Concrete is the most widely used construction material in the world, thanks to its affordability and strength under compression.
However, it requires steel reinforcement to handle tension, which leads to excessive use of both materials. This overuse contributes significantly to carbon emissions, fueling climate change.
To address this, researchers at ETH Zurich, led by Professor Philippe Block, have developed innovative vaulted concrete floors that use up to 60% less concrete and 90% less steel reinforcement.
These floors rely on clever geometry for structural stability and do not need embedded steel, making them a more sustainable option.
This technology is now being commercialized through the ETH spinoff, VAULTED AG.
One of the challenges with creating vaulted concrete floors is the formwork—the molds used to shape the concrete.
Traditional formwork is often made from single-use, petroleum-based materials like Styrofoam, generating waste and reducing sustainability.
To solve this, ETH doctoral student Lotte Scheder-Bieschin designed a reusable formwork system called Unfold Form.
It consists of thin, flexible plywood strips connected by textile hinges, which can be unfolded like a hand fan. These zigzag-shaped molds are light, compact, and sturdy, supporting up to one tonne of concrete while weighing only 24 kilograms.
Once the concrete cures, the formwork can be folded away and reused multiple times.
This system uses far fewer resources to produce and is simple to assemble without the need for specialized tools or skills. “The materials cost just 650 Swiss francs, and all you need is a template and a stapler,” Scheder-Bieschin explains.
The design of the Unfold Form system is inspired by nature and origami. The zigzag pattern, similar to the ridges of seashells, provides extra stiffness without adding weight. This ribbing strengthens the formwork and the concrete, helping it transfer loads efficiently.
The technique also uses curved-crease unfolding, a concept derived from origami. The plywood strips are connected along curved edges, which makes the structure both stable and lightweight. This simple yet effective design allows for easy transport and assembly.
The Unfold Form system has already been tested in real-world scenarios. A prototype was built at ETH Zurich, and another was created in South Africa using bio-concrete made from shredded invasive vegetation. Both tests proved the system’s durability, reusability, and adaptability to different types of concrete.
In South Africa, the formwork was used to build affordable and sustainable housing in townships. The lightweight materials were transported in surfboard bags, demonstrating how easy it is to ship and use this system in remote areas.
Scheder-Bieschin plans to continue developing her invention and bring it to market. She is also designing a market hall in a Cape Town township using the formwork and plans to launch training programs to teach locals how to build with it themselves.
“This innovation is not just about sustainable construction,” she says. “It’s about empowering people to create dignified and affordable housing with fewer resources.”
