Right, and when doing such a large job, at least in the USA, the concrete would be getting delivered by a third-party material services company. From what I re

Right, and when doing such a large job, at least in the USA, the concrete would be getting delivered by a third-party material services company. From what I recall (my dad had a concrete construction company back in the day) the material services co. played a significant role in selecting appropriate mix ratios and additives for the application and conditions. They're not going to be deliberately sending out a mix with insufficient binders, especially not on such a massive order. The whole system runs on credit; the material services company doesn't get paid for the concrete they delivered until the whole job gets paid, sometimes years later. So they're incentivized to be quite involved and engaged in the whole process and ensuring success to the maximum extent available to them. The last thing they want is some finger-pointing lawsuits over a faulty mix getting in the way of collecting payment, or worse, get stuck with the bill of demolishing and disposing it all for a redo on top of it.