Goodness Joel,
You get some good ones don't you.
So, not sure I can give you a code at the moment that would support or reject such a procedure.
Personal experience, yes, heating on/in concrete is a very hazardous situation depending upon the size of the plate for square surface and how much pre-heat is wanted. Pushing it to 225°F is going to take it to the caution zone but the concrete itself should not get that hot. And if the plate has enough surface area so you don't have to get on it with the rosebud/bertha heater then it should be able to be done.
Wear full face shields and heavy shirts, sleeves, etc to protect whole body if popping does occur.
Again, depending upon some of the particulars, you may have to reheat a couple of times.
He Is In Control, Have a Great Day, Brent
I have nothing of value to offer but maybe they should switch to a different code, may I recommend Farm Code 2015? LOL!
Trapped moisture, steam at 225 degrees, what's the concrete going to do at 225 degrees. Maybe some test runs on something fabricated to experiment with?? Put another plate on top with column, drill and blast existing plate and put in mega concrete anchors? I'm just throwing out off the wall things that are popping into my head.
Will be curious to hear how this one plays out.