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

Abstract

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.

Ladle Furnace Slag: Synthesis, Properties, and Applications

“…The use of LF slag alone [60], activated LF slag, and the inclusion of additives like fly ash [129][130][131][132][133][134][135][136][137][138][139][140], fibers [141][142][143], and metakaolin [59,144] has been studied for forming geopolymers. The most critical factor in developing geopolymers is the hydration of binders, cement, slag, or fly ash to activate calcium aluminum silicate minerals using an alkali activator.…”

Out-of-plane performance of structurally and energy retrofitted masonry walls: geopolymer versus cement-based textile-reinforced mortar combined with thermal insulation

“…Recent attempts to reduce the environmental impact of TRM systems focused on geopolymers as new binding materials for the textiles, which have potential to become an alternative to Ordinary Portland Cement (OPC) binders ( Arce et al , 2022a ; Askouni et al , 2021 ; Cholostiakow et al , 2023a ; Ghiassi et al , 2016 ; Gkournelos et al , 2022 ; Skyrianou et al , 2022 ; Tamburini et al , 2017 ; Wang et al , 2021 ; Zhang et al , 2019 ; Zhang et al , 2022 ). Geopolymers, which can be formed by mixing silicate dry products with an alkaline solution, exhibit excellent mechanical properties, high durability, and resistance to elevated temperatures, thus making them potential candidates as an alternative to cement-based materials, but also in a variety of uses as a fireproof adhesive for fibre-reinforced composites and laminates ( Arce et al , 2022b ; Chen et al , 2021 ; Giancaspro et al , 2009 ; Giancaspro et al , 2010 ; Katakalos & Papakonstantinou, 2009 ; Mobili et al , 2016 ; Papakonstantinou et al , 2001 ; Papakonstantinou & Balaguru, 2006 ; Papakonstantinou & Balaguru, 2007 ; Papakonstantinou & Katakalos, 2009 ; Zhang et al , 2018 ).…”