ECJ:

Don't worry about the concrete block. We only use that here for building BBQs.

The problem here lies in the fact that there is no paperwork relating to the exact mix used, ad-mixes, water added, etc. We can only go by a rebound hammer test (5500 psi) now that the slab has cured. That will not tell us with any degree of accuracy what the original mix was.

As with most residential (and some commercial) slabs-on-grade here there is little or no oversight. The correct preparation for and placement of the concrete is always left to the discretion of Juan y Jose. No engineers watch over their designs as they are implemented. Few municipal inspectors even walk the site prior to pour, much less do they stand there while it is being poured. No paperwork is required to be provided. It is a GD free-for-all.

The builder poured this slab and was planning to go full steam ahead with framing on it the next day. I doubt like hell that the compressive strength would have reached 2000 psi by then. I know you were touting high-strength mixtures, but these are expensive and never used on residential work here. They are mostly for TX DOT for when they need to load a road in less than three days.

Any suggestions now that I have provided more pieces to the puzzle?

Thanks,

Aaron