Hey Newtothis,
As sometimes as I'd like to think I am the opposite of your name (Oldtothis), I'd like to welcome you to the community!
Hopefully, your plumber didn't have to take up a lot of your driveway. I am with you in your concern regarding some sort of reinforcement like rebar before putting the material in completely. Now, depending on how big of the hole and how deep it is, that will be the deciding factor in if you want to use rebar. If he had to cut through rebar, you should be able to see where he cut through. Most often than not, if its a shallow and somewhat narrow puncture of the driveway, you will be able to use a combination of plastic to use as a vapor barrier over the pipe as well as a higher qualty Concrete mix so as to give yourself a bit of that reinforcement you need. First off lets look at what is cement vs. concrete, as in your situation you may want to use the easier route of concrete.
Concrete is a mixture of sand, gravel, water and cement. Cement refers to the dry powder substance to be combined with other components that form various types of concrete once mixed together. The gravel component is sometimes referred to as crushed rock or aggregate. Mixing these ingredients in the right proportion is essential to producing durable, high-quality concrete. Therefore, using a high quality bag of concrete will allow you possibly even not use rebar, provided its a shallow enough hole. Below is a pic of that item I was talking about, it works great and has a 4000 psi and has amazing impact resistance....
Use 6 mil plastic in a sheet so as to allow for a buffer for the new pipe and to cover it up. Install the concrete depending on how much volume you need to fill in the hole. One bag will do a 2 sq. ft 4 inch thick slab, as a point of reference. You will need a patching trowel alongside the other materials I mentioned. All of those can be found at your local Home Depot. Just come into the building materials department and we can get you squared away with getting you the best concrete and tools for getting the driveway back up and running again.
Hope this helps you out,
aboveaveragejoe
