Environment

C-Crete hailed as a planet-friendly alternative to cement

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In a pilot project, concrete containing C-Crete is used to retrofit a 120 year-old Seattle building's foundation
R. Savary, C-Crete Technologies
In a pilot project, concrete containing C-Crete is used to retrofit a 120 year-old Seattle building's foundation
R. Savary, C-Crete Technologies
A new shear wall cast and finished with C-Crete concrete in the Seattle building
R. Savary, C-Crete Technologies

According to some estimates, the generation of the heat used to produce traditional portland cement is responsible for 5% to 8% of all human-made CO2 emissions. A new substance known as C-Crete, however, is claimed to be a much greener – yet still practical – alternative.

C-Crete is being developed by a California-based startup of the same name, which was founded by MIT Civil and Environmental Engineering grad Rouzbeh Savary.

Although the product's exact ingredients are a closely guarded trade secret for now, it is said to contain "patent-pending materials" that bind with unspecified mineral feedstocks and industrial byproducts which clients can obtain locally. Importantly, no heat is required in its production.

When C-Crete is combined with water and an aggravate such as sand or gravel, the end result is cement-free concrete. Third-party testing has reportedly shown that C-Crete meets performance requirements for portland cement, such as strength and flowability.

And as an added bonus, once the substance has cured, it absorbs atmospheric carbon dioxide. That trapped and mineralized CO2 is claimed to actually increase the strength of the concrete over time.

A new shear wall cast and finished with C-Crete concrete in the Seattle building
R. Savary, C-Crete Technologies

Importantly, C-Crete is utilized just like portland cement, using the same equipment and the same mix ratios. Savary believes this fact will be key to its widespread adoption by the mass market.

"Because the industry is so used to portland cement, and also because of the liabilities involved in construction projects, if a new product is complicated to use or behaves differently, contractors and workers won’t switch," he says.

"It had better be a drop-in technology that bears minimal to no changes in the current behavior of concrete, from its dry mix components to its liquid and hardened stages. We wanted to make C-Crete as easy and as close as possible to conventional practices."

C-Crete is currently being produced in relatively small quantities at a dedicated facility, although it is hoped that production rates will soar once commercial partners get on board. The material has already been utilized in the restoration of a historic building in Seattle.

Sources: MIT, C-Crete

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9 comments
Smokey_Bear
more important that its green street cred, is how does it hold up over time. Current concrete is shit, it cracks after just a year or two, and needs maintenance all the time. I hope this handles wear & tear better, and the freeze/thaw cycles.
Spooky
There are 2 factors that produce CO2 one being the heating involved and secondly the chemical reaction the produces a significant amount of CO2 so take away the heat you still produce CO2 as a chemical reaction.
b@man
The human impact on ALL green house gases... .000006 Please stop the insanity, the earth needs about 8 times as much co2 as it currently has.
TechGazer
The "absorbing CO2" part suggests that it's some form of lime. If it's made with high-value electricity or chemicals instead of heat, it might (or might not) be a bit greener, but it's hardly miraculous.

It doesn't mention whether its durability in wet conditions is the same as regular concrete.
Jay Gatto
Worth noting, that the Great Wall of China mortar included rice flour, and Romans added volcanic ash to their mix. It's tough, waterproofing, and bonding.

(b@man you might want to read more widely, post less widely)
Karmudjun
b@man - the medical and biological sciences are not in agreement with your assessment. 415.33 ppm is equal to 0.04%. When I was studying atmospheric gas levels by volume N2 was 78.08%, Oxygen at ~20.95 %, and Argon was 0.93%. remaining gases in total were 0.04%. In the USA, the OSHA levels of CO2 by volume was set for 0.05% since headaches, sleepiness, and CO2 retention to levels of CO2 narcosis were seen with youth, elderly, and pulmonary patients. This "insanity" is proven science, while retained CO2 (breathing into a paper bag to calm yourself down) may be therapeutic on occasion, it is deadly for some mammals - humans included.
Gordien
A geopolymer concrete that is tougher than standard concrete would be great, and some basalt rebar would make it suitable for wet environments.
Without heat, the Earth would freeze, so I think we could use 10x more heat. And to lay that concrete well, we could use about 4x more people - our find ways to use fewer materials - use up some of our plastic garbage for affordable housing.
TechGazer
Rather than making concrete slightly greener, there's probably much more gains to be had by designing buildings to last longer. Instead of tearing down a residential tower, if it was designed so that the plumbing, wiring, and other services could be inexpensively replaced, and the interior surfaces refurbished, you could get another few decades of use out of it, rather than tearing it down and using new concrete.

I haven't seen a detailed comparison of concrete vs the "new, improved" types of wood construction, but wood certainly seems "greener".
Expanded Viewpoint
Refer back to elementary school, where you were supposed to learn that CO2 is a necessity for green plant life. If you take away CO2 from plants, they starve to death because they cannot make their food out of it. Add CO2 (like they do in real greenhouses) and the plants thrive much more than the ones that are outside of it. Case closed, plants need CO2.