Abstract: The surface chloride concentration profiles of coral concrete exposed to substitute ocean water were investigated ,and influences of curing age , exposing time and strength grade of coral concrete on free chloride diffusion coefficients of coral concrete were discussed by using the natural diffusion method .Results show that surface chloride concentration profiles of coral concrete decreases with the passage of curing age and strength grade.However, that increases with the passage of exposure time and gradually tends to stabilize .The surface chloride concentration profiles of C 50 coral concrete is 3.5 times higher of C50 normal concrete in the same conditions.Under the same curing age and exposure time , the surface chloride ion concentration of the south china sea island and reef actual enviroment cubic specimen is 60%-90% higher than the laboratory data.The surface chloride ion concentration of coral in practical engineering concrete structure value is 1.2-1. 6 times higher than the laboratory data .Therefore, in terms of concrete structures under the actual marine environment , in order to ensure the structural strength and considering the influence of the surface chloride ion concentration, we should prolong wet curing time and adopt approximately strength grade of coral concrete have such great influence on extending the service life of coral concrete .

Key words: coral concrete;marine environment;surface chloride concentration profile;curing time;exposing time