STUDY ON CONCRETE DURABILITY OF DIFFERENCE STRUCTURAL REGIONS UNDER MARINE ENVIRONMENT

In order to study the damage characteristics and deterioration mechanism of concrete in difference structural regions, the appearance, mechanical properties, carbonation depth, distribution of free chloride content, apparent chloride ion diffusion coefficient, alkali content and the cover thickness of concrete for plate girder(atmosphere zone), cross beam(tidal zone) and square pile(underwater zone), at the typical region of a marine dock in Ningbo, were tested.The test data show that the structural concrete in the atmosphere and tidal zone have a better compressive strength state, while concrete in underwater zone has a poor compressive strength state, the carbonation depth and Dne/Dnd of the cover thickness are decreased from upper part to lower part, atmosphere zonetidal zoneunderwater zone, the distribution law of free chloride content, apparent chloride diffusion coefficient(Da) and alkali content of concrete are underwater zone tidal zoneatmosphere zone.The conclusions are drawn that CO2 of erosion action at atmosphere zone results in deterioration of the cover thickness, the combined action of harmful chloride ion and CO2 erosion lead to steel corrosion and deterioration of cover thickness at the tidal zone, due to the chloride ion and salt permeate into concrete of underwater zone, the coupling effect of chloride ion and high salt concentration accelerate the deterioration of cover thickness at the underwater zone.