Useful: Making concrete from coal ash

WSU researchers use coal waste to create sustainable concrete

New coal concrete reduces energy demand, greenhouse emissions

PULLMAN, Wash. – Washington State University researchers have created a sustainable alternative to traditional concrete using coal fly ash, a waste product of coal-based electricity generation.

The advance tackles two major environmental problems at once by making use of coal production waste and by significantly reducing the environmental impact of concrete production.

Xianming Shi, associate professor in WSU’s Department of Civil and Environmental Engineering, and graduate student Gang Xu, have developed a strong, durable concrete that uses fly ash as a binder and eliminates the use of environmentally intensive cement. They report on their work in the August issue of the journal, Fuel.

Reduces energy demand, greenhouse emissions

Production of traditional concrete, which is made by combining cement with sand and gravel, contributes between five and eight percent of greenhouse gas emissions worldwide. That’s because cement, the key ingredient in concrete, requires high temperatures and a tremendous amount of energy to produce.

Fly ash, the material that remains after coal dust is burned, meanwhile has become a significant waste management issue in the United States. More than 50 percent of fly ash ends up in landfills, where it can easily leach into the nearby environment.

While some researchers have used fly ash in concrete, they haven’t been able to eliminate the intense heating methods that are traditionally needed to make a strong material.

“Our production method does not require heating or the use of any cement,” said Xu.

Molecular engineering

This work is also significant because the researchers are using nano-sized materials to engineer concrete at the molecular level.

“To sustainably advance the construction industry, we need to utilize the ‘bottom-up’ capability of nanomaterials,” said Shi.

The team used graphene oxide, a recently discovered nanomaterial, to manipulate the reaction of fly ash with water and turn the activated fly ash into a strong cement-like material. The graphene oxide rearranges atoms and molecules in a solution of fly ash and chemical activators like sodium silicate and calcium oxide. The process creates a calcium-aluminate-silicate-hydrate molecule chain with strongly bonded atoms that form an inorganic polymer network more durable than (hydrated) cement.

Aids groundwater, mitigates flooding

The team designed the fly ash concrete to be pervious, which means water can pass through it to replenish groundwater and to mitigate flooding potential.

Researchers have demonstrated the strength and behavior of the material in test plots on the WSU campus under a variety of load and temperature conditions. They are still conducting infiltration tests and gathering data using sensors buried under the concrete. They eventually hope to commercialize the patented technology.

“After further testing, we would like to build some structures with this concrete to serve as a proof of concept,” said Xu.

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The research was funded by the U.S. Department of Transportation’s University Transportation Centers and the WSU Office of Commercialization.

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188 thoughts on “Useful: Making concrete from coal ash

    • How about actual numbers for how it compares to traditional concrete for strength & durability?

      • I suspect they have focused on permeable concrete because it doesn’t have the same strength requirements as structural concrete. All concrete companies have dozens of “recipes” for different strengths and properties, and most would produce a permeable concrete if requested. Also known as “no fines” concrete as it has the fine aggregates omitted, it is only suitable for lower strength applications such as parking lots and pavements. Perhaps their cement has setting or strength issues so can’t be used for standard concrete applications.

        • The permeability probably just happens and they haven’t worked out how to make it impermeable yet.

          That’s not a bug, it’s a feature.

      • Traditional concrete typically has fly ash in it as a cheaper replacement for some of the cement. On my current project, our mix designs are running 2-3% fly ash, sourced from Bridger, WY. This concrete is being used for concrete footings and concrete floors in central California.

        • Flyash was being used in concrete in the early 1960s. No idea how long before that. Not exactly a new idea but maybe a new application or technique.

          • I suppose what is new is that fly ash previously was probably only a cost reducing filler, not the binder.

        • Many get flyash wrong. There are different types of flyash depending on the composition of the minerals in the coal seam. Flyash from lignite is generally detrimental because the SiO2 content is low (ie more like clay) and has high alkali content. Some flyash has high CaO content (>5%) and it can then have possolanic properties similar to some volcanic ash (as that from Santorini in Greece also I think Vesuvious in Italy). The Greeks developed Roman cement using volcanic ash with burnt lime as an initiator. This can be done with pozzolanic flyash and ground granulated blast furnace slag. It is also possible to use caustic soda but more expensive than and troublesome than cement. Most flyash from good quality bituminous coal as in NSW and Qld Australia has a very high silica content and has been used as a cement extender since at least the early 1960’s pioneered around the world by Australian companies. Very fine flyash (no carbon remaining), silica fume and very fine limestone act as a filler replacing unhydrated cement in concrete in the range 5-10% (silica fume limit 10%) for equal or higher strength. Good flyash in concrete acts to improve workability so allowing a relative water reduction in the concrete which helps improve strength. Upto 20% good quality flash replacement can be used with little affect on concrete strength at 28day but maybe some minor benefit at 120day, also some benefit for sulphate resistance (sea water application). In Australia 30% flyash is common for jobs that have lower strength requirements such as footpaths

          • I recall Wyoming Anthracite flyash being trucked from the power plant where I worked in the ’70s to a local concrete plant.

            This is another example of academia “losing it’s memory” as each new generation draws duplicate conclusions for different reasons and spins them in unique new ways.

            Real discoveries are rare these days, and face much opposition from the status quo.

          • Thanks for a detailed an knowledgeable comment. I was sure that flyash was already widely used in concrete production but ignored all that detail. Thanks.

          • My understanding is it is entirely dependent on the uranium and thorium content of the original source coal. It is not the same from one source deposit to the next.

          • You are correct. In most cases it is not much, but in some cases it can be significant. Here is a Scientific American article on the subject:
            https://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/

            Caveat: Scientific American is no longer a reliable source of unbiased scientific information, and this article is an example of why. The article blatantly attempts to scare readers in an effort to convince them that coal is evil, Facts have been twisted and sensationalized to the point that the truth is misrepresented.

          • I do not know of any flyash or coal seam that has measureable radioactivity.
            Uranium usually occurs with metal ores such as the copper deposit at Olympic Dam in South Australia (the worlds largest uranium producer)
            Thorium occurs as the minor ore monazite in some heavy mineral deposits along with rutile and zircon. These deposits have been concentrated in old beach dunes through wave action.
            Coal formation begins in swamps starting with peat. Floods can deposit minerals through the swamp but it is difficult to imagine how heavy minerals would get spread through out a large depression of hundreds or thousands of square kilometres.

          • Cementafriend – you are right about thorium and wrong about uranium.
            Here is an unbiased review of uranium contents of coal:

            https://pubs.usgs.gov/fs/1997/fs163-97/FS-163-97.html

            Hexavalent uranium (from weathering of rocks like granite) is readily soluble in water and when groundwater carrying U+6 in any concentration comes in contact with a reductant (like decaying organic material en route to becoming coal) it precipitates the highly insoluble tetravalent form of uranium as UO2. This is how most of the uranium deposits in the western USA formed. The organic debris that caused precipitation of UO2 never made it as coal, but did generate massive amounts of uranium in hundreds of small to medium-sized mines – which sustained the buildup of the American nuclear arsenal in the 1950s.

            Thorium behaves quite differently. It never gets soluble in water to any meaningful extent and occurs mainly in heavy minerals in the surficial environment. Hence doesn’t appear in coal.

            And the SciAm article is right: power plants burning uraniferous coal do emit more radioactivity than nuclear power plant (including Three Mile Island but unfortunately not Chernobyl)

          • I was told when I worked at a power station burning Wyoming anthracite that if the unit attendants who worked near the mills and burners wore radiation badges like the nuke plant operators, they would get paid leave due to exposure limits. I have always wondered if that was true.

      • Geopolymers are extremely strong and very cheap (20% of the cost of cement). I have some numbers. Tens of MPa. They are as solid as vibrated concrete, or can be foamed as you wish with a low density and big R values even at refractory temperatures.

