Hiroki FUKUCHI
Studies on the Surface of the Chloride Ion Concentration of Concrete Structures
Takumi SHIMOMURA
It is obvious that the appropriate setting of the surface chloride concentration is necessary for the improvement of accurate prediction for the degration of concrete structure by chloride attack.Then, (1) the exposure test was conducted in order to examine the relation between airborne salt, surface chloride concentration, and the chloride transport properties into concrete, and (2) the surface chloride content of service structure in which under the salinity environment for a long term is also examined with the aim of investigation for the relation of the chloride attack, and environmental actions such as airborne salt and rain water.Considering the intensity of airborne salt, exposed surface and thickness of specimen as influential parameter, the mortar specimens were placed into the wind tunnel which produces airborne salt, and surface chloride content of specimen and depth of chloride ingress were measured.
According to those results, when the specimen is under high intensity of airborne salt, the surface chloride content is greater; when the specimen is exposed aggregate surface, surface chloride content is large and chloride penetration depth is shallow; and different specimen thickness give different chloride diffusion coefficients.For (2), surface chloride content and diffusion coefficient with respect to depth were examined from 36 year old serviced structure (Urokozaki Bridge) which located at the salinity environment.The surface chloride content distribution and chloride iron ingress profile for the serviced structure can be draw out from the observed results of Urokozaki Bridge.Moreover, it is clear that at the surface chloride content is increasing with regarded to move towards the edge of the girder at bottom face. That phenomenon is caused because of chloride iron was carried by water droplet due to rainfall, etc.
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