Unveiling the role of reactive magnesia and red mud in CO2-cured aerated concrete

Instead of using ordinary Portland cement (OPC), this study investigated the use of hydrated magnesia carbonates, which is derived from the carbonation of reactive magnesia, as the binding material for the production of aerated concrete, where the impacts of material design (e.g., the Ca/Mg ratio) on the properties of aerated concrete were studied. The results showed that the selection of Ca/Mg and water/binder ratio in raw materials directly determined most properties of the aerated concrete, and the use of reactive magnesia enabled the samples to reveal excellent carbon sequestration and a good pore structure. Further, substituting fly ash with red mud improves early strength by forming small amounts of AFt (3CaO center dot Al2O3 center dot 3CaSO(4)center dot 32H(2)O) and hydrotalcite. In view of the above, adopting CO2 curing for aerated concrete involving reactive magnesia and red mud is beneficial when producing high-quality aerated concrete (AC).