For the purpose of providing references for further research and practical application about the quality improvement of RCA, in this paper, various treatment methods were firstly classified into four categories: removing old mortar (OM), strengthening OM, multi-stage mixing methods, and combination methods. Thereafter, the improvement mechanisms and important conclusions of various treatment methods were elucidated and summarised respectively. In the section of discussion, the improved effects as well as advantages and disadvantages of various treatment methods were compared and discussed respectively, and recommendations for the selection of treatment methods were proposed. Finally, the further research directions were pointed out, and an integrative programme on the quality improvement of RCA was recommended.