Effect of Exposure to Alkaline Environment on the Mechanical Properties of TRM Composites

The long-term durability of textile-reinforced mortar (TRM) composites is essential for their effectiveness in masonry strengthening applications. Despite growing research efforts, the impact of prolonged environmental exposure, particularly in alkaline conditions, on TRM mechanical performance remains inadequately understood. This study evaluates the durability of TRMs subjected to dry, water-immersed, and alkaline conditions for 1000, 3000, and 5000 h. A total of 462 specimens, incorporating glass and basalt textiles embedded in a lime-based mortar, were analyzed through a comprehensive experimental campaign, including mechanical testing of the mortar (compressive, flexural, and elastic modulus), pull-out and single-lap shear tests on TRM composites, and microstructural investigations using XRD and TGA. The results demonstrate that environmental exposure significantly influences TRM performance through a combination of mechanical and chemical interactions. Carbonation in dry conditions improved the mortar's strength, whereas prolonged water exposure led to minor reductions. In alkaline environments, the mortar exhibited notable improvements, with flexural and compressive strength increasing by 13 % and 53 %, respectively, after 5000 h. However, the response of TRM composites varied based on textile type. Glass TRM exhibited enhanced bond behavior, as reflected by a 4 % increase in peak strength from single-lap shear tests, whereas basalt TRM experienced a progressive decline, with a 37 % reduction in peak strength after long-term alkaline exposure. These findings highlight the critical role of textile selection in TRM design, providing valuable insights into the durability and mechanical performance evolution of TRM composites under aggressive environmental conditions.