Textile reinforcement mortar: Natural fiber TRM system for integrated (structural and thermal) retrofitting

The retrofit of existing masonry buildings requires solutions capable of simultaneously improving structural safety and energy efficiency while reducing environmental impacts. Although Textile Reinforced Mortar (TRM) systems are widely used for structural strengthening, integrated thermo-structural solutions based on natural and recycled materials remain largely unexplored. This study investigates an innovative Natural Fiber Textile Reinforced Mortar (NFTRM) system combining flax fiber textiles, sheep-wool insulating mortars, jute-fiber diatons, and recycled fine aggregates for the integrated upgrading of masonry walls. An experimental campaign was conducted on eighteen masonry wall specimens representing six retrofit configurations. To enhance sustainability, 30% of the natural sand was replaced with recycled fine aggregates (recycled sand) derived from construction and demolition waste. Thermal performance was assessed using a climate chamber, while structural behavior was evaluated through diagonal compression tests. The results demonstrate significant improvements in both thermal and mechanical performance compared with the unreinforced reference walls. The combined textile-and-insulation system (TRMTL) achieved the highest thermal enhancement, increasing thermal resistance by 73.7%, while TRMTLD and TRMD improved thermal resistance by 54.7% and 48.1%, respectively. Structurally, the retrofitted walls exhibited increases in load-bearing capacity ranging from 17.5% to 59.3% compared with unreinforced masonry, with the best performance achieved by diaton-enhanced configurations. The proposed NFTRM systems successfully combine structural strengthening, thermal insulation, and circular-economy principles by bio-based and recycled materials. These findings demonstrate the potential of sustainable NFTRM solutions as an effective strategy for the integrated seismic and energy retrofit of existing masonry buildings.