In order to reduce the carbon footprint of concrete by accelerated carbonation, the FastCarb project will apply two approaches, one directed upstream and the other directed downstream:
- the goal of the upstream approach will be to validate theoretically and experimentally the technical proof of the concept of accelerated carbonation of RCA that has already been obtained in the laboratory. This part of the project will also allow us to accurately determine the parameters that affect the process (the water content of the aggregate, the treatment temperature, the gas pressure…) and model the processes at work.
- the goal of the downstream approach will be to design an accelerated carbonation process and implement it at the pre-industrial scale, to verify that the concretes manufactured with the treated aggregate have the required properties and to characterise the environmental and economic viability of the considered industrial recycling process. This last point will also provide some findings which depend on economic conditions (such as the cost of a tonne of CO2) concerning the optimum between CO2 capture, the cost of the treatment and the improvement in the properties of the aggregate.
The research structure consists of working groups which reflect the points mentioned above. WG1 deals with the upstream “laboratory” and is subdivided in three sub-groups:
- WG1.1 deals with the experimental approach in the laboratory. It will supply the experimental data that are necessary to analyse the processes that occur during the acceleration carbonation of RCA and to understand the influence of the major parameters (such as water content) in order to be able to optimise the process.
- WG1.2 will model the accelerated carbonation process. A comparison will be conducted between different carbonation models that are appropriate for accelerated carbonation. We will also take advantage of the fact that several research teams which are specialised in carbonation are involved in the project in order to provide input that will assist the inclusion of natural carbonation in the environmental section of the future “Product Category Rules for Concrete” standard. The reason for this is that natural carbonation may have a non-negligible impact on the greenhouse gas balance (Xi et al., 2016).
- WG1.3 will deal with a specific treatment – bio-carbonation – which is a possibility that is much further in the future than those covered in WG2.