        They are not directly comparable with cement products because they are not made from filler (aggregate) glued together with something. The entire volume of material is transformed chemically into a matrix something like a crystal. You could put in fillers of course if there was good reason such as even lower cost. One possibility is wax beads (1-2mm) or expanded polystyrene beads.

        One impact of using this material (coal ash) is that it directly offsets CO2 from cement production. If people are worried about CO2, they should support the use of all coal power station fly ash as geopolymer input materials, and correctly calculate the offset. There is a heck of a lot of coal ash lying around on this planet. Burn high ash coal to make electricity, make concrete products out of the ash, mitigate to your heart’s content. Soon they will be selling mining rights to old ash ponds.

        • The Eygptians used a geopolymer to form the limestone blocks for the pyramids see https://www.geopolymer.org/library/archaeological-papers/i-chapter-1-of-the-pyramids-book/. The French have reproduced the method plus other geopolymer products which you can find on the website of the Geopolymer institute. A number of papers have been written about making geopolymer from flyash but to my knowlege there has been no commercial production anywhere and I would dispute that it is cheaper than cement (of various types including use of ground granulated slag and flyash) in concrete. Using caustic soda (NaOH) or KOH as a reaction initiator is more expensive with safety concerns than lime or cement.
          With the stupid move to renewables such as wind and solar and peak electricity using gas there is now not enough good quality flyash in many countries such as Australia, UK and USA. I believe most of the Indian coal gives poor quality flyash. The power station producing a pozzolanic flyash in south Australia was blown up by the stupid government and power prices there are now amongst the highest in the world.
          Finally, so called “climate change” is a political scam with no science or engineering technological behind it. It is costing the world (except for a few scammers) (mainly poorer people) dearly

      • AAC – Autoclaved Aerated Concrete has been doing this for years. Better thermal properties than brick.

  1. I wonder if they have performed any tests on this “pervious” concrete when it is saturated with water and in sub-zero conditions. Can it withstand the expansion of water to ice?

    • Concrete is generally pervious to water. When used where it needs to be less pervious it is painted or tarred. Cement block foundations for non basement applications are sat on poured concrete footers placed below the frost line. The part of the foundation exposed to freeze thaw is tarred or otherwise sealed.

      • Short answer: Close but wrong. Driveways are not coated, roads are not coated. And this is because of degree of pervious.

    • Porous concrete is used in the Midwest in freezing areas. The design involves making a granular base for the water to drain into. The water then soaks into the ground below. By design the water does not stay in the concrete: it soaks away before freezing.

      • You are wrong. Polyethylene water barrier is placed over fill/gravel before poring slab. Concrete is poured directly on water barrier. No PhD (post hole digger) needed, just a quick look at building codes.

        • Building codes do not apply to street or site plan design.

          It was a bad idea to place plastic under streets or parking lot pavements. Water could get through the pavement through cracks but could not get way, then froze. Far better to wet the sub-base before placing the pavement, which would prevent the sub-base from pulling water out of the concrete before it cured. Inside a building you should put the plastic under a slab on grade but not outside.

          I know current design having just retired from engineering. My first street pavement design was in 1974: that pavement is still in use. I also designed for stormwater control until a year ago.

          You should look for “porous pavement” with your favorite search engine.

        • That reminds me of my experience with a ground-worker team on construction building sites (south-west England). A house’s foundation would begin with rocks, larger then smaller, topped off with sand and pounded flat. Then a thick sheet of polythene plastic would seal off the whole foundation area and the cement was poured on top of the plastic. The presence of the plastic layer made it clear that the cement by itself was not expected to be impervious to water.

    • I think that there is a related issue. What happens as the water percolates through the “pervious” concrete? Does it dissolve any of the fly ash? The article remarks that the landfills are a problem because of leaching. Will this just spread out the problem and change the problem from being local to being regional?

      • Clyde, the leaching is of sulphates from the flue gas scrubbing with lime to produce calcium sulphate which is sparingly soluble. The ash (fly ash and bottom ash) is burned shale associated with coal seams. BTW the scrubber gypsum is now a valuable product for production of drywall board, and as agricultural soil conditioner, and is a major competitor with gypsum mining. The press release should have given credit for its use in cement to developers 60 -70 years ago and then talked about 5heir modification. Piracy is an everyday event among our post modern researchers.

    • Geopolymers are not all “pervious”. I have seen three layer versions with a very dense outer layer with a foamed centre to provide an insulated, impervious, wall-like structure, or floor. Close up it looks a lot like black arborite as used in chemistry lab bench tops.

  2. I grew up in a house made of cinder blocks. Back when coal was burned by stoking boilers and home furnaces with chunks of coal instead of coal powder the coal burning process created cinders. Cinder blocks were lighter than cement blocks and better insulated. They were also a bit stronger though perhaps more brittle.
    I would be interested in knowing if the nano process is mostly turning fly ash back into cinders by getting it to aggregate into larger cohesive particles similar to cinders?

    • Structurally cinder blocks were unpredictable because of the inability to control cinder quality. They were porous and leaky basements were the norm. They also cracked when foundations settled, or in earthquake prone areas were they failed miserably. They have been replaced with concrete blocks used by masons who don’t want call backs.
      I have never used anything but Insulated Concrete Forms. I started using the Styrofoam Forming Systems on all the houses I constructed as early as 1982. Forms have evolved over the years through several manufacturers (including a regular poster and inventor who developed his own system) .
      The formwork involves a network of rebar ( concrete posts & bond beams ) that when completed results in a structurally superior ( earthquake and settlement resistant ) wall that when finishes are added gives an R-35 + insulated wall.
      Not building anything lately but https://www.foxblocks.com has made many improvements to the system—almost wants me to come out of retirement–nah.

  3. That’s nice, but what does graphene oxide cost? And what environmental risks are associated with the production?

  4. It’s worth experimenting with. I’m curious if it could be pumped back into defunct coal mine veins with the idea that new adjacent veins could then be mined.

    Also:

    “concrete can also absorb carbon dioxide and store it in a process commonly referred to as carbonation.”

    [ http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-design-production/concrete-as-a-carbon-sink ]

    “But as cement ages and weathers over time, it also absorbs carbon dioxide in a process called carbonation”

    [ http://www.abc.net.au/news/science/2016-11-22/concrete-is-a-carbon-sink/8043174 ]

  5. The team designed the fly ash concrete to be pervious, …

    That may spell disaster in a freezing climate. Where I live, air-entrained is a must to prevent damage due to water freezing in cracks and other voids.

    • Why would they make the concrete be porous to water? It is not as if every last cm of ground is going to be concreted.

      • If you’re going to build an earth retaining structure or bridge abutment, you better think about drainage. link

        • Although Pervious Structural Concrete wouldn’t spell well for a Building that would leak like a Sieve.
          Also the water infiltration would lead to eventual Rebar Failure due to water induced oxidation of the structural component

          • In areas where there is going to be a lot of water infiltration they have rebar that has been coated to protect it from water.

          • Rebar failure is super expensive.

            Every year the nation spends about $8.3 billion, directly from the cost corrosion in our national highway bridges. link

      • Many local governing agencies have ordinances that limit the amount of non-pervious surfaces in a development. Pervious concrete and pervious asphalt, especially for parking lots, is a solution to that limitation where large paved areas are required but otherwise prohibited.

    • Porous concrete is in common use in stormwater control in urban areas. It is designed so the water soaks or drains away before the water freezes.

    • commieBob

      Dear God. I thought I was amongst a community of optimists.

      The guy’s found a use for landfill material. It might not be perfect, or solve all our concrete problems, but come on, at least it’s a start.

      This is an example of technology everyone on WUWT lauds as the buffer against AGW (assuming it’s a problem) yet you guys are condemning it like grumpy old men.

      Jesus H, you all sound like my Dad.

      “Can’t be done, impossible, impractical, technically beyond our reach. Watch TV anywhere other than in black and white, on a box in the living room? Just not possible……..Oh! fork me, a WiFi, 4G mobile phone, not just that, a smart phone, in colour, and you say I can stream my favourite programmes from almost anywhere on the planet?…….where the eff did that come from?”

