Analysis of Chloride Ion Diffusion in Concrete Structure under Non-penetrating Crack Condition

Abstract:

According to the crack depth ,concrete structure is divided into two parts，cracks zone and sound zone. Based on Fick’s second law, diffusion equation of chloride ions in cracked concrete structure is established. Combined with the initial and boundary conditions, analytical solution of the diffusion equation of chloride ions in cracked concrete structure was derived by the Laplace transform method. Finally, the influence of crack width and depth on the distribution of chloride ions and the durability life of reinforced concrete structures was analyzed. The results show that the smaller the depth and the larger the width of the crack, the greater the difference between the chloride ion concentration in the case of crack nonpenetrating crack and the chloride ion concentration in the case of penetrating crack. With the increase of the ratio of crack depth to cover depth, the service life of reinforced concrete structure decreases first and then increases. When dcr/dc=1.0, the service life approaches to the minimum. When dcr/dc>1.6, the service life can be approximately calculated according to the condition of penetrating crack.

Key words:chlorine diffusion; concrete structure; crack; service life prediction