Reducing carbon emissions brick by brick

November 30, 2019 2:17 PM

Cement has a carbon problem. Here are some concrete solutions. By Maddie Stone.
posted by MartinWisse (14 comments total)

I’ve used LC3 cement! Or rather, type 1L, which is a blended limestone-Portland cement mix that’s more common in the us. It’s now the standard cement base for concrete at UCSD as it’s got a lovely creamy white color. Getting the carbon out of cement is critical- we can find replacements for a lot of carbon-intensive building materials but I doubt we’ll find one for concrete any time soon.
posted by q*ben at 2:33 PM on November 30, 2019 [3 favorites]

More about CO2 absorbing versions of cement.
posted by Bee'sWing at 3:42 PM on November 30, 2019 [3 favorites]

Thanks for this. There are so, so many alternatives but the cement, construction and government sectors are the real barrier. Cement has obviously invested heavily to ensure they're an afterthought. q*ben - Solida is a great story.

ETH in Switzerland seems to be a leader:
A world of construction without cement - Warning! ETH is a wormhole if you're into low embodied energy and low carbon solutions.

Vogt-LA's work is really worth searching out - a Swiss landscape architect seeking concrete alternatives like at bahnhofsplatz-landquart - using natural binders and careful aggregate selection for durable play surfaces.
posted by unearthed at 6:05 PM on November 30, 2019 [4 favorites]

By Maddie Stone.

Almost eponysterical...
posted by Foosnark at 6:23 PM on November 30, 2019 [2 favorites]

Hempcrete - which is not a concrete for every application, but quite useful in house building, for example - also has the ability to "lock" away carbon as it cures.

We've been planning to knock down and rebuild our house this last year or so, and we're making it an passivhaus (quite unusual in Australia), and as renewable and green as possible. There are so many fantastic, affordable technologies for construction now that just a few years ago were either ridiculously expensive or hard to source, or just pipe dreams. It's a genuinely exciting time.
posted by smoke at 6:39 PM on November 30, 2019 [5 favorites]

Here in SE Arizona folks are using several building techniques which make minimal use of Portland cement, such as bubble-injected aircrete and mixtures of mud or cob with small quantities of cement. Many of the conventional uses of concrete mixes are stronger than they need to be, especially in a desert region which doesn't have the northern problems of frost-heaving, etc.
posted by Agave at 4:54 AM on December 1, 2019 [2 favorites]

Superheat calcium carbonate, aka marble, and you get lime, which is useful for mortar, which if you medieval and renaissance you can build with.

Which is why there is so little ancient Greco-Roman marble statuary today.

Anyway, this fellow suggests that the older technology might be less obnoxious than Portland cement. He could be right. And when you consider the amount of concrete needed to form the bases of modern windmills, esp. out at sea, well....
posted by BWA at 5:47 AM on December 1, 2019 [1 favorite]

Good that people are thinking about this. One positive with cement is its longevity - it lasts quite a while.

This is especially relevant when used as pavement, compared to e.g. common road/sidewalk surfaces like asphalt. Also unlike asphalt it's easily recyclable. Asphalt is essentially refinery byproduct mixed with aggregate AFAIK, and emits all sorts of fun volatiles during application and in the heat of the sun.

I'd be curious to see other comparisons in that particular use-case, if anyone has them. Otherwise I'll see if I can dig something up at work tomorrow.
posted by aspersioncast at 8:46 AM on December 1, 2019 [2 favorites]

There are some companies playing with lignin- based “bioasphalt” that use non-petroleum binders. In Texas there is a company called Petraviam doing something along these lines.
posted by q*ben at 9:42 AM on December 1, 2019 [2 favorites]

Secretive energy startup backed by Bill Gates achieves solar breakthrough - "The breakthrough means that, for the first time, concentrated solar energy can be used to create the extreme heat required to make cement, steel, glass and other industrial processes. In other words, carbon-free sunlight can replace fossil fuels in a heavy carbon-emitting corner of the economy that has been untouched by the clean energy revolution."

A Solar 'Breakthrough' Won't Solve Cement's Carbon Problem - "A Bill Gates–backed startup called Heliogen uses concentrated solar power to produce cement. The carbon-belching industry needs that—and much more."

A pair of Australian bridges try to cure concrete cancer (ungated) - "Normal concrete is bound with Portland cement, which is made by roasting a mixture that includes limestone (calcium carbonate). This process drives off carbon dioxide, a greenhouse gas, and cement-making is a big source of such emissions. Coincidentally, one of the ingredients of the Pantheon's concrete dome is pumice, another volcanic rock. Whether basalt-fibre concrete will similarly stand the test of time only future architects will know."

The material that built the modern world is also destroying it. Here's a fix - "Unlike Portland cement, Solidia's mixture doesn't harden simply after adding water; it requires the absorption of climate-killing CO2. The concrete blocks resulting from the process capture about 240 kg of carbon dioxide for every 1,000 kg of cement used in the mixture. That's on top of fewer emissions producing during the manufacture of Solidia's cement. Over its lifecycle—from limestone to cement to concrete—Solidia produces up to 70% fewer emissions, compared to Portland cement."

Secrets of ancient Roman concrete could make modern structures more durable, cut emissions - "Romans released far less carbon into the air while creating this long-lasting concrete."
posted by kliuless at 10:04 AM on December 1, 2019 [3 favorites]

That quartz article about Solidia is quality, thanks for the link!
posted by q*ben at 10:42 AM on December 1, 2019

Same metaphor, different technology:

A team of international researchers plan to turn the greenhouse gas carbon dioxide into rock by permanently injecting it beneath the Earth’s ocean floor.

posted by ipsative at 6:49 PM on December 1, 2019

mixtures of mud or cob with small quantities of cement

I've heard this called earthcrete (although there are some TM type earthcrete things and I am not familiar with them).

I've yet to see a reduction in utility in the places where I've used earthcrete rather than concrete as-per-bag instructions. That said, I'm not building bridges or windmill foundations either. It's a thought anyway and certainly makes a fully functional fencepost anchor and outbuilding/composting toilet pier foundation.
posted by RolandOfEld at 7:00 PM on December 1, 2019 [1 favorite]

Also called cement stabilized soil or soil-cement in road construction .
posted by q*ben at 8:09 AM on December 2, 2019 [2 favorites]