Effect of thermal ageing and salt decay on bond between FRP and masonry

Abstract

An experimental research on of masonry has been carried out. Thermal cycles and salt crystallization test were carried out on solid brick samples and small masonry assemblages, using bricks and mortars produced in Italy and in Poland. The specimens were strengthened with CFRP textiles or laminates in different configurations. To perform thermal accelerated ageing tests, specimens were subjected to a temperature variation ranging between −10 and +70 °C, applied cyclically. The procedure was validated during testing. The results showed the influence of the properties of the adhesive and of the strength of the brick in the failure of specimens. As for salt decay tests, a RILEM pre-standard procedure was followed to evaluate the resistance of tested materials to sulfates. Damage evolution was monitored by visual observation and by quantification, at each 4-week cycle, of material loss by a laser profilometer. The results showed the rising of salt from the uncovered surface as from the first week of observation, and also a concentration of stresses underneath the fibres. The pull-off test was chosen as reference test, in order to the loss of bond. The durability was also checked on reference unreinforced specimens. Pull off tests were carried out on the surviving specimens at the end of the tests. The results among the various series of specimens are compared. This costly repair technique can show adhesion problems due to humidity and high temperature.