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It’s becoming an accepted* fact in the world of science research, that the manufacture of cement is the second most carbon-intense activity on the planet (after petroleum fuel consumption) – accounting for between 5 to 20%* of anthropogenic or man-made carbon dioxide (CO2).
This article explores the mitigation or reduction of man-made CO2 by replacing Portland cement with magnesium oxide-based cements & cement aggregates – by at least 3.5%… it could be by as much as 18%, but certainly by an increasing amount each year* !
*1 – UndergroundNewYork published this article originally on Jan 2014, in the same month Climatic Change Journal published an article: Tracing anthropogenic CO2 & methane emissions to fossil fuel & cement producers reporting that 63% of man-made CO2 emissions are from fossil fuel consumption & cement production.
*2- According to a Chemistry World magazine article published March 2008, 5% of Co2 emissions were from cement production. Additionally Columbia University research establishes world cement production growing by 2.5% annually (7×2.5=17.5%+5=23.5%). As 1 ton of cement produces 1 ton of CO2, hence logically CO2 emissions also increase by 2.5% annually (at least, see point 4 below).
*3 – Even the powerful concrete lobby which is entrenched in the World Business Council, admits that 3 tons of cement is used for each person on this planet – per year. Global population according to the UN is at 7.3billion (July 2015) projected to reach 8.5billion in 2030. Growth of world population is slowly levelling out at around 1.13% percent.
*4 – However, for emerging economies, the increase in wealth results in far greater material expenditure which increases the amount of cement production. Basing this partly on statistics from the US Geological Survey which show the opposite: that significant declines during the 2008 economic slowdown, resulted in a slowdown in domestic production of minerals used in construction, such as cement, gypsum, construction sand, gravel, & crushed stone.
Climate change directly reflects population growth & human activity, so addressing cement manufacturing will bring about exponential change in the world’s atmosphere too.
By far the greatest amount of cement production (over half the world’s consumption & rapidly rising) is happening in China. The pie chart below shows in 2010 a global production of 3.3 billion tons… 54% of which was produced by China. Followed by India at 7% & USA at 2%.
According to this Washington Post article quoting Bill Gates’ blog, China used more cement between 2011 & 2013 than the U.S. used in the entire 20th Century.
Not to rag on China – relative to the number of people there (population size is 4x that of the US), their cement use is probably very efficient. And China is the world leader in clean energy investment (in 2014 they invested a record $89.5 billion in renewables). Still, China (& India) are the key players on which much of the planet’s future hangs. Luckily China also has the second largest magnesite reserves in the world, 500-550 million tons.
Digital sunset on a huge screen in Tiananmen Square, Beijing – Getty Images, Jan 2014
A vanguard of chemists/builders/entrepreneurs from Australia, the US & the UK is pushing for mankind to return to more sustainable cement-manufacturing methods which would:
Magnesium oxide-based (MgO-based) cements have been used in architectural wonders of the world since time immemorial – the pyramids of Egypt, the Forum in Rome, the Great Wall of China, the stupas of India & many ancient buildings still standing today.
Compare this with Portland cement buildings & structures that will be dust in 30 to 50 years’ time (such as the 16,000ft long Tappan Zee Bridge in Greater New York Metropolitan area), built in 1950 & soon to be de-commissioned & replaced with a new one costing $3.9 billion – if the new bridge lasts 100 years, it will still cost NYC taxpayers $390 million per year.
Portland cement manufacture
Cement factory in Sichuan, China
Very briefly: Portland cement is made by heating limestone (calcium carbonate) with clay or sand in huge kilns, to 1,515-2,800 deg. F (825-1,500 deg. C), a process known as calcination. For the kilns to reach these temperatures, the fuel required will burn & produce at least a ton of carbon dioxide.
Three ways to make concrete greener – from Architect magazine (Aug 2012):
1. Reduce carbon-intensive ingredients in concrete mixtures
– by mixing in fly-ash, rice husk & other supplementary cementitious materials (SCMs), thus reducing CO2 emissions.
