The role of biomass bottom ash in Carbonated Reactive Magnesia Cement (CRMC) for CO2 mineralisation

This work evaluates the incorporation of biomass bottom ashes on Carbonated Reactive Magnesia Cement-based (CRMC) mortars. For this purpose, four mixtures were designed to verify the influence of biomass bottom ash as partial or total sand replacement. The specimens were moulded through static compaction pressure and submitted to an accelerated carbonation curing period of 24 h under controlled conditions. The devised mortars were evaluated through mass, dimension, pH measurements, and compressive strength tests. Furthermore, TG-DTG, SEM, FT-IR, XRD, and MIP analyses were performed to investigate the microstructure of the materials developed in this study. Therefore, the devised mortars reached compressive strength results from 9.9 to 24.5 MPa. The TG-DTG, FT-IR, SEM, and XRD analyses support the formation of HMCs in all mixture designs being their volume carbonated in different degrees. Finally, the use of fine particles of biomass bottom ash collaborated for compressive strength enhancement and higher CO2 uptake degree while larger particles do not.