Summary

A European research team led by Empa is developing a revolutionary concrete construction method in the EU project "CARBCOMN" that drastically reduces material consumption and binds CO₂. Through 3D printing, alternative binders such as steel slag, and intelligent geometries, stable structures are created without conventional steel reinforcement. The process makes it possible to disassemble and reuse building components after their useful life – a decisive advance for climate-neutral and circular construction.

People

Topics

  • Sustainable building materials
  • 3D printing technology
  • Circular economy
  • CO₂ reduction in the construction industry
  • Shape memory alloys

Clarus Lead

The "CARBCOMN" project replaces conventional concrete construction with digital manufacturing and sustainable materials. Instead of cement, industrial waste such as steel slag is used, which binds CO₂ rather than releasing it. The 3D-printed structures require 50–70 % less material than conventional concrete and dispense with elaborate steel reinforcement – a game changer for construction companies under pressure to improve their CO₂ balance.

Detailed Summary

The consortium is based on three innovation principles: First, digital shape optimization, which strategically leaves cavities where no reinforcement is needed. The robot plans these openings directly in the digital model, eliminating expensive formwork material. Second, iron-based shape memory alloys (Fe-SMA) replace classical prestressing steel reinforcement. These special metals are inserted into the concrete after printing and contract when heated – rather than expanding – and subsequently put building components under tension. This enables automated manufacturing and, above all: the reinforcement bars can be separated again later, enabling disassembly and reuse.

Third, the team uses CO₂ as a curing agent. After 3D printing, components are placed in a chamber where CO₂ is injected and chemically reacts with the steel slag-based mixture. This hardens the concrete and simultaneously binds CO₂ – a circular process. Lighter elements also reduce seismic stress proportionally to the weight loss, an advantage in earthquake-prone regions. ETH Zurich, University of Ghent and architectural firms such as Zaha Hadid Architects work closely together – architects design freeform structures, while the Empa team develops technical feasibility and connection technologies.

The four-year project with a budget of 6 million euros (of which over 1 million for Empa and its spin-off re-fer) runs until 2028 and aims for a 3D-printed building prototype – robust residential construction modules, not spectacular forms.

Key Messages

  • Material Reduction: 3D printing with optimized geometries reduces material consumption by 50–70 % compared to conventional concrete
  • CO₂ Binding: Steel slag replaces cement; CO₂ curing additionally binds carbon dioxide rather than releasing it
  • Circular Construction: Fe-SMA reinforcement enables disassembly and reuse of components after end of service life
  • Automation: Digital planning and robotic manufacturing reduce manual labor and error rates
  • Seismic Safety: Lighter structures reduce earthquake load proportionally to weight savings

Critical Questions

  1. Scalability and Cost Competition: How do production costs develop in the transition from prototype to series production? Will 3D printing systems for concrete become economically viable for small and medium-sized construction projects?

  2. Long-Term Behavior of Fe-SMA Reinforcement: What long-term data exist on fatigue, corrosion, and reliability of shape memory alloys in concrete environments? How secure is the automation when inserting these bars?

  3. CO₂ Balance of Overall Production: How is the CO₂ footprint of the 3D printing process itself (energy consumption, robots, logistics) calculated? Is the CO₂ binding through steel slag and CO₂ curing actually greater than the emissions from manufacturing?

  4. Disassembly in Practice: How complex is the disassembly of components after 20–50 years of use? What costs and labor expenses arise in recycling, and can the material actually be reused 100 %?

  5. Standardization and Approval: What building code hurdles exist in EU countries for novel, non-conventional concrete construction methods? How long does certification take until market readiness?

  6. Comparison with Alternatives: How does this approach compare to timber construction, recycled concrete, or other decarbonization methods – in terms of CO₂, costs, and availability?

Source Directory

Primary Source: Sustainable Concrete Construction: Custom-Made Concrete from 3D Printing – https://www.news.admin.ch/de/newnsb/lPLLl1ut2bnc2m9lqfxDZ

Project Information: CARBCOMN (Carbon-negative compression dominant structures for decarbonized and de-constructable concrete buildings) – EU Horizon Europe Programme, 2024–2028

Verification Status: ✓ 17 March 2026

This text was created with the support of an AI model. Editorial responsibility: clarus.news | Fact-checking: 17 March 2026