2. Sequester CO2
– The Carbonate Mineralization by Aqueous Precipitation (CMAP) method passes waste CO2 through pH-modified seawater, which solidifies calcium carbonate into a cement. California-based company Calera claims that for every ton of concrete manufactured with this process, up to half a ton of CO2 is sequestered – 50% that of conventional cement production offgassing.
3. Re-absorb atmospheric CO2 during curing
While cement hardens or cures, the cement mix slowly re-absorbs CO2 from the atmosphere in a reaction called carbonation. The liquid reacts with the alkaline calcium-containing components in the concrete matrix to deposit calcium carbonate crystals (below image), this can reduce the integrity of the cement because it increases corrosion of any steel encased within.
John Harrison, the entrepreneurial, engineering, science-based force behind TecEco who I emailed with several times during the course of this article, states that their patented products have the capacity to reabsorb about 0.6 tons of carbon dioxide, or 60%, for every ton of material. Even the more cautious estimates (according to scientist Dr Mark Shand who conducted definitive research on magnesium) place that at the very least at 12%.
An additional fourth method:
Magnesium Oxide-based cements
Using MgO-based cements & cement aggregates, a total reduction in CO2 being produced would be between 72-92% if magnesia ore is readily available in a given country. Unfortunately many magnesia mines in the US were shut down when Portland cement became the monopolising industry supplier, according to Jerry Rademan. And at present, the main methods of magnesia extraction (such as desalination from seawater) are prohibitive against large-scale use, more efficient extraction methods being one of the technologies each of these scientists is working on.
However China has an abundance of magnesium mines that could support an alternative cement industry.
In any case, a global move away from Portland cement would decrease at a conservative estimate, 2.5-5.6% of all the CO2 in the earth’s atmosphere being produced through man-made activities. (And according to John Harrison, replacing cement aggregate with synthetic carbonate rock would very significantly increase these numbers further – in fact one of his new patents – called Syncarb – does exactly that.)
According to diverse online articles (listed below in footnotes), the experts (which include published scientists & writers, building consultants & industry suppliers) seem to agree that with MgO-based cements:
1. The production processes emit at minimum 50% less carbon dioxide than Portland cement processes, though it could be 60-80% less. Meaning instead of 5-7% anthropogenic or man-made CO2 emissions, we could have as little as 1-2%!
2. MgO-based cements allow water vapor to pass through so they never rot because they temper & regulate indoor air humidity & expel moisture, hence they’re mold- & mildew-proof & effect healthy, comfortable air quality
3. Coupled with the fact that some MgO-based cement products are designed to cure rapidly & also have very high early strength, both tensile & compressive. These are utilized as a rapid patching mortar for road & aircraft runways (operable after only 45 minutes!).
Commercial magnesium phosphate cements typically reach a compressive strength of about 2,900 psi after 1 hour, with an ultimate strength of 8,000-10,000 psi according to an article by Mark Shand, author of “The Chemistry & Technology of Magnesia” & R&D Director for Premier Magnesia.
4. Also greater freeze-thaw resistance, reduced dimensional change including zero shrinkage & zero cracking hence its use in highways & bridges
According to Jerry Rademan (business & technological development executive for Premier Magnesia), the company was called in for the failing repair of Glen Elder dam in Kansas: this reconstruction project was being massively threatened by widespread shrinkage-cracking of the envelope. Their product Prevent-C, a MgO-based admixture when added to Portland cement, effected a 100% reduction of cement shrinkage & the repair project was underway again.
5. Bonds naturally with almost every organic substance – wood chips, hemp, cotton cloth & other cheap filler material have been used as aggregates to make it cement lighter-weight, hence MgO-based cements are often called “living cements”.
This is in contrast to Portland cement which repels cellulose, plastic binders are often used in Portland cement to assist artificial adhesion to wood, styrofoam or stone but such petroleum-based binders can also bind in moisture & increase likelihood of mold damage – from Green Home Building article.
