Influenza di ambienti aggressivi sull’aderenza FRP-calcestruzzo

Bonding is a very important issue when Fiber Reinforced Composites (FRP) are used to strengthen reinforced concrete beams. Bonding depends on the mechanical and physical properties of concrete, composite and adhesive. This type of failure can be influenced by the exposition to deicing salts, polluted air, freeze-thaw cycles and other aggressive environmental conditions. Nevertheless, only few studies can be found on the effect of these degrading actions. Due to the lack of information, design rules against the effect of the aggressive environment are currently very conservative, even in recent recommendations. The present experimental study is a preliminary investigation aimed at the definition of basic correlations between degradation phenomena and changes in the mechanical parameters of the FRP-concrete bonding. A number of specimens have been preconditioned by thermal cycles and/or immersion in salt-spray fog environment. Then, pull-pull delamination tests have been performed under standard conditions. Obtained interface laws and force-plate elongation curves have been finally compared with those obtained from unconditioned FRP-concrete systems.