Cyclic shear-compression tests on masonry wall strengthened with FRCM systems: preliminary results

The study presents the first results of a broader experimental program aimed at investigating the cyclic response of masonry members strengthened with innovative, eco-friendly FRCM systems. A more sustainable strengthening solution was developed by replacing the commercially available lime-based mortar - typically used to impregnate the fiber sheets - with a novel mortar formulated from a waste product: a cement-free, alkali-activated slag-based mortar, where the slag is a by-product of the cast iron production process. The behavior of masonry walls strengthened with this system was experimentally assessed through cyclic shear-compression tests conducted on two types of masonry: (a) artificial masonry (clay bricks), and (b) natural masonry (tuff units). Both the commercial and the “sustainable” mortars were used in combination with two different fabrics: (a) a unidirectional fabric made of high-strength steel cords (S-FRCM system), and (b) a bidirectional basalt fabric (B-FRCM system). The complete experimental program comprises 20 tests on specimens strengthened using different configurations. In particular, the unidirectional steel fabric was arranged in a grid pattern, with strips applied in both vertical and horizontal directions, while the basalt fabric covered the entire specimen surface. The initial tests provided preliminary insights into the influence of the mortar type (commercial vs. “sustainable”) on peak load capacity, rotational ductility, and failure modes of the strengthened members. It is noted that this experimental program is part of the STRIPES research project, funded by PRIN-PNRR 2022, and involves two Italian research teams from the University of Salerno (UniSa) and the University of Calabria (UniCal).