Since you only mentioned treads not risers or stringers, I assume this is primarily an appearance issue? You could use concrete drive screws to attach wooden strips on the front and rear edges of the existing treads. Then make matching dadoes in the bottoms of the oak treads, and epoxy the treads to the wooden strips. This
creates both a mechanical and a epoxy bond to secure the oak treads.
2. Another approach would best be described as a keyhole using the same concrete screws into a slot milled across the width of the treads trapping the screws. the keyhole slots could be faced with a bull nose to conceal them.
3. Pursuing this concept, a dovetail could be milled across the bottom of the treads and then a mating piece could be screwed to the existing concrete. The new treads slide onto the mating dovetails trapping the treads. Face off the front edge with a bull nose
4. Since the most force will be at the leading edge of the treads if there is any overhang, secure a metal angle on the riser surface that fits into a slot to keep the rear of the riser from tipping upward.
Then the treads can be secured using Liquid Nails or some other adhesive, not a glue. The concrete must be sealed first however, so the adhesive will adhere.
5. If all else fails....just use the drive screws through the top of the oak treads and plug the holes in a uniform pattern. Probably the best/easiest approach!