Green Cement Absorbs Carbon

Peace Corps Online writes "Concrete accounts for more than 5 percent of human-caused carbon dioxide emissions annually, mostly because cement, the active ingredient in concrete, is made by baking limestone and clay powders under intense heat that is generally produced by the burning of fossil fuels. Now Scientific American reports that British start-up company Novacem has developed a 'carbon-negative' cement that absorbs more carbon dioxide than it emits over its life cycle. The trick is to make cement from magnesium silicates rather than calcium carbonate, or limestone, since this material does not emit CO2 in manufacture and absorbs the greenhouse gas as it ages. 'The building and construction industry knows it has got to do radical things to reduce its carbon footprint and cement companies understand there is not a lot they can do without a technology breakthrough,' says Novacem Chairman Stuart Evans. Novacem estimates that for every ton of Portland cement replaced by its product, around three-quarters of a ton of CO2 is saved, turning the cement industry from a big emitter to a big absorber of carbon. Major cement makers have been working hard to reduce CO2 emissions by investing in modern kilns and using as little carbon-heavy fuel as possible, but reductions to date have been limited. Novacem has raised $1.7M to start a pilot plant that should be up and running in northern England in 2011."

Strength?

[plnb]

No mention in the article of the strength of the new material. How would this compare to regular concrete?

Re:Strength?

[Anonymous Coward]

Or the ramifactions of the extra weight caused by absorbing the CO2..

Less CO2 = $Green$

[Scubaraf]

I see one of the early tags is 'negligible.'

Maybe it is in terms of global CO2 levels, but under a cap and trade system, this will turn an industry that might have to buy CO2-emission rights into one that could make money selling them!

Who honestly cares about carbon?

[Anonymous Coward]

What is the purpose of going to all the trouble of actually creating a product that produces more or less carbon. Global warming may or may not be happening, but if so we don't exactly know what is causing it and we definitely can't stop it - but the companies that seek to profit from global warming hysteria don't care in the slightest that anything is actually being done about carbon - just that one pays the extra global warming carbon tax.

Re:Strength?

[mysidia]

Strength is important, and so is longevity.

I don't want to be in the car on that 50 year old bridge that collapses, because they didn't do right trials to detect aging and absorbing CO2 having an adverse effect on the material's strength over time.

Concrete is a rather proven material that has been proven over hundreds of years; spontaneously replacing it now could be highly dangerous.

Much like replacing the OS on a computer system that's been chugging a way for 500 years, with a brand new release version.

Sure, there may be an efficiency improvement. There can also be unexpected bugs.

Seriously...

[redmond]

"The building and construction industry knows it has got to do radical things to reduce its carbon footprint and cement companies"

Seriously? At least here in the Midwest (USA), construction bids still go to the lowest bidder and there are huge piles of construction waste that go straight to the landfill. They won't change until someone makes them change.

Re:Less CO2 = $Green$

[Mad Merlin]

Even if it is negligible, "going green" is the trendy thing to do nowadays, so as long as it seems like they're making an effort, that's far more important than if it actually helps.

Re:Strength?

[GeigerBC]

You're right in that we want strong and durable concrete. As another poster pointed out we are constantly changing the concrete mix proportions and admixtures. Admixes themselves are relatively new (~50 years) in the grand scheme of making concrete. It gets introduced slowly...and the universities then test it beyond belief for different properties. Maybe you'd like to be a grad student in civil engineering and make hundreds, or perhaps thousands of ever so slightly different mixes to determine the properties of your variable. I'm all for making concrete more "green" and I figure the universities and companies will test it before they use it in important projects.

Re:Less CO2 = $Green$

[Dragonslicer]

A solution that fixes only 1% of a problem may be considered negligible, but gather together a hundred such "negligible" solutions and see what you get.

Green is the new Black

[tengeta]

and by that phrase, I mean its popular bullshit. Most of the "green" things that have been devised over the past few years do NOTHING other than hold the carbon and make it the next generations problem instead. I thought the entire idea here was to NOT do that, but then again we live in an excessively hypocritical society that makes things up so they can make money, and this may just have been the latest and greatest. I'm not saying environmentalism is bad, but the majority of it so far isn't actually doing any good for the environment, its just helping the stock holders behind the products involved.

