Na_2SO_4侵蚀下粉煤灰对砂浆开裂的抑制作用  

Inhibition of fly ash on cracking of mortars immersed in sodium sulfate solution

作　　者：刘开伟[1] 邓敏[1] 莫立武[1] 黄蓓[1] 

机构地区：[1]南京工业大学材料科学与工程学院材料化学工程国家重点实验室,江苏南京210009

出　　处：《南京工业大学学报（自然科学版）》2014年第4期34-38,共5页Journal of Nanjing Tech University(Natural Science Edition)

基　　金：江苏省普通高校研究生科研创新计划(CXZZ12_0414)

摘　　要：将不同粉煤灰掺量的砂浆浸泡在5%Na2SO4溶液中养护,利用表面观察和超声波测试等无损测试技术跟踪浸泡过程中砂浆表面裂纹和内部裂纹的变化,通过热分析对侵蚀产物相进行分析,并采用激光共聚焦显微镜(LSCM)和扫描电子显微镜(SEM)对浸泡360 d的样品进行内部微观结构分析。结果表明:钙钒石是导致开裂的主要原因,掺入粉煤灰能够提高砂浆的抗渗性、阻止外部SO2-4的持续侵入,减少钙钒石的生成从而抑制砂浆表面和内部裂纹的形成,且粉煤灰掺量越高抑制效果越明显。The mortars,prepared with various contents of fly ash,were immersed in 5% Na2SO4 solutions.Non-destructive testing,surface observation and ultrasonic test were used to track the changes of the surface cracks and the inner cracks of mortars attacked by sodium sulfate solution. Thermal analysis was used to identify the compounds and laser scanning confocal microscope（ LSCM） and scanning electron microscope（ SEM） were used to examine the microstructure of the mortars immersed in 5% Na2SO4 solution for 360 days. Results showed that the formation of ettringite was responsible for cracking,and the incorporation of fly ash could reduce the permeability and prevent the sulfate ingress. The surface and inner cracks were reduced by reducing the amount of ettringite,thus the effect was better with the increase of the dosages of fly ash.

关 键 词：硫酸盐侵蚀 无损检测 粉煤灰 钙钒石 

分 类 号：TU528[建筑科学—建筑技术科学]