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对不同集料体积掺量及掺合料配制的水泥基材料在室温、Na_2SO_4溶液浓度为5和50 g/L时的损伤破坏过程进行分析,并采用压汞法、扫描电镜-背散射电子图像分析和能谱扫描等方法得到相应水泥基材料的微观结构,研究了矿物掺合料和集料含量对水泥基材料抗硫酸盐侵蚀性能的影响机理.结果表明:单掺石灰石粉造成的硬化浆体孔隙率增加,不利于水泥基材料抗硫酸盐侵蚀;尽管大掺量矿粉使得体系孔隙率有所增加,但仍能有效改善浆体孔结构,使大于10 nm以上毛细孔明显减少,从而显著提高水泥基材料抗硫酸钠侵蚀能力;纯硅酸盐水泥或单掺石灰石粉体系中,经Na_2SO_4溶液腐蚀后,试件的损伤程度随集料体积掺量增大而有所加剧.集料对矿粉试件抗硫酸盐侵蚀性能的影响却并不明显;微观分析表明,主要膨胀性产物石膏倾向于分布在临近集料区域,这也是导致含集料试件加剧破坏的重要原因.
The damage and destruction process of cement-based materials with different aggregate volume contents and admixtures prepared at room temperature and Na_2SO_4 concentrations of 5 and 50 g / L were studied. The effects of mercury intrusion on the surface of the cement-based materials were studied by mercury intrusion, scanning electron microscopy-backscattered electron images The microstructure of the corresponding cement-based materials was obtained by means of analysis, energy spectrum scanning and other methods, and the influence mechanism of mineral admixtures and aggregates content on the sulfate-resistant corrosion resistance of cement-based materials was studied.The results show that the hardened pulp The increase of bulk porosity is not conducive to the sulfate resistance of cement-based materials. Although the porosity of the system increases with the high volume of slag, the pore structure of the slurry can be effectively improved, and the pores above 10 nm can be significantly reduced. The corrosion resistance of cement-based materials to sodium sulfate was significantly improved. In pure Portland cement or limestone mixed powder alone, the damage degree of the samples increased with the increase of volumetric volume of the aggregate after corrosion by Na_2SO_4 solution. However, the effect of sulphate erosion on mineralized slag samples was not obvious. The microscopic analysis showed that the main expansive product gypsum tended to be distributed near the aggregate area, which led to the increase of aggregate content An important reason for failure.