Tensile behaviour and durability assessment of Flax Textile Reinforced Mortar composite systems

The use of Textile Reinforced Mortar (TRM) composite systems is getting more and more common for enhancing shear and bending capacity masonry walls. In this context, employing natural fabrics deriving from vegetal fibres is a possible evolution in TRM technology, intended at enhancing the sustainability of the material. However, the organic nature of the aforementioned fibres raises new questions about the durability of the material. Therefore, this paper investigates the tensile behaviour of Flax-TRM coupons also considering the effect of their being exposed to different environmental condition. Specifically, according to the acceptance criteria AC434 issued by the ICC-Evaluation Service (USA), the specimens have been immersed either in water or salt-water or alkali solution for a period of 3000h. The composite material components (namely, the mortar matrix and the flax fabric) have been subjected to the same treatments to quantify their influence in the global response. A series of specimens has been left in ambient condition to get a reference behaviour. The obtained results show that neither the composite system as a whole, nor its components have shown any significant decay in terms of mechanical behaviour with respect to the reference series. The results demonstrate that the investigated Flax-TRM system, exposed to the conventional protocols provided by AC434, complies with the acceptance criteria generally considered for qualifying composite materials