高性能混凝土构件中碱硅酸反应与延迟性钙矾石形成共存破坏

Coexistence of Alkali Silica Reaction and Delayed Ettringite Formation in a Cracked High Performance Concrete Element

针对短期服役4 a即开裂破坏的某混凝土构件,采用化学分析、X射线荧光分析、X射线衍射分析和热重分析检测了混凝土芯样浆体的化学和矿物组成,采用岩相法和扫描电镜/能谱分析观测了芯样的微观结构。结果表明:混凝土中部分细集料和少量粗集料发生了明显的碱硅酸反应;混凝土浆体-集料界面区存在大量不同形貌钙矾石异常富集生长,且在浆体-集料界面区发现相伴而生的碱硅酸凝胶和钙矾石产物。混凝土构件破坏是一较为典型的碱硅酸反应与延迟性钙矾石形成共存破坏案例。

The concrete cores drilled from a cracked elements were examined by various testing methods to clarify the cracking of some concrete elements after 4-years in service. The chemical and mineral compositions of the paste in concrete cores were characterized by chemical analysis, X-ray fluorescence, X-ray diffraction and thermogravimetric analysis. The microstructure of the cores was analyzed by the petrographic method and scanning electron microscopy/energy dispersive spectrum. The results show that the amount of fine aggregates and some coarse aggregates show typical signs of the alkali-silica reaction. Ettringites with various morphologies were richly formed in the interfacial transition zone （ITZ） between aggregate and paste. The coexistence of the alkali-silica gel and ettringite also occurs in the ITZ between aggregate and paste. The deterioration of the concrete elements is a typical case caused by the combination of alkali silica reaction and delayed ettringite formation.