Influence of moistness and high temperature on bond between FRP reinforcement and calcarenite ashlars

The use of Fibre Reinforced Polymer (FRP) plates and sheets for strengthening masonry and concrete structures is a promising technique but further investigations are needed in this area in order to accomplish design requirements. Composites present a potentially costefficient and more durable alternative to the use of externally bonded steel plates for the rehabilitation and strengthening of masonry structures, due to their high stiffness-to-weight and strength-to-weight ratios, corrosion resistance and overall ease of application in the field. The bond performance at the interface substrate-reinforcement is fundamental, affecting in great extent the response of the structural system and therefore the effectiveness of the strengthening technique. Therefore experimental and theoretical investigations are needed to assess reliable design models taking into account the influence of all parameters involved in the bond performance between masonry and composite reinforcement and addressing also the durability of the system under typical service conditions. In this paper an investigation aimed to analyse the durability of the bond between masonry and composites under different environmental exposure regimes is presented, the specimens have been exposed at a 40°C temperature and 90% humidity. Differences in pul-off force, type of failure and stress transfer mechanisms at the interface based on material and environmental influences are presented and discussed