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Monday, 16 July 2018 01:00

Concrete that traps CO2 emissions for good

Written by  TheStructuralEngineer.info
Concrete that traps CO2 emissions for good Concrete that traps CO2 emissions for good

A new method to produce concrete that traps harmful CO2 emissions and increases the compression strength is implemented by Carbocure, a Canadian Start-up company.

While being the most abundant man-made material on earth, concrete poses a threat to the environment since its essential ingredient, cement, has a huge carbon footprint. Cement is the binder that bonds the aggregate together making concrete strong but the process of making cement requires superheating calcium carbonate, or limestone, and releases massive amounts of carbon dioxide into the atmosphere.

According to The International Energy Agency, cement is responsible for 7% of global greenhouse emissions, making it the world's second largest industrial source of carbon dioxide. The scientific agency of the US government (United States Geological Survey) reveals that global cement production was responsible for about 4 billion pounds of CO2 emissions in 2017 alone. The way that this method absorbs CO2 is by injecting the captured gas into concrete as it is being mixed. Over time, concrete hardens trapping the carbon inside. Even if the construction that the concrete is used for collapses, the carbon is not emitted in the atmosphere. That's because it reacts with the concrete and becomes a mineral. This reaction provokes another beneficial effect as it improves the compressive strength of the concrete, according to Christie Gamble, director of sustainability at CarbonCure. "The best thing about it is the mineral itself improves the compressive strength of the concrete. Because the CO2 actually helps to make the concrete stronger, concrete producers can still make concrete as strong as they need to but use less cement in the process."

Thomas Concrete of Atlanta has been using the CarbonCure system since 2016. The company says it has prevented 10 million pounds of CO2 emissions since it adopted the process. Justin Lazenby, manager of technical operations at Thomas Concrete, told CNNMoney that the move toward greener tech is a long-term decision that should be embraced by the concrete industry. "The industry as a whole has always kind of looked at trying to solve today's problems with yesterday's technology, which doesn't really work". Thomas Concrete has an agreement where it pays to use the CarbonCure system and buys captured CO2 from a fertilizer plant. The company says the savings they see by using less cement equal the costs involved with the system. "We understand that to make environment impact, you have to make business sense," CarbonCure's Gamble said. 725 Ponce, a new mixed-use development in Atlanta will become one of the largest structures ever made with CarbonCure concrete when it opens next year.

Two other startups (Carbicrete and Carbon Upcycling) working on more sustainable solutions for concrete exist. CarbonCure is just one of the first to market. Gregg Lewis, executive vice president of strategy for the National Ready-Mix Concrete Association, said these types of technologies will help push the concrete industry toward a more sustainable future. "[It will] offer a huge advantage to how we build as an industry," he said to CNNMoney. CarbonCure's Gamble noted if the industry is able to reduce 5% of its carbon footprint, that is a significant change from where it is right now. "If this technology is deployed across the globe, we could reduce about 700 megatons of CO2 each year. That's the same as taking 150 million cars off the road every year," Gamble said. To sum up, despite the fact that there is no intention to replace concrete production, it is feasible to promote new methodologies improving its negative effect on the environment.

Sources: Money.cnn.com (Video included)EnergiNews

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