Accelerated mineral carbonation dynamics within a low-pressure advective gas flow regime

Accelerated mineral carbonation has been identified as a key pathway to decarbonise cementitious construction materials, which can include chemically stabilised soil. The methodology hinges on the introduction of carbon dioxide (CO₂) gas in soil mixed with reactive alkali minerals to precipitate a carbonate binder that permanently sequesters carbon dioxide. Motivated by the potential to accelerate the carbonation process, this paper experimentally demonstrates properties influencing carbonation dynamics and the efficacy of carbon sequestration within a low-pressure advective carbon dioxide gas regime. Carbon dioxide was injected top-down in a lime-mixed silt column instrumented with pressure sensors and thermal imaging to monitor the evolution of carbonation throughout the experiments. Post-carbonation binder contents were also measured. Thermal imaging and pressure measurements showed rapid, top-down carbon dioxide sequestration. Carbonation and lime utilisation decreased with increasing water and lime contents, with degree of saturation exerting the dominant control by restricting gas-phase continuity and increasing aqueous diffusion distances for carbon dioxide dissolution and reaction.