      Sadly, my old man barely saw a mobile phone, but in his youth, he was a techno freak and would have loved our progress today.

      And I’m a grumpy old man now as well, but I still embrace logical technology.

      Goddamn, when I think of the old bugger now, he would have been watching F1 on his smart phone, on the golf course playing a medal, whilst texting me his scores and commenting on the driving, both his and F1.

      I’m really sad he missed what we are going through now, he would have loved it.

        • Greg Cavanagh

          There is a problem in following in a successful man’s footsteps. One can rarely match up to him. I tried, but failed miserably.

          Now I simply focus on my family. I succeed in my own way.

      • The team designed the fly ash concrete to be pervious, …

        Apparently there’s a use for pervious concrete, probably just not where I live.

        Presumably they could also design it to be impervious. They should also do that.

        Anyway, when you come up with something new, you should expect surprises when people use it.

      • Commie, my complaint is it has been used for about 60 years. Now if they have a superior formulation, well and good, but dont rob the old guys who invented the idea. It looks like they are taking credit for use of fly ash in concrete. BTW, siliceous volcanic ash and some aluminosilicate residues from chemical processes is also used. They are all called pozzolanic materials in reference to their cementitious properties. I believe the Romans used the “fly ash” from Vesuvius for cement.

    • Impervious is easy. Light and insulating are preferred traits. Check out ‘geopolymers’.

    • Absolutely! Eliminate the large aggregate, use a graded series of fine aggregates, add acrylic emulsion and crystalline waterproofer to the mix. My mix for lining the walls of water features.is fine sand, ordinary portland cement, calcium sulfo-aluminate cement, metakaolin, silica fume, Xypex or Penetron crystalline waterproofer, polyvinyl alcohol fiber, and acrylic emulsion in water. Waterproof, impervious to chloride and sulfate, high compressive and tensile strength and cracks are self-healing.

    • Dolores, The “ash” is what you get when you burn the small amount <10% of shale which encloses the coal seam. Your volcanic story is fake news. Coal is lush swamp vegetation that gets buried under successive layers of shale, sandstone etc. under an advancing sea and pressure and heat at depth compresses and carbonizes the vegetation.

    • Good on you Dolores. I knew 25 years ago that new coalification had been found to be taking place at St Helens within six months of the eruption. But you’ll never break through the cognitive dissonance on this site. So many here think that climate science is the only science affected by corruption. The video you link to doesn’t support the consensus view of evolution, so the good skeptics of CAGW will eagerly turn their backs on real science in another field. What a crazy world!

  6. At Thorn EMI Central Research Laboratories we were using coal ash, aeriated as insulation material. Think light weight building blocks. We even made an oven that had superior insulation properties to glass fibre for ovens at 250 deg C. However the domestic appliance division turned it down as the material was no good at lacerating newly born cockroaches, which apparently nested in ovens.

    • The geopolymers parts I ordered in April are good to 1300 C. Some blends fail at 700. It depends on what is in it.

  7. They’d better study this product much more than FIU did when they built a walk bridge out of an untested construction material that ended up collapsing and crushing a pobrecita.

    • There’s a good bet that they are, but have been coated with a sealant to prevent intrusion.

    • In Iowa it is common use as an amendment to Portland cement as well as a treatment to reduce swelling in some soils below streets. There are occasional shortages of flyash.

      The flyash that is landfilled has already reacted with water and is not useble.

      • It is not useable for that purpose. Geopolymers are operating on a different chemistry: alkali-bonded glasses.

  8. Ignorant dupes attempting to fool experts by re-inventing what has been known for a very long time…

    “FLY ASH FOR CONCRETE”

    “How Fly Ash Reduces Heat of Hydration in Concrete
    The hydration of cement is an exothermic reaction. Heat is generated very quickly, causing the concrete temperature to rise and accelerating the setting time and strength gain of the concrete. For most concrete installations, the heat generation is not detrimental to its long-term strength and durability. However, many applications exist where the rapid heat gain of cement increases the chances of thermal cracking, leading to reduced concrete strength and durability. In these applications, replacing large percentages of cement with fly ash (fly ash generates only 15 to 35 percent as much heat as compared to cement at early ages) can reduce the damaging effects of thermal cracking. While the first structures to apply this concept in earnest were hydroelectric dams built in the 1930s and 1940s with 40% to 50% cement replacement,”

    “Who Supports Fly Ash Use?
    * U.S. Bureau of Reclamation – Has used fly ash extensively on dam projects.

    * U.S. Army Corps of Engineers – Specifies fly ash in roughly 95% of projects.

    * U.S. Environmental Protection Agency – Requires that fly ash must be allowed on federally funded projects and
    promotes fly ash utilization through its Coal Combustion Products Partnership (C2 P2) program.

    * U.S. Department of Energy – Has reported to Congress that “[T]he increased utilization of coal combustion
    byproducts could provide numerous environmental and economic benefits to the United States. Positive environmental effects include (1) reduced solid waste, (2) reduced use of natural resources, and (3) reduced energy consumption and CO2 emissions from the reduced use of natural resources and the production of cement.”

    * U.S. Federal Highway Administration – Supports fly ash use and publishes information in its “Fly Ash Facts
    for Highway Engineers” guide. American Concrete Institute – Allows use of “water to cement plus pozzolan” ratio in lieu of “water to cement” ratio. Has no limit on the amount of fly ash used in concrete that will not be exposed to deicing chemicals.

    * All 50 U.S. States – Allow or mandate use of fly ash in state-funded projects.”

    It’s so new and especially “designed” by “students” that it’s been used and well known to virtually everyone since coal was used as fuel.

    “Fly ash is comprised of the non-combustible mineral portion of coal. When coal is consumed in a power plant, it is first ground to the fineness of powder. Blown into the power plant’s boiler, the carbon is consumed — leaving molten particles rich in silica, alumina and calcium. These particles solidify as microscopic, glassy spheres that are collected from the power plant’s exhaust before they can “fly” away — hence the product’s name: Fly Ash.

    Chemically, fly ash is a ‘pozzolan’.”

    ” There are examples on the west coast of Italy, in a town named Cosa, where a mixture of natural pozzolans (volcanic) were combined with lime to produce concrete that has withstood waves and attack from seawater for over 2,000 years and is still intact.

    – The Pantheon in Rome is a pozzolan and lime concrete structure built around 300 B.C. and still stands today. It features a cast concrete dome 124 feet in diameter and was the world’s largest domed structure until modern times.”

    • The Roman engineers were well ahead of the game. The Dark ages and superstition set us back 2000 years of development. The Pantheon is still standing while the BQE is tumbling into the east river.

      • The Pantheon was built during the reign of Hadrian (117-138 CE) so it is only about ~1900 yro. But, that makes it the oldest standing building with a useful interior volume in the world.

        Your view of history is excessively bound to Northwest European. It is true that civilized (i.e.) urban life disappeared in Northwestern Europe after the collapse of the Western Roman Empire in the 5th Century CE. The Eastern Roman Empire continued in Constantinople (n/k/a Istanbul), where Hagia Sophia, was built in 537 CE. The Umayyad Muslims built the Dome of the Rock in Jerusalem at the end of the 7th century and the Umayyad Mosque in Damascus a generation later.

        What were the Dark Ages in Northwestern Europe were productive times of high Civilization in the Middle East, South, and East Asia. Still important technologies such as wind mills, magnetic compasses, gunpowder, and printing derive from those places and times.

    • A careful reading beyond the first few paragraphs reveals that the fly ash is used here as a replacement for cement, not as an admixture.

      “Our production method does not require heating or the use of any cement,” said Xu.

    • ATheoK

      Wrong product. Check geopolymers and then come back. You are thinking of fly-ash cement. They are talking about alkali-bonded high temperature glass-phase coal ash produced above 1300 C, typically. Cement products start to burn at 400 C. This stuff (stuffs) can take 1300-1400 C.

      Another cement displacer is the whole group of phosphate bonded alumina materials. They are also cold-setting and have very high application temperatures.

