Ryohei OHARA
Moisture diffusion in concrete with through and non-through cracks
Takumi SHIMOMURA
Durability of concrete structures is affected by the occurrence of cracks in the concrete. As this cracks increase, resistivity to salt damage of the structure decrease and deterioration due to substance permeation increase.
The purpose of this study is to evaluate mass transfer in concrete cracks and characteristics of the cracked surface. A moisture diffusion test on cracked concrete was made, and results were compared to a two-dimensional moisture transport simulation. Moreover, in order to verify the results of this research, this study considered the validity of the assumptions proposed by previous studies.
At first, moisture diffusion tests of cracked concrete with various crack widths and depths were carried out. From this test, it was confirmed that substance permeation in concrete is deteriorated by cracks regardless of depth or width, and that moisture flux in concrete is increased as crack width increases regardless of the depth.
Secondly, a comparison of the numerical simulation and experimental results was made. The numerical simulation considers the moisture transport model in uncracked concrete and moisture diffusion in cracks proposed by previous studies. Results obtained show that the tendency of experimental tests can be reproduced by numerical simulation. Results also clarified the need of investigating more deeply the influence of moisture transport in concrete cracked surface.
Finally, as a result of the boundary layer on the crack surface of each specimen obtained from the two-dimensional moisture transport analysis, it can be confirmed that moisture transport characteristics concrete surface are different to those of cracked surface.
In future investigations, a wide range of verification of moisture transfer characteristics on cracked surface needs to be considered, as well as the application of numerical simulation not only for diffusion, but also for pressure and absorption mechanisms.
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