Using Creatherm radiant panels for my under slab insulation, run our pex for radiant heat and lay re-bar, then pour the slab.
Link to video that I use the concrete in    • Building a small shed  
The creatherm radiant panels https://www.creatherm.com/
Rebar chairs https://sandbaggy.com/products/heavy-...
0:00 - Ryan Farish : Northern lights
15:31 - Ryan Farish : Restoration