Investigating the potential of CO2 sequestration in concrete through natural and accelerated carbonation

Abstract

This thesis explores the potential End-of-Life (EoL) management of demolished concrete from Million Program buildings (MP) to act as a carbon sink through the process of natural and accelerated carbonation. The study presents speculative scenarios, natural carbonation in stockpiles and the use of accelerated carbonation through a fluidized bed unit, which involves the utilization of flue gases to enhance the carbon sequestration of concrete aggregates (CA). A significant amount of CO2 is sequestrated in the service life of a building but the largest potential is at the EoL, where the study indicates that concrete can reabsorb between 11.1-55.5 % of CO2 emissions from cement production. This is when accounting for process emissions related to transporting, crushing and using loaders to move the concrete into stockpiles. The thesis suggests the need for more processing sites and optimized stockpile dimensions to maximize carbon uptake. The thesis also highlights the complexity of the carbonation process and calls for further studies to accurately determine the carbonation degree and operational planning for CO2 sequestration in concrete aggregates. The research underscores the importance of natural carbonation and its role in reducing the carbon footprint of concrete.