超细矿粉对混凝土界面区硫酸盐腐蚀的影响

为了研究骨料与水泥石界面区(ITZ)的组成及结构对混凝土抗硫酸盐腐蚀性能的影响,利用紫外分光光度计绘制了硫酸钠溶液浸泡混凝土试样的SO2-4浸入浓度/深度曲线,并辅以扫描电镜(SEM)和电子探针能谱(EDS)等对ITZ进行观测;同时利用XRD定量分析研究了混凝土本体相和界面相的水化产物富集的差异.结果表明:Ca(OH)2、钙矾石(AFt)等晶体富集于硫酸钠溶液浸泡后试样的ITZ,引起AFt二次结晶型的硫酸盐腐蚀破坏.在适量石膏的激发下,掺入超细矿粉(GGBS)可阻止AFt转变成单硫型水化硫铝酸钙(AFm),减少AFt二次结晶的生成,明显提高抗硫酸盐侵蚀能力,试样的同深度硫酸根浓度最低,抗硫酸盐侵蚀性能最好.

Influence of ultrafine GGBS on sulphate corrosion in interfacial zone of concrete

In order to study the influence of both composition and microstructure in the interfacial transition zone(ITZ)of aggregate and cement stone on the sulphate erosion resistance of concrete, the SO^2-₄ invaded concentration versus depth curve of concrete specimen soaked in Na₂SO₄ solution was obtained with an ultraviolet spectrophotometer, and the ITZ were characterized with scanning electron microscope(SEM)and energy dispersive spectrum(EDS). Additionally, the difference in the enrichment of hydration products between matrix phase and interphase was studied by x-ray diffraction(XRD)quantitative method. The results show that the Ca(OH)₂ and AFt are enriched in the ITZ of concrete specimen soaked in the Na₂SO₄ solution, which leads to the secondary AFt crystallized sulphate erosion. Under the excitation of appropriate gypsum, the admixture of GGBS can prevent the transformation from AFt to AFm, reduce the secondary crystallization of AFt, and obviously improve the sulphate erosion resistance. Consequently, the equivalent depth SO^2-₄ concertraion of corresponding sample is the lowest, and the sulphate erosion resistance is the best.