The Fourth International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2015) was held 5-7 October 2015 in Leipzig, Germany. This conference is a collaborative venture by researchers from the South African Research Programme in Concrete Materials (based at the Universities of Cape Town and The Witwatersrand) and the Material Science Group at Leipzig University and The Leipzig Institute for Materials Research and Testing (MFPA) in Germany.ICCRRR 2015 continues to seek and to extend a sound base of theory and practice in repair and rehabilitation, through both theoretical andexperimental studies, and through good case study literature. Two key aspects need to be addressed: that of developing sound and easily applied standard practices for repair, possibly codified, and the need to study seriously the service performance of repaired structures and repair systems. In fact, without making substantial efforts to implement the latter goal, much of the effort in repair and rehabilitation may prove to be less than economical or satisfactory.The conference proceedings contain papers presented at the conference which can be grouped under the six main themes of (i) Concrete durability aspects, (ii) Condition assessment of concrete structures, (iii) Modern materials technology, (iv) Concrete repair, rehabilitation and retrofitting, (v) Performance and health monitoring and (vi)Education, research and specifications. The large number of high quality papers presented and the wide range of relevant topics covered confirm that these proceedings will be a valued reference for many working in this important field and that they will form a suitable base for discussion and provide suggestions for future development and research. Set of book of abstracts (244 pp) and a searchable full paper CD-ROM (1054 pp).