6. Additionally MgO-based cement bonds perfectly with brick, tile, wood & even steel – in addition, whatever is encased in MgO-based cement is protected in multiple ways since the cement encases perfectly with zero shrinkage, & also it’s a refractory cement (meaning it functions well even at extremely high temperatures).
Industry insiders have theorized that the Twin Towers fell because the reinforcing steel columns encased in WTC I & II’s cement supports melted. Had MgO-based cement been used instead, such support failure may not have happened, again due to the super-stable nature of the Magnesium-Oxygen matrix (due to the covalent bonds or molecular attraction between the double Magnesium & double Oxygen molecules), as well as its bonding & encasing abilities which would have protected the steel – as well as pH level. See points #6, 11 & 13.
According to John Harrison, “If the pH drops too low, the “passive” Fe3O4 coating on steel will morph to other forms like Fe2O3 which are less stable or expansive, causing the steel to be compromised wherein corrosion will ensue.”
An additional outcome of the bonding & encasing functions is observed reduction of corrosion of steel & other reinforcing materials that are set into the cement.
7. Fibrous organic materials such as canvas can be dipped in ceramic concrete to form quick-setting sculptural forms (see below, a temporary shelter built in 24 hours by eco-builder Michael Collins, designed for possible use in war-torn areas).
8. Improved durability & performance. Many ancient historical structures & monuments in the world still standing used MgO to build with – the Terracotta Army at Xi’an, the Great Wall of China (MgO-based mortar & soil-brick stabilizer), the Pantheon in Rome (“pozzolana” in the cement contained MgO & other metal oxides mined at Magnesia, Rome), ancient Hindu stupas in India & many more – this “green” technology has in fact been around for thousands of years.
10. Insecticidal properties
George Swanson, a building consultant whose company Swanson Associates specializes in non-toxic design-build construction for chemically-sensitive clients, relates of a 2,500 year old temple restoration project in China where wood columns set into MgO cement & mimicking marble perfectly, when chipped away, the wood was found in perfect condition, termite- & rot-free because magnesium repels insects.
Presidential nominee & Nobel prize winner (for his work on climate change), Al Gore is reported by Treehugger to have used AirKrete MgO foam insulation for his California residence too – possibly also due to the next property AirKrete has…
11. MgO is a refractory material that is physically & chemically super-stable at extremely high temperatures. Wikipedia says it’s thermally stable up to 700K though John Harrison notes that refractories containing periclase (high lattice energy) fire at even higher temperatures (well over 1,450 degrees C).
MgO is used as a basic refractory material for lining crucibles (used for burning chemicals in laboratories) as well as a principle ingredient in construction materials used for fireproofing. It doesn’t burn or release any smoke hence it may be used as a fire-stop material.
Additionally as an insulator it has R value 4.0-6.0 per inch.
12. MgO is also a soundproofing material & is used very effectively in interior sound partitions. In encasing plumbing pipes, water noises are very effectively reduced.
13. Excellent performance for dealing with toxic waste:
Research at Argonne National Labs (pre-eminent science/engineering research lab initiated by UChicago, backed by Dept of Energy with possible military funding) with the Russian Federal Nuclear Centre, documented that immediate neighbors of the Chernobyl reactor living in traditionally-built houses made with MgO-based cements, survived – even though they were right next door – whereas people living in modern stud-frame & concrete homes miles away, succumbed to radiation sickness – from Swanson Consulting archives.
From this research Argonne developed a material they call “Ceramicrete” which safely encases nuclear waste & prevents radioactive pollutants leaking into the environment, performing well even in high-temperature, radioactive environments – from Green Home Building article. – If only they had gotten this to Fukushima before it blew!
14. Furthermore, on a life-cycle cradle-to-grave assessment, MgO-based cements go beyond green & sustainable to actually enhancing the wellness of the whole planet: repleting soil, healing humankind, livestock & other living creatures – see following quote from Jerry Rademan of Premier Magnesia about soil pH.
