AecObjExplode

If you want to save a step and not do a save as use the AecObjExplode command. Isolate the objects you want explode, you have them on there own layers right?

Then type AecObjExplode on the command line. A dialog box should pop up asking you questions on what you want to do.

Uncheck the Erase AEC Objects box and the Explode To Anonymous Blocks options.

Then press OK, you will end up with the original Civil 3D object as well as a copy of the Primitive objects. No need to do a save as since you retain the original objects.