Effect of acid attack on FRP-to-concrete bonded interfaces

Due to a wide range of fibre reinforced polymer (FRP) material applications in structural strengthening, the long-term performance of FRP-to-concrete bonded interfaces has become an important area of research. Aggressive environmental factors such as temperature variation, wet/dry cycles, sulphate attack, acid attack, or UV radiation may noticeably change the service life of an FRP-strengthened reinforced concrete (RC) structure. Amongst the possible external aggressive conditions, acid impact on FRP-strengthened structures has received limited research attention in comparison to other environmental conditions. Industrial growth and climate changes within the last century has increased the exposure of structures to acidic environments arising from acidic rainfalls, acidic soils, sewage systems, mining, agriculture, and power stations. This paper provides an overview of the impact of acidic conditions on FRP-to-concrete bonded interfaces. Such interfaces are of central importance to the success of FRP strengthening measures for concrete structures. The individual components of concrete, resin matrix, fibre, and the interface between the FRP and the concrete are investigated. Potential degradation mechanisms are discussed, as well as experimental methodologies and research needs.