Meso-scale Simulation On Chloride Diffusivity And Cracking Of Concrete Cover Induced By Rebar Corrosion

In saline environment, RC structures will be attacked by chloride ions and then the rebars will be corroded. As a result of rebar corrosion and expansion, concrete cover cracks. The cracks will accelerate the ingression of harmful substances and the cracking process of concrete cover will also be accelarated. And then, the durability of concrete failures. This illustrates the importance of the research on chloride diffusion and the cracking process of concrete cover induced by rebar corrosion.Concrete is a typical composite material, whose physical and mechanical properties are determined by its micro-/meso-components. Therefore, it needs to employ the micro-/meso-scale analysis to describe the physical and mechanical properties of concrete. The objective of the present work is to investigate the chloride diffusivity in concrete and the cracking behavior of concrete cover induced by rebar corrosion. The main works of this thesis can be decomposed in detail as follow:1. Analysis of chloride diffusivity in concrete1) A multi-scale model for predicting the chloride diffusivity of concrete subjected to mechanical loadings was presented based on the theories of elasticity and mass diffusion. On the basis of the model, the effects of the ingradients, proportions and the intrinsic structure of concrete as well as external loading on chloride diffusiviy were explored.2) A meso-scale numerical model for the simulation of chloride diffusivity in cracked concrete was established by combining the micro-/meso-scale physical and mechanical properties of concrete. Based on the model, chloride diffusion behavior in cracked concete was simulated and the effects of crack width and crack depth were studied.2. Simulation of the cracking behavior of concrete cover induced by rebar corroison1) A non-uniform corrosion-expansive distribution pattern for corner located rebar was developed on the basis of the analysis results of chloride diffusion.And a mesoscale mechanical analysis moded was built for the simulation of the cracking bebaviors of concrete cover induced by rebar corrosion. The cracking behaviors under different corrosion distribution types were simulated and compared, and the effects of corrosion distribution types and heterogeneity of concrete were discussed.2) On the basis of meso-scale mechanical model, cracking behavior of concrete cover induced by two adjacent rebars was simulated and the effects of the thickness of concrete cover, rebar diameter and the distance between the reabars were researched.