Yuki INO

Clarification of Mechanism of Adhesion of Chloride on Concrete Surface and Development of its Mathematical Model

Takumi SHIMOMURA

In concrete structures located near to the coast, salt damage leads to corrosion of reinforcement due to adhesion-penetration action of the salt generated from the sea area. In order to accurately evaluate and predict the deterioration from salt damage as viewpoint of maintenance, it is necessary to clarify a series of processes from the generation of salt in sea areas, its arrival-penetration to concrete surface and penetration inside of concrete. Therefore, the purposes of this research is to clarify the state of salt attaching at the concrete surface and to develop a salt balance model at surface boundaries.
At the start, in order to estimate the state of salt attaching to the concrete surface, the process of salinity adhesion state on concrete surface of previous studies were rearranged. To confirm the adhesion status of salt particles at the concrete surface, a new method that can quantify these particles using images analysis from digital camera based on a program was developed, which measures the gamma distribution of attached salt particles and its amount.
Then, a salinity balance model at the boundaries of outlet surface part was developed, capable of expressing the balance of salt content at surface by considering the adsorption phenomenon of salt particles in the model of salt penetration process in concrete. In order to verify the effectiveness of the developed model, a wind tunnel experiment was carried out and its results were compared with field observation results of real environments.
As a result, it was clarified that the developed method could roughly estimate the state of adhesion of salt particles at the concrete surface, and the amount of salt particles adhered to the surface were effectively measured. In addition, the developed salt balance model shown that can represent the process of salinity equilibrium at surfaces that was not able to simulate with models of previous researches. Also, this developed model validity was prove from the comparison between the wind tunnel experiment and field measurement results of the real environments.