high volume flyash concrete

If you have to use concrete, try to minimize the portland cement content

Concrete is almost a mandatory part of building these days, especially in seismically active regions. Unfortunately concrete production causes some problems for our environment.

The production of portland cement, the glue that usually binds concrete together, puts carbon dioxide into the atmosphere both from the fuel used to cook the raw limestone and from the chemical reaction that calcifies the limestone.) Worldwide, the production of portland cement accounts for 5-8% of the human-generated carbon dioxide. The Portland Cement Association gives this perspective.

(In case you havent heard, many scientists are alarmed by dramatic increases in atmospheric CO2 and the resultant greenhouse effect.)

Fly ash is a waste product generated by coal burning power plants. It is generally either landfilled or, where lack of regulations permit, it is just billowing out of smokestakes into the atmosphere. Fly ash can pollute groundwater with heavy metals and in the air becomes particulate pollution...or smog.

Fortunately, flyash can be used as a replacement for portland cement in concrete, and according to many experts, makes for better concrete. It is generally considered inert and safe once bound up in concrete.

Economic & environmental benefits: The United States imported over 11 million tons of portland cement in 2008. (despite the economic downturn.) If this cement import could be replaced with flyash, the trade deficit could be improved by at least 1 billion dollars. It is expensive to retrofit coal-burning powerplants to keep the flyash from entering the atmosphere, so perhaps the economic incentive of being able to sell the flyash that is captured could fund the installation of this equipment.

There is much more to say on this topic, so I encourage you to read further if you are about to undertake any construction activities requiring concrete.  Often it is difficult to convince your contractor to try something new,  But there are many technical resources out there, and high volume flyash concrete is readily available from concrete suppliers.  Some suppliers are also offering mixes with other portland cement replacements such as rice hull ash and steel  blast furnace slag. 

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5 comments

CIVIL ENGINEER 8 years ago

i need the theoretical framework for this flyash.


sarahd profile image

sarahd 8 years ago Author

dear civil engineer, I am not sure what you mean by the "theoretical framework"

please explain.

there are several links to my sources for further reading.

sarah


Ahsan habib 8 years ago

Fly ashes mainly are the composition of some oxides metal & Non-metals.Most of them have little or no binding properties until it reacts with Ca(OH) in OPC to form additional CSH.If there is no Cement (Clinker based) in the mix, then how Fly ash will contribute in binding properties ( i.e when Fly ash completly replaces cements)?

Would you pls explain ?

or am I wrong in understanding the phenmena of gaining binding capacity of FA?


tony k. 8 years ago

Fly ash, ASTM C618

Silice fume, ASTM C1240

Blast Furnace Slag, ASTM C989

All are waste materials listed by the USA EPA and are considered supplementary cementitious materials, and can be used alone or combined with a synergistic effect to the hardened properties of portland cement concrete. Most of today's high-performance concretes (HPC) contain one or multiple SCMs to increase performance, strength, durability and service life. Search any of these key words for the many uses. www.silicafume.org


Joel 3 years ago

If Fly ash of the right oarticle size(in microns ) is used then the construction project and the company can save a lot in terms of usage of cement and water. Not all type of fly sh can be used.To find a deatil report on how to use fly ash for export can be found at http://morningtadka.com/1785/ecocrete-best-fly-ash...

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