THE USE OF CFRPs IN STRENGTHENING OF HISTORICAL MASONRY STRUCTURES: INVESTIGATION ON DURABILITY BY ACCELERATED TESTING.

摘要

The present work deals with experimental investigation of CFRP strips bonded by epoxy adhesive to calcarenite stone elements. The effectiveness of using CFRPs in strengthening applications strongly depends on the capability to maintain mechanical and chemical properties during their lifetime. "Long term durability" depends on both environmental (temperature, humidity, UV-rays, chemical agents, etc.) and mechanical (static loads, dynamic loads, cyclic loads, etc.) parameters. Experimental investigation was carried out to evaluate reinforcement-support system efficiency vs. time, through the comparison between "non-aged" specimens and specimens subjected to artificial ageing process obtained by cyclic variations of environmental parameters, in particular humidity, temperature and UV-radiation. A mechanical test was ad-hoc designed and performed by the application of an increasing load in the parallel direction (Double Shear Pulling Test) to evaluate adherence at the interface. Chemical-physical analyses were also performed in order to point out any change in the materials structure and/or composition, with special attention to the interface between resin and stone. Preliminary results seem to indicate some effect of ageing procedure on the way the fracture propagates in the system CFRP-stone under stress. The final aim of such experimental investigation is to give useful suggestions for assessing standard procedures to identify CFRP systems, which are compatible, and consequently durable, in strengthening of historical masonry.