Reports on CO2 Uptake from the Carbonation of Concrete - CO2 balance

The CO₂ balance of concrete in a Life Cycle perspective
by K.O. Kjellsen (Norcem), M. Guimaraes (Aalborg Portland) and Å. Nilsson (Cementa), published by Danish Technological Institute, Denmark

Abstract
The amount of atmospheric carbon dioxide absorbed in Nordic concrete structures over a 100 year period has been calculated. The CO₂ uptake, or carbonation, occurs gradually and was calculated for an initial service life period of 70 years followed by a 30 year post-demolition period. The processing of demolished concrete to recycled concrete aggregates increase the CO₂ uptake, this was taken into account in the calculation of the total CO₂ uptake.

Over 100 years, one year of Nordic concrete construction is calculated to absorb 0.34, 0.22, 0.24 and 0.021 million metric tons of CO₂ in Denmark, Norway, Sweden and Iceland, respectively. These are quite notable numbers, and imply that about 0.5% of the total national CO₂ emissions will be re-absorbed in concrete in Denmark, Sweden and Norway. The corresponding number for Iceland is about 1%. The calculations show that up to 30% of the total CO₂ emission from cement production, or up to 57% of the CO₂ emission from the so-called calcination process in cement manufacturing, is re-absorbed when the cement is utilized in concrete construction in the Nordic countries.