Analytical modelling of concrete cover cracking caused by corrosion of reinforcement

Corrosion-induced cracking of the concrete cover poses a serious problem for serviceability of reinforced concrete structures. In the paper a new analytical model for predicting cover cracking due to corrosion of reinforcing steel is presented. In the model, concrete around a corroding reinforcing bar is considered as a thick-walled cylinder subjected to uniform pressure at its inner surface, which represents expansion caused by corrosion products. The pressure leads to formation of radial cracks near the inner surface of the cylinder. In order to account for it, the cylinder is divided into two parts-a partially cracked inner cylinder and an uncracked outer one. Cracks in the inner cylinder are taken into account by gradually reducing its tangential stiffness along the radial direction. The model ensures a consistent stress-strain description within both inner and outer cylinders and complete continuity of stresses and strains on the boundary between the cylinders that distinguish it from previously published analytical models. The model is calibrated using available experimental data and then employed to estimate the amount of corrosion products penetrated into concrete pores before full cracking of the concrete cover. Estimates obtained in the paper show that this amount may be higher than has been assumed previously.