水性环氧-混凝土复合修补材料的设计、制备与机理

A large number of concrete structures are vulnerable to crack, erosion, surface detachment and even collapse, thus it is urgent to repair and strengthen concrete structures due to their severe safety and durability. The aim of this study is to carry out the basic research on waterborne epoxy-concrete composite repair materials. The design principle and selection principle are proposed on waterborne epoxy molecular structure matching with cement hydration and microstructure. To quantitatively analyze the interaction between waterborne epoxy polymerization crosslinking process and cement hydration process as well as to reveal the mechanism of action of organic-inorganic components, a set of characterization methods is firstly employed including DSC-TG, IR-LM, AFM and X-CT, hydration heat test and other methods. A high-adhesion and low shrinkage of water-based epoxy-concrete composite repair material is correspondingly prepared. During the preparation, the regulation method is discussed and an efficient interface modifier is prepared. Noticeably, a new method of hydrolyzing silane coupling agent catalyzed by hydrothermal treated nano-SiO2 is proposed. It can efficiently promote not only the formation of reactive groups bonded with inorganic and organic materials, but also hydration of cement. Afterwards, SEM, nano-CT and macroscopic mechanical methods are used to evaluate the bonding mechanics properties and reveal the law of crack growth in the interface between the old concrete and repair materials. Finally, the durability of repair materials and the repaired performance of concrete are evaluated. It is expected to provide a new material combined with a scientific basis for the rehabilitation of concrete through this investigation.

目前我国大量混凝土结构出现开裂、剥蚀和表层脱落甚至塌陷等病害，安全性和耐久性受到严重侵害，亟待修补加固。本项目开展水性环氧-混凝土复合修补材料的基础研究，提出与水泥水化相匹配的水性环氧分子结构设计和改性方法，采用DSC-TG、IR-LM、AFM、X-CT、水化热等方法分析水性环氧聚合交联过程与水泥水化进程之间的交互规律，揭示有机-无机组分作用机理，制备高粘结和高耐久的水性环氧-混凝土复合修补材料。提出使用水热处理纳米SiO2催化硅烷偶联剂水解合成界面剂的新方法，形成可同时与无机、有机材料产生化学键合的反应性基团；探讨界面剂合成和调控方法，制备出高效界面剂。采用SEM、纳米CT和宏观力学方法，研究涂界面剂的旧混凝土-修复材料间的粘结力学特性和裂缝扩展规律，揭示界面粘结机制。研究修复材料耐久性能和修复后性能评价方法。为混凝土结构修复提供新材料，具有重要的理论意义和实用价值。

目前我国大量混凝土结构出现开裂、剥蚀和表层脱落甚至塌陷等病害，安全性和耐久性受到严重侵害，亟待修补加固。水泥混凝土材料脆性大、抗拉低、粘结差、耐久性不足，难以满足结构修补需求。本项目以水性环氧-混凝土复合修补材料为研究核心，针对水泥混凝土高碱性体系，提出了自乳化水性环氧树脂的分子设计和改性增韧优化方法，设计并制备水性环氧分子，制备了与水泥体系相容的水性环氧树脂；提出了纳米二氧化硅水热处理方法与硅氧烷分子催化水解方法，揭示了界面剂中笼结构硅氧烷水解缩合机理；获得了水性环氧胶液及固结体性能，环氧固结体抗压强度约59MPa，抗折强度约27MPa，最大挠曲角23°，抗拉强度约9MPa，极限拉伸应变率达7%，对混凝土表面的界面粘结强度约3MPa，大部分为混凝土内聚破坏。其次，制备出延展性好、收缩小、与旧混凝土相匹配的水性环氧-混凝土复合修补材料，确定了水性环氧-水泥基修复材料的适宜的配合比范围，P/C=0.2是水性环氧增强混凝土抗折、抗拉强度的转折点，P/C在0.2~0.4范围内是水性环氧在混凝土中的适宜掺量，为水性环氧-混凝土复合修补材料的配合比提供依据；探讨了水泥水化硬化与水性环氧交联固化的反应过程，揭示了有机-无机间的相互作用和复合修补材料微结构的演变规律;阐明了自乳化水性环氧（NEP）、乳液型水性环氧（EEP）对水泥基体性能影响的作用机理与异同点，分析并阐述水性环氧-水泥基复合修补材料的水化-硬化-破坏过程和有机-无机作用机理。最后，探索了水性环氧-混凝土复合修补材料的静态和动态力学性能、粘结性能和耐久性能的发展规律，复合修补材料28天粘结强度达到2.5MPa，抗拉强度达到5.14MPa，抗折强度达到10.85MPa，轴拉韧性比达到4.8；探究了旧混凝土-界面-复合修补材料的裂缝扩展机理和对粘结性能提升作用，阐述了界面剂的催化水解缩合机理和对修补材料界面粘结性能的增效机理和复合修补材料的劣化规律，为材料的实际应用提供了实践、数据支撑。