Hi - hope you are doing well
Your program on PBS twice mentioned the use of fly ash in your concrete.
I think I understand the purpose of fly ash in concrete but can you please
tell me the concrete mix formula you prefer? I usually think of these things
in parts per cubic yard. One formula provided to me elsewhere is - 6 bag,
6 slump, and 6 fly ash, remainder in sand and preferred aggregate. My
preferred aggregate is 1/2 to 1 inch flint rock.
But i became interested in your formula after one of your guests mentioned
fly ash for a second time.
Thank you
Wayne
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Use of Fly Ash in Counter Tops
Last night on the CBS program 60 Minutes, they had a segment on the dangers posed by fly ash when used as part of land development. Apparently fly ash produced from burning coal contains high levels of dangerous heavy metals like arsenic, beryllium, boron, cadmium, chromium, chromium VI, cobalt, lead, manganese, mercury, molybdenum, selenium, strontium, thallium, and vanadium, along with dioxins and PAH compounds (see the Wikipedia article for more details at: http://en.wikipedia.org/wiki/Fly-ash).
Given the dangersous nature of these contaminants, how can one be sure that a kithchen counter top made of this substance will not pose a health hazard over an extended period of use?
Fly Ash addition
Hi Wayne,
The specifics of Fly Ash, where it comes from and why to use it are outlined in the following article http://www.buildinggreentv.com/keywords/cement/978 as Max mentioned.
Forget mix design for a second because you can add fly ash to virtually all mix designs. Whatever you mix design is, simply replace a portion of the cement with fly ash. It is generally accepted that up to 35% ash is beneficial for a variety of reasons including adding strenth to fully cured concrete.
We have experimented with many variations and find that replacing 30% of the cement with fly ash works best in our application.
A good source for Fly Ash is Boral Materials. Good Luck.
Janet
Coulee Concrete Designs, LLC
fly ash mix / formula
See if this helps, Wayne - I think I remember from that episode that most people use 30-35% fly ash. Eric Freed has also suggested that you check out FlyAsh.com
- maxmsf