      • Sorry Crispin. I didn’t realize all of those coal fires used to smelt or heat iron were such tepid temperature smokers.

        Run air through a coal fire and temperatures soar well past molten glass temperatures.

    • At last! A comment from someone who has a clue about the use of fly ash in concrete. (Previous commenters? Not so much!)

      A lot of generally ill- informed discussion about porous concrete (or air-entrained concrete), usually specified for concrete highways where subjected to salting for ice conditions. But you would not want to use ordinary steel mesh or reinforcement!

      And normal dense concrete is highly impervious. Have you never seen a concrete dam?

      But let’s get back to this team of academics. Their process apparently eliminates ordinary Portland cement. And there have been other ‘natural’ cements (pozzolans) used since Roman times and still commercially available today in the UK for special applications. So nothing revolutionary there.

      But here, they are using Graphene Oxide in the mix. Super. But as the very first comment asked, how much does that cost? Did someone nip down to Walmart and buy a couple of sacks?

    • Makes sense to me. There is enough of it to mine that it would guarantee that a superior method of producing energy will be developed by mankind before the coal supply runs out.

    • If fly ash starts to be something that power companies can sell, rather than having to pay to dispose of, that will have an impact on the profitability of coal plants.

      • And don’t forget the CO2 offset payments that will be due to coal burning companies. It literally replaces Portland cement.

  9. This is a joke right. Please tell me it’s a joke. Please

    I went through some amount of concrete in agriculture and the very last thing any/every peasant wants is animal slurries, silage effluents, sanitisers & disinfectants disappearing through the concrete.

    Good Grief, The European Union via the Carrot/Stick mechanism that is laughingly called ‘Support’ are now wanting all manure stores to be airtight as well as watertight. (To prevent the escape of Ammonia, which we all know is 97 thousand million billion times more potent than carbon oxide)

    Where I farmed, North Cumbria was/is famous for its rainfall and the general rule of thumb for houses such as mine with cement (concrete) roof tiles was to replace them every 40 years because: (get this and do tell me you knew it) after that sort of time they become porous and let the rain into your house.
    You know they’re at the end of their lives because they start growing moss & lichen and everyone in the house gets colds, general ill health and something akin to asthma and then, keeps turning the heating up.

    Would anyone ever contemplate using this shyte in a nuclear reactors, sea-walls or even a fish pond in your own garden?
    Would you?

    When laying concrete, do you not first remove all the top soil, more often than not revealing clay or something that is not porous. So wtf is the point of porous concrete? Where does the water go next?

    Then, I see mention of Calcium Oxide AKA Quicklime in this stuff’s manufacture.
    Quicklime is just found laying about the planet great copiousness is it.
    Yeah right. Pull the other one… Not like it comes out of lime/cement kilns or anything. Oh no, The Unicorns deliver it just like storks deliver babies.

    Fly Ash is NOT just some benign stuff. It’s full of metallic horrors like mercury, chromium, copper and arsenic not least and these clowns want to spread that all around everywhere, leaching into the groundwater as they so glowingly profess.
    It needs to be inside a landfill, where we know where it is: THE best place for it by yer average Country Mile.
    No. Make that a parsec

    Are they COMPLETELY insane or just 99.97% insane.

    • Stormwater runoff in urban areas is a major problem. Providing a place for the runoff to to be stored spreads the discharge over time reduces the peak discharge so that downstream properties do not flood. Storing the runoff in granular material under the pavement of a parking lot is one method. It would usually be used to receive water directly from a rooftop or other impervious surface. It can also be used to cool down water before streams that are sensitive to temperature.

    • Peta of Newark

      First let me say, I’m on your side, especially regarding EU farming regulations. Fishing is another EU screw up where dead catches were thrown overboard because they didn’t conform to quota. I’m sure there are many other examples of both.

      But fly ash is a useful material. It might not be perfect for your use, but some concrete’s need to be porous. So if it can be used for humankind’s benefit, instead of being chucked away, then why not?

      And I’ll refer you to ATheoK’s link (above). It seems fly ash has been used for centuries as a concrete additive in structures lasting thousands of years.

      http://flyash.com/data/upfiles/resource/Fly%20Ash%20for%20Concrete%202014.pdf

    • Peta, please read further about geopolymers.

      “Fly Ash is NOT just some benign stuff. It’s full of metallic horrors like mercury, chromium, copper and arsenic”

      Then how would locking it into a glassy state not be a good thing?

      But I still object to the alarm. Just because something is measurable does not mean it is harmful. All soil has “mercury, chromium, copper and arsenic” and so does all food. So do you, and so do I because it is a natural part of the environment. Soil has uranium in it too, and thorium. Standing out in the sun subjects you to continuous radiation of about 17 micro-Sieverts. Horrors! Stepping into a concrete building to shield yourself from it can raise that radiation level to 26 because granite is radioactive and it’s in the concrete.

      You get my drift? Unlax!

    • A lot of anti-civilization fake news in there Pete. I think the new EPA is going to fix this for us, though and cull out those horror stories for us.

    • Peta: “It’s full of metallic horrors like mercury, chromium, copper and arsenic not least and these clowns want to spread that all around everywhere, leaching into the groundwater as they so glowingly profess.”

      Those minerals and others were originally “spread around everywhere.”
      They were collected when the coal was mined.
      They were concentrated when the coal was burned.
      They can be dispersed to their original state by water and gravity.
      Insanity is not necessary to this equation.

    • Concrete is normally permeable. Yes, that stuff laid down for barn floors, especially if it’s a cheaper grade is quite porous.

      It’s a major cause of damage to concrete, especially long term.

      Use of pollozan
      “A siliceous, or siliceous and aluminous, material which in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties”

      Fine grade glassy ash, volcanic or coal, forms a concrete that is less porous.

      “Most people have seen concrete or masonry walls or slabs with the white, chalky surface coating or streaks called efflorescence. Efflorescence is caused by the face of the concrete being wetted and dried repeatedly, or by the movement of water vapor from the damp side of the concrete to the dry side through the capillaries (voids), drawing out the water soluble lime from the concrete, block or mortar.
      A typical 5 sack concrete mix having 470 pounds of cement per cubic yard has the potential of producing 118 pounds of lime. Fly ash chemically reacts with this lime to create more CSH, the same “glue” produced by the hydration of cement and water, thereby closing off the capillaries that allow the movement of moisture through the concrete. The result is concrete that is less permeable, as witnessed by the reduction in efflorescence.”

      “How Fly Ash Protects Concrete
      An extremely important aspect of the durability of concrete is its permeability. Fly ash concrete is less permeable because fly ash reduces the amount of water needed to produce a given slump, and through pozzolanic activity, creates more durable CSH as it fills capillaries and bleed water channels occupied by water-soluble lime (calcium hydroxide).

      Fly ash improves corrosion protection. By decreasing concrete permeability, fly ash can reduce the rate of ingress of water, corrosive chemicals and oxygen — thus protecting steel reinforcement from corrosion and its subsequent expansive result.

      Fly ash also increases sulfate resistance and reduces alkali-silica reactivity. At this point a distinction between Class C and Class F fly ashes needs to be made. While both improve the permeability and general durability of concrete, the chemistry of Class F ashes has proven to be more effective in mitigating sulfate and alkali-silica expansion and deterioration in concrete. Some Class C fly ashes have been used to mitigate these reactions, but must be used at higher rates of cement replacement.

      Fly Ash in concrete can reduce sulfate attack in two additional ways:
      – Fly ash reduces calcium hydroxide, which combines with sulfates to produce gypsum. Gypsum is a material that has greater volume than the calcium hydroxide and sulfates that combine to form it, causing damaging expansion.

      – Aluminates in the cement also combine with sulfates to form expansive compounds. By replacing cement, the amount of available aluminates is reduced, thereby lowering the potential for this type of expansive reaction.

