Cementitious versus alkali-activated textile reinforced mortars for combined energy and seismic upgrade of masonry panels

Abstract Masonry retrofitting systems combining seismic with energy upgrading features are increasingly gaining popularity in the scientific community during the past years since they simultaneously address two of the most pressing needs related to the existing building stock. This is commonly realized by applying textile reinforced mortar (TRM) overlays combined with thermal insulation boards on building envelopes. At the same time, the urge for eco-friendly and environmentally sustainable interventions calls for low-cement or even cement-free solutions. This study aims to combine these requirements by experimentally investigating an integrated seismic/energy retrofitting system that incorporates alkali-activated materials (AAM) based on industrial waste. The system is compared to a counterpart one comprising conventional cementitious materials. The relative position of the strengthening and the thermal insulation layers is yet another parameter of this study. The latter includes tests performed on retrofitted masonry specimens aiming to assess their mechanical performance in terms of masonry-to-overlay bond and flexural capacity. This is achieved by shear bond tests, and in-plane and out-of-plane bending tests, respectively. The results show that the replacement of cementitious binders by alkali-activated ones in TRM jackets is a promising alternative, eliminating cement consumption while ensuring comparable load bearing capacities with ‘conventional’ TRM systems. It is also indicated that the effectiveness of the AAM-based system is improved when the strengthening layer is applied externally, i.e., on top of the insulating boards. However, further research is needed for the optimization of the system’s mechanical and long-term performance.