Durability of repaired concrete facade elements

This paper illustrates the major criteria for designing and performing repairs on reinforced concrete facade elements, as identified through experimental investigations of repair durability and work at a pilot site. A number of fundamental aspects of repair work are discussed, including the need to understand the causes of degradation and the condition and characteristics of the area to be repaired, the need to develop a correct design procedure that specifies each stage of repair, and the need to identify the methods for monitoring and inspecting repairs that are most appropriate from the standpoint of durability. A series of experimental investigations have been carried out at the Politecnico di Torino Second School of Engineering in Vercelli, together with the LTS laboratory at DACD - SUPSI of Canobbio (CH), and with the cooperation of a number of manufacturers in the sector. Through this work, accelerated aging tests for repair mortars were developed, product behavior was analyzed, and comparative tests were carried out on the basis of recently issued European standards EN 13687-2 and 13687-4. The experience gained during work at the pilot site demonstrated the advisability of approaching repair projects case by case, analyzing the specific deterioration conditions, performing preliminary investigations, and planning repair work on an ad hoc basis for all stages, from selecting the products to be used to specifying application methods. To ensure durability, it is essential that the critical stages of repair work be monitored through on-site tests.