Comparative analysis of time-dependent CO2 uptake in cement and geopolymer concretes via diffusion-induced carbonation

Concrete production accounts for about 8 % of global CO₂ emissions, yet its carbonation potential offers a pathway toward carbon neutrality . This paper presents an analytical model that describes the diffusion of CO 2 and the subsequent processes of dissolution and carbonation in concrete. The aim of the research is to provide an analytical method to calculate the time-dependent CO 2 uptake by concrete during the diffusion and subsequent carbonation processes . Additionally, the impact of environmental CO 2 concentration and concrete composition on carbonation depth and corresponding CO 2 consumption is examined. Findings indicate that higher calcium oxide , magnesium oxide , sodium oxide, and potassium oxide content, along with increased CO₂ exposure, enhance carbonation. Under natural conditions, ordinary Portland cement (OPC) concrete absorbs ∼5.14 % of its weight in CO₂, while geopolymer (GP) concrete absorbs ∼3.38 %. With 50 % CO₂ exposure, carbonation depths in OPC and GP concretes after 10 years are estimated at ∼20 mm and ∼25 mm, respectively. These insights guide concrete design to maximize CO₂ sequestration in construction materials.