Using the distribution of free chloride concentration (Cf) and total chloride concentration (Ct)measured by
different grades and species of coral concrete (CPC) soaking in sea water, the chloride binding capacity (R),
surface free chloride concentration (Cs) and apparent chloride diffusion coefficients (Da) of CPC were
calculated. Then, the influence of curing age and exposure time on the durability of chloride in coral
concrete were discussed, and the superior of magnesium sulfate cement (MSC) in resisting chorine salt
erosion were verified. The results indicated that the CPC R values increased whereas the Cs values decreased
with the extension of the curing age. The relationship between the exposure time and Cs followed an
exponential form; however, its growth rate was considerably lower than that of ordinary concrete (OPC)
due to its high water absorbability. Furthermore, the decreasing relationship between Da and the exposure
time conformed to the power function. The CPC Da exposed for 10–25 a under a laboratory-simulated
marine environment was 88.9–99.1% lower than that in an actual marine environment. The Da of CPC
was 0.5–6.6 times higher than that of any other type of concrete but decreased more quickly with the
exposure time. After studying the CPC chloride diffusion parameters Cf, Ct, R, Cs and Da, the advantages
of MSC against the erosion due to chloride salt were fully demonstrated. Hence, for a CPC structure under
an actual marine environment, extending the moisture curing age or using MSC will improve its ability to
resist chloride diffusion, reduce the speed of chloride intrusion and prolong the service life of the structure.