偏高岭土改善海工混凝土抗氯离子侵蚀性的效果及机理  

Improvement Effect and Mechanism of Metakaolin on Marine Concrete Chloride Penetration Resistance

作　　者：曾俊杰[1,2] 王胜年[1,2] 范志宏[1,2] 熊建波[1,2] 

机构地区：[1]水工构造物耐久性技术交通运输行业重点实验室,广州510230 [2]中交四航工程研究院有限公司,广州510230

出　　处：《武汉理工大学学报》2015年第4期22-28,共7页Journal of Wuhan University of Technology

基　　金：交通运输部应用基础研究项目(2013329765250)

摘　　要：以不同掺量偏高岭土单掺以及与粉煤灰、矿粉复掺制备混凝土,分别采用浸泡法和RCM法测试混凝土氯离子扩散系数,采用压汞法测试混凝土的孔结构;同时制备相应掺NaCl水泥净浆,采用自动电位滴定仪测试水泥浆中总氯离子和游离氯离子量,计算氯离子固化率,并通过XRD法分析其物相组成。结果表明,偏高岭土可显著降低混凝土氯离子扩散系数,其与粉煤灰或矿粉复掺时效果更优,且与粉煤灰复掺时对后期氯离子扩散系数的降低作用显著;偏高岭土提高了水泥浆对氯离子的固化率,提高掺量可改善固化效果;偏高岭土复掺粉煤灰或矿粉进一步增强了固化效果,且与粉煤灰复掺效果最优;偏高岭土细化了混凝土孔结构,降低了毛细孔含量,促进了含氯水泥浆中F盐的生成,从减少氯离子传输通道和提高氯离子固化作用两方面改善海工混凝土的抗氯离子侵蚀性能。Concretes were prepared with cement solely substituted by metakaolin （MK） and double substituted by MK and fly ash （FA） or slag （GGBS）. Concrete chloride diffusion coefficient was tested both by NT BUILD 443 and NT BUILD 492, while the pore structure of concrete was tested by MIP. In addition, cement pasles were prepared with the same cementitious materials with the concretes,and NaCl was incorporated during the preparation process. The total and free chloride contents of pastes were tested by automatic potentiometric titrator, and the chloride binding rate was also calculated. The phase compositions of the pastes were analyzed by XRD. The experimental results revealed that chloride diffusion coefficient of concrete decreased significantly by MK, especially when FA or GGBS were blended. The chloride diffusion coefficient at the later stage obviously decreased when MK and FA were double blended. The chloride binding rate of the pastes increased with the incorporation of MK. The higher the replacement level, the higher the binding rate. The binding effect improved if FA or GGBS was blended, especially for FA. MK can refine the concrete pore structure, reduce capillary pore volume, promote the appearance of Friedel salt, decrease the chloride transport way and enhance chloride binding capacity with the incorporation of MK for marine concrete, which can improve the chloride penetration resistance.

关 键 词：偏高岭土 氯离子扩散系数 固化率 孔结构 海工混凝土 

分 类 号：TU528[建筑科学—建筑技术科学]