Guide you can find in the CRSI technical notes or so.
For what I remember heating (when the bar chemistry so allows) was only starting to be commendable #11 and above, but check.
These diameters shouldn't be used, because tests show that over 20 mm of diameter the bars distroy the concrete on dynamic solicitation, i.e., the steel punches the concrete in spite of rib protrusions. As long as you can, use 20 mm or less diameter bars.
