Chloride penetrating under co-effects of initial curing and exposure conditions
XUE Wen1, JIN Wei-liang1, YOKOTA Hiroshi2
1. College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China; 2. Division of Built Environment, Hokkaido University, Sapporo, 0608628 Japan
The co-effects of initial curing conditions and the following exposure environments were discussed in this study. Concrete cylinders were cured in five conditions characterized with different humidity and curing duration and were moved into three kinds of marine environments for half a year’s exposure. The apparent diffusion coefficient and the effective diffusion coefficient of the chloride ions were obtained. The chloride transportation model in unstructured concrete was adopted to simulate the testing. The results indicate that inadequate water curing in the very beginning few days and the environmental wettingdrying cycles have a marked negative influence on chloride capillary suction and accumulation in the skin concrete. With the increasing of environmental wetting-drying ratio, diffusion dominates the moving of chloride ions in core concrete. Conventionally, by the decreasing of wetting-drying ratio, diffusion effect fakes out. Based on the results, the co-effect of initial curing conditions and the wet-dry interval ratios of the environments is suggested to be concerned during the durability design of the concrete.
［1］ ATIS C D, OZCAN F. Influence of dry and wet curing conditions on compressive strength of silica fume concrete ［J］. Building and Environment, 2005, 40(12): 1678-1683. ［2］ SHAFIQ N, CABRERA J G. Effects of initial curing condition on the fluid transport properties in OPC and fly ash blended cement concrete ［J］. Cement and Concrete Composites, 2004, 26(4): 381-387. ［3］ RAMEZANIANPOUR A A. Effect of curing on the compressive strength, resistance to chlorideion penetration and porosity of concretes incorporating slag, fly ash or silica fume ［J］. Cement and Concrete Composites, 1995, 17(2): 125-133. ［4］ KHATIB J M, MANGAT P S. Influence of super plasticizer and curing on porosity and pore structure of cement paste ［J］. Cement and Concrete Composites, 1999, 21(5/6): 431-437. ［5］ JAEGERMANN C. Effect of watercement ratio and curing on chloride penetration into concrete exposed to mediterranean sea climate ［J］. ACI Materials, 1990, 84(4): 333-339. ［6］ TOMOSAWA F. Japan’s experiences and standards on the durability problems of reinforced concrete structures ［J］. International Journal of Structural Engineering, 2009, 1(1):1-12. ［7］ MCCARTER W J, WATSON D W, CHRISP T M. Surface zone concrete: Drying, absorption, and moisture distribution ［J］. Journal of Materials in Civil Engineering, 2001, 13(1): 49-57. ［8］金伟良, 赵羽习.混凝土结构耐久性研究的回顾与展望［J］.浙江大学学报:工学版,2002,36(4): 371-380. JIN Weiliang, ZHAO Yuxi. Stateoftheart on durability of concrete structures ［J］. Journal of Zhejiang University: Engineering Science, 2002, 36(4): 371-380. ［9］ SONG H W, ANN K Y, PACK S W, et al. Factors influencing chloride transport and chloride threshold level for the prediction of service life of concrete structures ［J］. International Journal of Structural Engineering, 2010, 1(2): 131-144. ［10］ NILSON H, DARWIN D, DOLAN C. Design of concrete structures \ [M\]. Dubuque, USA: McGraw Hill Higher Education, 2003. ［11］ CHAUBE R P, SHIMOMURA T, MAEKAWA K. Multiphase water movement in concrete as a multicomponent system ［C］ ∥ Proceedings of the 5th RILEM International Symposium on Creep and Shrinkage in Concrete. Barcelona: RILEM Publications, 1993, 139-144. ［12］ CORLESS R M, GONNET G. H. On the lambert W function ［J］. Advances in Computational Mathematics, 1996, 5: 329-359. ［13］ 金伟良,张奕,卢振勇.非饱和状态下氯离子在混凝土中的渗透机理以及模型计算［J］.硅酸盐学报,2008,36(10): 1362-1369. JIN Weiliang, ZHANG Yi, LU Zhenyong. Mechanism and mathematic modeling of chloride permeation in concrete under unsaturated state ［J］. Journal of the Chinese Ceramic Society, 2008, 36(10): 1362-1369.