      In reducing alkali-silica reactivity, fly ash has the ability to react with the alkali hydroxides in portland cement paste, making them unavailable for reaction with reactive silica in certain aggregates. Certain studies suggest that greater than 30% replacement with fly ash for cement has a dramatic effect in combating this expansive reaction.”

      Basically, fly ash from coal is very old news. Fly ash from coal is mandatory for dams and the Army Corps of Engineers uses fly-ash concrete in 95% of their projects.

      As the Romans proved so well, ash, including volcanic fly-ash has been known and used very effectively for millennia:

      “In fact, the term “pozzolan” is derived from the name of an Italian city — Pozzuoli — that is regarded as the birthplace of ash concrete technologies. Famed Roman structures such as the Pantheon and Colosseum, as well as many roads and aqueducts, are still standing over 2,000 years after their construction — in part because of the durability of their ash-based concrete.”

      The WSU researchers are claiming to reinvent technology known for over 2,000 years. Nor is using coal fly-ash new by many decades. These WSU researchers are duping their publisher and people who fall for their lines.

      “WSU researchers use coal waste to create sustainable concrete

      New coal concrete reduces energy demand, greenhouse emissions

      PULLMAN, Wash. – Washington State University researchers have created a sustainable alternative to traditional concrete using coal fly ash, a waste product of coal-based electricity generation.

      The advance tackles two major environmental problems at once by making use of coal production waste and by significantly reducing the environmental impact of concrete production.

      Xianming Shi, associate professor in WSU’s Department of Civil and Environmental Engineering, and graduate student Gang Xu, have developed a strong, durable concrete that uses fly ash as a binder and eliminates the use of environmentally intensive cement. They report on their work in the August issue of the journal, Fuel.”

      Heavy metals in fly ash used in concrete is not much different than the heavy metals contained in all granites.

  10. Very old idea to get rid of all the coal ash from power production. It does not make concrete, it is a concrete additive. This has been extensively studied for its properties in the concrete.

    • According to the article they are replacing the cement with fly ash. It’s not just a supplement.

  11. Fly ash, like rice hull ash, have both been extensively studied for their use in concrete. Something like 10% of the concrete can be ash. The silica in the ash is cristobalite, a carcinogenic respiratory hazard, so getting rid of it has been studied for at least 30 years.

  12. This appears to be a new way to use coal fly ash in concrete. However the use of fly ash in concrete is not new.

    Having run a state’s artificial reef program where we used concrete rubble and manufactured reef modules made from concrete we got major blow back from the environmental and part of the regulatory community. They screamed about heavy metals specifically mercury. When we pushed back noting we had a federal and state mandate to build artificial reefs they came back with the precautionary principle as a standard. By then we had enough political backing to require them to come up with leaching studies demonstrating the risk. They tried to insist we use artificial reef construction dollars. All that did for them was gain us more political backing.

    Ironically Division of Solid Waste wanted to know exactly how much fly ash we could use per year.

  13. Very interesting! The paper is pay walled but the abstract provides some insights.

    Here’s the abstract to the key paper:
    Influence of graphene oxide in a chemically activated fly ash
    Authors: Gang Xu a Jing Zhong bc Xianming Shi a
    https://doi.org/10.1016/j.fuel.2018.04.033

    Highlights (GO = graphene oxide)
    •GO can affect the distribution of hydration precursors as a functional material.
    •GO increases the polymerization degree of fly ash geopolymer.
    •GO promotes the formation of low quartz and jennite-like hydrates.
    •GO improves the mechanical strength of fly ash geopolymer notably.

    Abstract
    To divert fly ash from hazardous waste stream to beneficial uses, this work aims to improve the solidification of fly ash as a geopolymer material by using graphene oxide (GO). The hydration precursors, morphology, elemental composition, mineralogy, chemical structure and ordering of GO-modified fly ash geopolymer were investigated by means of Raman spectroscopy, SEM/BSE, EMPA, XRD/TGA and 29Si/27Al MAS-NMR, respectively, to unravel the role of GO. The experimental results suggest that GO regulated the Ca/Si, Si/Al and Ca/(Si + Al) mole ratios to facilitate the formation of fly ash hydrates with improved mechanical strength, as GO showed the ability to selectively affect the distribution of different hydration precursors. GO also promoted the formation of low quartz and jennite-like hydrates. Overall, the 28-day compressive strength of fly ash geopolymer (w/b = 0.35) in this study was improved by 23% (from 33.6 MPa to 41.4 MPa) with GO admixed at 0.02% by mass of fly ash. The NMR study showed that GO improved the polymerization degree of fly ash geopolymer by increasing the total Q3 and Q4 Si-tetrahedrons, which suggests potential for improving the immobilization of heavy metals in fly ash.

    Additional publications by the authors on this topic are here:
    Characteristics and applications of fly ash as a sustainable construction material: A state-of-the-art review
    Xu, G., Shi, X.
    Characteristics and applications of fly ash as a sustainable construction material: A state-of-the-art review
    Resources, Conservation and Recycling, Volume 136, Issue undefined, September 2018

    Influence of graphene oxide in a chemically activated fly ash
    Xu, G., Zhong, J., Shi, X.
    Influence of graphene oxide in a chemically activated fly ash
    Fuel, Volume 226, Issue undefined, 15 August 2018

    Graphene oxide-modified pervious concrete with fly ash as sole binder
    Xu, G., Shi, X.
    Graphene oxide-modified pervious concrete with fly ash as sole binder
    ACI Materials Journal, Volume 115, Issue 3, May-June 2018

      • In English, HotScot!
        Coal fly ash is a ‘disposal cost’ problem for most coal fired power plants. If a valuable use for the fly ash can be created, it could become a source of revenue for the coal fired power plants. Modern engineering attempts to create valuable products out of these industrial waste streams.

        This paper details an ‘early stage’ series of experiments to develop a high fly ash content concrete, as compared to low fly ash content or no ash content conventional concretes. The lab level experiments have shown adding graphene oxide to the high fly ash content (HFAC) concrete mix causes chemical reactions that improve both the stiffness and strength of the fully cured concrete. They used a variety of chromatography, scanning electron microscopy, and nuclear magnetic resonance methods to characterize the unique chemical reactions that took place during the mix-and-cure process and define the distribution of the phases in the concrete that resulted. This is fundamentally important. If they understand the underlying chemical reactions that improve bonding of particles in the concrete, they can use that information to guide the next series of experiments to get even better material properties in the final product.

        The results look promising. They plan to install some of the current recipe/mix of HFAC concrete in outdoor test applications around the WSU campus in Pullman WA USA. This will provide additional information about how the HFAC concrete ages and performs over time in the hot summers and freezing winters typical for Pullman. If the combined lab and outdoor tests prove the HFAC concrete has structurally useful and reliable properties at a competitive price, more coal fly ash becomes a valuable commodity rather than a waste disposal problem for coal fired power plants. Bear in mind that the structural properties will have to be independently verified by test batches processed through commercial concrete manufacturing and testing companies and industry specifications will have to be written, test results validated, and all approved before the HFAC concrete can be used for critical structural applications.

        They are also planning additional lab experiments to further improve the material properties of the end product. If they succeed again in the lab, they will deploy further outdoor structural tests around the WSU campus and ….. the wheel of continuous improvement goes round and round!

        Hope this helps!

        • Yep. That’s the way it’s supposed to work! So rather than us being grumpy old men, intoning “It will never work!” over and over again, we could at the very least phrase it as, “Have you thought about…?” I see an interesting concept. OK, maybe just an extension of an existing concept, but at least they’re going someplace with it. Their goal is to make it a commercial product, the experiments are to help them to determine where, and I don’t mean just geographically, but where in the infrastructure does this stuff fit. Like I said already, let’s check back with them in a year or two.

  14. Fly ash has been a concrete additive for decades. Back in 1980 we used it as an additive for a soil cement parking lot sub base in Maryland. Interesting that they are expanding its use.

  15. Great, radioactive cement. Coal ash is a common source of uranium for countries that don’t have any domestic mineral sources.

        • Twice nothing is still nothing.

