Abstract. The scientific research in the field of masonry structures is increasingly welcoming the adoption of innovative and sustainable rehabilitation techniques aimed at the safeguard of the Built Cultural Heritage. Textile Reinforced Matrix (TRM) composites are the most widely investigated strengthening systems for ancient masonry structures, thanks to their high compatibility level with the material substrates in terms of fire resistance, chemical/physical aspects, reversibility property, little impact on dimensions, stiffness and weight. Nevertheless, in the last years, the growing concern on sustainability increased the interest towards products with low environmental impact, for promoting circular economy approaches in the design of the structural interventions. In particular, efforts have been done to replace the most common composites by materials less harmful to the environment, as natural fibres, for developing compatible and sustainable rehabilitation techniques for masonry structures. This paper presents the preliminary results of an experimental campaign conducted by the authors at the Laboratory of Materials and Structures of Politecnico di Torino on specimens of TRM composites made with natural, vegetable, flax-fibre grids and natural hydraulic lime mortar, the latter suitable for applications on ancient masonry substrates. The mechanical characterization tests aimed at detecting the tensile behaviour of the natural TRM system compared to the results available in the literature on different flax-fibre composites and TRMs made with classical fibres, whose mechanical response is today considered a quite consolidated knowledge. The experimental tests highlighted the promising mechanical effectiveness of natural TRM systems under traction and offered the hint to further researches aimed at improve the mechanical strength and stiffness by the optimization of the main geometrical and material parameters such as the mesh size and the density.  

Keywords: TRM; FRCM; Inorganic Matrix Composites; natural fibres; vegetable fibres; tensile behaviour; experimental testing.