European researchers develop circular, low-carbon concrete using 3D printing and innovative materials

Researchers across Europe are developing a radically different approach to concrete that aims to cut embodied carbon, shrink material use and enable genuine circularity in load-bearing building elements. According to the report by myScience, a consortium led by partners including Empa and ETH Zurich is using digital design, additive manufacturing and alternative binders to produce slender, high-performance components that can be dismantled and reused rather than demolished and buried.

The EU-funded CARBCOMN initiative seeks to avoid the traditional trajectory of adding ever more concrete and steel by exploiting the material’s compressive strength through what the partners call compression-dominant geometries. “Concrete can withstand a lot of compression, but little tensile stress,” Empa researcher Moslem Shahverdi said in an interview with myScience, describing why the team is concentrating on arches, vaults and other forms that primarily carry compressive loads. Digital modelling and optimisation allow such shapes to be defined precisely, reducing mass while maintaining safety margins.

Material innovation is central. Rather than relying on Portland cement, the project’s mixes use industrial residues such as steel slag and are hardened through accelerated carbonation, a process in which injected CO2 reacts with the matrix and is chemically bound. According to the ETH Zurich Block Research Group’s project summary, this approach aims for a carbon-negative or at least carbon-neutral outcome at the construction level by treating CO2 as a feedstock rather than a waste stream. The consortium’s public materials state the mix is composed exclusively of recycled industrial streams, with a controlled option to add a small cement fraction where structural performance requires it.

Reinforcement strategy departs from convention. To avoid ubiquitous steel rebar and the complex pre-stressing workflows that accompany it, CARBCOMN plans to use iron-based shape memory alloys (Fe‑SMA) in targeted locations. Empa’s team, which has worked on Fe‑SMA technologies for two decades and is connected to the spin‑off re‑fer, says these alloys can be inserted after printing and activated thermally to induce compressive pre-stress. Shahverdi explained: “We have been working with these special alloys for around 20 years.” The company claims this makes reinforcement placement more precise and reversible, facilitating later component disassembly.

Additive fabrication is the production backbone. Large‑format 3D concrete printing removes the need for formwork and enables designers to program voids and cavities directly into the digital model so the robotic printer leaves them in place. The result is filigree elements that reduce both material consumption and seismic mass; Shahverdi noted even modest weight reductions translate into lower seismic demand. The project roadmap envisages eventual automation of the post‑print reinforcement step, with a second robot placing Fe‑SMA bars immediately after deposition.

CARBCOMN is coupling materials and fabrication with a unified computational pipeline. According to ETH’s project briefing, the work integrates discrete element modelling, finite element structural analysis and lifecycle assessment within a single digital platform to allow designers and engineers to optimise for structural performance, resource use and circularity from the outset. Architectural partners such as Zaha Hadid Architects and Mario Cucinella Architects contribute form-finding and constructability studies while research teams develop connection technologies that permit robust, earthquake-resistant assemblies that can be taken apart.

Independent laboratory research from Empa supports aspects of the materials strategy. A Materials and Structures study on 3D‑printed, Ca(OH)2‑activated geopolymer concrete found that adding steel fibres improved flexural and tensile performance and enhanced interlayer cohesion, an important property for layerwise printing. The authors reported significant gains in flexural strength at early ages and meaningful increases in tensile and bond strength at 28 days, data that informs durability and design choices for printed elements.

The consortium is explicit that the work is not about formal experimentation alone but about producing practical units for residential construction. Ghent University’s project site and the CARBCOMN portal describe an ambition to produce a demonstrator module by 2028 that proves the combined approach at building scale. The four‑year Horizon‑funded project, launched in 2024, brings together eleven institutions and firms from across Europe; project communications indicate a total budget in the order of six million euros, with Empa and its spin‑off receiving more than one million euros.

While the technical programme is ambitious, there are pragmatic trade-offs acknowledged by the partners. Accelerated carbonation can sequester CO2 but requires process control and curing infrastructure; steel-slag‑based mixes must meet durability and code requirements; and the reversible use of Fe‑SMA will demand validated installation and deconstruction procedures to ensure long-term performance and safety. According to public project documents on CORDIS and the consortium websites, the team is addressing these risks through lab testing, structural modelling and collaboration with architects and industry partners to align designs with regulatory practice.

For professionals in industrial decarbonisation, CARBCOMN offers a synthesis of techniques that matter for scaling low‑carbon construction: material substitution using industrial by‑products, geometry‑led structural efficiency, robotic fabrication to minimise waste, and reversible reinforcement to enable material recovery. The consortium’s approach, treating CO2 as a resource and designing for disassembly, signals a shift from single‑use concrete toward systems that embed reuse and carbon management into the component lifecycle. If the demonstrator due in 2028 validates performance and cost pathways, the project could provide a practical template for lowering the sector’s carbon intensity without sacrificing structural ambition.