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Innovator and industrial partner/s:

Mineral Products Association (MPA), Ricardo, Heriot-Watt University

Expected impact:

The programme aims to provide a model to quantify the CO2 sequestered by concrete in the UK built environment so that this important CO2 sink can be included in the UK National Inventory Report (NIR). It will improve understanding and quality of historic emissions, reduce uncertainties in emissions estimates, and improve the UK ability to assess progress towards international and national targets.

Sectors likely to benefit:

Cement, Construction


Carbonation is a slow process where concrete absorbs CO2 from the atmosphere throughout its lifetime. It is essentially a reversal of the chemical reaction that occurs when cement is produced and CO2 is released from calcium carbonate raw materials when they are heated to volcanic temperatures (these emissions are known as process emissions).

Carbonation Mechanism

Carbonation of concrete is a process by which carbon dioxide from the air penetrates into concrete through pores and reacts with calcium hydroxide to form calcium carbonates

Ca(OH)2 + CO2    →   CaCO3 + H2O

The Innovation

The Intergovernmental Panel on Climate Change (IPCC) recognizes that carbonation happens in concrete and that it is an important carbon sink. However, there is limited international literature on the process and no formal IPCC method of calculation. Some initial methods of calculation have been development by IVL (the Swedish Environmental Research Institute) using Swedish data and reflecting national circumstances in Sweden.

The Project

The Project will:

  • Identify reliable sources of data to enable quantification of the carbonation that occurs in the UK
  • Identify/develop appropriate emissions factor data for estimating the size of the emissions sink
  • Develop/verify a model of emissions conforming to a tier 2-standard that calculates the size of the annual greenhouse gas sink
  • Produce a methodology document describing the methods used to produce the model.


This project was part funded by BEIS through the annual inventory improvement programme that commissions research and development projects to improve and develop the NAEI (National Atmospheric Emission Inventory).