Bond behaviour of steel FRP/FRCM systems on concrete substrates: an experimental investigation

Fiber reinforced polymer (FRP) and Fiber Reinforced Cementitious Matrix (FRCM) systems have emerged as attractive technologies for the external strengthening of RC structures. The use of steel textiles, externally bonded to the substrate via wet lay-up, represents an innovative and alternative solution to the application of carbon and glass sheets. Furthermore, the use of inorganic matrices could be useful to overcome the problems of fire endurance or meet the preservation criteria required for applications to architectural heritage. Within their mechanical response several aspects still need a deeper examination. Among them, the steel FRP/FRCM-to-concrete shear bond behaviour is the crucial one for the effectiveness of most applications since it represents the means of stress transfer between concrete and the composite materials. This paper helps to fill these gaps by summarizing the main results of a wide experimental program performed on the steel FRP/FRCM systems bonded to concrete members. The influence of the concrete strength, the bonded length, the steel tape density and the quality of the surface preparation were investigated.