Fly Ash and Pervious Concrete 4

[CPENG78]

Can someone point out to me the different between Class C and Class F Fly Ash? In my research it appears to be the difference in curing time only but wondering if there is a larger issue.

 

[CPENG78]

forgot to add on a separate question...infiltration test for pervious concrete once cured is to be 100 inches per hour per ASTM C1701 according to a spec I came across. Does this sound correct? I am trying to get my hands on the ASTM standards but wanted to get someone's input on here.

Thank you everyone.

 

[cvg]

http://knowledge.fhwa.dot.gov/cops/...79bd395dc0540c8a852570fa006d0056?OpenDocument

 

[Ron]

You can buy the standard from ASTM....

https://secure6.astm.org/STORE/review_order.html

100 in/hr is not unreasonable. It needs to be initially high as it will decrease rapidly with time.

 

[beej67]

Most pervious concrete test pills I've seen could convey a lot more than 100 inches per hour.

In the end, how many inches per hour your concrete should convey should probably be dictated by your site hydrologist, based on the design storm. But that presumes the guy who wrote the regulations has some sense, which isn't always the case.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[Hoaokapohaku]

Class F is pozzolanic only; Class C is pozzolanic and cementitious. Pozzolans require mixture with calcium hydroxide (present in portland cement) for hydration. Class C fly ash includes higher percentages of calcium oxide than Class F giving it cementitious properties independent of the portland cement. The difference is inconsequential since fly ash isn't used alone. Practically, the main difference is geography. In the U.S., Class C is more generally available in the western U.S., Class F the eastern U.S.

Generalizations are made about the effect of fly ash on concrete properties, but fly ash from different sources is highly variable in both classes. Its affect on various concrete properties is also highly variable depending on the specific fly ash used. Therefore, generalizations are helpful for determining what affects a particular fly ash might have, but the affect on concrete properties must be determined by trial batching.

 

[CPENG78]

Wanted to say thank you to everyone for your responses. They have been all very helpful. Thanks again.