Nesquehonite (MgCO3⋅3H2O) as a source of solid carbonate for pre-cast elements

Carbon capture and utilization (CCU) is the major approach to mitigate the carbon footprint of cement industry. However, carbonation processes face non-trivial challenges and tradeoffs in optimizing their parameters and upscaling. Here, we report a novel carbonation approach using metastable nesquehonite (MgCO 3 ·3H 2 O) as a solid carbon source. The combination of nesquehonite with other Ca-rich precursors (e.g., slags and fly ashes) under hydrothermal treatment can produce hardened products containing CaCO 3 and magnesium silicate hydrate (M-S-H) as main strength-giving phases. Our experimental results reveal that the carbon retention using nesquehonite reached 80–100%. The produced samples attained suitable mechanical strength for brick and paver applications. Thermodynamic modeling correctly predicted the phase assemblage and formation of carbonate species. The work reported here offers a new horizon in using nesquehonite to enable effective and low-energy CO 2 sequestration in construction materials and foster the integration of CCU/S processes with construction industry.