In this study, a new type of composite comprised of steel cords embedded in a mortar matrix—referred to as steel-reinforced grout (SRG)—is explored for use in the confinement of masonry columns. This paper presents the results of an experimental study carried out to understand the behavior of solid clay brick masonry columns confined by single-layer SRG jackets. Thirty-one confined and three unconfined columns with a square cross-section were tested to failure under a monotonic concentric compressive load. Test parameters considered were the SRG matrix type, column corner condition, and steel cord sheet density (i.e., steel cord spacing) in the SRG jacket. SRG confinement improved the compressive strength, ultimate strain, and energy absorption of masonry columns relative to the unconfined condition. Models from the literature for FRP-confined masonry were examined for their applicability to predict the strength increase from the SRG jacket, with certain models predicting the confined compressive strength within 9% of the test values.

In this study, the behavior of clay masonry columns confined by steel reinforced grout (SRG) composite with a natural hydraulic lime mortar is investigated. An experimental study was carried out to understand the behavior of masonry prisms with a square cross-section confined by SRG composite jackets subjected to a monotonic concentric compressive load. Test parameters considered in this study are the density of steel fibers and column corner radius. The effectiveness of the confinement is studied in terms of load-bearing capacity with respect to unconfined columns.

The use of composite materials to strengthen masonry structures has become common practice within the civil engineering community. Steel-reinforced grout (SRG), which comprises high-strength steel fibers embedded in a mortar matrix, is part of the family of the fiber-reinforced cementitious matrix (FRCM) composites that represent a suitable alternative to fiber-reinforced polymer (FRP) composites for strengthening existing structures. Although studies on FRCMs have already reached a certain level of maturity, some key issues remain open, such as the role of matrix type and layout, substrate properties, and test rate. This paper focuses on some of these issues. The results of single-lap direct shear tests on masonry blocks strengthened with SRGs are presented to analyze the bond behavior between the composite material and the substrate. Four aspects are considered: (1) the change in the width of the SRG mortar matrix while keeping the width of the fiber sheet fixed; (2) the type of mortar used for the SRG; (3) the influence of the test rate, and (4) the type of substrate (i.e., concrete vs. masonry). The results obtained indicate the active role of the matrix layout and the importance of the test rate, encouraging further investigations to clarify these aspects.

This paper presents the results of single-lap direct shear tests on steel reinforced grout (SRG) strips bonded to fired-clay brick and tuff masonry blocks. For this experimental campaign, fifteen masonry blocks were constructed and reinforced with SRG composite strips. Fired-clay bricks and tuff blocks herein employed were collected from demolished historical structures in Modena and Naples (Italy), respectively. Eight out of fifteen blocks were subjected to an artificial weathering procedure to induce salt crystallization, and therefore reproduce the degradation conditions that the buildings could be subjected to during their life. Bond behavior of unconditioned strengthened specimens (i.e. SRG-masonry joints) was compared with the behavior of conditioned joints. Salt distribution, open porosity, and water absorption of brick and tuff masonry units as well as of the SRG composite matrix were analyzed to understand if and how the salt crystallization influenced the adhesion between the SRG strip and the block.