Researchers at the University of Colorado Boulder have discovered that a seaweed-derived ingredient can improve the 3D printing of earthen construction materials. The ingredient is already widely used in food products such as ice cream. According to the researchers, it could help transform excavated soil and construction waste into low-impact building materials.

The study, published in Nature Communications, investigates how naturally derived biopolymers can improve the printability of earth-based materials such as clay and sand. The team took inspiration from biological construction systems found in nature. Termites, wasps and marine organisms all build complex structures without using cement. Instead, they rely on natural biopolymers to bind soil particles together.

Learning from Nature

The researchers tested five biopolymers commonly used in food and industrial applications. These included guar gum, locust bean gum, cassia gum, xanthan gum and sodium alginate. Among them, sodium alginate delivered the most promising results.

Sodium alginate is a polysaccharide extracted from seaweed. Rather than acting as a conventional binder, it changes the electrical charge of clay particles. As a result, the particles repel each other and remain evenly suspended within the mixture. This allows the material to flow smoothly through a 3D printer nozzle while maintaining its shape after printing.

Faster Printing and Stronger Structures

The team added just 0.12% sodium alginate to earth sourced from a granite quarry in Colorado. This formulation improved both printability and performance. Compared with untreated earth, the material with sodium alginate withstood 25% more pressure and printed 33% faster.

To demonstrate its capabilities, the researchers printed an 8 mm-thick wall. The structure remained stable even when tilted at an angle of 60 degrees. This result highlights the potential of biopolymer-enhanced earth for creating complex architectural forms through additive manufacturing.

Turning Excavated Soil into a Resource

The construction industry generates large volumes of excavated soil when creating foundations, basements and underground infrastructure. Much of this material ends up in landfill. The new approach could allow builders to reuse soil directly on-site, reducing waste and lowering the environmental impact of construction projects.

Earthen materials can also improve indoor environmental quality. They help regulate humidity, absorb certain pollutants and provide thermal insulation. These properties can contribute to healthier and more comfortable interior spaces.

Clay and sand are among the most abundant building materials on Earth. Because these resources are available in many regions, the researchers believe the technology could support local material sourcing and reduce reliance on carbon-intensive construction products.

Source & photos: University of Colorado Boulder