| This thesis focused on the concrete cover under the expansive force. Based on the electrically accelerated method, the effects of the bar diameter, water/cement ratio, cover depth, and corrosion current density on the cracking time to concrete surface and the surface crack width were studied.The experimental results showed that the water/cement ratio has little influence on the cracking time to concrete cover. The cracking time to concrete cover increases with the increase of the ratio between the tensile strength and elastic modulus of concrete, cover depth, and bar diameter, but decreases with the increase of the corrosion current density. It was found that the most important factors are the cover depth and corrosion current density.By analyzing the variations of the surface crack width, it was found that, after the concrete cover is cracked, the variations of the surface crack width are roughly divided into three stages: (a) slow development; (b) accelerating development; and (c) steady development. For a given time, the water/cement ratio has a limited influence on the surface crack width. The effect of the bar diameter on the surface crack width is mainly attributed to the delay of the cracking time to concrete cover. When the cover depth is increased, the surface crack width is decreased at early ages but no obvious effect is observed at late ages. The surface crack width decreases with a decrease in corrosion current density and the effect is more noticeable at late ages.Based on the principle of the transfer matrix method, the concrete cover was divided into a series of annular elements. By solving the differential equation of the radial displacement in concrete, the analytical solution for the element transfer matrix was obtained. The validity of the numerical simulation method was preliminarily verified with the experimental results.The studies in this thesis could provide some reference for the durability assessment and design of reinforced concrete structures.
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