Carbon mineralization and rheology of ultrafast stiffening mineral thermoresponsive suspension

Carbon mineralization is a natural process where carbon dioxide (CO2) chemically interacts with specific minerals, especially those rich in calcium, resulting in the formation of stable carbonate minerals. This study focuses on developing a mineral suspension with a thermoresponsive polymer that effectively captures carbon while allowing for precise control over its rheological properties. The integration of these features holds potential for advancing sustainable construction materials, offering both environmental benefits and improved performance. The study examines the rheological properties and carbon mineralization potential of four different mixtures: Portland Cement (PC), slag, Class F fly ash and Class C fly ash, each blended with portlandite and a thermoresponsive polymer. Results showed that PC and fly ash-based mixtures present a maximum rapid stiffening rate of approximately 1000 Pa/s under temperature stimuli due to the polymerization. Fly ash-based mixtures showed better flowability due to fly ash's ball-bearing effect. After thermal and CO2 curing, the pozzolanic reaction and carbonation process both contribute to the compressive strength of the mineral thermoresponsive suspension, reaching 30 MPa at 7 days. Thermodynamic modeling indicates the carbonation process consists of three stages, with the carbonation sequences of (1) portlandite, (2) C-S-H/C-(N-)A-S-H, and (3) AFm, hydrogarnet and ettringite, indicating the evolution of phase assemblage of reaction products during carbon mineralization. The designed mineral thermoresponsive suspension can acquire sufficient strength under polymerization, carbonation, and pozzolanic reaction, providing a new avenue for sustainable construction materials.