I’m a Civil Engineer specializing in structural for most of my career. For almost all in-ground concrete installations, the nature and strength of the subgrade is more important than the strength of the concrete. Subgrade means whatever the concrete is sitting on. In other words, no matter how strong the concrete or asphalt, it isn’t any stronger than what it is bearing on.
I’ve never been associated with residential work but in commercial, government,, etc. work, testing the subgrade is very important. It should be to you too. If you’re spending a lot of money on asphalt or concrete in a non-controlled environment, for your own sake. please call a local geotech outftit, explain your circumstance, and get a proposal.
If you’re spending couple to several 10’s of thousands, please spend a couple of hundred ensuring it doesn’t fail in a year or two.
Thanks Tom. I’ll do that before I think about any major construction. I knew this crowd was chock-a-block with smart guys. Great minds should congregate.