Support the Arctic Sea Ice Forum and Blog

Author Topic: Concrete - CO2 Villain or Solution?  (Read 5908 times)

Bob Wallace

  • Young ice
  • Posts: 3855
    • View Profile
  • Liked: 41
  • Likes Given: 5
Concrete - CO2 Villain or Solution?
« on: July 18, 2017, 05:52:03 PM »
"The concrete industry is one of two largest producers of carbon dioxide (CO2), creating up to 5% of worldwide man-made emissions of this gas, of which 50% is from the chemical process and 40% from burning fuel." - Wiki

Is this fixable?  Or even as bad as is commonly believed?

Quote
Cement manufacturing is among the most carbon-intensive industrial processes, but an international team of researchers has found that over time, the widely used building material reabsorbs much of the CO2 emitted when it was made.

"It sounds counterintuitive, but it's true," said Steven Davis, associate professor of Earth system science at the University of California, Irvine. "The cement poured around the world since 1930 has taken up a substantial portion of the CO2 released when it was initially produced."

For a study published today in Nature Geoscience, Davis and colleagues from China, Europe and other U.S. institutions tallied the emissions from cement manufacturing and compared them to the amount of CO2 reabsorbed by the material over its complete life cycle, which includes normal use, disposal and recycling. They found that "cement is a large, overlooked and growing net sink" around the world - "sink" meaning a feature such as a forest or ocean that takes carbon dioxide out of the atmosphere and permanently tucks it away so that it can no longer contribute to climate change.

Cement manufacturing is considered doubly carbon-intensive because emissions come from two sources. CO2 molecules are released into the air when limestone (calcium carbonate) is converted to lime (calcium oxide), the key ingredient in cement. And to generate the heat necessary to break up limestone, factories also burn large quantities of natural gas, coal and other fossil fuels.

 Through a process called carbonation, CO2 is drawn into the pores of cement-based materials, such as concrete and mortar. This starts at the surface and moves progressively inward, pulling in more and more carbon dioxide as years pass.

More than 76 billion tons of cement was produced around the world between 1930 and 2013, according to the study; 4 billion tons were manufactured in 2013 alone, mostly in China. It's estimated that, as a result, a total of 38.2 gigatons of CO2 was released over that period. The scientists concluded, however, that 4.5 gigatons - or 43 percent of emissions from limestone conversion - were gradually reabsorbed during that time frame.

"Cement has gotten a lot of attention for its sizable contribution to global climate change, but this research reinforces that the leading culprit continues to be fossil fuel burning," Davis said.

https://www.eurekalert.org/pub_releases/2016-11/uoc--cjf111516.php

Adding basalt or olivine to the mix should increase CO2 absorption.  Basalt fibers are already added to some concrete in order to strengthen it.  Adding basalt fiber can reduce or eliminate the need for rebar (another CO2 source) and make the concrete less likely to crack. 

Quote
An advanced materials manufacturer in Calumet, Michigan, Neuvokas (Finnish for “resourceful”) blends purchased fiber and internally formulated resin at high speeds to produce lightweight basalt fiber-reinforced polymer that is cost-competitive with traditional steel counterparts and also preferable to ordinary fiber rebar. Similar in chemical composition to glass fiber, basalt fiber is stronger and highly resists alkaline, acidic, and salt deterioration. Basalt rebar can also tolerate higher temperatures and more abrasion. Lack of developed standards for the product have held up its general institution.

Here are some of the other advantages of the Neuvokas product:

100X increase in production speeds of basalt rebar compared to current FRP production,
Price parity with steel,
Immunity to rust,
Increased tensile strength,
7X weight reduction with basalt rebar, and
Capability of using 30% less concrete.

http://cleantechnica.com/2014/11/06/neuvokas-basalt-rebar-lighter-stronger-cost-steel/


Bob Wallace

  • Young ice
  • Posts: 3855
    • View Profile
  • Liked: 41
  • Likes Given: 5
Re: Concrete - CO2 Villain or Solution?
« Reply #1 on: July 18, 2017, 05:53:46 PM »
Quote
a team of MIT researchers, led by senior researcher Roland Pellenq, decided to take a closer look at the cement mix, going down to molecular level.  They questioned the standard calcium to silica ratio of 1.7, which is commonly accepted as the one resulting in the most stable and strong cement.

