Structural strengthening of masonry elements by reinforced repointing combined with FRCM and CRM

Within the framework of the seismic vulnerability of existing masonry constructions, a current issue is represented by the need of performing structural strengthening interventions to increase or restore the capacity of these buildings to resist seismic actions. Retrofitting solutions are therefore often proposed using innovative materials and techniques, such as Fiber Reinforced Cementitious Matrix (FRCM). It should be highlighted that the application of FRCM usually consists of a continuous reinforcing system covering the entire surfaces of the masonry panels. These strengthening solutions are very effective in improving the structural behavior of existing masonry elements, but they are not applicable when the surface of the masonry should remain visible, i.e., in historical buildings. Therefore, other techniques should be adopted, such as the reinforced repointing technique. In this paper, a series of diagonal compression tests are performed on clay brick masonry panels strengthened using different techniques, involving the use of reinforced repointing combined with the application of Fiber Reinforced Cementitious Matrix (FRCM) and Composite Reinforced Mortar (CRM). The tested masonry panels are strengthened either symmetrically, by using FRCM on both sides, or unsymmetrically, by applying the reinforced repointing technique on one side and FRCM or CRM on the other side of the panels. The results of the experimental campaign shows that the strengthening systems can improve the structural behavior of the masonry panels, both in terms of bearing capacity and ultimate deformations.