Researchers at the University of Colorado Boulder, working alongside scientists from Columbia University, have identified a surprising solution to one of additive manufacturing’s more unconventional frontiers: getting natural earthen materials like clay and sand to behave reliably inside a 3D printer. The answer, it turns out, has long been sitting in the ice cream aisle.
The research draws its conceptual foundation from the animal kingdom. Termites raise towering mounds, wasps construct elaborate nests, and honeycomb worms build reef-like formations along coastlines, all without a gram of cement. What these organisms rely on instead are biopolymers, large biological molecules that act as natural binders, frequently found in saliva, to hold soil and organic matter together into cohesive structures.
Seeking to replicate that logic in a laboratory setting, the team evaluated five biopolymers against earthen substrates to determine which could make those materials both structurally sound and compatible with 3D printing equipment. The candidates included guar gum, locust bean gum, cassia gum, xanthan gum, and sodium alginate, compounds already widely used in food manufacturing to stabilise emulsions and control texture.
“From termite mounds to adobe buildings, humans and animals have been building with earth since the dawn of time,” said Wil Srubar, professor in the Department of Civil, Environmental and Architectural Engineering. “But there hasn’t been a lot of science to how earthen builders design the materials. So, we wanted to use scientific knowledge and tools to understand it.”
The Seaweed Advantage
The testing phase revealed that locust bean gum, for instance, bonded soil particles into a tight network, strong on paper, but too viscous to move cleanly through a printer nozzle. Sodium alginate, the seaweed-derived compound familiar to food technologists for its role in ice cream and popping boba, worked through an entirely different mechanism.
Rather than acting as a glue, sodium alginate altered the electrical charges on individual clay particles, causing them to repel one another. The effect produced a stable suspension that retained structural integrity while flowing smoothly enough for extrusion. Adding just 0.12% of the compound to locally excavated granite quarry earth near Golden, Colorado yielded a mix capable of withstanding 25% more compressive pressure than untreated earth and printing at speeds 33% faster. The team successfully produced a wall just 8 millimetres thick that remained stable when tilted to 60 degrees, a steeper lean than the Leaning Tower of Pisa.
Turning Construction Waste into Building Material
Beyond the technical performance, the researchers point to a practical dimension with high environmental implications. Construction projects routinely generate large volumes of excavated soil from foundation and basement work, the bulk of which ends up in landfills.
“Our study suggests that there are ways to reuse waste earth material onsite, and that could largely reduce the environmental footprint of construction,” said Samuel Armistead, a research associate in the same department.
Earth-based building materials also carry passive performance benefits. Armistead noted that earthen walls can regulate indoor moisture, absorb airborne pollutants, and serve as natural thermal insulators. Given that clay and sand rank among the most abundant raw materials on the planet, the team’s framework could, in principle, be adapted to local soil conditions almost anywhere.
“The science and engineering we’re developing can be applied almost anywhere in the world,” said Srubar.
Earthen 3D Printing: Solving the Material Control Problem
The CU Boulder and Columbia University study addresses a core obstacle in earth-based additive manufacturing: natural soils vary widely in composition, making consistent printability difficult to achieve at scale. By linking biopolymer-mineral behaviour directly with printability outcomes, the research offers a more systematic route for turning variable local earth into reliable, print-ready material.
Other institutions have been pursuing parallel solutions with different approaches. Oregon State University developed a fast-curing clay-based material that hardens instantly as it is extruded from a 3D printer, using an acrylamide-based binding agent that triggers frontal polymerisation, a mechanism that enables the construction of multilayer walls and unsupported overhangs without waiting for the material to set.
Elsewhere, Swinburne University of Technology tested robotic 3D printing with soil reinforced by natural fibres, targeting dense structural elements from locally sourced earth, with researchers estimating that combining such techniques with automated construction could reduce building costs and timelines by as much as 60%.
What unites these efforts is the recognition that earth is not a limitation to work around, but a resource to be unlocked. Where concrete dominates largely out of habit and standardisation, earthen materials offer a lower-carbon, locally available alternative, one that 3D printing may finally make viable at construction scale.
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Featured image shows Earthen Rituals, exhibited at the 2026 Venice Architecture Biennial, is constructed with 3D printed earthen materials. Photo via Alessandro Terranova.