After conducting a series of experiments, however, the team established that the optimal calcium-to-silica clay ratio should in fact be 1.5. Not only that the final product has incredible mechanical resistance , which is double the one achieved with a ratio of 1,7, and it is much less prone to fracturing, but also the team estimated a reduction in carbon dioxide emissions from the manufacturing process of up to 60%.

https://www.greenoptimistic.com/mit-researchers-cook-eco-friendly-cement-20140929/#.WW4lyYjyvIV

Bob Wallace

  • Young ice
  • Posts: 3855
    • View Profile
  • Liked: 41
  • Likes Given: 5
Re: Concrete - CO2 Villain or Solution?
« Reply #2 on: July 18, 2017, 06:11:32 PM »
Quote
And now, in a new paper in Science, representatives of Reykjavik Energy and a team of scientists from a large number of universities, including the University of Southampton in the U.K. and the Lamont-Doherty Earth Observatory at Columbia University, show not only that the process of injecting carbon dioxide into basalt rock at the Iceland site works, but that moreover, the carbon dioxide is mineralized, or turned into rock, very rapidly. In two years, they report, over 95 percent of injected carbon dioxide had become mineral.

“We demonstrate that by using this method, you can permanently remove the CO2, store it in the rock, and the rock isn’t going anywhere, it stays there for geological timescales,” adds Edda Aradottir, who works with Reykjavik Energy and is also an author of the study. “So I would hope that other types of industries would be interested in this method.”

The finding could be quite important because of the ubiquity of basalt in the world. The researchers say that 10 percent of the rocks that make up continents are basalt, and so is “most of the ocean floor.”

https://www.washingtonpost.com/news/energy-environment/wp/2016/06/09/scientists-in-iceland-have-a-solution-to-our-carbon-dioxide-problem-turn-it-into-stone/?utm_term=.82b8b505be24


Hefaistos

  • Guest
Re: Concrete - CO2 Villain or Solution?
« Reply #3 on: July 18, 2017, 09:56:13 PM »
"The concrete industry is one of two largest producers of carbon dioxide (CO2), creating up to 5% of worldwide man-made emissions of this gas, of which 50% is from the chemical process and 40% from burning fuel." - Wiki

An additional aspect of concrete, is that after its use in building things, it starts to carbonate, i.e. it takes up CO2 in a process that lasts for decades.
"The carbonation depth is approximately proportional to the square root of time. For example, if the carbonation depth is 1mm in a one-year-old concrete, it will be about 3mm after 9 years, 5mm after 25 years and 10mm after 100 years."

http://www.understanding-cement.com/carbonation.html

"...the concept that the world’s concrete infrastructure could provide the single largest human-made carbon sink has genuine scientific merit."
However, the extent of carbonation is less understood, it remains to be quantified how much CO2 concrete actually absorbs over its lifecycle.

http://www.sustainableconcrete.org.nz/page/co2-absorption.aspx

Hefaistos

  • Guest
Re: Concrete - CO2 Villain or Solution?
« Reply #4 on: July 18, 2017, 10:00:43 PM »
Here are some interesting results from research on concrete carbonation, showing that more than 50% of CO2 emitted during production of cement is later absorbed during the lifecycle of concrete.

The CO2 balance of concrete in a Life Cycle perspective
by K.O. Kjellsen (Norcem), M. Guimaraes (Aalborg Portland) and Å. Nilsson (Cementa), published by Danish Technological Institute, Denmark

Abstract
The amount of atmospheric carbon dioxide absorbed in Nordic concrete structures over a 100 year period has been calculated. The CO2 uptake, or carbonation, occurs gradually and was calculated for an initial service life period of 70 years followed by a 30 year post-demolition period. The processing of demolished concrete to recycled concrete aggregates increase the CO2 uptake, this was taken into account in the calculation of the total CO2 uptake.

