Abstract: A method for producing carbon negative cementitious materials utilizing a carbon mineralization-based direct-air capture process. The method comprises a mineralization step wherein a mineral feedstock is contacted with an aqueous carbonate solution at a high initial pH to form a carbonated feedstock containing reactive silica, along with an alkaline solution containing dissolved aluminum. The resulting alkaline solution is then contacted with gaseous carbon dioxide to form a carbonate solution that can be recycled for use in the mineralization step. The dissolved aluminum in the alkaline solution precipitates during carbon dioxide capture and is subsequently redissolved in a hydroxide solution to form alumina. The alumina can be combined with the carbonated feedstock to create geopolymer concrete.

Abstract: A method for producing carbon negative supplementary cementitious materials utilizing a carbon mineralization-based direct air capture process. One version of the method comprises pre-treating a mineral feedstock with an alkaline solution, resulting in a pre-treated feedstock and an alkaline solution comprising dissolved alumina or silica. The pre-treated feedstock has enhanced carbonation reactivity in the subsequent carbon mineralization-based direct air capture process. Another version of the method comprises post-treating precipitates yielded from carbon mineralization-based direct air capture process of a mineral feedstock with an alkaline solution, resulting in a residue and an alkaline solution comprising dissolved alumina or silica. The alkaline solutions resulted from the pre- and post-treatments can be directly used as supplementary cementitious materials, or as a sorbent solution for carbon capture.