Building a Better World With Green Cement

With an eye on climate change, a British startup creates a new form of the ancient building material

Novacem plans to test its experimental cement (above: sample blocks) first in structures like doghouses and patios. (Alex Masi)
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“The dust will eventually settle and one of these ideas will work,” Jennings said.

Early on, one of Novacem’s biggest skeptics was the largest privately owned construction company in Britain, Laing O’Rourke. The executive in charge of keeping tabs on promising university work, Dheeraj Bhardwaj, heard about Novacem’s product through his scholarly connections. He looked at the chemistry, thought everything checked out and a few years ago took the idea to the chairman, who had plenty of doubts. There was no way the cement could be strong enough for commercial use, he said. It needed limestone. When Novacem’s material reached 40 megapascals—the bare minimum amount of strength needed for structural stability—then he might be interested.

Seven days later, a small chunk of Novacem cement placed in a vise-like instrument hit that mark. Twenty-eight days later, it hit 60 megapascals. Bhardwaj then took the results to the chairman, who said, “Let’s make this work.” Laing O’Rourke is now a major Novacem partner. Today, after much tinkering, the cement is approaching 80 megapascals. Concrete made with Novacem cement is comparable in strength to some standard concrete.

Novacem’s other partners include Lafarge, in Paris, the world’s biggest producer of building materials, and Rio Tinto, a London-based global mining company eager to help Novacem dig up magnesium silicates.

“The cement industry is now stepping up in financially significant, in scientifically significant ways right now,” said Jennings, referring to all of the various experimental approaches. “The world is changing. Everyone, including all the cement companies, will need to be as green as possible and take care of the world a little better.”

Jennings declined to endorse any particular new cement. “If Novacem’s works,” he said, “it’s a very attractive idea.”

Bhardwaj is more committal. He said he recently went to his engineering team. “Honestly, don’t be polite,” he told them. “Put aside any question about the carbon. Do you think this is something close to Portland cement?” The answer surprised him: They said it was better. Why? Not only was it strong, but it was pure white. Portland cement is slightly gray. “You could add colors to this cement,” Bhardwaj said. “Imagine having any color cement wall in your house that you wanted.”

The cement is a lovely shade of white, as Vlasopoulos pointed out while showing off his company’s prototype cement factory. Referring to the neighboring bioscience labs, he said, “We’re louder,” adding: “They are curing people in there; we are curing something else.” A hulking machine in front of him, idle at the moment, has long pipes that bang and clank, alarms that go off, and mixers that churn and spit out buckets of Vlasopoulos’ creation.

Vlasopoulos was in a peppy mood, having just proposed to his girlfriend the day before. (She said yes.) Over in a corner of the room was what he called “our museum.” On a small table were early chunks of Novacem cement—they looked like children’s blocks, just dustier. “This was not so good,” he said, holding up a fragile-looking one that was chipped. “Now we know what we are doing.” The plant can produce about five tons of cement per year. The company is also working on another facility that would produce 200 tons per year. If all goes well, the company intends to license its recipe to cement makers around the world.

The major obstacle that the company still has to overcome is history. Portland cement works. Always has, since that afternoon in 1824 in Joseph Aspdin’s kitchen. “Cement has been around a very long time,” Bhardwaj said. “People trust that. They can look around at all the buildings that have survived hundreds of years. So for Novacem, the proof of durability will take time. They will have to go slow. If I have to build a bridge or a building using Novacem cement, how do I convince people that that is OK? That’s the challenge. Nobody wants a bridge to fall down.”


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