Study On The Influence Of Calamities At Early-Age On The Performance Of Concrete For Ocean Construction

For ocean construction, the durability of concrete for ocean construction was very important, because the caustic ions in the ocean environment would erode the concrete. In practice, because the technology and facility of construction was not enough, furthermore the ocean environment in field was very complex; the concrete for ocean construction might be eroded by caustic ions at early-age. There were two ever-present calamities: 1) because of the poor curing conditions at early-age (as 1 day～7days), the curing and early-aged concrete was eroded by ocean or sea breeze; 2) in order to turn over steel mould, early-aged concrete was cured in at elevated-temperature(mainly in producing concrete piles). But the present researches focused on the mechanical performance of concrete for ocean construction that was cured under standard condition for 28days then was dipped in ocean, and delayed ettringite formation (DEF) in cement mortars that were cured at elevated-temperature.In this thesis, we designed the progress of this experiment that was similar to the calamities, and made research on the influence of calamities at early-age on the performance of concrete for ocean construction. The content of this research included: 1) concrete for ocean construction was dipped in ocean when cured for 1～7days, later we estimated the influence of this calamity on durability of the concrete through finding variable laws of its compressive strength, flexural strength and chloride permeability. 2) Early-aged concrete for ocean construction with expansive agent (including high SO₃) was cured at elevated-temperature, later was dipped into ocean. We estimated whether DEF happened and whether to be dipped in ocean later furthered DEF. 3) whether concrete for ocean construction with slag added improved its ability of salt resistance and whether concrete with slag added (including high Al₂O₃) inhibited DEF was also discussed.At the end of this thesis, comprehensive summaries and the expectation of future study were stated.