One of our core theses has been that Coal Ash is a valuable raw material resource, one which can be used in the making of Portland-type Cement, PC, and Portland-type Cement Concrete, PCC, both as an aggregate for concrete, with the Ash having valuable and additive cementitious properties of it's own, and, as a basic feed into a cement kiln, substituting for some of the limestone and other basic mineral ingredients.
As we have documented, the use of Coal Ash in those applications leads to a significant reduction in the amount of Carbon Dioxide emitted from the cement-making process; a reduction in the amount of energy required to make cement; and, a stronger, more durable and chemical-resistant finished concrete; all while reducing the need to extract natural raw materials, with the attendant environmental disruptions those extraction activities entail.
We recently reported, via:
West Virginia Coal Association | Coal Ash Can Reduce Construction Costs | Research & Development; concerning: "United States Patent 5,624,491 - Compressive Strength of Concrete and Mortar Containing Fly Ash; 1997; Inventors: John Liskowitz, et. al.; Assignee: New Jersey Institute of Technology; Abstract: The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. Such materials can thus significantly reduce construction costs. Government Interests: The research leading to the present invention was conducted with Government support under Contract No. DE-FG22-90PC90299 awarded by the Department of Energy. The Government has certain rights in this invention"; Incorporation of fly ash in concrete improves workability and thereby reduces the water requirement with respect to the conventional concrete. This is most beneficial where concrete is pumped into place. Among numerous other beneficial effects are reduced bleeding, reduced segregation, reduced permeability, increased plasticity (and) lowered heat of hydration";
that, our US Government hired a significant school of engineering to, further, demonstrate that Coal Fly Ash used as a fine aggregate in PCC also significantly reduced the costs of handling and placing that PCC, while at the same time resulting in a superior finished product.
Herein, we learn that our US Government was encouraged enough by those results to further finance the New Jersey Institute of Technology's demonstration of the facts, that, PCC made with Coal Ash also offers much more durability and resistance to chemical attack than conventional PCC.
As seen in excerpts from the initial and one following link in this dispatch to:
"United States Patent 5,772,752 - Sulfate and Acid Resistant Concrete and Mortar
Date: June, 1998
Inventors: John Liskowitz, et. al., New Jersey and Thailand
Assignee: New Jersey Institute of Technology, Newark
Abstract: The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance.
Government Interests: The research leading to the present invention was conducted with Government support under Contract No. DE-FG22-90PC90299 awarded by the Department of Energy. The Government has certain rights in this invention.
Claims: A hardenable mixture comprising cementitious materials, fly ash, and a fine aggregate, wherein the cementitious materials comprise fly ash as well as cement; and wherein the total amount of fly ash ranges from about 60% to about 120% of the total amount of cement in the hardenable mixture, by weight, wherein the fly ash is characterized by at least 99% of the particles having a particle size (as specified).
The hardenable mixture ... wherein the cementitious materials comprise from about 5% to about 35% fly ash, and the fine aggregate comprises sand and fly ash.
Field: The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties."
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We abbreviate our excerpts so that the points are emphasized:
A concrete mixture which can contain "35% fly ash" as the cement portion, and in which the aggregate comprises a blend of "sand and" additional "fly ash", "demonstrate(s) significant levels of acid and sulfate resistance".
And, our US Government owns a portion of the rights to make and utilize such a Coal Ash-based, obviously superior, concrete, which, as per the teachings of the precedent "US Patent 5,624,491 - Compressive Strength of Concrete and Mortar Containing Fly Ash", as cited above, also costs less to make than conventional Portland Cement Concrete.
Those points are reaffirmed in the subsequent:
"United States Patent: 6802898 - Preparing Fly Ash for High Compressive Strength Concrete
Date: October, 2004
Inventors: John Liskowitz, et. al., New Jersey and Ohio
Assignee: New Jersey Institute of Technology, Newark
Abstract: The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific example, processing fly ash by grinding to the desired size distribution range gives a 100% yield of fly ash for utilization in high quality concrete and mortar. Such materials can thus significantly reduce construction costs, as well as provide a useful outlet for material that is generally regarded as a pollutant and a nuisance.
Claims: Fly ash characterized by a. substantially uniform spherical shape; b. greater than about 90% of the particles have a diameter (as specified, and) which is prepared by grinding unfractionated fly ash.
(Note: Yes, we have to mill it. Would we rather pay to do that, so that we can sell it and make a few bucks; or, just pay to have it hauled off and buried? The "Claims" section goes on at some length to define various concrete and mortar compositions that also contain other things, like "silica fume" and reinforcing "glass fibers", along with up to "50%" Coal Fly Ash as prepared by the process of "US Patent 6,802,898".)
Field: The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention further provides means to produce fly ash of a desired size modulus with a 100% yield in desirable production quantities for use in hardenable mixtures, along with hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only cement without fly ash over the time period relevant for construction. Also provided is a method for the continuous production of fly ash with a 100% yield in desirable production quantities.
Fly ash is used in concrete in two distinct ways, one as a replacement for cement and the other as a filler.
