Effects of carbonation on carbon dioxide capture and the mechanical properties of concrete with amine sorbents

Carbon dioxide (CO₂) uptake and the mechanical strength of concrete with and without carbon-dioxide-philic (CDP) amine sorbents were assessed in this study. Cement pastes with three amine-based sorbents (5-amino-1 pentanol, piperazine and 3-amino-1-propanesulfonic acid) were hydrated for 28 d. They were then assessed for carbon dioxide uptake and compressive/bending strength. The carbon dioxide in the atmosphere was sequestrated into the concrete as simulated carbonation weathering occurred, and the carbon dioxide uptake was measured using thermogravimetric analysis. Carbon dioxide uptake increased when CDP amine sorbents were mixed into the concrete specimens, with 5-amino-1-pentanol and piperazine showing the best efficiency, with carbon dioxide uptakes of 2·44% and 2·24%, respectively. The compressive and bending strengths also increased with carbonation. The strengths of the concretes with CDP sorbents were higher than that of ordinary concrete due to the microstructural densification, indicating that urban carbon dioxide sequestration can be performed using concrete structures without damaging their structural strength.