混凝土碱-硅酸反应破坏机理及其进程影响研究进展

碱－硅酸反应（Alkali-silicareaction,ASR）作为一种混凝土中所含碱与骨料中碱活性成分在一定湿度条件下发生的物理化学反应,在混凝土内部生成凝胶产物,进而引起混凝土发生变形、开裂、强度下降等病变行为,严重时将威胁结构物长期运行的功能性和安全性。随着非活性骨料的日益减少以及混凝土种类的不断改进和创新,ASR及其相伴的工程隐患和危害等问题的探究和防范应更加予以重视。在对混凝土工程ASR病害典型案例进行剖析的基础上,综述了ASR产生机理以及“吸水膨胀”和“渗透压”两种ASR诱发破坏假说的研究现状;从内部骨料特征和外部环境两个视角,论述了骨料活性、骨料粒径、骨料含量与级配以及环境温度和环境相对湿度等因素对ASR进程的影响;从完善ASR诊断方法与病害评估体系的目标出发,提出了混凝土ASR破坏机理及其进程影响研究方面亟待攻克和值得进一步关注的问题。

Review on damage mechanism and influence factors of Alkali-Silica Reaction

Alkali-Silica Reaction (ASR) is a kind of complicated physical and chemical reaction in concrete. Its reaction process can be simplified to alkali ions in pore solution and reactive components in aggregate to generate gel products in the wet condition. The occurrence of the ASR product can cause the deterioration of concrete, including deformation, cracking and strength loss of material, and even pose a threat to the structural health and safe operation of structures. As the amount of nonreactive aggregates reduces and novel types of concrete emerge, it is worth paying more attention to ASR and its potential damage. The damage examples caused by ASR were listed. The overview on the ASR mechanism was reviewed in this paper. Two controversial assumptions about the expansion mechanism due to ASR, water imbibition and osmotic pressure, and their latest research progress were discussed. The effects of aggregate characteristics (internal) and environmental factors (external) on the development of ASR were reviewed comprehensively, including reactivity of aggregate, aggregate size, aggregate distribution, curing temperature and relative humidity. To improve the comprehensive diagnostic method of ASR and evaluation standard of ASR damage, the questions to be further studied about the damage mechanism and the influence factors of ASR were raised.