I'm wiring up my detached garage for 220v/50amps for a TIG Welder and air
compressor. The plan is to change the breaker in the main panel for the
220v/30amp to a dryer outlet that is not being used to a 60amp breaker.
I'm planning on running some new 6 AWG copper wire, 8 AWG neutral, about
75 feet to the garage into a subpanel with a 50amp breaker.

My problem is the routing of the wire. The wire will start out from the
main breaker, go up to the attic, down another wall, to the outside via a
1" Schedule 80 PVC piping. Here it will go into the ground, minimum of 18"
deep. This is where I get stuck, the outside wall of the garage is
surrounded by a 3 foot section of concrete. Is it permissible to run the
PVC on top of the concrete floor to enter the garage wall?

Or is the only way to somehow cut the concrete and lay the pipe?

Thanks in advance!

Darius