[pbmonster]

> But perhaps still useful for planning, as a starting place?

Yeah, lots of value in just having an app go "the mix you're trying to do is likely to fail the slump test". So you still have time to adjust the water ratio, or get better sand.

[sidewndr46]

That's the job of whatever engineer writes the spec. for the concrete. If they can't get that right, they apparently have failed to learn anything from decades of engineering literature.