Numerical investigation of chloride diffusivity in cracked concrete

Abstract

Cracks within concrete accelerate the ingress of chloride ions, causing acceleration of the degradation of the mechanical performance of reinforced-concrete (RC) structures. The effects of cracks should therefore be considered in the durability design of RC structures. However, the available test observations show large discrepancies regarding the quantitative effect of cracks on chloride diffusivity in concrete, and the corresponding developed empirical formulas have some limitations. In the present study, a unified quantitative relation between the chloride diffusion coefficient in cracks and crack width was developed. The parameters in the proposed formula have their own physical meanings, and the corresponding curve of the formula is smooth without an inflection point. The rationality and accuracy of the developed simplified formula were verified through comparisons with test data. Furthermore, chloride diffusivity in cracked concrete was studied and simulated based on the developed simplified formula, and the effects of crack width and crack depth were examined. The simulation results indicate that chloride diffusivity in cracked concrete is significantly affected by both crack width and crack depth. Moreover, the chloride diffusion behaviour in higher strength concrete with lower porosity is much more sensitive to cracks than normal- and lower strength concretes.