纳米SiO2-砂浆受半浸泡硫酸盐侵蚀后的微观分析

Micro-analysis of Nano-SiO2 Composite Mortar Subjected to Partial Immersion Sulfate Attack

研究了纳米SiO2(NS)复合水泥砂浆遭受半浸泡硫酸盐侵蚀后的破坏特征,并利用扫描电镜(SEM)与X射线衍射仪(XRD)对试样进行了微观结构分析。结果表明:掺入NS降低了砂浆在半浸泡硫酸盐侵蚀下的破坏程度,且掺量越高,降低程度越高;NS复合水泥砂浆的浸泡和水分蒸发区的硫酸盐侵蚀产物分布与纯水泥砂浆是一致的,即表层生成了大量的石膏晶体,而内部生成的主要是钙矾石;但NS复合砂浆的石膏与钙矾石数量少于纯水泥砂浆,且NS掺量越高,侵蚀产物越少;硫酸盐化学侵蚀是导致砂浆水分蒸发区破坏的主要原因。

The damage characteristics of nano-SiO2(NS)composite cement mortar subjected to partial immersion sulfate attack were investigated,and the microstructure of the sample was analyzed by scanning electron microscope(SEM)and X-ray diffraction(XRD).The results showed that the incorporation of NS reduced the damage degree of mortar subjected to partial immersion sulfate attack,and the higher the incorporation of NS,the higher the reduction degree.The distribution of sulfate attack products in the immersion and evaporation portions of NS composite cement mortar was consistent with that of plain cement mortar,that was,a large number of gypsum was formed in the surface layer,while ettringite was mainly generated in the inner part.However,the amount of gypsum and ettringite in the NS composite mortar was less than that in the pure cement mortar,and the higher the NS content was,the less the attack products were.Sulfate chemical attack was the main cause of the damage of mortar’s water evaporation portion.