Research Of Chloride Ion Permeability Of Concrete And Coating Protective Effect Under The Wet-dry Cycle

Marine concrete structures such as crossing sea bridge, cross-harbour tunnel,cross-river tunnel and offshore drilling platforms, often occurs premature durabilityfailure even destroyed due to the marine environment corrosion. Therefore, the studyof the physical and mechanical properties of concrete under long-term marineenvironmental effects and corrosion protection is very important. In this paper, highperformance concrete was selected as the subject of the study. The permeability andmechanical properties of chloride eroded concrete as well as the preventive effect ofcoating on concrete under wet and dry cycling conditions were systematically studied,and the main results are as follows:(1) By measuring the chloride ion concentration of chloride eroded concrete atdifferent depths, the influence law of dry and wet cycle corrosive time and protectivecoating characteristics on the chloride permeability of concrete was studied, givingthe relationship between the chloride ion diffusion coefficient and dry and wet cyclecorrosive time, thereby establishing a chloride salt erosion prediction modelconsidering the time factor.(2) The variation of stress-strain curve, compressive strength, elastic modulusand peak strain of chloride eroded concrete with the change of dry and wet cyclecorrosive time was obtained by uniaxial compression tests; Through comparativelyanalyzing the mechanical properties of none coating concrete and three surfacecoating concretes, the influence of the coating on the corrosion resistance of chlorideeroded concrete.(3)Based on damage mechanics, the damage effect of chloride corrosion onconcrete was studied, obtaining the variation law of damage degree with the change ofwet and dry cycle time. The damage distribution of chloride eroded concrete wasgiven as well as the uniaxial compression damage constitutive model and equation ofchloride eroded concrete. Comparing the constitutive equations and results of uniaxialcompression experiment of chloride eroded concrete, we get that the constitutivemodel can well describe the damage evolution properties of chloride eroded concreteunder dry and wet cycle condition.The research results can provide a reference for theoretical research of marineconcrete durability and engineering applications.