Mechano-Carbonation of Mineral and Construction Waste Streams: Manufacturing High-Performance Cement Replacements through Advanced CO2 Capture and Utilization

SCM production is far from reaching the levels demanded by industry, with the US relying heavily on fly ash and slag imports to meet this requirement. To address this challenge, we have developed a novel method, referred here to as mechano-carbonation, that utilizes CO₂ during simultaneous milling to manufacture supplementary cementitious materials (SCMs) from abundant volcanic rocks, namely basalt, as well as concrete waste. For basalt, this innovative process accelerates the natural formation of carbonic acid during processing, enabling the creation of pozzolanic silica gels that enhance the reactivity of basalt by 4.5-fold. This presentation will also demonstrate that the formed silica gels not only improve reactivity but also agglomerate into larger particle sizes—up to 1,000 microns—significantly reducing water demand in concrete mixtures. In concrete waste, mechano- carbonation achieves a maximum 34.5 wt% carbonation. This inert filler, comprised primarily of limestone, when combined with pozzolanic carbonated basalt, represents the potential of a new ternary cement blend capable of CO2 storing nearly 10.7 wt% of their mass. Combining these two resources within novel mechano-carbonation processes accelerates CO2 sequestration and produces domestic SCMs and CO2-dense fillers. Thus, our findings here offer a viable pathway to overcoming current SCM shortages and enabling mass storage of CO2 emissions in novel cement replacements.