15. Many sources even point out the curative properties of Magnesium: two household names many of us may be familiar with, Epsom salts & milk of magnesia, are both Magnesium compounds.
“In human biology, magnesium is the eleventh-most-abundant element by mass in the human body. Its ions are essential to all living cells, where they play a major role. Hundreds of enzymes require magnesium ions to function – Wikipedia. (List of benefits of magnesium in diet listed below from Epsom Salt Council.)
Skin & sinus allergies among concrete masons is commonly reported. The cement dust generated when Portland cement is mixed is a respiratory & mucous membrane irritant in high concentrations. When it settles on skin & mixes with sweat, & when wet concrete is sprayed in place, it can cause dermatosis to the workers.
On the other hand, when working with MgO cement products, construction workers reported their cuts & other wounds healed quickly. In fact MgO (Osteocrete) is used by surgeons for complex fractures & bone graft replacement surgery. It aids calcification or bonding in bones & ligaments thus quickens healing.
According to George Swanson, toxic building syndrome is a very real disease, it could even be a nationwide epidemic: poor air quality & daily & long-term exposure to indoor toxins in our homes & furnishings can bring about not just nausea, headaches & allergies but also prolonged illness like asthma, autism, learning & behavioral problems & cancer especially among babies, the elderly & the immuno-compromised. There is also a chronic medical condition called multiple chemical sensitivity directly attributable to our immediate environment or shelter.
“We’re being asked to endure a great science experiment that started 60 years ago when ‘modern’ materials were brought into construction. The data is in. They are awful. We are the only place on earth using these materials in a nearly unbridled fashion & we must stop immediately.”
In a book he co-wrote & self-published, he names over 30% of all products used in American construction which are highly restricted or banned in Europe & Asia, some like formaldehyde have been banned since the early 1990s.
(According to an article he wrote himself, Swanson himself sustained a tragic, personal loss when he & his wife lost a child due to pre-natal exposure to formaldehyde.)
Homeowners, business owners & builders can start small, purchasing certain plants that increase oxygen levels & help purify the air.
Swanson & many others in this rising field of healthy buildings (correspondently producers/distributors of MgO-based cement products) are advocates of the German discipline of building biology – in the US represented by architect Helmut Ziehe‘s non-profit International Institute for Building-Biology & Ecology, the mission of which is going beyond green & sustainable, to creating built environments that actually support human health & wellness.
In countries like Germany & Switzerland, building biology is required training. Design professionals & builders are held responsible for the indoor air quality of their buildings & can be prosecuted for doing what is standard practice in America. We need to make educated choices & push the government to move their subsidies from chemical-laden products to sustainable ones.
Ideally from this point onwards, everything new that’s produced should be assessed cradle-to-grave before it’s produced & manufactured. We need to stop things going into landfills which are polluting our already-depleted soil.
Strangely enough & as a final note, Magnesium can actually be used as a fertilizer (“it neutralizes the pH of soil” confirmed Rademan of Premier Magnesia, when I asked him). In fact the company also produces animal feed which “strengthens the bones of livestock, relaxes them & improves their general health”! Hence it’s a 100% recyclable building product & completely non-toxic, in fact beneficial to the earth compared to so many Portland cement-based building materials which when laid into landfills are poisoning our soil!
MgO-based cement processes compared with Portland cement
The cook-out process of making MgO cement is at half the temps of calcining Portland cement: 400-800 deg. F, which produced 50-80% less CO2. Yet the MgO cement matrix is up to 12x stronger, or 12x more stable which reduces the amount of cementitious materials used since one can effectively add organic substances to the mix without weakening the matrix. This is by far the more efficient formula.
Carbonation is also quicker & more efficient with MgO-based cements – & the matrix is actually strengthened through the process. The amount of CO2 being reabsorbed is between 12% (Dr Mark Shand) to 40% (John Harrison) to 60% (Novacem, UK) in weight. Either way it’s an added bonus.
