http://www.builditgreen.org/
We've documented for you a number of times that Coal power plant Fly Ash can be utilized in the making of a Portland-type Cement; a cement that offers advantages in terms of reduced energy consumption and reduced Carbon Dioxide emissions, relative to conventional Portland Cement, in it's making; and, higher strength and other improved performance, relative to Portland Cement, in it's use in traditional cement and concrete applications.
One recent example of our reportage concerning those facts can be accessed on the West Virginia Coal Association's web site, via the link:
US Government Coal Ash Cement Stronger than Portland Cement | Research & Development; concerning: "United States Patent 4,256,504 - Fly Ash-based Cement; 1981; Assignee: The United States of America (as represented by the Secretary of the Interior); Abstract: A cement composition comprising a high calcium-content fly ash and calcium sulfate, and mortar and concrete compositions containing the cement. Claims: A cement composition consisting essentially of (1) a major proportion of a fly ash ... and (2) about 5 to 15 percent by weight of calcium sulfate."
We Coal miners and backwoodsmen in United States Coal Country haven't, apparently, figured any of that out, yet; and, we still try to dodge, or sometimes even eat, the Baloney Sandwiches concerning our Coal Combustion Byproducts that self-professed "environmentalists", some perhaps of murky lineage and questionable motivation, throw at us.
However, we see herein that some genuine, state-certified tree huggers, out in the very cradle of the "green" movement, also recommend Coal-ash cement as an environmentally superior alternative to Portland cement, and, as an aggregate for that cement, to make concrete.
And, maybe, in this case, we should start paying a little attention to them.
Concerning who the "them" we cite in this report might be, more can be learned via the links:
About Build It Green - Build It Green and History - Build It Green; wherein we're told, that:
"Build It Green is a membership supported non-profit organization whose mission is to promote healthy, energy- and resource-efficient homes in California.
Established in 2003, we offer a comprehensive package of local government support, professional training, collaboration forums, consumer education, and green product marketing to a range of stakeholders. Three strategic objectives guide our work:
(1) Drive policy development: We partner with government to establish credible and accessible green building policies that promote private sector innovation and provide consistent guidelines statewide.
(2) Increase supply of green homes: We train building professionals on latest best practices and connect green product suppliers with consumers.
(3) Stimulate consumer demand: We build awareness of the benefits of green building by providing GreenPoint Rated as a trustworthy, recognized brand for green homes.
Build It Green’s program development strategy has been to incubate good ideas in the San Francisco Bay Area and then expand them statewide, helping to establish California as a role model to other states and the nation for developing pragmatic solutions to environmental challenges.
Build it Green is the result of the 2005 merger of the Green Resource Center and Bay Area Build It Green. The merger combined the resources of these two successful organizations and furthers the goal of transforming the California building industry to embrace green building."
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We do apologize for that lengthy digression; but, we felt it important to establish the environmental conscience bona fides of someone who tells us that building our homes and our offices, among many other things, out of Coal Ash can be a good thing.
Following, with additional links and comments inserted and appended, are excerpts from the initial link in this dispatch to:
"Fly Ash Concrete: Concrete, typically composed of gravel, sand, water, and Portland cement, is an extremely
versatile building material that is used extensively worldwide. Reinforced concrete is very strong and can be cast in nearly any desired shape.
Unfortunately, significant environmental problems result from the manufacture of Portland cement.
Worldwide, the manufacture of Portland cement accounts for 6-7% of the total carbon dioxide produced by humans, adding the greenhouse gas equivalent of 330 million cars driving 12,500 miles per year.
Fortunately, a waste product can be substituted for large portions of Portland cement, significantly improving concrete’s environmental characteristics.
Fly ash, consisting mostly of silica, alumina, and iron, forms a compound similar to Portland cement when mixed with lime and water.
Fly ash is a noncombusted by-product of coal-fired power plants and generally ends up in a landfill. However, when high volumes are used in concrete (displacing more than 25% of the cement), it creates a stronger, more durable product and reduces concrete’s environmental impact considerably.
(Relative to Portland Cement Concrete) High Volume Fly Ash Concrete (is):
Less energy intensive (to) manufacture
(Has) Higher ultimate strength (and is) More durable
(And) Creates fewer global warming gases.
Although high volume fly ash concrete has significantly lower embodied energy, its energy performance at its point of use is no different than conventional concrete. Concrete has high thermal mass and therefore is good at moderating interior temperatures.
The principal ingredients of concrete are gravel, sand, water, and Portland cement. Although the cement only comprises 10-15% of concrete by weight, its production is responsible for most of concrete’s environmental impacts. The cement, composed of lime and silica (sourced from limestone, clay, and sand), is fired in a rotary kiln at 2700 F, consuming enormous quantities of fossil fuels and thereby producing high amounts of CO2. In addition, the chemical reaction that creates Portland cement produces CO2 as a by-product. By displacing a large percentage of the cement in concrete, fly ash significantly reduces the associated environmental impacts of CO2 production and air pollution.
