Roman Engineering Could Help Solve Our Climate Problem



All roads lead to Rome, as they say. And as the building sector struggles with the climate issue posed by concrete, some engineers believe a Roman-era invention may provide the solution.

Speaking at the Climate Smart Engineering conference in Melbourne, durability engineer Miles Dacre of the consulting firm AECOM notes that emissions related to concrete are coming under more and more scrutiny.

Dacre is involved in large-scale infrastructure projects that typically require a lot of concrete.

Demand for concrete has doubled in the last 20 years, he says. “It’s our number one building material that our whole civilization requires to function the way it does,” Dacre says. 

However, the Rocky Mountain Institute estimates that 5-8% of greenhouse gas emissions worldwide are attributable to concrete, and cement plays a significant role in those emissions. Heating limestone during the cement-making process results in direct greenhouse gas emissions as well as indirect ones from burning fossil fuels to heat the kiln.

According to Dacre, calcined clay is a low-carbon substitute for Portland cement that dates back 2000 years and is "probably the same concrete that the Romans used."

He declares, "We have to switch to that content as soon as possible."

recent research paper in Applied Clay Science proposed that using the old Roman concrete will decrease emissions and environmental issues.

Clinker, limestone, gypsum, and calcined clay—a clay that has been heat-treated—combine to create calcined clay.

“In addition to the environmental considerations, Roman concrete also represents the epitome of extremely durable cement-based materials,” the paper says. “Roman concrete exposed to harsh maritime environments remains in a remarkable condition even 2000 years after construction, while modern ordinary Portland cement concrete shows degradation within 32 weeks of exposure to seawater,” the authors write.

Dacre says anyone working in the engineering and construction industry who doesn’t know about calcined clay needs to educate themselves. The cement alternative has the potential to reduce emissions by roughly 40% compared to ordinary Portland cement.

“We’ve just got to prove it as quickly as possible; it’s going to take everyone in the engineering business to do that.”

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