Need Help on this concrete mix

[High5]

We're in the process of building a new garage. In our specifications, we asked the contractor to provide a 4,000psi concrete mix for the slab floor and it was not to be watered down at the job site. So he went back to the sub-contractor who contacted the concrete supplier and this is what they came up with (please see attachment). This mix is rated to 5,000psi with 6" slump max. So flags are up since we didn't ask for this high a rating. Can any of you guys decode what we have here? Your help is much appreciated.

 

[1rahamay]

No need for red flags. Nothing strange here. 5000 will be fine. Why are they using a #8 aggregate though and not something larger like a 57? Are they pumping it with a sidewinder? Is this a large footprint slab and/or no truck access to back up to it?

 

[High5]

We had the structure framed and sided before the slab is to be poured. So yes, they will be using a sidewinder. And the footprint is quite large covering an area of 60' x 48' with two separate rooms all taking this mix.

Thank you for your help.

 

[joes169]

That mix looks fine, other than the pea stone, but it shouldn't really affect the final product in a negative way.

Personally, I'd cut the flyash back for a machine finish at this time of year, but that's just a personal preference.

The mix you linked to will easily reach 5000 psi if they take samples, even with a 6" slump.

 

[High5]

Thanks Joes169. I will discuss the flyash with the contractor tomorrow. I do plan on applying an epoxy finish. So the end result will need to be quite smooth.

Your help is much appreciated.

 

[rburke65]

If you/they apply a concrete sealer it will have to be removed prior to the epoxy.......I believe.

 

[High5]

I do not plan on applying a concrete sealer. But the concrete contractor may. Good advice. Thank you.