Class F vs class C flyash

[WWTEng]

Which one is the more common type of flyash for general residential and smaller commercial projects (sog, foundation wall, basement wall etc)? When to use one class vs the other?

Thanks.

 

[JedClampett]

I'm not sure you get the choice. In Eastern area, where bituminous coals are used, you get class C, in the West, where they burn anthracite, you get Class F. I might have the coals mixed up, but I think in general, you get Class C in the East, Class F in the west.
I think Class F combines more completely with the other cementatious materials.
Ask your local batch plants what they use.

 

[concretemasonry]

They (the local producer) will use what is available and common in the area and not stock a separate product for a single project, which would require a new set of silos and mix designs (and testing). Most supplies of fly ash are under long term supply contracts with major distributors and cement companies. The concrete supplier is the end user and vaules a steady, guaranteed supply of known materials.

It is a local situation and depends on availability and freight costs.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[TXStructural]

Yes, rely on the local supplier to guide you. Particularly on small projects, you don't want to invent a new mix. Use a mix they already have experience in producing. If there are performance or appearance parameters, then performance spec the concrete (strength, aggregate size if it is critical to placement due to bar spacing, and anything particular about appearance or use), rather than WCM ratio, amounts of CM, slump, etc. unless required by Code.

On large projects, where new mixes are critical to function, the development and testing costs are worth while. Not so much on small projects.

 

[WWTEng]

Thanks all.

Jed, yeah I heard somewhere that east of Mississippi is class C and west is class F.

I'll contact 2 or 3 major suppliers in the area to get a more definite answer.

 

[cvg]

it makes very little difference which one used, except in the mix design which is usually handled by the supplier. The benefits are about the same to the designer and contractor.