Advancements in techniques and materials for structural retrofitting of unreinforced masonry structures

Abstract The structural vulnerability of unreinforced masonry (URM) structures, particularly under excessive loading has driven significant research into effective retrofitting techniques over the past decade. This study presents a comprehensive review of emerging techniques and materials used for retrofitting masonry structures, with a focus on experimental investigations. Techniques such as reinforced overlay, surface coating, external reinforcement, near surface mount, and repointing were identified. The techniques used materials such as Fibre Reinforced Polymers (FRP), Textile Reinforced Mortar (TRM), Fibre Reinforced Cementitious Matrix (FRCM), Engineered Cementitious Composites (ECC), Oriented Strand Board (OSB), Cross Laminated Timber (CLT) panel, and hybrid systems. The techniques and materials were critically analysed in terms of their mechanical performance, compatibility, sustainability, and practical application. The review synthesises findings from laboratory tests, including cyclic loading tests, shear strength evaluations, and full-scale simulations, to assess the effectiveness and limitations of each material type. While high-performance materials like FRP and ECC offer superior structural enhancements, they are often limited by irreversibility and cost. Conversely, materials such as TRM and FRCM provide better compatibility with historic masonry and environmental benefits but may underperform in high-stress conditions. The study highlights the need for standardised testing protocols, life-cycle assessment, and multi-criteria decision-making frameworks to support informed material selection for masonry retrofitting. These findings have significant implications for advancing resilient and sustainable retrofitting strategies for existing masonry structures.