Understanding the CO2 utilisation potential of various cementitious materials through review and analytical modelling

Abstract

Carbon dioxide sequestration in cement-based materials has emerged as a promising avenue for utilising captured carbon dioxide (CO2) and reducing the carbon dioxide footprint of the concrete industry. This article presents a comprehensive review of various studies conducted in this domain with a particular emphasis on factors affecting the carbon dioxide uptake potential of various concrete types and the effect of carbonation on the critical properties of concretes. Studies conducted on the micro-mechanical analysis of carbon sequestered concrete show that carbonation significantly improved the microhardness of the concrete samples, thereby increasing the strength and reducing the cement intake requirement. Further, keeping two parameters, namely water/solid (w/s) ratio and carbonation reaction time, in focus, the carbon dioxide uptake capacity in concrete slurry waste (CSW) was evaluated using non-linear regression analysis. It was observed that CSW paste had a maximum carbon dioxide uptake with an intermediate w/s ratio of 0.2 due to carbon dioxide reaction hindrances during diffusion at a higher w/s ratio and lack of hydration at a lower w/s ratio. On the contrary, for belite-rich cement, a higher w/s ratio led to higher carbon dioxide uptake owing to belite phase consumption leading to increased calcite production. Additionally, comparing the  maximum carbon dioxide uptake capacity of CSW at a particular condition with various other cement-based materials, it was observed that belite-rich cement had the ability to sequester the maximum amount of carbon dioxide compared to the other cement-based materials considered in this study.