[sdkemp]

Any negative consequences to high fly ash content in structural concrete? My sub just poured a foundation with 40% fly ash content. I specified 20% -25% because I had heard somewhere that content above 35% can have adverse consequences. Any thoughts, experiences to share?

 

[rustyjames]

Any negative consequences to high fly ash content in structural concrete? My sub just poured a foundation with 40% fly ash content. I specified 20% -25% because I had heard somewhere that content above 35% can have adverse consequences. Any thoughts, experiences to share?

High Volume Flyash for foundations is becoming more and more common.

http://www.buildinggreen.com/features/flyash/middlebrook.cfm

 

[concretemasonry]

What does the engineer have to say?

Fly ash is a retarder and can delay finishing of a slab, but the ultimate strength can be the same.