Over 100 years, one year of Nordic concrete construction is calculated to absorb 0.34, 0.22, 0.24 and 0.021 million metric tons of CO2 in Denmark, Norway, Sweden and Iceland, respectively. These are quite notable numbers, and imply that about 0.5% of the total national CO2 emissions will be re-absorbed in concrete in Denmark, Sweden and Norway. The corresponding number for Iceland is about 1%. The calculations show that up to 30% of the total CO2 emission from cement production, or up to 57% of the CO2 emission from the so-called calcination process in cement manufacturing, is re-absorbed when the cement is utilized in concrete construction in the Nordic countries.

https://www.dti.dk/reports-on-co2-uptake-from-the-carbonation-of-concrete/co2-balance/18487,6

Bob Wallace

  • Young ice
  • Posts: 3855
    • View Profile
  • Liked: 41
  • Likes Given: 5
Re: Concrete - CO2 Villain or Solution?
« Reply #5 on: July 18, 2017, 11:29:24 PM »
Much of the CO2 problem seems to come from heat processing materials.  Currently fossil fuels are used for the heat source.  I wonder if we could have electric furnaces processing the limestone?

Quote
...the major compound in portland cement is tricalcium silicate, which hardens like stone when it is combined with water. Tricalcium silicate is produced by combining lime with siliceous sand and heating the mixture to 1,500 degrees Celsius.

Of the total carbon dioxide emitted in cement manufacturing, 65 percent is released when the limestone is calcined and 35 percent is given off by the fuel burned to heat the tricalcium silicate compound.

Sant and his team showed that the carbon dioxide given off during calcination can be captured and recombined with calcium hydroxide to recreate limestone—creating a cycle in which no carbon dioxide is released into the air. In addition, about 50 percent less heat is needed throughout the production cycle, since no additional heat is required to ensure the formation of tricalcium silicate.

https://phys.org/news/2015-09-technique-cement-carbon-neutral.html#jCp

Aluminum smelters operate at 960 °C.  And they use electricity, not FF.




TerryM

  • First-year ice
  • Posts: 6002
    • View Profile
  • Liked: 893
  • Likes Given: 5
Re: Concrete - CO2 Villain or Solution?
« Reply #6 on: July 19, 2017, 01:20:13 AM »
Here are some interesting results from research on concrete carbonation, showing that more than 50% of CO2 emitted during production of cement is later absorbed during the lifecycle of concrete.

The CO2 balance of concrete in a Life Cycle perspective
by K.O. Kjellsen (Norcem), M. Guimaraes (Aalborg Portland) and Å. Nilsson (Cementa), published by Danish Technological Institute, Denmark

Abstract
The amount of atmospheric carbon dioxide absorbed in Nordic concrete structures over a 100 year period has been calculated. The CO2 uptake, or carbonation, occurs gradually and was calculated for an initial service life period of 70 years followed by a 30 year post-demolition period. The processing of demolished concrete to recycled concrete aggregates increase the CO2 uptake, this was taken into account in the calculation of the total CO2 uptake.

Over 100 years, one year of Nordic concrete construction is calculated to absorb 0.34, 0.22, 0.24 and 0.021 million metric tons of CO2 in Denmark, Norway, Sweden and Iceland, respectively. These are quite notable numbers, and imply that about 0.5% of the total national CO2 emissions will be re-absorbed in concrete in Denmark, Sweden and Norway. The corresponding number for Iceland is about 1%. The calculations show that up to 30% of the total CO2 emission from cement production, or up to 57% of the CO2 emission from the so-called calcination process in cement manufacturing, is re-absorbed when the cement is utilized in concrete construction in the Nordic countries.

https://www.dti.dk/reports-on-co2-uptake-from-the-carbonation-of-concrete/co2-balance/18487,6


So - - - We will save, and have been saving between .005 and .01 of the CO2 emitted in some of the smaller cold countries because of concrete reabsorption. Why doesn't this give me a warm feeling of relief?


Terry

Bob Wallace

  • Young ice
  • Posts: 3855
    • View Profile
  • Liked: 41
  • Likes Given: 5
Re: Concrete - CO2 Villain or Solution?
« Reply #7 on: July 19, 2017, 02:23:11 AM »
Quote
up to 57% of the CO2 emission from the so-called calcination process in cement manufacturing, is re-absorbed when the cement is utilized in concrete construction in the Nordic countries.

