Ambient concrete carbonation is a trivial contributor in mitigating carbon dioxide emissions from cement production

Rui Xiao, Dale P. Prentice, Manas Sarkar, Aditya Kumar, Fabian Rosner, Narayanan Neithalath, Erika Callagon La Plante, Mathieu Bauchy, Gaurav Sant

Abstract Ambient carbonation—the passive uptake of atmospheric carbon dioxide into the alkaline pore solution of concrete—has been proposed to mitigate carbon dioxide emissions from cement production. Herein, we apply thermodynamic and diffusion-based analyses within a Monte Carlo framework to evaluate the extent and rate of ambient carbonation across concrete formulations and geometries (i.e., described by their surface-to-volume ratio, ranging between 0.01-to-80, /m), globally. The analysis indicates that, by 2030, the carbonation of concrete placed in service, globally, under ambient conditions, is projected to uptake around 0.23 gigatonnes annually (i.e., <10% of annual cement clinker emissions). Thus, the amount of carbon dioxide sequestered by ambient carbonation is negligible compared to the quantities emitted during cement production. Importantly, this analysis underscores the importance of prioritizing near-term industrial decarbonization and of advancing intentional climate change mitigation solutions that deliver meaningful and timely reductions in anthropogenic carbon dioxide emissions.