Insight on the Durability of Steel Reinforced Grout (SRG) Systems for the Strengthening of Historical Constructions

Steel reinforced grout (SRG) composites, due to their high performance, proved effective for the external strengthening of existing structures and for the seismic protection of historical constructions. Nonetheless, to comply with the conservation criteria for ancient buildings, they have to ensure an adequate level of durability against environmental agents. Within this framework, the study aims to investigate the durability of galvanized (zinc-coated) SRG, the most adopted typology today, considering four different textiles and four cement or lime mortars, and the most critical aging conditions for the tensile behaviour. Tensile tests were conducted following immersion in saltwater and alkaline solutions, exposure to freeze-thaw cycles, aggressive soil conditions, and high temperatures. The results demonstrated the beneficial performance of galvanized SRG while also identifying some issues that warrant further investigation. These findings suggest the need for a more thorough evaluation of its appropriate use for the long-term preservation of built and historical heritage.