Effectiveness of Flax-TRM composites under traction

The scientific research in the field of masonry structures is increasingly welcoming the adoption of innovative and sustainable rehabilitation techniques aimed at the safeguarding 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 in 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 with materials less harmful to the environment, such as natural fibres, for developing compatible and sustainable rehabilitation techniques for masonry structures. This paper presents the preliminary results of experimental tests conducted by the authors on specimens of TRM composites made with natural, vegetable, flax-fibre grids and natural hydraulic lime mortar. 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 vegetable-fibre composites and TRMs made with natural basalt fibres. The experimental tests highlighted the promising mechanical effectiveness of natural TRM systems under traction and offered a hint to further research aimed at improving their mechanical strength and stiffness.