Would you typically specify epoxy coated rebar in a concrete headwall for a pipe culvert?
I saw a note saying that the headwall rebar should be epoxy coated when doweled into the roadway. Otherwise, I believe the rebar is typically not epoxy coated. Right?
We use epoxy coated rebar on any concrete exposed to salt-laden water, such as bridge decks, approach slabs and the top slabs of at-grade box culverts, but not for substructures or anything buried. Typically, we would not use epoxy coated for a culvert headwall. However, if the headwall is exposed to de-icing salts or the soil bad enough to be corrosive to concrete, we'd consider using epoxy coated.
It's difficult for me to sort out the cost difference, because we pay for reinforcing in-place, but it doesn't seem to be more than a $0.20 per pound difference.
This highly depends on corrosiveness of the environment you are in. For instance, if deicing salts are used in your area or you are near the ocean, a combination of rebar protection and increased concrete cover should be used. The epoxy coated dowels in this case are because there is potential for the rebar to be exposed to the elements in the joint.
For non-corrosive environments, rebar is typically not epoxy coated.