Time Dependency And Similarity Of Chloride Diffusivity Of Concrete Under Dry-wet Cycle Environments

Under a marine environment,chloride diffusivity of concrete is an important factor affecting the durability of concrete.Field tests for concrete usually take long time and large economical cost.Therefore,indoor accelerated simulated tests are usually designed based on the on-site environmental conditions to obtain the relevant penetration parameters in a relatively short time.In order to reflect the chloride penetration process of concrete in natural environment by the results of accelerated simulated test more accurately,it is necessary to investigate the time dependency of chloride diffusion in concrete and its similarity between natural and simulated environments.In this paper,the main contents are shown as follows:1.The analysis method of instantaneous chloride diffusion coefficient in concrete is further studied.The differences between apparent and instantaneous diffusion coefficients of concrete and their time dependent characteristics are analyzed.In addition,the time dependent model of instantaneous chloride diffusion coefficient in concrete under the natural tidal environment is established and verified.2.Based on the experimental results of the artificial simulated tidal environment,artificial simulated salt-spray environment and natural marine tidal environment,the effects of exposure environments,water-cement ratios and admixtures on peak chloride concentrations,convection zone depths and instantaneous chloride diffusion coefficients of concrete were studied.In addition,the time dependency of chloride transport parameters in concrete was analyzed and the time dependent models of instantaneous chloride diffusion coefficients in concrete under different dry-wet cycle environments were established.3.The randomness of apparent and instantaneous chloride diffusion coefficients in concrete under different exposure environments were analyzed.The random distribution types were obtained and the effects of water-cement ratios,admixtures,exposure times and environmental factors on the distribution types of chloride diffusion coefficients in concrete were studied.4.The similarities of free chloride concentrations,peak chloride concentrations,convection zone depths,and apparent and instantaneous diffusion coefficients of concrete under three different environments were compared and analyzed.