能及损伤机理研究

Geopolymers possess comparative mechanical properties, high temperature performance and durability with Portland cement, but exhibit lower energy requirements and lower carbon dioxide emissions during production than that of Portland cement. Thus, geopolymer is regarded as the most promising alternative for Portland cement. In this study, geopolymer concrete would be prepared by alkaline solution activating metakaolin and fly ash blend. The mechanical properties at ambient and elevated temperatures, thermal behavior, microstructure of geopolymer concrete, and bond-slip behavior between steel bars and geopolymer concrete would be tested. And then load tests on reinforced geopolymer concrete beams and columns at ambient temperature and in standard fire would be conducted, followed by the finite element analysis on these components. Based on the results from tests and finite element analysis, the feasibility of geopolymer concrete applied to structural components would be evaluated. A mix design method of geopolymer concrete and a bond-slip model between steel bars and geopolymer concrete at elevated temperatures would be proposed. Also the development of mechanical properties and degradation mechanism of geopolymer material and components at elevated temperatures would be investigated. Finally, empirical formulas on bearing capacity of normal section at ambient temperature and duration of fire resistance of geopolymer concrete beams and columns would be established. The progress of this study would propel the development of geopolymer concrete and its application in construction, and also provide the basis for design of geopolymer concrete structure, thus this study will be of great theoretical significance and practical value.

地聚物具有与波特兰水泥相近的力学性能、高温性能和耐久性，但其生产过程中的能耗和二氧化碳释放量远低于波特兰水泥，因此被认为是最有前途的水泥替代物之一。本项目采用碱激发偏高岭土和粉煤灰的混合物制备地聚物混凝土，首先对地聚物混凝土材料的常温和高温力学性能、热工性能、微观结构以及钢筋-地聚物混凝土之间的粘结-滑移性能进行实验研究，然后开展钢筋-地聚物混凝土梁柱构件的常温静载试验和明火试验及相应的有限元分析。基于实验研究和有限元分析结果，评估地聚物混凝土应用于结构构件的可行性，提出地聚物混凝土的配合比设计方法和钢筋-地聚物混凝土之间的高温粘结-滑移模型，查明地聚物混凝土材料和构件的高温损伤规律及损伤机理，建立地聚物混凝土梁柱构件的正截面承载力计算公式和耐火极限计算公式。本项目的顺利开展将推动地聚物混凝土材料的研发及工程应用，并为地聚物混凝土结构设计提供参考依据，因而具有重要的理论意义和实用价值。

地聚物具有与波特兰水泥相近的力学性能、高温性能和耐久性，但其生产过程中的能耗和二氧化碳释放量远低于波特兰水泥，因此被认为是最有前途的水泥替代物之一。本项目采用碱激发偏高岭土和粉煤灰的混合物制备地聚物混凝土，首先对地聚物混凝土的工作性能、热工性能、常温和高温力学性能、高温爆裂性能、微观结构以及钢筋-地聚物混凝土的粘结-滑移性能进行了试验研究，然后开展了钢筋-地聚物再生混凝土梁柱构件和纤维编织网增强地聚物砂浆抗剪加固钢筋混凝土梁的常温静载试验、改进的地聚物粘贴纤维布加固钢筋混凝土梁的明火试验以及钢丝网增强地聚物砂浆约束素混凝土柱的常温和高温力学性能试验。基于试验研究和理论分析结果，获得了地聚物混凝土的优化配方，提出了钢筋-地聚物混凝土的高温粘结-滑移模型，查明了地聚物混凝土和地聚物材料加固构件的高温损伤规律及损伤机理，建立了地聚物再生混凝土梁柱构件的正截面承载力、纤维编织网增强地聚物砂浆抗剪加固钢筋混凝土梁的抗剪承载力以及钢丝网增强地聚物砂浆约束素混凝土柱的高温后剩余承载力计算公式。本项目的顺利完成将推动地聚物材料的进一步研究和实际工程应用，尤其是在混凝土结构加固领域的应用，从而产生较大的环境效益和经济效益，因而具有重要的理论意义和应用价值。