CONCRETE SURFACE CHLORIDE ION CONCENTRATION VARYING WITH HEIGHT IN MARINE ENVIRONMENT

Chloride ion is the main reason that impacts the durability of reinforced concrete structures in marine environment, while the surface chloride concentration of concrete structures is one of the most important factor influencing the transport process of chloride into structural concrete. Because of the different local environments for concrete structures at different heights, the surface chloride concentration varys with the heights. Based on the inspected data of surface chloride concentration from a concrete port which locates at eastern coastal area of Zhejiang Province, a single peak Gaussian distribution is proposed to describe the surface chloride concentration along the height of structure. A model of surface chloride using BP neural network is established to predict the distribution of the surface chloride concentration along the height. To find out the most serious chloride aggression region of reinforced concrete structures, probability based statistical analysis of inspection data from concrete ports of eastern coastal area of Zhejiang Province and Japan is carried out. The most serious chloride aggression height is from 0. 4 to 1. 6 m above the sea level, from 0. 285 to 0. 478 of water infiltration time ratio, where the anti-aggression capacity of chloride should be strengthened. Finally, according to the normalized inspected data, empirical equations are proposed to describe the influence of height and water infiltration time on surface chloride ion concentration based on a Gaussian Function.