In recent decades, many strengthening interventions on masonry elements were performed by using fiber reinforced polymers (FRPs). These advanced materials proved to be effective to increase the load-carrying capacity of masonry elements and to improve their structural behavior, avoiding the most critical failure modes. Despite the advantages of this technique compared to more traditional methods, FRP systems have disadvantages related to their low resistance to high temperatures, impossibility of application on wet surfaces, low permeability, and poor compatibility with masonry supports. Therefore, composite materials made of a fiber textile embedded in an inorganic matrix were recently proposed as alternatives to FRPs for strengthening historic masonry constructions. These composite materials are easier to install, have higher resistance to high temperatures, and permit higher vapor permeability than FRPs. The inorganic matrix is frequently a cement-based mortar, and the composite materials made of a fiber textile embedded in a cement-based mortar are usually identified as FRCM (fabric reinforced cementitious matrix) composites. More recently, the use of natural lime mortar as an inorganic matrix has been proposed as an alternative to cement-based mortars when historic compatibility with the substrate is strictly required, as in case of restoration of historic buildings. In this paper, the effectiveness of a fabric made of basalt fibers embedded in lime mortar matrix (Basalt-FRLM) for the strengthening of masonry arches is investigated. An experimental investigation was performed on 1:2 scaled brick masonry arches strengthened at the extrados with a layer of Basalt-FRLM and tested under vertical load. The results obtained are compared with previous results obtained by the authors by testing masonry arches strengthened at their extrados with FRCM and FRP composites. This investigation highlights the effectiveness of Basalt-FRLM in increasing load-currying and the displacement capacities of masonry arches. The Basalt-FRLM-strengthened arch exhibited higher displacement capacity when compared to arches strengthened with polymeric and cementitious matrix composites.

In the past, steel hoops were applied over the height of columns to increase their load-bearing capacity. Currently, innovative strengthening techniques, namely fiber-reinforced composites, are successfully replacing traditional systems. Although fiber-reinforced polymers were demonstrated to be effective in the confinement of columns, the use of fabric-reinforced cementitious matrix (FRCM) systems is preferred in the case of masonry columns belonging to architectural heritage buildings because of the compatibility with the masonry substrate as well as the reversibility of the intervention. In this paper, the influence of different matrices on the effectiveness of confinement of masonry columns is investigated both experimentally and analytically. Three different matrices are considered to assemble the composite: a natural lime mortar with poor mechanical properties, a cement mortar, and a commercial mortar with high compression strength. The FRCM system was obtained by embedding a polyparaphenylenebenzobisoxazole fabric within these matrices. Results of axial compression tests demonstrate the effectiveness of confinement in all cases, highlighting the different increases in the load-bearing capacity and ductility of the columns provided by the use of different matrices. The main predictive formulas available in the literature were used to compute the increase in the load-bearing capacity of the tested columns, providing values very different than those obtained experimentally. For this reason, the authors believe that these formulas, which are affected by coefficients fine-tuned by the various authors based on their experimental results, need to be further calibrated and tuned to be successfully used in practical applications. Accordingly, the use of two different equations in the case of matrices having a compression strength higher or lower than the strength of the unconfined column is proposed.

The paper presents the results of an experimental campaign on the confinement of masonry square columns with fiber-reinforced lime mortar (FRLM) composites made of a natural lime-based matrix. The experimental results show the effectiveness of such a composite for increasing both strength and ductility performances of strengthened columns. Predictive formulas from the literature and from the Italian guidelines CNR-DT 215/2018 do not perfectly fit the experimental outcomes and do not confirm the strength increase of the confined columns. The reason can be attributed to the very low mechanical properties of the natural matrix used to form such a composite. Therefore, considering that the use of a natural and sustainable matrix fully compatible with the masonry substrate is a fundamental requirement for strengthening masonry columns of buildings belonging to architectural heritage, an additional future effort should be made by researchers involved in this field. In particular, for a reliable prediction of the strength of masonry columns confined with composites made of natural matrices, wider experimental campaigns are necessary to refine available formulas with respect to different substrates and component materials.

Usually, energy and structural improvements for historic masonry buildings are addressed separately using distinct methods and protocols. This paper covers an integrated assessment of new composite materials to reduce the seismic vulnerability of historic masonry buildings while complying with sustainable conservation requirements, emissions’ reduction, and energy savings. Firstly, this study focused on selecting suitable thermal mortars that could serve as the base material for the innovative composite. Subsequently, the mechanical characteristics of these mortars were examined by subjecting them to compressive and three-point bending tests. Dynamic thermo-hygrometric simulations were conducted using commercially available software to check the energy performance of the composite material when used on walls of existing masonry buildings. The thermal mortar that exhibited the most favorable mechanical and thermal properties was subsequently reinforced with a basalt fabric. A composite sample was assembled and subjected to direct tensile testing to determine its stress–strain behavior.