PSI - Issue 64

Rosario Lombardi et al. / Procedia Structural Integrity 64 (2024) 1919–1926 Rosario Lombardi et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction In recent years, more and more attention has been paid to the development of innovative solutions for the structural strengthening and retrofitting of masonry structures. Among these, TRM (Textile Reinforced Mortar) systems (or similar composites, such as Textile-Reinforced Concrete, TRC, and Fabric-Reinforced Cementitious Matrix, FRCM, systems) have demonstrated potential for being employed for strengthening historic masonry buildings (Gkournelos et al., 2022; Bournas, 2018). TRM is a composite system, consisting of a cement- or lime-based matrix incorporating one or more layers of textile reinforcement made of synthetic/industrial textile, such as steel, PBO, glass fiber, aramid , basalt, carbon, etc. (Corradi et al., 2023; Ferrara et al., 2019). However, these reinforcing materials have among their disadvantages the lack of compatibility with the objective of sustainability of existing building restoration, in terms of production and disposal at the end of their life cycle (Olivito et al., 2018). Therefore, several researcher studies worldwide have recently investigated the possible replacement of those materials with more environmentally friendly ones. Specifically, the focus was placed on the use of fabrics made of natural fibers, and more specifically of vegetal origin (Majid Ali, 2012; Laverde et al., 2022). These studies have shown that the natural textiles present promising characteristics and can be adopted to realize the so-called NTRM (Natural TRM). In this area, therefore, the most studied and used fabrics are flax, jute, karanja, sisal, coconut and hemp (Majid Ali, 2012; de Carvalho Bello et al., 2019). Obviously, these solutions also bring with them some issues that deserve to be investigated and possibly fixed. In particular, critical aspects in the use of plant fiber fabrics are, among others, the variability in the mechanical and physical characteristics, the high water absorption capacity, and the durability of plant fibers (Codispoti et al., 2015; Kohan et al., 2022). In the literature, the possible strategies analyzed and proposed for the resolution of these problems are many (Kohan et al., 2022; Arsne et al., 2007). Several studies investigate the possible application of a coating treatment on the employed natural fibers by using an organic material – polymers or resins, generally epoxy resin – leading to a new composite material with different characteristics (Bompadre & Donnini, 2022). This solution, however, while on the one hand allows to partially overcome the problems previously mentioned in terms of durability and long-term performances, on the other hand leads to the creation of a reinforcement that has lost its biodegradability, and therefore one of the main characteristics for which this solution was sought in the first instance (sustainability). In this context, the objective of the present study is to evaluate the possible application of alternative coating system to be employed for the impregnation of vegetable fibers, which at the same time keeping the biodegradability characteristic of the fabric reinforcement. The attention was mainly focused on the application of bio-polymers: plastic polymers deriving from renewable materials while at the same time having the fundamental characteristic of degrading in a much shorter period of time than the synthetic polymers used today. Specifically, the use of PLA (poly-lactic acid) was envisaged, a polymer which is increasingly used for its physical and mechanical characteristics, as opposed to petroleum polymers (Thakur et al., 2017; Coppola et al., 2018). The present work proposes a preliminary physical and mechanical characterization of two different plant fabrics (jute and flax) available in different textile configurations, impregnated with PLA by considering different impregnation concentrations. This was done, first of all, to understand if the application of the biopolymer considered was possible and easy and, furthermore, to unveil the effects of this impregnation technique on the resulting mechanical behavior of the fabric. 2. Materials and Methods 2.1. Natural fabric The natural fabrics under consideration (symmetrical in both directions) are obtained from two different sources: jute and flax.

FLAX (124 g/m 2 )

FLAX (265 g/m 2 )

JUTE (318 g/m 2 )

Figure 1 – Representative samples of flax and jute yarns/textiles