Researchers from ETH Zurich have introduced Impact Printing, a new robotic construction technique that uses Earth-based materials, including sand, silt, clay, and gravel, to create building structures.
Designed to reduce carbon emissions, the team claims this approach may offer a more sustainable and cost-effective alternative to conventional 3D printing. Published in Springer Nature, impact printing takes advantage of locally sourced, recyclable materials, which are available at low costs.
Lauren Vasey, an SNSF Bridge Fellow at ETH Zurich, explained that the team developed a robotic tool and method capable of transforming excavated materials from construction sites into usable building products. This process, designed to be both cost-effective and efficient, reportedly results in significantly lower CO₂ emissions compared to current industrialized building techniques, including 3D printing.
How impact printing works
Unlike conventional 3D printing, which typically requires materials reinforced with cement to enhance strength, impact printing is designed to work with Earth-based materials that need minimal additives.
To begin, the excavated materials are mixed to create a balanced composition of fine and coarse particles, which ensure stability and ease of use. In this mix, finer materials like clay act as binders, while coarser materials, such as sand and gravel, contribute to structural strength. This mixture allows the material to move through the robotic system efficiently, without causing blockages.
The impact printing process begins with a digital blueprint, which the robotic tool follows to build the structure. Mounted on a mobile platform, the tool shoots the material at high velocities up to 32 feet (10 meters) per second, bonding layers of Earth-based materials without requiring cement.
Vasey explains that this technique has yielded a stronger and stiffer material, with an initial strength greater than 28 kPa, which gives it a significant advantage in strength gain from the outset.
Using this approach, the team successfully built 6.5-foot-tall (2-meter) walls that can support the load of a similar structure without the need for additional chemical stabilizers. Vasey said that their system allows the material to be in a state capable of withstanding the load of a 2-meter-high structure right from the start of printing.
Although the material has a compressive strength of around 2 megapascals (MPa), which is lower than that of typical concrete, it is adequate for constructing walls and can support buildings up to two stories tall.
Environmental and economic considerations
Traditional 3D printing is known for lowering labor costs and potentially making housing more affordable. However, it often relies on cement, a material responsible for nearly 8% of global CO₂ emissions, and on non-recyclable additives.
Vasey pointed out that although impact printing currently incorporates a small amount (1-2%) of mineral stabilizers, the team aims to remove these additives in the future, creating a fully circular method where materials can be reused for future construction without contributing to landfill waste.
Vasey explained that while 3D printing offers the advantage of placing material precisely where needed, it often involves a high proportion of mortars, additives, and accelerators in the mix. This combination tends to increase the CO₂ emissions per volume significantly.
ETH Zurich’s research team aims to bring impact printing to market through a prefabrication facility, where parts would be produced for on-site construction. Vasey projects that they could establish a start-up within a year, with a product ready for market within three years.
If successful, impact printing could provide a sustainable alternative to traditional 3D printing methods in construction, addressing both environmental and cost concerns.
Sustainable construction research
ETH Zurich isn’t the only one focusing on sustainable construction practices. This week, University of Virginia researchers developed a sustainable concrete alternative for 3D printing by blending graphene with limestone-calcined clay (LC2). This new material, created under the guidance of Professor Osman Ozbulut, enhances strength and reduces environmental impact.
By adding only 0.05% graphene nanoplatelets, the team boosted compressive strength by 23%, making it ideal for 3D printed structures. A Life Cycle Assessment showed that this mix could cut greenhouse gas emissions by 31% compared to traditional cement. The research, supported by the Virginia Transportation Research Council, shows promise for greener infrastructure solutions.
In 2022, researchers at TU Berlin and Brunel University developed a more environmentally sustainable 3D printing concrete by partially replacing traditional sand with recycled glass, limestone, and plastic fillers. This adjustment significantly improved the concrete’s strength and thermal insulation, enhancing its energy efficiency.
Tests showed that the material retained shape well after printing, achieving a 40% improvement in insulation and increased compressive strength as more glass was added. The team viewed this development as a promising step toward low-carbon construction through sustainable, efficient 3D printing technology.
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Featured image shows in the production hall, various construction elements are on display that a robot has ‘shot’ from clay balls. Photo via ETH Zurich.