Incorporation of fly ash in concrete improves workability and thereby reduces the water requirement with respect to the conventional concrete. This is most beneficial where concrete is pumped into place. Among numerous other beneficial effects arc reduced bleeding, reduced segregation, reduced permeability, increased plasticity, lowered heat of hydration, and increased setting times.
(What) is needed are methods of grinding fly ash into particles that have a size that permits its use in concrete or mortar that undergo strength development comparable to, or superior to concrete and mortar comprising no fly ash, and which are readily used in the construction industry.
There is also a need utilize all of the fly ash produced in coal-dust fired boilers, thus decreasing the amount of waste produced by boilers, and decreasing the amount of cement used in the construction industry.
There is a further need to process fly ash efficiently to provide about 100% yield of useful product in desirable production quantities.
There is a further need in the art for high strength concrete and mortar containing fly ash.
There is yet a further need in the art for the utilization of fly ash generated during coal combustion.
These and other needs in the art are addressed in the instant application."
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So, not only can we utilize nearly "100%" of our Coal Ash in "concrete and mortar", the end result is structural material "superior to concrete and mortar comprising no fly ash".
How superior?
Well, the New Jersey Institute of Technology, in the full Disclosures of their several inventions concerning the use of Coal Ash in PC and PCC, explain some of that. But, there are also some graphic examples available that illustrate and emphasize the potentials.
First, one way in which Coal Ash acts in concrete mixtures is as a "pozzolan"; which label derives from an area in Italy where volcanic ash - - which, almost logically, is, or can be, very, very similar to Coal Ash in terms of mineral composition and physical structure - - was once gathered and utilized in the making of cement and concrete.
Which practice has been going on not just for a long time, but, for, literally, thousands of years.
As can be learned via:
Pantheon, Rome - Wikipedia, the free encyclopedia; and:
File:Rome-Pantheon-Interieur1.
"The Pantheon ... (was) commissioned ... in ... Ancient Rome ... (and) rebuilt in about 126 AD. The building is circular ... under a coffered concrete dome ... . Almost two thousand years after it was built, the Pantheon's dome is still the world's largest unreinforced concrete dome."
And, as taught by the Canadian Society of Civil Engineers, via:
What is Civil Engineering ? "The Pantheon was constructed in 120 AD as a temple. During the middle ages the structure was used as a fortress and poultry market. After almost 1900 years, it is still in use but now as a church. A 43.3 metre high dome covers the circular rotunda. Thick brick walls support the unreinforced and lightweight concrete dome. Brick arches are embedded in the wall and help distribute the weight of the dome. The cement was made of lime, volcanic ash and crushed brick."
Now, a huge item constructed of concrete made with volcanic ash, which ash is, rather obviously, in terms of mineralogy and composition, closely similar to Coal Ash, is, after 2,000 years, still standing.
And, we ask, hypothetically, how much, do you suppose, looking at the pictures of the Pantheon that are accessible via the above links, of any objectionable chemical compounds that might have been in that volcanic ash, which, perforce, based on it's natural geologic origins, is likely to have contained some of the things which Coal Ash is accused of containing, might have seeped, or leached, out of that structure, exposed as it has been to the elements, in the last 2,000 years?
More to the point and closer to home, we've actually been using Portland-type cement in the United States for only a relatively brief period of time.
Here are a few, sort of antique, examples:
Burnside Bridge; wherein you'll find a photo of a bridge in Connecticut, right on a river, in a humid and moist environment, that is right around 110 years old. And, here's another:
North Main Street Bridge; which is more than one hundred and ten years old.
Both of those bridges are made of cast Portland-type Cement Concrete. They are in moist, high-use and high-wear areas.
See, in the photos, how crisp their lines still are, how solid and intact they still appear to be.
How much, or how many, if any, objectionable chemicals or compounds, do you suppose, might have been leached out of them and into the waters of the rivers they span in the last century?
They don't, as far as we know, contain any Coal Ash in their composition, but:
Keep in mind, that, as the New Jersey Institute of Technology teaches, and as our US Government affirms, in United States Patent's 6,802,898, 5,772,752, and 5,624,491; cement and concrete made with Coal Fly Ash will be even stronger, and even more resistant to chemical attack and water intrusion than conventional Portland Cement and Portland Cement Concrete, with which those two bridges are made.
According to recent news reports, one objection that has been raised to the increased use, and the promotion, of Coal Ash in such and similar cement and concrete applications is that objectionable compounds, if there are any, might, somehow, "leach" out of the structures made with Fly Ash cement and Fly Ash cement concrete.
Get real.
Such objections or expressions of "concern" should be met with what they deserve:
Public derision.
They are nothing more than another platter full of Baloney Sandwiches being hurled at the Coal industry.
It's far past time we started applying some logic and common sense in our "debates", if we are for whatever unfathomable reason compelled to have them at all, about such and similar applications for the valuable solid residua co-produced by our essential use of Coal in the generation of economical electrical power.
Coal Ash can be utilized in the making of, as our own US Government affirms, "superior" Portland-type Cement and Portland-type Cement Concrete; an employment of Coal Ash, that, as the New Jersey Institute of Technology testifies, "can ... significantly reduce construction costs".