UC Berkeley researchers find groundbreaking way to make greener concrete

Cracks in the Concrete
Sunny Shen/Staff
Researchers at UC Berkeley have found a way to incorporate polymer lattices into the structure of concrete, making it possible to build using less concrete and decrease the material’s natural brittleness. UC Berkeley organizations such as Cal Concrete Canoe have taken interest in the researchers’ developments.

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A team of UC Berkeley researchers developed an innovative way to reinforce concrete using 3D-printed structures known as polymer lattices, drawing the attention of the world of concrete.

With polymer lattices, it is possible to build using approximately 30% less concrete and cut down significantly on the brittleness of the material. Despite containing a smaller percentage of concrete, the structures are just as load-bearing as traditional cement, which is typically reinforced with steel, according to Brian Salazar, the lead author of the study.

“As we’re building more and more complex structures, I think it’s important for us to know, ‘How is it that we can best reinforce that structure?’” Salazar said. “At the moment, there are just some traditional techniques that you use to reinforce structures that have been going on for decades, and there hasn’t been too much questioning of whether that’s the best way to be reinforcing things.”

Cement consists of a mixture of sand, concrete powder, other powders and water. It is very useful in bearing heavy loads, but it suffers from a natural brittleness, according to the study. If a crack appears, it can grow and disintegrate the structure, Salazar said.

That is where reinforcement comes in: typically made out of steel, it prevents cracks and keeps everything from bridges to buildings structurally intact. However, steel is expensive, corrodes over time and is very heavy, Salazar said.

The 3D-printed polymer lattices are much lighter and avoid many of the flaws of traditional reinforcements, Salazar added. They also take up far more space than steel, encompassing nearly 30% of the structure’s volume. The decrease in the amount of cement used is unprecedented, and it is good news, according to Claudia Ostertag, study co-author and campus professor of civil and environmental engineering.

“Cement causes a huge release of CO2 in the air,” said Paulo Monteiro, campus professor of civil and environmental engineering. “The challenge is going to be how to scale up, but the approach that they found really indicates that some very creative methods can be used.”

Campus organizations are taking notice.

UC Berkeley student Matthew Michalek, a project manager at Cal Concrete Canoe, a campus club in which members seek to build a working canoe out of concrete, said the study was “very interesting.”

“When you make a concrete canoe, your main problem, at least in my experience, is density,” Michalek said. “If you’re able to reduce the cement volume by that much, it would be a very interesting prospect for making a canoe.”

For Monteiro, the value of the concrete is not limited to its green footprint. His vision is a modular system of construction in which parts can be built around the world and assembled “like LEGO blocks,” cutting down on construction costs and making work safer.

Construction companies and architects are also paying attention to the development, Monteiro said.

Today, the production of concrete accounts for 7-9% of the planet’s carbon dioxide emissions. Salazar’s goal for the future is to make the polymers even more environmentally friendly by making them out of recycled plastic or finding ways to make them carbon-absorbing. 

“The whole concept for 3D printing of concrete is arguably one of the hottest areas of research in engineering,” Monteiro said. “In principle, we could have a breakthrough in terms of construction practice.”

Contact David Villani at [email protected] and follow him on Twitter at @davidvillani7.