Early Career Award Will Advance Research on Soil as Building Material

Michelle Bernhardt-Barry, assistant professor of civil engineering at the University of Arkansas, has received a $500,000 Faculty Early Career Development award from the National Science Foundation to expand her research on the use of soil as a 3D-printed building material.

The award supports work that could lead to more sustainable, cost-effective construction methods, using improved soils to build structures in underdeveloped or war-torn areas. The material could also be used to construct roads, buildings and other infrastructure in remote areas or extreme environments where it is difficult to deliver conventional construction materials and equipment.

Michelle Bernhardt-Barry

Bernhardt-Barry studies the way soil responds to the physical demands from load-bearing structures. The award will allow her to deepen her investigation of mechanisms in nature that have proven to be efficient at bearing loads. She will also examine whether 3D-printing can be used to exploit these mechanisms to improve the ability of soil to bear weight.

“Nature has many examples of materials with hierarchical structure that demonstrate ultimate efficiency through various cellular or geometric patterning, biological drivers and other weight-bearing mechanisms,” Bernhardt-Barry said. “These mechanisms maximize strength and toughness while minimizing material and energy consumption.”

As a simple example of hierarchical structure in nature, Bernhardt-Barry points to the honeycomb. It has greater strength and toughness because of its geometric form – the arrangement or order of its open, hexagonal cells – rather than its material composition alone.

Previous research has produced many ground-improvement methods, but most of these augment the soil with cement or aggregates rather than exploiting load-bearing mechanisms within the soil. Also, exploiting the natural, load-bearing mechanisms in soil is not possible with traditional construction materials and equipment, Bernhardt-Barry said.

Bernhardt-Barry will develop laboratory and field-scale models based on these naturally occurring, load-bearing mechanisms. Through the use of 3-D printing, she will then integrate these mechanisms into the construction of soil layers.

In the field, this process would involve gathering soil as a raw material on site and then enhancing its load-bearing ability through the 3-D printing process. By improving soil’s ability to bear weight, printed layers could replace inferior soil and reduce the amount of expensive and sometimes difficult-to-obtain materials, such as concrete and rock aggregate. Bernhardt-Barry said 3D-printed soil layers could also be customized for location-specific demands, such as shallow foundations, aggregate columns, lightweight backfills, flood-relief wells and levee or dam filters.

Because they will use native soil and rocks, both as foundation and construction material, printed soils could be used to build structures in underdeveloped or war-torn areas. The material could also be used to construct roads, buildings and other infrastructure in remote areas or extreme environments, such as Antarctica or even the moon and Mars, where it would be difficult to deliver conventional construction materials and equipment.