Aerated concrete made of MSW incineration ash: Effect of blending materials and CO2 curing condition

Municipal solid waste (MSW) incineration ash is used to produce aerated concrete blocks (ACB). To reduce cement usage and improve ACB quality, steel slag and blast-furnace slag were tested as cement substitutes, and CO2 mineralization technology was applied to cure ACB. The effect of steel blending ratios (MSW incineration ash, cement substitutes, water, aluminum powder) and CO2 curing conditions (temperature, pressure) on ACB properties was investigated. Under different conditions, the compressive strength, CO2 uptake and microstructure of ACB were determined. Higher fly ash content in ACB increases CO2 uptake but reduces compressive strength; ACB shows better mechanical properties when the cement is completely replaced by blast-furnace slag, but steel slag will cause ACB to fail to form; the optimal water-to-solid ratio enhances carbonation rate and compressive strength, and reducing aluminum powder content improves compressive strength. As the CO2 curing temperature increases from 25 to 105ºC, the carbonation rate and compressive strength of the ACB initially increase and then decrease, with the maximum CO2 uptake ratio of 20.0 % and peak compressive strength occurring at 65ºC. When CO2 pressure increases from 0.2 MPa to 1 MPa, the carbonation rate rises to 23.4 %, and the compressive strength first increases and then decreases, reaching 1.86 MPa at a curing pressure of 0.6 MPa, meeting the GB/T 11968–2020 B03 A1.5 grade standard. Approximately 0.58 tons of CO2 emissions can be reduced for every ton of ACB produced. This study established an innovative method to produce an environmentally friendly, low-carbon building material. [Display omitted] •Using blast-furnace slag instead of cement improves aerated concrete properties.•A new method for harmless treatment of waste incineration ash is proposed.•CO2 curing MSW incineration ash aerated concrete is studied.•Producing an environmentally friendly, low-carbon building material.