Long-term performance of structural concretes in China southeast coastal environments exposed to atmosphere and chlorides

This paper investigates the long-term performance of structural concretes in China southeast coastal area, the city of Shenzhen, exposed to atmosphere and chlorides. The structural concretes, incorporating large quantity of supplementary cementitious materials (SCM), were among the first massive application of such mixtures in construction in China. In both cases, in-field sampling and tests have been conducted during more than 20 years for the resistance of concretes to carbonation and chloride ingress respectively. The synthetic analysis of these results shows that (1) the concretes have substantial strength growth in atmospheric environment with exposure age, but the carbonation rate does not all obey the square root law of exposure time; (2) the protection of silane impregnation of high-performance concrete against chloride ingress maintains its hydrophobic effect after nearly 20 years; (3) Notable “skin” effect of surface concrete was observed for both atmospheric and marine exposures.