This documentation should be used for environmental assessment of concrete buildings and structures, and to evaluate the effect of concrete carbonation on the overall CO2 emissions from cement and concrete production in the Nordic countries.
The objective of this project is to provide documentation of concrete carbonation during service life and secondary use.
Approximately half of the CO2 emission from cement production stems from the calcination of limestone, i.e. a process where limestone is burnt and CO2 gas is released to the atmosphere. Theoretically, hardened concrete binds approximately the same amount of CO2 in a process called carbonation. The concrete’s ability to bind CO2 and the rate of the process depends on many variables, including the type of concrete and its application.
The methodology and the impact that concrete carbonation has in the assessment of CO2 emissions from concrete has not been fully documented. Specifically, there is a lack of knowledge about the carbonation of demolished and crushed concrete. The existing models for calculating carbonation do not take into account that the concrete is crushed and recycled after use.
Consequently, the contribution of the cement and concrete industry to net CO2 emissions is strongly overestimated. This overestimation has a significant influence on CO2 policy; on the criteria for environmental labelling; and on the selection of materials based on principles of environmentally correct design. A comparison of the environmental impacts from different building materials (e.g. concrete versus wood and steel) is at present unfair because of the lack of documentation of the CO2 uptake in concrete.
The results from this project are presented in two reports. The main results and conclusions are also presented in a brief summary report.
Three additional reports cover the background data from the project:
See also article in Innovate 2, 2006:
Carbonation and climate change: A greener shade of concrete
Project duration:01.08.2003 - 31.12.2005