It will depend on many factors such as : Void space under slab, Over all drop in concrete, the type of soil under the slab,how thick the slab is and the dimensions. But a patio walkway could be as little as $800.

We drill 5/" hole approx 3'-4' apart in strategic locations and once the injection is done with use a cement mix and fill the holes. Compared to large heavy equipment that can cause ruts in your yard.

In most cases the project is completed in one day.

In about 20 minutes, you can drive a full size truck right over the work we have done?

No, because it will be thin and it would likely crack an chip. Also we void fill all areas under the slab to prevent future settlement. Adding concrete could be adding to weight and more settlement.