Firstly, I've had RA for 12 years and deal with physical limitations. On this project, the limitation is the weight of a bag of concrete. So, I had to use Quikrete - Polymer Modified Structural Concrete Repair. It comes in a 20 lb bucket for $20. I ended up using 2 buckets. This is a type of cement that you can actually sculpt if you wanted to. I've used it on vertical repairs, so I'm comfortable working with it.
I needed to keep costs down, so I added various fillers and supports from leftover scrap. At the top of the ramp, I placed two pieces of concrete block cut-offs. At the bottom of the ramp, I used scrap wood with a couple of rocks to hold it in place.