(We have several times explained that calcining Limestone, CaCO3, aside from and in addition to, perhaps, generating CO2 by burning fuel to achieve the necessary temperature, generates Carbon Dioxide from the calcination reaction itself, via the equation: CaCO3 + Heat = CaO + CO2.
Replacing at least some Limestone with Fly Ash would reduce both the fuel combustion and the Limestone calcination contributions of Carbon Dioxide. More concerning that fact can be learned from another center of the California environmental movement, via:
Energy Citations Database (ECD) - - Document #21004766; concerning:
"Coal Fly Ash: The Most Powerful Tool for Sustainability of the Concrete Industry; P.K. Mehta; University of California, Berkeley, CA; Ash at Work; 2008; In the last 15 years the global cement industry has almost doubled its annual rate of direct emissions of carbon dioxide. These can be cut back by reducing global concrete consumption, reducing the volume of cement paste in mixtures and reducing the proportion of portland clinker in cement. It has recently been proved that use of high volumes of coal fly ash can produce low cost, durable, sustainable cement and concrete mixtures that would reduce the carbon footprint of both the cement and the power generation industries."
For a look at the full article, visit the American Coal Ash Association, ACAA, at:
http://www.acaa-usa.org/
The nature of fly ash, tiny spherically shaped particles that act as ball bearings, make it able to fill small voids and produce denser concrete that requires less water for installation, resulting in water savings. Its density makes it less permeable to water in finished form, protecting reinforcing steel and increasing the concrete’s durability.
Able to produce more cementitious paste, fly ash produces a stronger concrete. It also lowers the heat of hydration, in turn reducing shrinkage and thermal cracking. Class F fly ash, as well as some Class C fly ashes, produce a concrete that is more resistant to sulfate attack and alkali-aggregate reactivity. Materials that last longer reduce the demand for natural resources and reduce the associated environmental impacts of extracting and processing them.
Furthermore, fly ash concrete has higher ultimate strength than conventional concrete, so in some applications less material is required to accomplish a given structural need.
Health Considerations: Some building health experts have raised concerns about the presence of trace heavy metals in the fly ash. Others maintain that the metals are effectively locked into the cementitious matrix, preventing their release. Furthermore, by using fly ash in concrete rather than sending it to a
landfill, the potential for the metals to leach into the environment is reduced.
Fly ash is composed of tiny spherically shaped particles that act as ball bearings, improving workability and aiding placement of concrete into formwork and around reinforcing steel. Consequently, less water is needed in the mix, reducing or eliminating bleed water (which) also makes it easier to work with in cold weather.
While higher ultimate strengths are realized with fly ash concrete, it sets and cures more slowly than conventional concrete in the first few hours of placement. This is not a problem for most applications, and designers should allow the specified strength to be met in 56 days. Once contractors understand the nature of high volume fly ash concrete, they do not report problems with using it.
Conventional procedures for screeding, finishing, edging, and jointing are applicable to fly ash concrete.
Fly ash concrete is denser and results in a smoother finish surface."
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So, according to some of California's environmentally-concerned citizens, we can make concrete structures, if we utilize Coal Fly Ash-based Cement, which would not only have "higher ultimate strength" than concrete structures utilizing traditional Portland Cement, but, which, since they would also have "smoother finish surfaces”, would look nicer, too.
And, all of that would be accomplished while we reduced the overall, combined Carbon Dioxide emissions of the electrical power-generating and cement-making industries taken in total, while we also further reduced "concrete’s environmental impact" and reduced the need to find suitable "landfill" space for Coal Ash.
Which needed "landfill" space would be even further reduced if even more Coal Ash, as seen in:
Consol Converts Coal Ash to Concrete Aggregate | Research & Development; concerning: "United States Patent 5,364,572 - Process for Making High-Strength Synthetic Aggregates; 1994; Assignee: Consolidation Coal Company: Abstract: A process for making high-strength aggregates ... containing coal combustion ash"; and: "United States Patent 6,054,074 - Manufactured Aggregates from Coal Combustion By-Products; 2000; Assignee: Consol, Incorporated; Abstract: This is a method of producing manufactured aggregates from coal combustion by-products";
were used to make "high-strength aggregates", i.e., instead of the "gravel" and "sand" suggested by "Build It Green" for their Concrete, to be made from their Cement, wherein Fly Ash, as they suggest, is employed to the end of "displacing a large percentage of the" conventional, Limestone-based, energy-intensive and Carbon Dioxide-emitting, Portland "cement".
It all sounds to us like a "win-win"; and, we wonder why we don't, apparently, have anyone in United States Coal Country as concerned enough about the environment, as some good folks in California are, to start publicly discussing the fact that Coal Ash can, in fact, be of such great service to the environment.