FRCM-confined masonry columns: experimental investigation on the effect of the inorganic matrix properties

Nowadays, the strengthening and the retrofitting are crucial issues in the civil engineering challenge for structural conservation. Innovative techniques, using fiber reinforced polymers (FRPs) composites, have been proven to be very effective in a wide range of applications. However, the organic matrix appears to be inadequate because of its difficult reversibility, especially when referring to historical masonry buildings. In this perspective, a new generation of strengthening systems has been studied, known as fabric reinforced cementitious matrices (FRCMs). They generally consist in a dry fabric-based reinforcement (typically an open-grid or a textile) embedded in an inorganic matrix. The present paper reports and analyses the experimental results on FRCM-confined masonry columns subjected to centred compression test. The main goal of this research consists in evaluating the role of the inorganic matrix in determining the effectiveness of FRCM-confinement. For this purpose, three different inorganic matrices, having different compressive strength, have been considered and used for confining a poor-quality masonry column. The different increases of the axial strength, due to the differences of the compressive strength of the matrices of the FRCM-system, have been assessed. Finally, the experimental results have been compared with the theoretical predictions obtained from the application of an analytical model, available in the literature.