          The vast majority of radioactive waste is things like the jumpers the workers were wearing.

        • This is just another fear mongered bit of fake news courtesy of the marxbrothers who would lead 7s snd protect us to death.

      • Correct. Fly ash just happens to be easy to process. Central and eastern Mongolia is uraniferous – the whole thing. Coal from that region has higher than average uranium content, but it is not in the least hazardous to park your yurt on top and sleep on a pile of it. The exposure from 500% concentrated coal ash is 1/40th of standing outside under the sky.

        Measurable does not mean dangerous.

        A red granite counter top is far more radioactive than coal ash.

    • Fake news – EPA will be culling out the stuff put there by the marxbrothers. There are 92 natural elements in a teaspoon of dirt. Some red granites widely used in construction countertops etc, are uranium ores at about $200 a lb for yellowcake.

      I used to chew petroleum tar I picked up as blobs along the railway tracks 75yrs ago and actually broke the stuff up into pieces and sold to my friends for two cents a chew. I used to play with mercury, I had about 50grams of it, had my teeth filled with mercury amalgam and my cuts dressed with mercurochrome and iodine. I found a chunk of lead on a broken strap from an anchor used to hold the delivery horses while the driver delivered milk, bread and blocks of ice to homes in Winnipeg. I used to melt it in a jam pail in our coal fired furnace and pour it into jar lids. Hey, Im still hail and hearty and working as a mining consultant. Okay, that, I agree was not good practice but is a measure of the over the top hysteria even fairly sensible people seem to fear in such stuff. Believe it, we are pretty safe, bordering on a hermetically sealed world. In the old days we ate todays superbugs for lunch!.

  16. “Molecular engineering
    This work is also significant because the researchers are using nano-sized materials to engineer concrete at the molecular level.”

    I think the word they are groping for, is “Chemistry”.

    I had thought that the one advantage of global-warming hysteria is that it had driven the term “nano-technology” and associated wastrels back into the funding woodwork whence it came. Alas, it would seem not.

  17. ‘“After further testing, we would like to build some structures with this concrete to serve as a proof of concept,” said Xu.’

    So why not wait til you have proof of concept before you make a public announcement?

  18. This is something that’s been done for a while but there are a couple of ways to improve it and one gotcha for cold climates.

    Fly ash has been used at up to 30% substitution for cement in concrete for decades. But not all fly ash is the same. It often contains residual carbon or soot and if a concrete is designed to be used in cold weather, surfactants are added to entrain air that makes it resist freezing and thawing. If there is too much carbon in the ash, it acts to remove the surfactant and you don’t get the air entrainment needed for frost resistance.

    When I did work with high fly ash contents in mortars, I’d get tremendous variability in the consistency but there were a few ash sources that processed really well. We also added silica fume (a byproduct of silicon production) which made the material really impermeable but this can also increase shrinkage in the cement matrix and cracking in the concrete. One surprising benefit of adding both fly ash and silica fume is that it eliminated problems with a phenomena called alkali (in the cement) silica (in the aggregate) reaction. That would allow you to use cements with high alkali contents in conjunction with a lower quality aggregate and still make good materials that were durable.

    As I recall, it was possible to get pretty decent mortars that had 20% cement, 70% ash and 10% silica fume but less than 50% ash was more practical. All this sounds great however until you encounter building codes. They often have upper limits on the amount of mineral admixtures (the fly and silica fume) and rules against using mixtures of mineral admixtures. Perhaps that’s changed in the last 20 years.

    • It is not a concrete product. It is an amorphous alkali-bound glass. They are collectively known as geopolymers.

  19. even IF fly ash had needed high heat to work would that still not have been acceptable?
    would have at least gotten rid of the fly ash.
    have not had chance to read up on it much, anyone know how compression strength is compared to standard concrete mixes?

    • joelobryan

      “And where does graphite come from?”

      The Moon?

      OK, I give in, where does graphite come from?

      • The high grade stuff is mined. Low grade amorphous “lampblack” is made from petroleum coke.

  20. OK, I am a chemist by UCBerkeley training, and have some modest hands-on experience in cement chemistry while taking Materials Science electives. So… what’s the REAL story here?

    Before I got to the critical two words (sodium silicate), I was wondering “how on Earth are they getting FLY ASH to bind in a classic cement hydration-and-crosslinking chemical reaction with graphene oxide?” I was reading slowly, and I thought “well, maybe they’re using a strong glassy binder like sodium silicate, and probably augmented with a ‘classic’ cement hydration-and-crosslinking compound like refactory quicklime/burnt lime (calcium/magnesium oxides)”.

    Then but a paragraph later, “sodium silicate” and “calcium oxide” are slipped in.

    THING IS — that as soon as you add “water glass” (Na₂SiO₄ sodium silicate) and “quicklime/burnt lime” (CaO calcium oxide) in some portion to fly ash, you are again making cement by an alternate route. The CaO does its job turning to various intermolecular bridge compounds thru slow hydration and water-mediated cross-linking. The Na₂SiO₄ does its work quickly, donating the silicate anion to cross-linking, binding to the various refactories of fly ash.

    The graphene oxide … to me … seems to be a 3 dollar bill. It might act as a rate-related catalyst, causing a slurry of the interrelated compounds to ‘set’ faster, or ‘set’ in a more crystalline (strength) fashion. But itself, it appears to not have a structural component. Moreover, if “graphene oxide” works as a catalyst, there are a number of other cheap, traditional cement-chemistry catalysts well documented in the literature and industrial practice.

    _______

    Point is, that there is another problem that is going for the asking.

    WHAT KIND OF FLY ASH? Coal ash. The problem? Radioactivity potential. Some (many, actually) fly ashes from coal sourced in the US are so radiactive that they set off radiation detectors while being driven by truck to waste sequestration facilities. They’re considered a potential ORE for uranium and thorium. “Cinder blocks” — the ubiquitous construction grey or tan blocks — made before 1985 when tough anti-radiation laws went into effect, were one of the strongest sources of airborne radon gas that bedeviled below-grade basement air domestically.

    That then is the problem.

    ALSO the “other three dollar bill” is that the claim of “not being energy intensive like conventional concrete(s)” is disingenuous: it takes substantial energy to kiln-convert limestone/dorite (calcium carbonate, magnesium carbonate, as a mixture) into calcium/magnesium oxide (“quicklime / burnt lime”). If the fly ash is a SIGNIFICANT (majority) component to the structural integrity of the cement-reaction, then that is good. If it is a stochiometrically modest amount, then the cost (energy) of producing quicklime and sodium silicate quite easily could offset the Green Ballyhoo marketing potential.

    Just saying
    GoatGuy

    • Goatguy

      That was a great chemical tour. I have seen some geopolymers and was very impressed. Applications needing less than 700 C can be made from two waste streams from industrial processes – both of which they will pay you to take away. High alkali bonded glass materials in high temperature coal ash makes a great geopolymer. I have seen a sheet somewhat akin to drywall that was foamed in the centre with tiny bubbles. Hit with a hammer, it dented and did not crack at all. Amazing stuff. Amazing insulation, amazing strength, no cement content, low price. If your ash has too much uranium, you can import ash from India, Africa and China. Heh heh…

      Crispin (father of materials engineer)

  21. It would be nice to find a valuable use for fly ash. May be that use in a concrete like application will work for some applications. But beware!

    I have a friend who had to dig out part of his concrete driveway against his garage due to fly ash expanding 15 years later and uplifting the entrance 8″ – 12″. Not sure if he placed any under the house foundation. There were other examples I heard about.

    I bid on a contract related to removal of fly ash from a local landmark hotel where fly ash was used under the new construction of a major addition. The floors were raised several inches, doors jammed, glass curtain wall breaking, etc. Not sure if it was fly ash from a local steel mill or coal burning. It took a few years to manifest itself. Cost was major.

    There was portion of I-81 in Virginia that was built using concrete due to Federal Regulations because a cement mfg was located in that county. Uplifting was severe and remedy took years but I don’t know if any fly ash was used in the base.

