Skip to comments.Unintended Consequences: Fly-Ash Shortage (Vanity)
Posted on 06/15/2014 12:07:35 PM PDT by BwanaNdege
I went to two different local concrete ready-mix plants on Friday, looking to get a small quantity (two buckets) of fly-ash for an R&D project. Both places mentioned the shortage of fly ash.
"Fly ash, also known as flue-ash, is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases. Ash which does not rise is termed bottom ash. In an industrial context, fly ash usually refers to ash produced during combustion of coal. Fly ash is generally captured by electrostatic precipitators or other particle filtration equipment before the flue gases reach the chimneys of coal-fired power plants, and together with bottom ash removed from the bottom of the furnace is in this case jointly known as coal ash."
"In the US, fly ash is generally stored at coal power plants or placed in landfills. About 43% is recycled, often used as a pozzolan to produce hydraulic cement or hydraulic plaster or a partial replacement for Portland cement in concrete production."
Obama's War on Coal has led to a shortage of fly ash which is used in Concrete to replace a portion of the Portland cement. Now in order to make the needed quantity of concrete, more Portland cement must be manufactured, producing even more CO2, to replace the missing Fly-Ash. Concrete made with Fly-Ash is generally better than that made without it.
"The Law of Unintended Consequences" once again bites the Progressives/Liberals/Eco-Freaks/Democrats.
LOLOLOL! The idiots are running the asylum!
There is a lot to this. I’ve seen a highway project have to stop because a power plant wasn’t putting out enough fly ash quick enough.
Dirka dirka jihad! Aloha snackbar!!! Your destruction is coming.
“Oh, come on. You didn’t really expect us to get our hands dirty with such details, right? This is something for low-level techs to figure out. They always do. We’ve been coasting, riding on the backs of these people our entire short lives”.
—Typical Obama Administration Policy Wonk
The Chinese will marvel at our fantastic stupidity, with selling them coal, and then paying for the ash from it after it’s burned!
There is a large pile of fly ash not far from here. We used to set fence posts in it as it alone hardened up just like concrete.
Whole bunch of it is here...
China Extracts Metallurgical Grade Aluminum Ore from Coal Ash
“All precast concrete producers can now use a group of materials called fly ash to improve the quality and durability of their products. Fly ash improves concretes workability, pumpability, cohesiveness, finish, ultimate strength, and durability as well as solves many problems experienced with concrete todayand all for less cost. Fly ash, however, must be used with care. Without adequate knowledge of its use and taking proper precautions, problems can result in mixing, setting time, strength development, and durability.”
I helped set up a coal-fueled industrial plant. The fly-ash was much desired for roads.
If you are doing High Strength Concrete R&D, look for “Silica Fume”. I participated (and won) the regional ACI High Strength Concrete competition for my school years and years ago...
Aside from the a Coarse Aggregate and Fine Aggregate (sand) you want Silica Fume, and the most critical thing is a low Water/Cement ratio... which can only be accomplished by adding a Superplasticizer.
The Fly Ash/ Silica Fume component is included with the Portland Type II as Cement in the W/C ratio... and what it does is imparts a charge to the cement particles so when the water is added, the particles space themselves out in the matrix.
Look for your base strength to be 8ksi... anything more is bonus.
C)2 is a known as a problem in Al Gore's religion, but the rest of us recognize it as food for plants.
Oh, don't worry. They'll be coming after them next. My employer (a cement manufacturer) is already making plans.
How I detest this shoddy excuse for a man!
The Chinese (and the U.S.) also make drywall using fly-ash, so while U.S. drywall production from coal fired powerplant wastes goes down the price will go up - and the Chinese will make even more.
Yes - there are always unintended consequences - but this (less fly-ash available in the US, reliance on China increased as they have increased the number of Coal fired plants and thus fly ash tremendously) may actually be an intended consequence.
As an aside. several years back the epa ruled that solid components - the ash and fly ash - after combustion were to be considered emissions. It doesn't take long for a high quality steam coal, with 10% ash content, to produce a boat load of HAZMAT emissions.
As for Silica Fume, yes, it absolutely increases the strength of concrete, irrespective of the fly ash component. I'm sure it effects the compressive strength, but I don't have any idea how to plug in the numbers to determine if the rebar components should be adjusted to reflect a change in the tensile strength. Our engineers always added the Silica Fume just before the pour to manage the final product. Myself, I would add a bit if I were pouring a patio or foundation for a house. Just be darn sure to wear a well fitting respirator with an NBC filter while handling the bags.
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