­­­Mechanical behavior of textile reinforced alkali-activated mortar based on fly ash, metakaolin and ladle furnace slag

The need for repair and maintenance has become dominant in the European construction sector. This, combined with the urge to decrease CO (2) 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 CO (2) 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.