GFRP筋增强地聚物混凝土梁高温后力学性能及劣化机理研究

Geopolymer concrete, which is made of fly ash, possesses excellent elevated temperature resistance and heat-insulating property. There are some problems for traditional reinforced concrete structures, such as high energy consumption and large amounts of carbon dioxide emission in cement production, and steel corrosion. Through combining geopolymer concrete with fiber reinforced polymer (GFRP) bars which are light weight, high strength and corrosion resistance, the mentioned problems of traditional reinforced concrete structures can be well solved. Meanwhile, GFRP-reinforced concrete structures could be applied to building structures with elevated temperature and fire risk. In this project, the mechanical properties and degradation mechanism of geopolymer concrete beams reinforced with GFRP bars after exposure to elevated temperatures will be studied using the methods including experimental test, numerical simulation and theoretical analysis. The main research contents are as follows: through research, the evolution of mechanical properties of GFRP bars wrapped in geopolymer concrete after exposure to elevated temperatures will be obtained, and the degradation mechanism of mechanical properties of GFRP bars considering the degradation of fiber-resin interface will be revealed; though investigating the evolution of bond properties between GFRP bars and geopolymer concrete after exposure to elevated temperatures, a degradation model of bond properties between GFRP bars and geopolymer concrete will be established. Based on above researches, though numerical simulation and verification tests, a calculation method of mechanical properties of geopolymer concrete beams reinforced with GFRP bars will be finally developed. This project provides a key scientific basis for evaluating the residual properties of geopolymer concrete structures reinforced with GFRP bars after exposure to elevated temperature. This study possesses academic research and engineering application significance.

采用粉煤灰等制备的地聚物混凝土具有优异的耐高温和隔热性能，与轻质高强耐腐蚀的玻璃纤维复合材料（GFRP）筋结合，可解决传统钢筋混凝土结构存在的水泥生产能耗高、CO2排放量大和钢筋锈蚀等问题，并可应用于存在高温火灾风险的建筑结构。本项目拟采用试验测试、数值模拟和理论分析等方法，研究GFRP筋增强地聚物混凝土梁的高温后力学性能演化规律与机理，具体包括，获得地聚物混凝土包裹下GFRP筋高温后性能演化规律，揭示GFRP筋考虑纤维-树脂界面粘结退化的力学性能劣化机理；研究GFRP筋-地聚物混凝土高温后界面粘结性能的演化规律与机理，建立GFRP筋-地聚物混凝土考虑GFRP筋劣化的界面粘结性能退化模型。在此基础上，通过数值模拟和试验验证，提出GFRP筋增强地聚物混凝土梁高温后力学性能计算方法。本项目研究将为GFRP筋增强地聚物混凝土结构高温后性能评定提供关键的科学依据，具有重要的学术研究和工程应用价值。

将耐高温和隔热性能优异的地聚物混凝土与轻质高强耐腐蚀的玻璃纤维复合材料（GFRP）筋结合替代传统钢筋混凝土结构，可以有效解决水泥生产能耗高、CO2排放量大和钢筋锈蚀等问题，并可应用于存在高温火灾风险的建筑结构。本项目通过试验测试、数值计算和理论分析等方法，研究了GFRP筋增强地聚物混凝土梁的高温后力学性能演化规律与机理，具体包括，制备了不同粉煤灰、矿渣掺量比的粉煤灰/矿渣基地聚物混凝土，研究了高温后地聚物混凝土力学性能、微观结构和内部组分等的变化特性，获得了高温后地聚物混凝土力学性能的演化规律，揭示了高温后地聚物混凝土的劣化机理，结果表明，地聚物内部含有耐高温的硅铝酸盐材料，因此地聚物混凝土具有比普通混凝土更优异的耐高温性能，但两者的隔热性能接近；研究了裸露GFRP筋和地聚物混凝土包裹下GFRP筋高温后力学性能，获得了地聚物混凝土包裹下GFRP筋高温后性能演化规律，揭示了GFRP筋考虑纤维-树脂界面粘结退化的力学性能劣化机理，结果表明，地聚物混凝土保护层阻热对GFRP筋高温后残余力学性能有明显的提升作用，并建立了高温后地聚物混凝土包裹下GFRP筋力学性能退化模型；研究了GFRP筋-地聚物混凝土高温后界面粘结性能的演化规律与机理，结果表明，高温后GFRP筋与地聚物混凝土界面粘结强度随暴露温度的升高呈现先上升再降低的趋势，具有比与普通混凝土界面粘结强度更优异的耐高温特性，并建立了高温后GFPR筋-地聚物混凝土界面粘结强度和粘结滑移本构关系退化模型，提出了高温后地聚物混凝土结构中GFRP筋锚固长度计算公式。在此基础上，通过试验验证和数值计算，提出了GFRP筋增强混凝土梁高温后受弯承载力、最大裂缝宽度和短期刚度等特性的计算模型，结合上述高温后地聚物混凝土、地聚物混凝土包裹下GFRP筋、GFRP筋-地聚物混凝土界面粘结等性能的退化结果，能够实现对高温后GFRP筋增强地聚物混凝土梁力学性能的准确预测。本项目的研究成果为GFRP筋增强地聚物混凝土结构高温后性能评定提供关键的科学依据，具有重要的学术研究和工程应用价值。