Transforming CO2 into added-value construction products

Project Information

Carbon4Minerals

Grant agreement ID: 101091870

DOI

10.3030/101091870

EC signature date 14 November 2022

Start date 1 January 2023

End date 30 June 2027

Funded under

• Digital, Industry and Space

Total cost

€ 20 332 100,00

EU contribution

€ 14 846 811,00

Coordinated by

VLAAMSE INSTELLING VOOR TECHNOLOGISCH ONDERZOEK N.V.
Belgium

Periodic Reporting for period 2 - Carbon4Minerals (Transforming CO2 into added-value construction products)

Reporting period: 2024-01-01 to 2025-06-30

Summary of the context and overall objectives of the project

The European Green Deal targets (40% GHG emission reduction by 2030, climate neutrality by 2050) are a major challenge for the energy-intensive process industry. While renewable energy can alleviate a major part of the GHG emissions, it offers no solution for process-inherent emissions. The cement industry (responsible for 6-8% of global GHG emissions) is looking for alternative materials to replace Portland clinker, to reduce the enormous amounts of CO2 emitted during calcination of limestone.
At the same time, the transitions in steel and energy production lead to dwindling supplies of low carbon resources commonly used for cement production such as blast furnace slag and coal fly ash.
Capture can assist in the abatement of CO2-emissions, but is costly.
The core concept of Carbon4Minerals addresses the simultaneous use of CO2 from industrial flue gases with current and future waste streams to unlock a vast stock of resources for innovative low carbon binders and construction materials (80-135% lower CO2-emissions than reference). A total of 8 industrial pilots will be built and operated across the process value chain from CO2 capture to cement production and low carbon construction products.
For CO2 capture, 2 technologies are included that aim to reduce energy requirements and costs compared to state-of-art technologies, namely 1) 3rd generation liquid amine solvent (80 – 99+ % CO2 purity, energy consumption < 2.4 GJ/tonne) and 2) porous structured sorbent materials.
On the cement level, a carbonation clinker will be created from steel slag and cement-based residues, targeting savings of 200 kg CO2/tonne. Carbon-negative supplementary cementitious materials (SCMs) will be made by CO2-mediated mechanical activation of steel slags and CO2 beneficiation of recycled cement-based construction and demolition waste (C&DW).
Carbon-negative carbonation cured facing bricks and pavers will be produced by direct carbonation of steel slags, while precast carbonation cured products (façade panels, roof tiles) are made using the carbonation clinker and SCMs.
Carbon4Minerals intends to showcase the potential of the technologies, while providing sufficient data for an integrated economic and environmental assessment. Reactive transport modelling in combination with durability testing will verify the suitability of current testing methods for the novel materials.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The work done so far has focused on the design, construction and commissioning of the pilots as well as laboratory experiments to define the process conditions.
CO2 Capture pilot 2a is constructed and commissioned, and is currently being tested and further improved.
CO2 Capture pilot 2b is constructed, and will be commissioned in September 2025. Meanwhile, structured sorbents are developed for the pilot. Preliminary results show more than 5-10x lower pressure drop compared to conventional packed beds. Further optimisation is ongoing to increase efficiency of the sorption/desorption cycles.

Carbonation clinker pilot 3a has been successfully executed. After laboratory optimisation of the clinker mixes, pilot trials were performed in February - March 2025 that produced > 1 tonne of carbonation clinker. The pilot materials performed equally well as the laboratory mixes, and will now be used for the development of mineral carbonation construction products. The clinkers capture 150-200 kg CO2/tonne. Preliminary LCA analysis has shown a significant reduction in CO2 emissions compared to traditional cement products.
The enforced carbonation reactor pilot 3c has also been successfully commissioned. While optimisation is still ongoing, the target carbonation degree has almost been reached, and it is expected that the carbonated cement replacements will be ready by September 2025 for further testing in construction products.
The MACE carbonation reactor has unfortunately experienced some delays, but is expected to be implemented early 2026. Meanwhile, laboratory batches have shown promising results.

The mineral carbonation facing bricks pilot 4a is operational, and is already producing its standard mix products. While adapting the mix to the use of BOF slags has proved challenging, experimental results are now looking good and BOF slag-based bricks are expected to be produced in the coming months.
For the other mineral carbonation products (fiber cement products and slurry-based carbonation), work will start at full speed now that the carbonation clinker and carbonated cement replacements are available.
Preliminary LCA analysis have shown potential CO2 savings for all technologies, but have also identified potential improvements that the partners will take up in the further technology development

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The carbon capture technologies piloted by Carbon4Minerals are expected to be much more energy efficient (and thus less costly) than state-of-the-art installations. The solid sorption capture technology is also suitable for small-scale installations.
The low carbon binders and mineral carbonation construction products capture 100-200 kgCO2/ton, in contrast to high CO2 emissions for the traditional Portland cement alternative. As such, these new products have the potential to reduce CO2-emissions by 80-135% compared to cement-based reference materials. Considering the potential market, European CO2 emissions could be reduced by up to 46Mt CO2/year, equivalent to 10% of the EU process industry emission.
Initial LCA analyses have shown that CO2 savings can be achieved for all technologies, but have also identified potential improvements that will be taken up by the partners. In the coming period, a full sustainability assessment will be performed to validate the environmental benefits, as well as the economic viability. The results of these pilots will be an important lever towards industrial implementation. Relevant results will also be shared with (pre-)standardization bodies to facilitate market introduction of the new materials.

Carbon4Minerals concept