One of the problems with doing termite work is what is under the concrete. The picture above isn’t under concrete but in a block wall holding up a RV gate. The problem that I have run into is cups and trash that were just thrown in before the concrete was poured. Cups are a real problem because they are coated with that waxy material and takes a zillion years to decompose.
A number of years ago I had an issue with a set of steps and finally after taking it apart we noticed trash, wood and cups which prevented the termiticide from reaching the dirt in a uniform way. Love to be Superman, but I can’t see through concrete.