Chloride ion invasion and stochastic model of diffusion coefficient for existing concrete

The hydraulic concrete structures under tidal environment bear types action of nature environment including chloride invasion and tidal water scouring and loads and so on. So, the chloride ion invasion problem of hydraulic concrete under the tidal environment is more particular, it is difficult to imitate the concrete invasion under the natural environment by a general indoor experiment. But it is a fact that the real chloride ion invasion depths of existing hydraulic concrete can report the invasion characteristics including invasion speed under the nature environment, and can provide the study basic dates for the existing structural durability under the environment. By the study background of estuary environment in the Qiantang River, the invasion depths and percentage composition of concrete chloride ions of actual hydraulic concrete are analysed, and the chloride ion permeability rule under the natural environment is studied. According to the measured result, the surface chloride concentration and initial chloride concentration are also analysed. Basis of the study above, the chloride diffusion coefficient of existing concrete under the tidal estuary environment is analysed by Fick´ s diffusion law, and the stochastic model of diffusion coefficient is also provided.