CARBon-negative COMpression dominant structures for decarbonized and deconstructable CONcrete buildings

Project Information

CARBCOMN

Grant agreement ID: 101161535

DOI

10.3030/101161535

EC signature date 13 June 2024

Start date 1 October 2024

End date 30 September 2028

Funded under

• The European Innovation Council (EIC)

Total cost

€ 3 603 457,50

EU contribution

€ 3 603 457,50

Coordinated by

UNIVERSITEIT GENT
Belgium

Periodic Reporting for period 1 - CARBCOMN (CARBon-negative COMpression dominant structures for decarbonized and deconstructable CONcrete buildings)

Reporting period: 2024-10-01 to 2025-09-30

Summary of the context and overall objectives of the project

The construction industry remains one of the largest contributors to global carbon emissions, with traditional concrete production responsible for a particularly high environmental footprint. This impact stems primarily from the heavy reliance on cement as a binder—a material that generates substantial CO2 emissions during its manufacture. Moreover, in conventional reinforced concrete, steel reinforcement is susceptible to corrosion, leading to reduced structural longevity and increased maintenance demands. Together, these factors highlight an urgent need for more sustainable, durable, and circular solutions within the construction sector. In this regard, the EIC-funded project CARBCOMN addresses a disruptive innovation in zero-carbon concrete load-bearing structures (combination of columns, beams, slabs or walls) by setting forth a design-fabrication-construction method, that is fully compatible with concrete that uses CO2 as raw material and is carbon-negative. The material design, incorporating recycled materials and by-products derived from other industrial processes (e.g. slags and ashes) will equally reduce raw material usage. Digital methodologies are exploited and developed to realise this innovative carbon-neutral construction system by implementing segmented structural geometries that are compression dominant, optimise the CO2 sequestration capability and make use of demountable 3D printed discrete blocks combined with system redundancy.

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

4 technical work packages (WPs) were initiated and achieved significant progress and outcomes.
In WP1, a carbon-negative concrete has been developed composed of 100% secondary binder and aggregates. The developed concrete was optimized for 3D printing through rheology control using chemical additives. Based on yield stresses measured by slow penetration tests, the concrete can reach a buildable height of around 0.7 m, meeting the requirement for block geometry. Successful 3D printing of the developed concrete has been performed through one-component system (see attached image). With the optimized carbon mineralization protocol, the developed concrete achieved a compressive strength of 21 MPa and a flexural strength of 6 MPa, meeting the basic requirement for compression dominant structures. This served as a key basis for further optimization and provided valuable input to WP2 on preliminary design of the structural system. In addition, pore structure analysis was performed on the developed concrete via micro computed tomography, mercury intrusion porosimetry and scanning electrical microscopy. Based on this, the pore model of developed material was initially constructed, which is essential for understanding CO2 migration kinetics and supports the development of a comprehensive carbonation model.
In WP4, chloride ingress, ionic bulk conductivity and water absorption tests have been performed to measure relevant transport property coefficients. These coefficients are used to simulate and optimize the carbonation process. The evolution of carbonation depth with exposure time has been measured. Mathematical models have been formulated to simulate the carbonation process of developed materials. This advances the understanding of carbonation kinetics and the durability of the developed concrete during service life.
In WP5, a digital pipeline has been initiated making use of the open-source computational framework COMPAS. Part thereof, core methods for geometry slicing have been completed, encompassing strategies for multiple block typologies, including Planar, Multi-Planar, Dual Multi-Planar, and Non-Planar configurations. Also, several core geometric data structure methods have been implemented. The integration establishes a critical interface between the high-performance C++ core and the Python-based computational ecosystem, facilitating further development and extensibility.
WP6 refined 3D printing parameters based on the concrete’s rheology, established a workflow from design to block production, and performing geometric assessment measurements, to ensure controlling production tolerances for use in segmented compression-dominant structures.

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)

Results achieved go beyond the current state of the art in low-carbon concrete, digital design-to-fabrication workflows, and carbonation simulation for 3D printed concrete.
1. A novel 3D printable concrete was developed using 100% stainless steel slag as both binder and aggregate, achieving intrinsic carbon sequestration capability. This innovation synergizes 3D printing with CO2 mineralization, introducing a new generation of low-carbon construction materials. Furthermore, investigations into pore structure and carbonation degree were performed, offering new insight into carbonation kinetics in mineralized printed materials. These findings pave the way for material design and printing parameters, enabling scalable, performance-based production of low-carbon concrete load-bearing members.
2. Simulation of carbon sequestration performance and durability of developed concrete builds upon the transport coefficients measured from chloride ingress, ionic conductivity, and water absorption tests. The outcome significantly enhances understanding of carbon mineralisation and long-term durability, advancing the scientific state of the art in this field.
3. Digital geometry slicing strategies for 3D printable models of segments of compression dominant structures, covering multiple typologies, which establish a robust foundation for adaptive geometric processing in complex block-based assemblies. In addition, several core geometric data structure methods are integrated in a design-fabrication-construction pipeline, which lays critical groundwork for interoperable, extensible, and open digital fabrication workflows.
4. The first successful 3D printing of compression-dominant blocks demonstrated the feasibility of fabricating structurally relevant components without formwork or reinforcement. This is exemplary for pushing the state-of-art centered on the convergence of sustainable materials, structural engineering principles, and digital fabrication.

SEM-BSD/EDS characterisation of CARBOMN concrete

3D printed CARBCOMN block with developed carbon curing concrete

Rapid prototyping of CARBCOMN bloc printing