    Anyway, if a waste product can be utilized that is a good thing. But don’t take a nano look and create a mega issue.

    • eyesonu

      “Anyway, if a waste product can be utilized that is a good thing. But don’t take a nano look and create a mega issue.”

      Doesn’t that personify science in general, and AGW specifically.

      Great comment.

  22. Well, this is not exactly news, is it?

    “The process creates a calcium-aluminate-silicate-hydrate molecule chain with strongly bonded atoms that form an inorganic polymer network more durable than (hydrated) cement.”

    These are collectively known as geopolymers. When I was in Potchefstroom I visited the producer of such materials who was making high accuracy coal stove components for us. It is not mentioned in the article that these materials have a very high melting temperature – they can be used in some cases up to 1400 C. Essentially it is a reaction between the glass in the ash and a high pH material (>11 will do).

    There are a couple of new items on the market that are very interesting substitutes for refractories. One is phosphate bonded alumina using aluminum dihydrogen phosphate and another is aluminum orthophosphate. Both make refractory materials without firing the product in a kiln.

    Something else not mentioned is that the fly ash has to have been subjected to temperatures above 1300 C so it is in a glassy phase. Your basic coal stove doesn’t produce the right raw material. It has to come from a power station or large boiler. The big attraction is the cost: far cheaper than cement, and I’d say it is worth burning coal to get the ash in some cases.

    Look for this at your modern construction sites. It can be foamed to make strong, insulative products. The research in South Africa is being funded by PPC (obviously) to get on top of these materials before someone else does. I saw kerb stones being made from it. It is strong and impervious to heat from a cutting torch.

    Multiple papers are available on the chemical mechanisms involved.

  23. “The research was funded by the U.S. Department of Transportation’s University Transportation Centers and the WSU Office of Commercialization.”

    It seems to me that research funded by the gov’t ought not be patented except for international use and mfg. We the People paid for, it belongs to us. The academics are doing work for hire.

  24. I think Fly Ash Concrete might arrive in your Home Depot (or be used to make concrete blocks for your next office building) about the same time my Flying Car is delivered.

  25. I’m concreting at the moment and coal flyash is listed as one of the ingredient in the Portland cement.

  26. call me crazy – isn’t this why they are called “cinder” blocks? This doesn’t seem like a new idea.

  27. I’m truly astounded, cement made from fly ash ? This ‘discovery’ has been in active use for a VERY long time already. Cement is the ‘active’ ingredient of concrete.

  28. I’ve been following this site for quite some time. I’m here to learn.
    Reading this particular thread, some of you are as bad as climate alarmists.
    How many of you are/were involved in building? You all sound like experts?

    I’ve been building for 40+ years.
    The house I live in has a so-called cinder block foundation (60+ years). The major addition we did 15 years ago has a block foundation. Not a crack in either the old or the newer.

    I’m not going to get into what you need for a deeper foundation, but if properly instituted, a cinder-block foundation is MORE THAN ADEQUATE. Ultimately, it depends on the footing you place your block foundation upon. All my projects had great footings!!

    I’m not going to post my education credentials because that’s really beside the point.

    AH

    • Well, I’ve been in construction for +40 years too and also studied material science in the 70s. Foundations / footings are designed dependant on soil mechanics. Concrete core-filled concrete (cinder) blocks reinforced with steel rod are commonly used everywhere in the world in a variety of applications long lasting and without consequence. My educational credentials somewhat exceed my professional needs … but that is beside the point.

      • I’d never laid a block until 3 months ago, now I’ve laid 860, N12/16 core-filled, all on nice chunky footings, about to render with exposed aggregate…also beside the point.

  29. Theyll should use that ash to forests, to prevent asidification of forests and lakes. When timber is taken from forest it takes minerals from the ground. If you don’t put those minerals back to forest in some way ….

  30. Nothing new, coal ash has been used in concrete and pavement for decades. How much of our tax money was pissed away on this boondoggle?

  31. I worked at a coal fired power plant for many years and the plant sold fly ash to a concrete manufacturer almost from the day it started operation. There are two problems, first the ash must be low in carbon, ie carbon must be almost all burnt in the combustion process. This itself is a problem because burning more of the carbon in the coal requires higher temps in the furnace and that increases the formation of nitric oxides (NOX) in the flue gas, NOX is a problem pollutant. So this requires careful control to efficiently burn the carbon while keeping NOX production low.

    The other problem is that flyash is somewhat radioactive, containing uranium and thorium. When concrete made with flyash was used in building construction (making cinder blocks IIRC) this led to radon buildup in the buildings. Not acceptable of course. So the concrete made with flyash is generally used here for highway construction.

    Flyash may become a more valuable product since I understand that experiments are underway to extract rare earth elements from flyash. I understand that the concentration of rare earths is somewhat lower than the clays used in China but still usable.

    • Exactly, I worked at a industrial plant (coal fired spreader stoker steam boiler) and the fly ash (fabric filter baghouse) was just too high in unburnt carbon. We did reduce the carbon content with some refurbishments and readjustments, but it was very difficult to keep the carbon content low constantly, in order to sell the flyash to a cement manufacturer.

  32. I prefer using fly ash blend cement for my backyard projects.
    It is typically called builders cement in Australia and is slightly cheaper and just as strong.
    It contains up to 25% fly ash, usually from blast furnaces.

  33. No, no, no. Can’t use graphene oxide. Graphine oxide is made up of oxygen, hydrogen and (drum roll) that nasty CARBON. We could also discuss the oxidizers that are used in processing graphene oxide.

  34. ‘….molecule chain with strongly bonded atoms that form an inorganic polymer network more durable than (hydrated) cement.’ “After further testing, we would like to build some structures…” Add a Three D Printer and……” In China they are building houses with Three D Printers.

  35. Yes, yes, fly ash has been added to concrete for thousands of years, in varying quantities. But this process, they say, “…eliminates the use of…cement…” Granted, they are still in the R&D phase, but it shows promise, its characteristics differ from concrete enough that many of the issues cited by other commenters may not be issues after all. Its performance also differs enough that I can immediately think of applications where this material could be better. Of course every graduate engineer’s research has invented the greatest thing since sliced bread, but they’re not all wrong. As an engineer, I’m intrigued. I might even agree that spending some of my tax dollars on further development could be worthwhile. Maybe we should just agree to check back with them in a year or two?

  36. Try substituting Idaho sourced pumice in the cement mix to reduce use of the Portland. The Roman cement recipe would set and retain strength with salty sea water. Required much lower temperature to prepare the ingredients saving energy. Pumice variant does not leave an excess of sodium hydroxide dispersed in the cured concrete as does typical cement mixtures.

  37. Another age old tech up for a Nobel or something. They have been using fly ash in concrete for over 1/2 a century. It has pozzolanic properties which means it sets up like cement when wetted and with addition of lime. Ditto for volcanic ash (glass), and a number of waste products. When you produce Lithium chemicals (Li- ion batteries, etc.) from the mineral spodumene -a lithium aluminosilicate, you roast the ore and extract lithium sulphate solution. The hydrous aluminu silicate residue sets up like concrete when water content is reduced to ~50%.

  38. Coal ash concrete designed to be previous so water can flow thru, that should be great on the foundation of your house. Good thing it wasn”t used on Hoover Dam. Apparently it won’t be good for all aplications.

  39. This sounds like “We have this fancy thing graphene oxide, let’s try to mix it up with other stuff and see what happens.”

    It’s an exploratory kind of research that can produce useful results.

    But it is kinda disheartening to read the litany of distrustful grumbling from grumpy men about anything new.

  40. Well I’ve read all the comments up until this time. This comment is for Crispin in Waterloo.

    Crispin- you tried mightily, to tell people that this was NOT cement with a fly ash filler, but a completely different product called a geopolymer. They should have all done what I did after reading your first comment- google “geopolymer”. A great learning experience.