I read that as concrete being only half as bad as we thought it was.  If we could use RE for the heat source during manufacturing we might be able to get concrete down to carbon neutral.

I'm not sure that Nordic has anything to do with the larger picture.  It's just where the study was run.  I don't see how location would increase carbon uptake unless heat is a catalyst.  And that suggests that things might be better in hotter locations.


Tor Bejnar

  • Young ice
  • Posts: 4606
    • View Profile
  • Liked: 879
  • Likes Given: 826
Re: Concrete - CO2 Villain or Solution?
« Reply #8 on: July 19, 2017, 03:23:37 AM »
By corollary, I think (I know a little about olivine, not concrete), a warmer climate will likely make it faster.
Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

ghoti

  • Grease ice
  • Posts: 767
    • View Profile
  • Liked: 12
  • Likes Given: 15
Re: Concrete - CO2 Villain or Solution?
« Reply #9 on: July 19, 2017, 05:37:44 AM »
There's been some hype about a process to add CO2 back into concrete when it is mixed to capture the carbon and strengthen the concrete. Not clear how much extra carbon storage this can account for.


http://carboncure.com/


johnm33

  • Guest
Re: Concrete - CO2 Villain or Solution?
« Reply #10 on: August 05, 2017, 01:00:51 PM »
From https://www.geopolymer.org/news/visit-airport-eco-building/
This project marks a very significant milestone in engineering – the world’s largest geopolymer concrete project. BWWA was built with approximately 40,000 m3 (100,000 tonnes) of geopolymer concrete making it the largest application of this new class of concrete in the world. The geopolymer concrete developed by the company Wagners, known as Earth Friendly Concrete (EFC), was found to be well suited for this construction method due to its high flexural tensile strength, low shrinkage and workability characteristics. Heavy duty geopolymer concrete, 435 mm thick, used for the turning node, apron and taxiway aircraft pavements, welcomes a heavy 747 cargo for regular air traffic between Toowoomba-Wellcamp BWWA airport and Hong Kong. For technical details read the paper by Glasby et al. (2015), EFC Geopolymer Concrete Aircraft Pavements at Brisbane West Wellcamp Airport, in our Library, Technical paper #23 GP-AIRPORT. Technical Paper on Geopolymer Aircraft Pavement
 They make a clear distinction between geopolymer and alkili activated materials, and for anyone interested in historic building techniques, or new possibilities, valuable insight. I'm not in a position to judge but their approach appears to be far less energy intensive and with a superior product, exploring the use of natural materials to a greater extent.
https://www.geopolymer.org/


Tom_Mazanec

  • Guest
Re: Concrete - CO2 Villain or Solution?
« Reply #12 on: September 20, 2019, 11:41:12 PM »
Europe’s Biggest Cement Maker Steps Up Push for Green Concrete
https://www.bloomberg.com/news/articles/2019-09-18/cement-maker-lafargeholcim-steps-up-spending-to-cut-pollution
Quote
Europe’s largest cement maker is stepping up investments in reducing its carbon emissions as pressure mounts on the industry to rein in pollution causing global warming.

LafargeHolcim Ltd. is spending 160 million Swiss francs ($161 million) on 80 projects across Europe to cut annual emissions from its cement manufacturing processes by 15% by 2022, according to Marcel Cobuz, the company’s head of Europe.


Tom_Mazanec

  • Guest
Re: Concrete - CO2 Villain or Solution?
« Reply #13 on: February 22, 2020, 12:54:48 PM »
How Much Cement Has China Used?
https://www.wired.com/2014/06/how-much-cement-has-china-used/
Quote
Bill Gates pointed out that China has used 6.6 gigatons of cement in the last three years compared to 4.5 gigatons the USA has used in 100 years. Not only is that a lot of cement, it is in a very short time.
Some mind-blowing visualizations of what that would look like.

johnm33

  • Guest
Re: Concrete - CO2 Villain or Solution?
« Reply #14 on: February 23, 2020, 10:44:47 AM »

Freegrass

  • Young ice
  • Posts: 4400
  • Autodidacticism is a complicated word
    • View Profile
  • Liked: 1094
  • Likes Given: 1347
Re: Concrete - CO2 Villain or Solution?
« Reply #15 on: May 23, 2024, 02:05:13 PM »
UK breakthrough could slash emissions from cement

https://www.bbc.com/news/articles/cxee01m5yero

Scientists say they've found a way to recycle cement from demolished concrete buildings.