According to Wikipedia, Magnesium is the eighth most abundant mineral constituting about 2% of the earth’s crust & it’s also the third most plentiful element dissolved in seawater (though desalination is a more expensive process) – but in the US it seems it’s fairly rare though Swanson believes we have ample ore, in his recollection, many mines actually shut down when Portland cement first came on the market in the mid-19th century.
Dolomite, magnesite, brucite, carnallite & olivine contain enough magnesium to merit extraction. There are large mineral deposits of magnesite in the US, namely in Nevada, brucite in Nevada & Texas; & olivine in North Carolina & Washington – according to Jerry Rademan.
One can buy bags of MgO powder from US distributors (& bulk them up with clay, hemp or fabric pieces) but most MgO-based sheeting is largely imported from China right now.
Rademan believes US manufacturers & distributers should push to supply our own markets with quality “Made in USA” product, hopefully in the near future with some government stimulus in the form of tax-breaks.
When eventually supply spurs new demand for such product, the mining & desalination industries will be motivated to seek new mining technologies & locations & later be able to offer more competitive prices so these cements can one day be on par price-wise with Portland cement products. Currently MgO-based sheetrock is as much as 2 to 6x more expensive than regular sheetrock.
We can all do our part in making this happen sooner rather than later by re-educating ourselves & making our personal demands known to suppliers: voting with our dollars & sense. 😉
The US Green Building Council also supports a parallel endeavor to push the building industry towards “greener” building practices but havn’t as yet addressed the topic of MgO-based cement though there continues to be numerous international discussions to date in mainstream media. (See this article from the Guardian, UK.)
The Cement That Eats CO2 http://www.theguardian.com/environment/2008/dec/31/cement-carbon-emissions
Concrete Unlikely Ally in Reducing Carbon Footprint http://www.architectmagazine.com/concrete/cleaning-up-concrete.aspx
World Coal worldcoal.org
US Green Building Council http://www.documents.dgs.ca.gov/dgs/pio/facts/LA%20workshop/climate.pdf
Wikipedia article http://en.wikipedia.org/wiki/Magnesium_oxide
George Swanson’s archives http://www.geoswan.com/html/mgo2424.html
Green Home Building http://www.greenhomebuilding.com
Dr Mark Shand, Premier Chemicals http://premiermagnesia.com/corner/articles/cements.htm
Electronic Library of Construction Occupational Safety & Health http://www.elcosh.org
International Institute for Building-Biology & Ecology http://www.buildingbiology.net
Natural Building Blog http://www.naturalbuildingblog.com/magnesium-cement-for-roofs-and-plaster/
The Concrete Producer http://www.theconcreteproducer.com/concrete/future-cement.aspx
Carbon dioxide sequestration in concrete http://www.claisse.info/special%20papers/Chun_full_text2.pdf
Press release by Tececo http://www.indiaprwire.com/pressrelease/construction-building/20130224157780.htm
From Epsom Salt Council, magnesium in one’s diet can restore:
– Improved heart & circulatory health, reducing irregular heartbeats, preventing hardening of the arteries, reducing blood clots & lowering blood pressure
– Improved ability for the body to use insulin, reducing the incidence or severity of diabetes
– Flushed toxins & heavy metals from the cells, easing muscle pain & helping the body to eliminate harmful substances
– Improved nerve function by electrolyte regulation. Also, calcium is the main conductor for electrical current in the body, & magnesium is necessary to maintain proper calcium levels in the blood
– Relieved stress. Excess adrenaline & stress are believed to drain magnesium, a natural stress reliever, from the body. Magnesium is necessary for the body to bind adequate amounts of serotonin, a mood-elevating chemical within the brain that creates a feeling of well being & relaxation
– Reduced inflammation to relieve pain & muscle cramps
– Improved oxygen use
– Improved absorption of nutrients
– Improved formation of joint proteins, brain tissue & mucin proteins
– Prevention or easing of migraine headaches