集料含量对掺矿物掺合料水泥基材料抗硫酸盐侵蚀性能的影响

摘要

The degradation of cement-based materials with different aggregate volume contents and ad-ditions, was analyzed when they were exposed to 5 and 50 g/L Na2 SO4 at 20℃.The microstructures of the corresponding cement-based materials was determined by mercury intrusion porosimetry (MIP), scanning electron microscopy backscattered electron ( SEM-BSE) image, and energy dispersive spec-trum ( EDS) analysis.The influence mechanism of the mineral addition and the aggregate volume con-tent on the sulfate resistance properties of cement-based materials was investigated.Results show that the addition of limestone powder ( LP) causes an increase in the porosity of hardened paste, exerting an adverse effect on the sulfate-resistance ability of cement-based materials.The incorporation of high amount of slag increases the total porosity, but refines the slurry pore structure from coarse pore to fi-ner one (>10 nm) .Moreover, the addition of slag strengthens the sulfate-resistance ability of ce-ment-based materials significantly.After corrosion by Na2 SO4 , the degradation of cement-based mate-rials prepared with pure Portland cement or Portland cement-limestone powder binary binders is more severe as the aggregate volume content increases.However, this negative effect caused by the aggre-gate is less remarkable in case of the slag blended system.From the BSE image and EDS analysis, the preferable deposition of gypsum in the region close to the aggregate is the main reason for the expand-ed degradation of specimens with a relative high amount of aggregate.%对不同集料体积掺量及掺合料配制的水泥基材料在室温、Na2 SO4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Na2 SO4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。