ATMOSPHERIC CHLORIDE PENETRATION INTO CONCRETE IN SEMITROPICAL MARINE-ENVIRONMENT

An atmospheric chloride content measurement was performed on air-dried concrete specimens in a marine environment under different conditions of exposure. The chloride content in the concrete generally increased with the test period and decreased with the depth of penetration, but the quantity of chloride depended on the exposure conditions of speci mens. The test results suggest that each part of a concrete structure must be examined rigorously, if the differential chloride ion penetrat ions are to be properly forecast. Based on the chloride ion concentrat ion profiles respecting concrete depth, surface chloride contents and diffusion coefficients of chloride were determined by using the standa rd diffusion equation as an experimental formula. The time-dependence of the two parameters indicates that upon using a diffusion coefficien t with a constant surface value, chloride profiles predicted by the st andard diffusion equation may not correlate well with the measured dat a on existing concrete structures of different ages.