Moisture and temperature influence on FRP masonry bonding

Durability and bonding of FRP system on masonry is crucial, especially for possible application in historical context, where moisture in the support can influence the application phases, and thermal cycles occurring in the environment can cause de-bonding. Durability tests as humidity variation and thermal cycles were programmed. The pull-off test was chosen as reference test in order to check the loss of bond. Solid brick samples, and small assemblages including mortar joints have been strengthened with CFRP strips in three different configurations. The bond was firstly checked on reference unreiforced specimens. Two types of damage were studied: the effects of three different humidity conditions of the support, and of ageing due to thermal cycles. Both the phenomena can happen in nature. As for thermal ageing tests, in a preliminary set of specimens, subjected to a temperature variation ranging between -10°C and +70°C, applied without stopping for 40 cycles, it was not possible to perform pull-off tests since most of the strips lost their bond. Then, for a second series of specimens, their conditions were controlled at low number of cycles, so that it was possible to identify the debonding cycle and to perform some pull-off tests. Although these tests are still in progress, some significant preliminary results are commented in the paper.