Influence of Fly Ash on Surface Chloride Concentration Under Shallow Immersion Condition

In this paper, the influence of fly ash content on concrete surface chloride concentration was investigated through periodical tests of surface chloride concentration of concrete by immersing three kinds of concrete specimens in 5.0 wt.% sodium chloride solution. One kind of specimen is common concrete without fly ash, whereas the other two kinds of specimens are mixed with fly ash. The results show that the surface chloride ion concentration ranges from 0.295 to 0.777 wt.% for the immersed concrete samples in this study; in the initial stage of immersion, the concrete surface chloride ion concentration is affected by added fly ash, and after 30 days of immersion, the surface chloride concentration of concrete with fly ash is 1.3 times that of concrete without fly ash at the same water–binder ratio; for the concretes without fly ash, the surface chloride concentration is linear with immersion time, whereas for the concrete with fly ash, the surface chloride concentration is nearly linear with square root of immersion time; for the concrete with fly ash, fly ash contents have little impact on the surface chloride concentration, and the surface chloride content of concrete without fly ash is gradually close to that of concrete with 15 and 30 wt.% of fly ash.