The effectiveness of commonly used epoxy mortar patch repair materials and methods is experimentally investigated in this study. In addition to patch repair, retrofitting is necessary for RC beam members with severely corroded longitudinal bars to restore loading resistance, employing steel supplementation and carbon fiber-reinforced plastic (CFRP) alongside patch repair. Thus, this research encompasses three key experiments, including evaluating the mechanical properties of epoxy mortar patch repair materials, studying the interface issues between the patch repair material and base concrete, and assessing the repairability of patch repair/retrofit methods. Ultimately, based on the experimental results, this study offers recommendations for the use of epoxy mortar in patch repair materials and retrofitting methods.