城市地下环境下超高性能混凝土耐久性能研究

Study on Durability of Ultra-high Performance Concrete in Urban Underground Environment

针对城市地下环境下氯盐和硫酸盐对超高性能混凝土共同侵蚀下SO42-和Cl-的扩散规律和侵蚀机理,配置侵蚀溶液在完全浸泡和喷雾循环条件下进行模拟试验研究,测定了离子浓度、孔径尺寸等数据,并对微观形貌进行分析。研究结果表明:完全浸泡与喷雾环境下,UHPC中氯离子、硫酸根离子含量扩散规律符合Fick第二扩散定律;90d完全浸泡条件下30%硅灰掺量UHPC中氯离子、硫酸根离子平均含量比普通混凝土低46.5%、37.2%,喷雾循环90次条件下30%硅灰掺量UHPC中氯离子、硫酸根离子平均含量比普通混凝土低37.2%、44.0%;含30%硅灰掺量UHPC的氯离子、硫酸根含量远低于掺量20%、10%硅灰掺量的UHPC。

In view of the diffusion rule and invading mechanism of SO_(4)^(2-)and Cl^(-)in ultra-high performance concrete under the joint invasion of chloride and sulfate in urban underground environment,the invading solution was used to conduct simulation test under the condition of full immersion and spray cycle.The ion concentration,pore size and other data were measured,and the microscopic morphology was analyzed.The results show that the diffusion rule of chloride ion and sulfate ion content in UHPC conforms to Fick's second diffusion law under completely immersed and spray environments.The average content of chloride ion and sulfate ion in UHPC with 30%silica fume content is 46.5%and 37.2%lower than that in ordinary concrete under the condition of 90d complete immersion,and the average content of chloride ion and sulfate ion in UHPC with 30%silica fume content is 37.2%and 44.0%lower than that in ordinary concrete under the condition of 90 spray cycles.The content of chloride and sulfate ions in UHPC containing 30%silica fume content is much lower than that in UHPC containing 20%and 10%silica fume content.