ADVERTISEMENT
2 /3 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Materials

Cemex goes global with carbon-neutral concrete

Success in Europe with inorganic polymeric binder leads to worldwide launch

by Craig Bettenhausen
October 29, 2020 | APPEARED IN VOLUME 98, ISSUE 42

 

09842-buscon3-pour.jpg
Credit: Cemex
Cemex's inorganic-polymer-matrix concrete uses standard storage, mixing, and delivery equipment.

When it comes to construction, concrete is king, but making it releases a lot of CO2—around 8% of global emissions. Demand for lower carbon emissions is creating a market for concrete with a smaller carbon footprint. The concrete maker Cemex is addressing that trend with what it says is the first net-zero CO2 concrete to be available worldwide.

Concrete packs a double wallop of CO2: manufacturers first have use fuel to heat limestone to 1,300 °C, and then the conversion of CaCO3 to CaO releases CO2 as a byproduct, explains Steven J. Davis, a professor of Earth system science at the University of California, Irvine. They further heat the CaO to 1,450 °C to sinter it with other components such as gypsum to form clinker, the cement that binds standard concrete together.

Cemex’s Vertua Ultra replaces limestone-based clinker with an alkali-activated alumina-silicate polymer matrix. Preparation of the binder doesn’t require high temperatures and doesn’t release CO2, dropping its carbon footprint by 70% compared to standard concrete, says Davidé Zampini, Cemex’s head of R&D. Cemex buys carbon offsets to make the concrete 100% carbon-neutral.

“I don’t think I’ve seen anybody else offering that yet,” says Ian Riley, CEO of the World Cement Association, a trade group. Riley says most concrete makers are reducing emissions through efficiency improvements, lower-carbon fuel sources, and partial replacement of CaO with industrial waste such as fly ash. Alternative binder chemistries aren’t as common and are mostly limited to prefabricated parts.

Cemex accelerated Vertua Ultra’s global release after successful launches in France in 2018 and the UK earlier this year. It is more expensive than standard concrete, but the lower carbon emissions are worth it for some customers. Zampini also says the polymeric binder makes it more resistant to acid and heat than standard concrete, a plus for applications like sewer pipes.

Jurisdictions such as Sweden, New York City, and California’s Marin County are putting policies in place to encourage low-carbon concrete, Riley says, but he’d like to see more. “I think that would accelerate change,” he says, and encourage commercialization of new cement chemistry.

Low-CO2 concrete is a growing market. In September, Amazon invested in CarbonCure Technologies as part of the online retail giant’s goal to be carbon-neutral by 2050. CarbonCure injects captured CO2 into wet concrete, which the firm says strengthens the final material. Solidia, which earlier this year expanded a partnership with the concrete maker LafargeHolcim, takes a similar approach, using captured CO2 to cure prefabricated concrete blocks and other components.

Advertisement
X

Article:

This article has been sent to the following recipient:

Comments
Craig barnes (November 2, 2020 1:58 PM)
No world shattering comment here .....just a note to let you know I appreciate these bites as way to track engineering technology. This is not unlike the process my father and I experienced [he being a 1932 graduate of RPI] and me a 1963 student at Northeastern University when I explained to his amazement that 60ksi reinforcement was readily available and 100ksi was just around the corner. You can imagine his amazement when I tried to explain the theory behind prestressing.
PS! Keep it coming.... :)
Geoff Daly (November 5, 2020 11:00 AM)
Craig, the Romans were making cement/concretes, back several thousands of years ago, and they are still pretty resistant today, even underwater [salt and fresh]. No one really wants to change the types of Portland Cements as it affects the bottom line of the industry for more replacement cements', and concretes..... all about profits and keeping Wall St/Bankers' and the 1% happy!
Just look at the sloppy concrete's of today spoiling on thousands of structures around the world just rotting and corroding due to wrong chemistries being used! More than 45 years ago folks wanted to use Composite Rebar, except the Steel Lobby did not want this to occur, and look what we have now! Concrete rotting from the inside out. Many Nuclear power plants are experiencing this and so are a number of Coal/Gas converted power plants where concrete is in Water environments. Never mind the road infrastructures built since the late Fifties!?

Leave A Comment

*Required to comment