Durabilità del confinamento mediante GFRP di colonne in calcestruzzo soggette ad ambiente fortemente aggressivo.

Confinement of reinforced concrete (RC) columns by using fibre-reinforced polymer (FRP) composites is commonly used as a modern strengthening technique. The high mechanical properties of the fibres, the light weight and low installation costs of FRP composites have contributed to making them a successful solution for column confinement. Although previous studies have demonstrated the high performance of FRP systems bonded to concrete elements, several concerns are related to the long-term behaviour of wrapped columns, which had limited implementation in terms of results and guidelines. Environmental effects, such as freeze-thaw cycles, wet-dry cycles, ultra violet (UV) radiations exposure, high temperatures and de-icing salts, may affect the material properties and the structural response of the wrapped elements. In this paper an experimental work is presented in order to study the long-term behaviour of Glass FRP-confined columns. A commercial GFRP system was used to wrap thirty-two small-scale concrete cylinders that were subjected to extreme conditions such as freeze-thaw cycles, immersion in water and saline solution, immersion in alkaline or HCl solutions. Epoxy adhesives, cured at four different temperatures, used for FRP bonding, were also studied after immersion in water, diffusion properties were measured after different times of exposure, also changes in glass transition temperature were monitored by using a differential scanning calorimeter. Changes in mechanical and physical properties of FRP-confined cylinders and adhesives are discussed herein.