硫酸盐在水泥基材料中的扩散和渗透特征

采用偏光显微镜和扫描电镜分析了含镁质类膨胀剂的水泥砂浆在硫酸盐溶液中浸泡1 a后的微观结构,提出了硫酸盐溶液在水泥基材料中的3种迁移方式;通过SEM-EDS分析得出了该水泥基材料被侵蚀后所形成的产物主要是石膏和钙矾石的结果,没有发现硫酸镁和碳硫硅钙石膨胀物形成;在水泥基材料中添加适当种类和掺量的镁质类膨胀剂,水化的与未水化的膨胀剂填充到集料与浆体的间隙内,增大了水泥基材料的密实度,改善了界面结构,提高了水泥基材料抗硫酸盐侵蚀能力.

Mechanism of sulfate diffusion and penetration in cementitious materials

The microstructure of cementitious materials with MgO expansive agent, which was immerged in sulfate solution for one-year,was analyzed by use of polarizing microscope and SEM,and three transfer ways of sulfate solution in cementitious materials were proposed.SEM-EDS analysis shows that gypsum and AFt are the main products formed after the corrosion of cementitious materials,but magnesium sulfate and thaumasite were not found.If MgO expansive agent of proper types and dosages is added to cementitious materials,hydrated and un-hydrated expansive agent will fill the interface of aggregate and cement,which will improve the compactness and interfacial structure.Therefore,it can improve the capacity of cementitious materials for resisting the corrosion by sulfate.