This study investigated four types of recycled concrete that had deteriorated in galvanostatic method and wet-dry cycle method for 3 similar to 5 cycles. The steel/concrete interfaces were observed and measured by SEM under BSE mode. The T-CP - T-CL model proposed by Zhao which describes the relationship between the thickness of the corrosion-filled paste (CP) and that of the corrosion layer (CL) is proved to be correct and reasonable in this study. Based on this T-CP-T-CL model, the narrow sense of CP are studied to complement the corrosion-induced cracking model.