凍結防止剤に用いる塩の種類と季節変動がコンクリート中の塩分浸透に及ぼす影響

抄録

On roads where deicer salt is sprayed, chloride is supplied only in winter and not in other seasons. The behavior of chloride penetration into concrete in such an unsteady environment has not been cleared, and the method of predicting future based on the measured data of the chloride ion distribution has not been standardized. Based on the above background, after actual states of spraying of the deicer salt and investigating of chloride penetration were organized, this study clarified the influences of type of salt used as deicer salt and seasonal behavior on chloride penetration in concrete. As a result, 2 types of NaCl and CaCl₂ were sprayed as deicer salt at expressway in Hokuriku area, these salt types did not influence the chloride absorption on the mortar surface. In addition, the surface chloride ion concentration was high in spring and decreased from summer to autumn, and the chloride ion concentration distribution fluctuated depending on the season. Therefore, when the chloride profile after 100 years was predicted based on the data measured at summer and autumn, the corrosion occurrence time was estimated to be longer than the actual time. When water cement ratio was high, these phenomena were appeared conspicuously. Also it was verified that this tendency of seasonal fluctuation was similar in the actual data measured on one existing bridge, too.