Re:Global Cooling On Its Way

[Nefarious Wheel]

On top of that, Farmer's Almanac, long a very trusted and reliable predictor of future events, has predicted a cooling ...

It's good to see the Slashdot audience moving back to reliance on such scholarly peer-reviewed journals. That's science, that is, science by the quart.

Re:Oh brother...

[thelandp]

Frankly, the mention of the term "carbon footprint" puts this squarely in the "hype" category.

Why did that get modded 5 insightful? Carbon Footprint is a valid and useful term.

The only reason I can see why some might like the above comment is if they are so conservative on climate change, they reject even the terms used in discussing it.

It would almost qualify as an example of the logical fallacy known as the "Appeal to Ridicule" but it wasn't quite intelligent enough.

http://en.wikipedia.org/wiki/Appeal_to_ridicule [wikipedia.org]

Re:Green is the new Black

[Raptoer]

I agree with you on the 'majority of it isn't actually doing any good' but I disagree on the hold carbon part. It's not like toxic waste where it's still a problem if something absorbs it. Carbon in the concrete isn't carbon in the air, and only carbon (dioxide) in the air is considered harmful to the environment. If it is in solid form (as calcium carbonate, or some other chemical, not as solid carbon dioxide) then it does nothing to the environment except sit, which it was doing before in the form of hydrocarbons (coal, gas, oil).

Ultimately a much better solution to the concrete problem would be to increase the efficiency of the production rather than change the end product to absorb carbon. As others have stated, not only is carbon release not the only problem with high energy use, but as this absorbs carbon what happens to its chemical structure? does it stay as strong as when it has finished curing? I can see it being used in applications where strength is unimportant like sidewalks, but no architect/civil engineer/ construction contractor worth anything is going to use an unproven concrete, just too risky.

Re:Strength?

[jelle]

Do you seriously believe that modern concrete is the same recipe, strength, and longevity as roman concrete?

Re:Strength?

[Z00L00K]

The weight may not be the issue, but will the structure and volume change when it absorbs CO2 over time?

If there is a volume change then there may be problems with warping and cracking. It's not easy to make a cement that can handle all construction requirements.

Then there is also the concerns about the availability of the magnesium silicates used.

CO2 Absorbsion

[matria]

Why not just plant more trees around buildings made of concrete? That seems to me to be a more useful, long-term "incentive" program than some we've seen lately.

Re:Strength?

[apoc.famine]

Indeed. And I doubt anyone will rush to build skyscrapers and bridges out of this stuff without some serious testing. However, there are plenty of non-critical applications for cement. Road beds, curbs, and sidewalks take up a lot of cement. Even if this wasn't as durable, as a net sink, replacing it 2x as often and landfilling it after you were done would be far more carbon-negative than using regular cement.
 
I'm imagining that single-home foundations wouldn't be an issue either - they don't (comparably) bear much weight, and the impact of replacing a house foundation earlier than normal bears no resemblance to the impact of replacing a skyscraper or bridge earlier.
 
There are tons of low-impact, low-danger applications to start testing this with. And I'd be damn surprised if a bunch of research colleges don't grab this and run with it. There's shittons of grant money for research and testing on "green technology" like this, and that's the bread and butter of a major materials science program.
 
We've got probably 75 years of really rigorous engineering science under our belts. The tests for concrete are very, VERY well established international and country-wide standards. I'd be surprised if this was steamrolled through an approval process. Building code is DAMN rigorous in most 1st world countries. Hell, there was just recently a story about some clay-based building product which was thermally amazing, to the point it stood in for insulation, and could withstand forest fires. It's not approved for building with in CA, due to its failure in earthquake tests.

Re:Strength?

[operagost]

That sort of "thinking", as you call it, is prohibited in the New World Order... you Climate Change Denier!

Re:Strength?

[drdrgivemethenews]

As a one-time construction industry veteran, let me say this about admixes. Go to a concrete company or flatwork outfit and ask the the old timers what kind of concrete holds up best. They'll all say, down to a man, that fly ash is evil, and you should stick to the old fashioned bag mixes.

Admixtures are almost all targeted at things like greater compression strength, lower price or tolerance of low temperatures during the setting process. They get tested to see if they effed up longevity, not to see if they enhanced it.

Not sure what engineering school parent went to, btw, but at mine, the civil grads spent a lot more time with ugly math on a blackboard than they did in a lab twiddling concrete mixes.