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Limited research has focused on the effect of high temperatures on the textile-reinforced mortar (TRM)-to-masonry bond. In this study, masonry prisms that were furnished with double-layered TRM strips were tested under shear bond conditions after their exposure to 200 °C and 400 °C for 1 h using the single-lap/single-prism setup. A total of four TRM systems were applied sharing the same type of textile –a dry AR glass fiber one– and different matrices: two cementitious matrices, namely a normal-weight (TRCNM) and a lightweight (TRCLM) one, and two counterpart alkali-activated matrices (TRAANM and TRAALM) based on metakaolin and fly ash. Specimens’ exposure to elevated temperatures did not alter their failure mode which was due to the sleeve fibers’ rupture along with core fibers’ slippage from the mortar. The residual bond capacity of the TRM systems decreases almost linearly with increasing exposure temperature. The alkali-activated textile reinforced mortars outperformed their cement-based counterparts in terms of bond strength at every temperature. All systems retained close to 50% of their original shear bond strength after heating at 400 °C. Per the type of binder, lightweight matrices resulted in either comparable (cement-based systems) or better (alkali-activated systems) heat protection at the TRM/masonry interface.

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The need for repair and maintenance has become dominant in the European construction sector. This, combined with the urge to decrease CO2 emissions, has resulted in the development of lower carbon footprint repair solutions such as textile reinforced mortars (TRM) based on alkali-activated materials (AAM). Life cycle studies indicate that AAM CO2 savings, when compared to Portland cement, range from 80% to 30%. Furthermore, in this study, recycled aggregates were considered with the aim to promote a circular economy mindset. AAM mortars formulation based on fly ash, ladle furnace slag and metakaolin were tested for compressive and flexural strength. Three out of all formulations were chosen for an analysis on the potential of these mortars to be used for TRM applications. Tensile and shear bond tests, combined with a concrete substrate, were executed as indicators of the TRM effectiveness. Scanning electron microscopy and chemical analysis based on energy dispersive X-ray spectroscopy were used to interpret the results and reveal the reasons behind the different level of performance of these composites. Results indicated that TRM based on high calcium fly ash are unsuitable for structural strengthening applications due to low bond between matrix and/or substrate and fibers. Metakaolin-based TRM showed good performance both in terms of tensile strength and bond capacity, which suggests potential as a repair mortar.

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