Tensile and Pull-Out Behavior of Steel Reinforced Grout Connectors

Mortar-based composites are an emerging technology for the repair and strengthening of reinforced concrete and masonry structures. In most cases, the effectiveness of the retrofitting work relies on the substrate-to-composite bond capacity but in some applications, connectors are also used to prevent debonding and improve the performance of the retrofitted structure. Indeed, the use of connectors is recommended by design guidelines and suppliers are required to test them for acceptance. The paper presents a laboratory investigation on steel reinforced grout connectors, made by rolling ultra-high tensile strength steel textiles, comprising either galvanized or stainless-steel micro cords. Tensile tests were first carried out for mechanical characterization. Pull-out tests were then performed on connectors installed in holes drilled in wall panels and injected with either cement or lime mortars. Concrete, tuff masonry, brickwork and limestone masonry were used as substrate materials. Test results are commented to analyze the effect of textile rolling on tensile response, of textile and matrix properties on pull-out strength and failure mode, as well as to highlight their significance for design purposes.