I'll be building a house using ICFs for the foundation. Do I need to use a concrete mix for the ICFs that is different from using conventional forms? Thanks.

It depends on which ICF product you use. Some require pea gravel, some don't. Check with the manufacturer.

You might not need to do too much special for the footing/short frost walls. How tall an ICF stack you are planning on pouring as part of your foundation? Are you pouring the ICF at the same time as the footing?

I think most ICF contractors use some form of water reducer/plasticizer to get a little better flow out for a given slump. The guy I have worked with uses a plasticizer and changes the aggregate from the typical 5/8" to a 50-50 mix of 5/8" and Pea Gravel so it will flow and consolidate a little better around the ICF crossties and rebar.

What do the concrete notes on your plans specify?

This is a DIY project. I did it once before about 15 years ago so I don't recall all of the details. I plan on using BuildBlock forms, 6 high for an 8' wall. I'll pour the footings first, in a separate pour from the walls. I also plan on using a vibrator during the pouring of the walls.

YES, it is definitely a different mix than you would use for a strip form walls, regardless of foam blocks or foam panels, we do all types. the best mix for ICF is simply a pea gravel mix 60/40 sand to gravel or 50/50, we always use a 3500psi mix, you can use plasticizer i don't particularly like to use it, but it does add flowability? but it also sets up the concrete quicker as well, so maybe that's what you want, but a regular pea gravel mix works just fine.

Thanks

Most Redi Mix companies here have their own recipe they like to use for ICF's. Most webs now are much better than they used to be. I tell people to just keep the agg size below 3/4"

Umh i dont know if i would really rely on the ready mix company to determine my icf mix, unless you know for a fact they have good experience with icf, just a note of caution there, but yes some ready mix companies do have their own icf mix just make sure it isnt the same mix they use for cmu block fill, not the same application and if they dont have experience with icf they will send out that mix, not a good experience!

You didn't specify what width block you are using. For a DIY job I recommend using 8" core. Easier to consolidate if it's your first time plus according to the PM you don't have to use as much rebar, which allows for a less restricted cavity. With 8" you can use a 3/4" stone but no bigger. As Bill said 3500 lb mix 5 slump delivered with pea stone would be the best for you. Also don't let the ready mix company determine the mix. Always do a first in the morning pour so you don't end up with someone's left overs.

See here for “Internal vibration was found to provide adequate consolidation for concrete with a slump of 6 inches or greater."

And remember - adding more water is probably not the right solution. But a mid-range water reducer or retarder might be.