PSI - Issue 78

Francesco Bencardino et al. / Procedia Structural Integrity 78 (2026) 1396–1403 Author name / Structural Integrity Procedia 00 (2025) 000 – 000

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2

Keywords: masonry; retrofitting; FRCM; sustainability; alkali-activated slag

1. Introduction Masonry structures are quite widespread across the world, since it is a relatively simple building technique and the most traditional one (Stepinac et al. 2020 and Lourenço 2014). Consequently, significant attention is nowadays paid to the issues of repair and strengthening of those constructions, by reducing deterioration and improving mechanical properties. Among all the available retrofitting systems, the strengthening obtained with Fabric Reinforced Cementitious Matrix (FRCM) systems seems to be a promising solution. Due to the several advantages related to their use, FRCM materials appear to be a valid and more environmentally sustainable alternative to traditional retrofitting methods as well as FRP systems (Ascione et al. 2014, Ascione et al. 2015 and Papanicolaou et al. 2007). However, despite the advantages linked to the use of a cementitious matrix, the severe environmental impact due to cement production process cannot be neglected. Even though cement is the worldwide most used construction material, its production process is responsible for significant carbon emissions and requires the consumption of massive quantities of energy, raw materials and water (Coppola et al. 2018). In this context, free-cement mortars could represent a valid solution to contribute to reducing the carbon footprint as well as the waste of natural resources provoked by the construction industry. Therefore, the replacement of traditional cementitious matrices with two more eco-friendly ones is herein proposed: lime- (M1) and alkali-activated ground granulated blast-furnace slag-based mortar (M2). This study aims at improving the performance of masonry structures against horizontal actions with these kinds of strengthening methods, since these constructions are usually quite inadequate to withstand seismic events (Mercedes et al. 2020 and Faella et al. 1992). The effectiveness of these techniques has been assessed by means of cyclic shear compression tests performed on masonry walls. This paper focuses on experimental results relative to tests performed on a total of six specimens made with clay bricks; among them, five were strengthened with B-FRCM (Basalt) or S FRCM (Steel) systems, comprising lime- or alkali-activated slag-based matrix, while the remaining one was left unreinforced to be used as a control specimen. Experimental results found by performing cyclic tests will be discussed and compared in terms of increase of strength, ductility as well as failure modes. These tests are part of an extensive r esearch project, namely “Sustainable Textile Reinforced mortar for strengthenIng and rePair Existing masonry Structures (STRIPES)”, aimed at the development and characterization of an innovative and environmentally more sustainable retrofitting systems for existing masonry buildings.

Nomenclature N

Applied axial load

F +/- s +/-

Maximum positive/negative horizontal load

max

max Maximum positive/negative horizontal displacement achieved s +/- 0.8 Horizontal positive/negative displacement corresponding to the 80% of maximum positive load μ +/- y Ductility

2. STRIPES research program The achievement of a more sustainable method to repair existing masonry structures is the focus of STRIPES research project, in which the replacement of cementitious mortars commonly employed in FRCM systems is proposed. Alongside commercially available lime-based mortars, an alternative “green” one has been developed by optimizing a mixture based on alkali-activated blast furnace slag, allowing both the decrease of consumption of natural resources and the recycling of an industrial residual by-product. The present experimental campaign aims at contributing to providing a better understanding of behavior by masonry structures externally reinforced with these kinds of reinforcements. In particular, this study focuses on enhancing the lacking capacity of masonry structures to bear seismic events, and the preliminary findings obtained from the first cyclic shear-compression tests on masonry walls is discussed here. Table 1 shows the complete test matrix and summarizes all the considered variables: