矿物自愈合法修复混凝土裂缝的愈合过程及其激励机制

Exploring new self-repairing methods for concrete cracks is one of important ways to imporve safety and service life of concrete structures, which is also one of international forefront hot issues in concrete research. In this project, according to chemical characteristics of concrete and the features of its application environment, a new innovative mineral self-healing method for concrete crack rehabilitation is proposed based on good rehabilitation compatibility. Transfering mechanism of information released from cracking in concrete structures is studied and the design method of concrete crack self-healing using mineral materials is proposed. Its key influencing factors is investigated, and its effective self-healing evaluation methods are proposed. Causes of crack self-healing using mineral materials is discussed based on the theories of reaction thermodynamics and kinetics, and the induction mechanism of mineral self-healing in concrete cracks is verified. Different processes of mineral ions in concrete cracks, such as diffusion, migration, induced nucleation and crystallization are tracked dynamically using the neutron imaging technique. And growing process of mineral sediments in crack interfacial zones and its compatibility with the matrix are monitered using micorscopic testing methods such as CT scanning technique. Finally through elucidating the healing process and mechanism of concrete crack rehabilitation using mineral self-healing method from micro-level to meso-level and macro-level, the key scientific problem of incentive mechanism of crack rehabilition using mineral self-healing method is clarified. The research results of this project will not only solve the scientific problem and key techniques of concrete crack rehabilition using mineral self-healing method, but also provide theoretical guidance for its application.

探索混凝土裂缝自修复新方法是提高混凝土结构安全性和服役寿命的重要途径之一，也是近些年混凝土研究的国际前沿热点之一。本项目根据混凝土材料的化学特性与应用环境特点，提出基于良好修复相容性的混凝土裂缝自修复的矿物自愈合新方法。研究混凝土结构损伤开裂信息传递机制，提出矿物材料自修复混凝土裂缝的设计方法；试验研究其关键影响因素，并提出自愈合效果有效评价方法；应用反应热力学与动力学理论探讨裂缝矿物自愈合成因，探明混凝土裂缝矿物自愈合的诱导机制；提出中子成像技术动态跟踪矿物离子在混凝土裂缝中扩散、迁移、诱导成核与结晶过程，采用CT扫描技术微观测试手段监测裂缝界面区沉积物生长过程及其与基体相容性，从微观、细观和宏观三个层次阐明矿物自愈合法修复混凝土裂缝的愈合过程与愈合机理，从而揭示矿物自愈合法修复混凝土裂缝的激励机制这个关键科学问题。研究成果为矿物自愈合法修复混凝土裂缝的理论与应用解决科学问题与关键技术。

本项目从理论、材料、方法三个层次设计出了混凝土裂缝的矿物自愈合新方法；探明了地下水环境新建结构混凝土矿物自愈合结晶沉淀过程的热力学关系和动力学控制方程，从动力学角度分析将碳酸钙结晶沉淀分为三个关键过程和四个控制方程，从热力学角度阐述了混凝土矿物自愈合中的碳酸钙结晶沉淀过程；提出了水养护条件对矿物自愈合法修复混凝土裂缝的影响，得出了充足的水养护、pH较高的碱性环境以及较高的温度对水泥基材料裂缝自愈合有着加速作用。探明了不同水灰比对水泥基材料自愈合性能的影响，较大的水灰比可以获得较好的前期愈合性能，较小的水灰比可以获得较好的后期愈合性能。提出了混凝土新建结构裂缝矿物自愈合效果的多尺度分析表征方法，结果表明优选矿物可以更好的促进自愈合，愈合产物主要为碳酸钙；建立了不同养护条件与矿物自愈合效果的关系，结果表明采用蒸养制度更有利于开裂试样相对渗透系数的降低；探明了钙离子含量对水泥基材料裂缝自愈合的作用机理，得出了钙离子为碳酸钙的沉淀提供物质来源，含量越高，对沉淀越有利；探明了沉积物与混凝土基层之间的耦合、界面粘结性能的影响因素，掺加矿物组的试块沉积物与基层的界面耦合及粘结性更好、更致密。研究了预制裂缝方式对自愈合效果的影响，劈裂和预压诱导形成自然的贯穿裂缝优于插片法产生的裂缝；基于Kaiser效应，提出了声发射技术对裂缝自愈合效果的表征，得出基准试样无法自愈合，而蒸养试样却有较好的愈合。从水泥基材料内部组成和外界环境因素的影响，揭示了矿物自愈合法修复混凝土裂缝主要基于碳酸钙结晶沉淀的激励机制，并得出提高温度、pH、初始钙离子浓度和一定范围内的二氧化碳分压能够提高碳酸钙的沉淀量。研究成果为矿物自愈合法修复混凝土裂缝的理论与应用解决科学问题与关键技术。