Upcycling end-of-life bricks in high-performance one-part alkali-activated materials

Abstract

Data availability: Data will be made available on request.Copyright © The Authors 2023. One-part alkali-activated materials (AAMs) can preserve natural resources and lower embodied carbon of the built environment by accommodating various wastes, industrial by-products, and end-of-life materials in their composition. This study investigates the feasibility of using end-of-life bricks in two physical states, powder and aggregate, to partially replace fly ash precursor and natural aggregate in AAMs, respectively. The mechanical characteristics, microstructure, water absorption, freeze-thaw and fire resistance of the modified AAMs were evaluated. The effect of adding different ratios of nano graphite platelets was also investigated. Results showed that brick-based one-part AAMs can achieve mechanical properties, pore structure, water absorption and freeze-thaw resistance comparable to fly ash-based AAM while having 65% better fire resistivity. Incorporating bricks as aggregate resulted in a maximum improvement of 17% and 27% in the AAMs' compressive and flexural strength levels, respectively, and a general enhancement in the freeze-thaw resistance with showing no reduction in compressive strength after exposure to elevated temperature. Incorporating 0.1 wt% nano-graphite further enhanced flexural strength by 30%, decreased water absorption by 18% and improved freeze-thaw resistance compared to the mix without nano-graphite. Moreover, adding up to 0.5% nano-graphite enhanced the fire resistivity of the composite, allowing it to exhibit 19% better strength performance than before exposure.This work was funded as part of the DigiMat project, which has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement ID: 101029471. The research leading to this publication benefitted from EPSRC funding under grant No. EP/W022583/1, EP/R010161/1 and from support from the UKCRIC Coordination Node, EPSRC grant number EP/R017727/1, which funds UKCRIC's ongoing coordination