Cement is the modern world's most common construction material, but it is also a huge source of planet-warming gas emissions.

That is because of the chemical reactions when you heat limestone to high temperatures by burning fossil fuels.

Recycling cement would massively reduce its carbon footprint. Researchers say that if they switched to electric-powered furnaces, and used renewable energy like wind and solar rather than fossil fuels, that could mean no greenhouse gases would be released at all.

And that would be a big deal. Cement forms the foundation of the modern economy, both literally and metaphorically.

It is what binds the sand and aggregate in concrete together, and concrete is the most widely used material on the planet after water.

It is also a major driver of climate change. If cement was a country, it would be the third biggest source of emissions after China and the US, responsible for 7.5% of human-made CO2.

The problem is the material’s uniquely polluting chemistry.

It is made by heating limestone to up 1600 Celsius in giant kilns powered by fossil fuels.

Those emissions are just the start. The heat is used to drive carbon dioxide from the limestone, leaving a residue of cement.

Add both these sources of pollution together and it is estimated that about a tonne of carbon dioxide is produced for every tonne of cement.

The team of scientists, from Cambridge University, has found a neat way to sidestep those emissions.

It exploits the fact that you can reactivate used cement by exposing it to high temperatures again.

The chemistry is well-established, and it has been done at scale in cement kilns.

The breakthrough is to prove it can be done by piggybacking on the heat generated by another heavy industry – steel recycling.

When you recycle steel, you add chemicals that float on the surface of the molten metal to prevent it reacting with the air and creating impurities. This is known as slag.

The Cambridge team spotted the composition of used cement is almost exactly the same as the slag used in electric arc furnaces.

They have been trialling the process at a small-scale electric arc furnace at the Materials Processing Institute in Middlesbrough.

The BBC was present when the first high grade, or “Portland”, cement was produced.

They are calling it “electric cement” and described the event as a world first.

The lead scientist, Cyrille Dunant, told the BBC it could enable the production of zero-carbon cement.

“We have shown the high temperatures in the furnace reactivate the old cement and because electric arc furnaces use electricity they can be powered by renewable power, so the entire cement making process is decarbonised.,” he said.

He said it also makes steel recycling less polluting because making the chemicals currently used as slag has a high carbon cost too.

Mark Miodownik, Professor of Materials and Society at University College London, described the way the Cambridge team have combined cement and steel recycling as “genius” and believes, if it can be made to work profitably at scale, it could lead to huge reductions in emissions.

“Can it compete against the existing infrastructure that is very unsustainably going to keep pumping cement into our lives”, he asks.

“Cement is already a billion-dollar industry. It’s David and Goliath we are talking about here.”

The hope is electric cement will be cheaper to manufacture because it uses what is essentially waste heat from the steel recycling process.

Spanish company Celsa will attempt to replicate the process in its full-scale electric arc furnace in Cardiff this week.

The Cambridge team estimate, given current rates of steel recycling, their low carbon cement could produce as much as a quarter of UK demand.

But the use of electric arc furnaces is expected to increase in the future, potentially allowing more “electric cement” to be produced.

And, of course, the process could be duplicated all over the world, potentially cutting the emissions from cement dramatically.
When factual science is in conflict with our beliefs or traditions, we cuddle up in our own delusional fantasy where everything starts making sense again.

morganism

  • Young ice
  • Posts: 2568
    • View Profile
  • Liked: 269
  • Likes Given: 171
Re: Concrete - CO2 Villain or Solution?
« Reply #16 on: May 25, 2024, 12:58:05 AM »
Electric recycling of Portland cement at scale

