Experimental studies of the long-term performance such have been done in this paper for sea water and sea-sand concrete and sea water and coral sand concrete, such as the elastic modulus, frost resistance and corrosion of reinforcement behavior. The test results show that the compressive elastic modulus of the sea water and sea sand concrete and the sea water and coral sand concrete are slightly lower than that of ordinary concrete, while the adding of fly ash or ground slag in them lead the late compressive elastic modulus slight increase. Compared with the ordinary concrete after freeze-thaw cycle, the mass loss rate and the compressive strength loss rate of the sea water and sea sand concrete and coral sand concrete are slightly larger, but slightly reduced by mixing with ground slag in the concrete, while a little high by mixing with fly ash. Due to the presence of Cl- in the saltwater and sea sand concrete and coral sand concrete, [Cl-] / [OH-] values will be larger, which leads to corrosion of internal reinforced, so it is necessary to adopt appropriate ways to modification for the concrete and reinforced.

The effect of early strength improvement of concrete with C-S-H type accelerator was studied for precast concrete efficient production under the steam curing condition. From the mortar test result, the effect of this improvement was confirmed to tend lager as the W/C is lower. This accelerator could short the curing time for 0.5-2.0 hours under the same temperature condition, and could reduce the curing temperature under the same curing time. Then the compressive strength was considered to be predicted by some formula, and it showed higher estimation accuracy of the Arrhenius’s Law than that of the Maturity Method.

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