A GFRP mesh strengthening technique applied to ancient masonry walls

The paper presents a study to assess the effectiveness of a novel technique to strengthen ancient masonry walls by using a thin mortar coating on both surfaces reinforced with a glass fibre reinforced polymer (GFRP) mesh. This study is divided into two parts. In the first part the results of an experimental campaign, carried out on masonry specimens, which considers various parameters, are reported: four types of GFRP mesh, three types of mortar for masonry walls and two different types of masonry. In particular, the behaviour of solid brick masonry (250 mm thick) and stone masonry was assessed. A detailed study was carried out to design the connection device to be used to join the mortar coating to the masonry, so as to optimize the effectiveness of the strengthening technique. In the second part the interpretation of experimental results is provided: the principal mechanical parameters of the masonry (reinforced or not) are defined and the relationships that enable to estimate the values of those parameters are reported. The results of numerous diagonal compression tests and the subsequent analysis of acquired data evidenced the effectiveness of the strengthening technique. In fact, there was a significant increase in tensile strength, particularly in rubble-stone masonry samples. It was considerable the residual tensile strength after the formation of the first diagonal cracks up to large values of deformation. Finally, this study is oriented to identify parameters of masonry panels through in-situ diagonal compression tests in order to evaluate the effectiveness of the proposed strengthening technique to other types of masonry.