Tensile Response and Durability of Flax-TRMs

Textile Reinforced Mortar (TRM) systems are currently among the most effective retrofitting solutions for masonry structures, thanks to their high compatibility with the substrate, and reversibility. Recently, the adoption of natural textiles as reinforcement in TRM systems has attracted the interest of researchers and industry, due to their great potential of providing a cost effective and sustainable solution while ensuring adequate structural performance. Despite the increasing number of studies focusing on the characterisation of short-term tensile properties, the long-term durability performance of natural TRMs, which is fundamental to ensure their viability in construction applications, has not been examined in detail. This paper aims to investigate the tensile behaviour of flax textiles and flax-TRM composites and assess their residual performance after exposure to accelerated ageing. Composites consisting of two and three layers of a bi-directional flax fabric embedded in a lime-based mortar were conditioned in water for 1000 h and 2000 h at controlled temperatures of 23 ℃ and 40 ℃. Bare textiles were also aged in an alkaline solution for equivalent exposure times and temperatures, to replicate the conditions within the lime-based matrix environment. Both unconditioned and aged textiles and composites were tested under uniaxial tension to determine their tensile behaviour. The complete load-deformation response was assessed employing both contact and non-contact methods (i.e. 2D Digital Image Correlation). It is shown that ageing strongly affects the textile reinforcement, resulting in a significant strength loss of the composite system.