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Li K.,Tsinghua University | Li K.,Key Laboratory of Safety and Durability of Civil Engineering of China Education Ministry | Li C.,Tsinghua University | Li C.,Key Laboratory of Safety and Durability of Civil Engineering of China Education Ministry | And 2 more authors.
Advances in Concrete Structural Durability - Proceedings of the 2nd International Conference on Durability of Concrete Structures, ICDCS 2010 | Year: 2010

Drying-wetting cyclcs arc identified as the most aggressive actions for various durability-related processes. This paper intends to investigate the moisture transport processes in concrete near surface under drying-wetting actions through experimental evidence, mechanism analysis and rational modeling. The widely-used diffusion-like model is retained for analysis and its application to moisture transport under drying-wetting actions is reviewed critically. After confronting model prediction with the available experimental data, the authors show that moisture transport model with a unified multi-phase diffusion coefficient is far from rational and can not account for the observed large difference of moisture diffusivities in drying and wetting phases, even with the hysteresis of absorption-desorption taken into account. The involved water absorption mechanisms are discussed in depth. Consequently, a rational diffusion-absorption model is proposed through the respective mechanisms of moisture transport during drying and wetting, and a numerical scheme is developed to solve the one dimensional transport problem in near surface. Afterwards, laboratory experiments are performed on concrete specimens for transport properties characterization and moisture transport under alternative drying-wetting actions. The obtained experimental data validate the proposed model and some fundamental aspects of moisture transport in concrete near surface arc put into evidence. ©2010 by Hokkaido University Press All rights reserved.

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