https://www.nature.com/articles/s41586-024-07338-8

Cement production causes 7.5% of global anthropogenic CO2 emissions, arising from limestone decarbonation and fossil-fuel combustion1,2,3. Current decarbonation strategies include substituting Portland clinker with supplementary materials, but these mainly arise in emitting processes, developing alternative binders but none yet promises scale, or adopting carbon capture and storage that still releases some emissions4,5,6,7,8. However, used cement is potentially an abundant, decarbonated feedstock. Here we show that recovered cement paste can be reclinkered if used as a partial substitute for the lime–dolomite flux used in steel recycling nowadays. The resulting slag can meet existing specifications for Portland clinker and can be blended effectively with calcined clay and limestone. The process is sensitive to the silica content of the recovered cement paste, and silica and alumina that may come from the scrap, but this can be adjusted easily. We show that the proposed process may be economically competitive, and if powered by emissions-free electricity, can lead to zero emissions cement while also reducing the emissions of steel recycling by reducing lime flux requirements. The global supply of scrap steel for recycling may treble by 2050, and it is likely that more slag can be made per unit of steel recycled. With material efficiency in construction9,10, future global cement requirements could be met by this route.


https://www.cam.ac.uk/stories/cement-recycling
Kalingrad, the new permanent home of the Olympic Village

Freegrass

  • Young ice
  • Posts: 4400
  • Autodidacticism is a complicated word
    • View Profile
  • Liked: 1094
  • Likes Given: 1347
Re: Concrete - CO2 Villain or Solution?
« Reply #17 on: July 25, 2024, 05:46:10 AM »
This video explores LEILAC’s innovative low-emission kiln technology for cement manufacturing. It highlights the process, benefits, and potential impact on reducing carbon emissions in the cement industry.

When factual science is in conflict with our beliefs or traditions, we cuddle up in our own delusional fantasy where everything starts making sense again.

morganism

  • Young ice
  • Posts: 2568
    • View Profile
  • Liked: 269
  • Likes Given: 171
Re: Concrete - CO2 Villain or Solution?
« Reply #18 on: August 11, 2024, 08:07:54 PM »
With sustainable cement, startup aims to eliminate gigatons of CO2

While today's cement is made through extremely high temperatures in a kiln, ancient Romans didn't have that option. Still, anyone who's been to Rome recently will tell you that ancient cement seems to have held up just fine.

The startup Sublime Systems thinks the Romans were onto something. The MIT spinout has created a drop-in replacement for today's most commonly used cement, known as portland cement, that uses electrochemistry to skip the ultrahigh temperatures of conventional production - and the immense carbon dioxide emissions that go with it.

"Romans couldn't go to those obscene temperatures, but they've proven their cement is hard and durable, and we now have 2,000 years of innovation to get that cement to meet the criteria we expect out of modern cement,"
(snip)
 In May, Sublime reached a major milestone when 3 tons of its cement was poured in Boston's largest net-zero commercial building in the Seaport district. Now the company is building a commercial-scale manufacturing plant in Holyoke, Massachusetts, that will be able to produce 30,000 tons of cement per year. The new plant is slated to come online as early as 2026.

"The Holyoke plant is designed to be a module that we can repeat to get to a million-ton-per-year plant," Ellis says. "That will allow us to eliminate scale up risk so we can deploy simultaneously all over the world."
(snip)
 At MIT, Sublime's team created an electrochemical process in which it breaks down calcium silicate rocks at ambient temperature using electrochemistry. The reaction works with abundant raw materials and creates reactive calcium and silicates that are dried and blended into Sublime's cement.

The mixture has the same final strength and hardened phases as portland cement and meets a standard performance specification in the industry that allows it to be used in building construction.

"To our knowledge, we are the only true-zero solution for manufacturing a drop-in replacement for portland cement, because we don't use fossil fuels and we don't use limestone, so we can avoid all of the emissions from making portland cement," Ellis says

https://www.energy-daily.com/reports/With_sustainable_cement_startup_aims_to_eliminate_gigatons_of_CO2_999.html

Kalingrad, the new permanent home of the Olympic Village

Paddy

  • Nilas ice
  • Posts: 1074
    • View Profile
  • Liked: 166
  • Likes Given: 185
Re: Concrete - CO2 Villain or Solution?
« Reply #19 on: August 14, 2024, 06:39:18 PM »
With sustainable cement, startup aims to eliminate gigatons of CO2


Worth noting that the cement industry is responsible for about 8% of global anthropogenic carbon dioxide (CO2) emissions , so this and similar initiatives could indeed be quite significant if they scale up to take the place of a large share of that industry.