External treatments for the preventive repair of existing constructions: A review

In the present paper different external surface treatments published in the literature as preventive solutions for improving the performance of existing concrete constructions are presented and discussed. They are categorized as repair materials for concrete conservation, protection surface methods against moisture and aggressive agent penetration, injection techniques for crack sealing and preventive repair solutions with smart functionalities. In a final section, the most extended testing methods for evaluating the effectiveness of the different repair solutions are summarized depending on the property to be enhanced: moisture control and resistance against penetration of aggressive agents. The review shows that although several possibilities exist for the repair of the existing constructions, there is a lack of comparative analysis between the different methodologies. SARCOS COST Action CA15202 stablishes as scientific objectives to carry out comparative studies including the most advanced solutions for the external repair of concrete, giving criteria for effectiveness assessment and defining robust and reliable methods for charactering the performance of the repaired structures.Authors acknowledge the financial support provided by COST Action CA15202. M. Sánchez acknowledges the Spanish Ministry of Economy and Innovation for the financial support through the projects BIA 2014-56825 JIN and RYC-2016-21422. As a Postdoctoral Research Fellow of the Research Foundation-Flanders (FWO-Vlaanderen), D. Snoeck would like to thank the foundation for the financial support (12J3617N). P. Faria acknowledges the Portuguese Foundation for Science and Technology for the financial support through project PTDC/EPH-PAT/4684/2014: DB-HERITAGE