CU Boulder engineers develop living hybrid building materials

Thursday May 16, 2019 0 comments Tags: Boulder, CU Boulder, Will Srubar

BOULDER -- CU Boulder engineers are developing living hybrid building materials that exhibit both structural and biological functions, a step toward more sustainable and eco-friendly construction practices.CU_logoUSE_1

Think of the sand and cement used in a mortar. It’s inorganic. Not living. But Will Srubar, a faculty member in CU’s Department of Civil, Environmental and Architectural Engineering and the Materials Science and Engineering Program, said his research has shown that inorganic particles, like sand, can provide a rigid framework for a biological component like bacteria to grow and thrive.

Combine the two, and you end up with a living material that has not only a structural load-bearing function, but also a beneficial biological one.

“We use bacteria to help grow the bulk of the material needed for construction,” Srubar said. “We know bacteria grow at an exponential rate, so rather than manufacturing bricks one-by-one, you may be able to make one brick and have it split into two, then four, and so on.

“That would revolutionize not only what we think of a structural material, but also how we fabricate structural materials at an exponential scale.”

Srubar said the possibilities for his work are endless and especially interesting in extreme environments and military applications. Bricks could self-heal after natural disasters or enemy fire, he said, or act as alarms by changing color when there are toxins in the air.

“What was intriguing to us as a team was that we were also trying to create a Frankenstein material while learning from our predecessors and avoiding the same fate by not losing control of our technology,” Srubar said.

“We often speak of this project as ‘The Post-Modern Prometheus,’ where we have finally, after three tries, wielded the technology we have created.”

At the center of the project are cyanobacteria, photosynthetic saltwater bacteria that can sequester carbon dioxide. Placing genetically altered versions of these bacteria into the building material would provide an environmental benefit, especially in terms of lowered carbon emissions from manufacturing materials.

Srubar is conducting the work with assistant professors Mija Hubler and Sherri Cook in the Department of Civil, Environmental and Architectural Engineering, and professor Jeff Cameron in the Department of Biochemistry.

The faculty members bring experience in the biological sciences, gene editing and structural mechanics — needed perspectives on an interdisciplinary project this large, Srubar said.

“They opened my eyes not only to different ways of looking at science and engineering, but also to ways in which we can address some of the challenges we encounter and then spin those challenges into opportunities,” he said.

“Sharing some of the common challenges in materials science has bolstered our work in micro- and synthetic biology, for example. That is leading us in wildly cool and crazy directions in the project.”

Srubar fsaid he feels his lab is pioneering a new field despite being deeply rooted in fundamental disciplines.

“For the first time we are questioning the paradigm of cementitious materials, and that is incredible because cement technology hasn’t changed in 100 years,” Srubar said.

“While we are still some years away from seeing a true application, we do feel that we are creating this new discipline.”