    To me your most telling comment as it applies to this post, is that the stuff is already commercially available. So what is new or novel about their research? The article doesn’t say,

    Anyway thanks for your comments.

    • Thanks, Old engineer.

      This material, or class of materials, is the most interesting thing to appear in ages for my type of work: design of domestic heating appliances. It permits single artisans to make products at least as good as huge companies because it eliminates kilns and clay-based parts.

      The only tech comment to add is a reply to aTheoK about ‘glass’. The term ‘glass’ does not mean soda glass like windows and jars. Amorphous metals without a crystal structure are also glassy. Bulk glassy alloys, they are called. So the ‘glass’ referred to above is melted ash that has a ‘clinker’ or ‘glassy’ appearance. Geopolymers can be based on bonding such glasses using high pH activators at room temperature. They set quickly and can be extremely strong – like re-melted rock. The age of limestone cement is closing its doors.

  41. For a time, maybe a decade ago, Xcel sold fly ash to a companion operation at its Ft. Morgan, colorado power plant, to make cement. Unfortunately, a new environmental mandate to capture yet more sulfur made the fly ash unusable for this purpose. It is possible to make perfect the enemy of good.

  42. Ok it’s not for building but the Chinese don’t have form in anything of quality-

    “Are NEW Chinese buildings really FALLING DOWN?”

  43. There’s an awful lot of blah blah going on in this discussion. I’ll start by saying that I have been deeply involved with cement systems for the past ~40 years so can claim to have some expertise on the subject (I think). I have worked with all kinds of cements, binders & aggregates including most that have been mentioned in this thread – Portland, GGBS, metakaolin, wollastonite, a multitude of pozzolans and fly-ashes, aggregates of a hundred flavours, compositions & densities and all manner of exotic admixtures to modify strength, rheology (flow properties), permeability, density, etc. As such, I welcome all research on improvements to existing materials used in construction, civil and industrial engineering.

    Having said that, the use of the words “graphene” (albeit as oxide) and “nano-“ immediately fire up my BS detectors. “Geopolymer” is another woed that sounds pretty cool. Let’s face it, these words are used to make otherwise mundane topics “sexy” so their inclusion, merited or otherwise, is suspicious to me.

    If truth be told, most “cementing” technology involves nano-materials and always has done…..we just didn’t call them “nano-“ until recently and most of this was for marketing purposes. Particle size ranges for cement and many binders/admixtures including fly-ash are in the nano- to micro- range – from say 100nm to 100 microns. The former represents the fines, he latter the coarser particles. So nano- isn’t new here although it’s true that appropriate deployment of carefully selected particle sizes can improve certain properties of the finished material. Geopolymers sound cool but clays may justifiably be given this descriptor since they are complex aluminosilcates.

    Flyash comes in many flavours and there are different classes defined by BS, ASTM, etc. Some of these are relatively inert and require the use of an alkali (usually provided by excess line from cement) to activate them and bind them. Others are intrinsically hydraulic and will set into a hard stone when combined with water alone, even in the absence of Portland cement.

    So, bottom line, this “novel” system needs to be looked at closely to see whether it really represents something new or whether it’s just a re-labelling of existing technology with judicious selection of the component materials. I’ll be interested to read more about it.

    • The place to start is the non-cement materials. While water may be involved, it is usually an activated surface of a glassy material or a phosphate bonded alumina over 40%. Aluminum dihydrogen phosphate (MW 318) releases three water molecules for each reacted ADP molecule. As it sets, it gets wetter! After drying it will take 1300 C the next day.

  44. This is nothing new. Coke slacks have been used to make cement for donkeys years in Europe.

  45. As an retired engineer at a coal plant, coal ash has been used in concrete for decades. A particular form of ash called spheroids that certain coals and/or boiler units produced was sold and used as a strengthening agent in concrete. The tiny spherical ash particles present would resist crack propagation in the cured concrete.

    Of course, nowadays the availability of this concrete additive has been reduced considerably.

  46. Australian company Wagners has been developing and commercializing geopolymer concrete based on flyash, blast furnace slag and activators entirely replacing portland cement, for over a decade. They have used it in their airport pavement and currently in their wharf project plus it has been used in other smaller projects. They note a number of potential benefits over Portland cement based concrete including higher tensile strength and chemical resistance in marine environments, acidic soil condition and sewer applications. They also indicate a saving of CO2 emissions and push the green credentials. Local design standards have yet to include non-portland cement based concrete so accepance has been limited.

  47. Wouldn’t the permeability to water be an issue w/ the re-bar used to reinforce the structure(s)?
    I’m thinking that the re-bar would rust/decompose MUCH faster w/ this product.
    Kudos to the researchers’ efforts: Keep on thinking clearly!

  48. That’s going to be a bit radioactive, as there is significant Thorium, U-238 and U-235 refined from coal in the ash by burning, enough U-235 to fuel a equivalent sized nuclear power plant in fact (Gabbard et el, ORNL 1987). Also by far the largest man made radiocative emissions to the environment, far more than nuclear p[ower, but its coal so that’s OK.

    BUT, if that is only elevating the background I’d build my house from it, as enhanced low background radiation up to around 500mSv pa tones up the immune system to resist cancer better. Normal background is 2mSv pa. evacuation level is 20mSv pa, but natural levels globally are up to 500mSv pa with no epidemiological effects, except some studies show positive immune responses, and such exposure is an adjunctive treatment to chemo and radiotherapy to enhance the immune response when they are not advisable.

    This was not understood when the regulations were made, and most evacuations following nuclear accidents have been unnecessary in fact, the bureaucrats in unnecessary haz mat suits wavig meters have killed thousands of people at Chernobyl and Fukushima as a consequence of wholly unnecessary evacuations. But why isn’t it mentioned?

  49. As other have posted “nothing NEW under the sun”..usually these reports NEVER refer to all others’ work gone before their “discovery”. The Portland Cement Assoc. and The National Lime Association, as well as the US Army Corp Eng. have massive amounts of reports on Pozzolanic materials/additives such as ash, lime, including RICE HUSK ASH “RHA” another waste product from burning of rice hulls- Many ‘natural home builders’ use the RHA, when available, to make their own “Roman cement” walls and floors. Of course breathing in this stuff kills your lungs, so the average dolt shouldn’t have access. But rice hulls themselves are used as light weight filler with clay and lime for walls and blocks. Fun to play with these materials for home-made projects.
    This from a 2004 report, based on much earlier studies: “Coal fly ash has been successfully used in Portland cement concrete (PCC) as a mineral admixture, and more recently as a component of blended cement, for nearly 60 YEARS. As an admixture, fly ash functions as either a partial replacement for, or an addition to, Portland cement and is added directly into ready-mix concrete at the batch plant. Fly ash can also be interground with cement clinker or blended with…” SEE: http://www.ce.memphis.edu/1101/notes/concrete/PCA_manual/Chap03.pdf

    • PrivateC

      While what you write is all true, this is not a cementitious material. It is a way to set materials chemically to produce a form of artificial rock. It can in some cases be argued it is a metal or a glass like borosilicate glass.

  50. My great great grandfathers business was doing this in 1857. They actually also produced moulded concrete fire places. The core business was Spence & Dixon based in Pendleton, Manchester and produced high value borax from gas producers waste ammonia and shale. They also produced prussian blue from waste leather soles. Those victorians could teach us a lot. I found the diary of Peter Spence in a Runcorn museum, hidden in a laboratory book and it is a treasure trove of information. You can source the information in the Manchester Evening News. Check out the first great pollution trial which involved the early pioneers of climate science, particularly Robert Angus Smith (who coined the term acid rain)-he appeared for the defence. Evidence included the first photographs of acid damaged trees.

  51. Your heading should read “Making Cement from Fly Ash” Concrete is the product, Cement is the binder

  52. In the Tampa Florida area there is a shortage of flyash that is used to reduce the cement required to make concrete. It is being imported by ship. Silica fume is used as a substitute when fly ash is unavailable.

    To my knowledge flyash has been used in concrete for over 30 years and this is not a new practice.

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