Modeling of carbon sink for concrete structures: From hydration kinetics to climate-driven carbonation

Abstract

Concrete production is estimated to contribute approximately 9 % of global greenhouse gas emissions. However, due to carbonation reactions, concrete buildings absorb CO<inf>2</inf> from the air during their service life. In order to accurately predict the carbon sink of concrete buildings, a carbon sink calculation model was developed. This model is based on a kinetic model that considers the cement hydration process, heat transfer, moisture transport, and carbonation. Moreover, time-varying exposure conditions (TVEC) are considered, including long-term and seasonal variations in climate. In the case study, the model was applied to a school building, and carbonation simulations were conducted under the Representative Concentration Pathway 8.5 (RCP8.5) scenario. The results show that the carbon sink of the building was 99.03 tons over 50 years, equivalent to approximately 27.6 % of the emissions generated during concrete production. In addition, the dynamic evolution of the building's carbon sink and the factors affecting the carbon sink were carefully analyzed.