Sure you can!
The shed folks said they would not work on that slab, and I don't blame them. So my only choice since I have to do all the work my self is to put a 2 inch cap on the 19x22. Which will now be an 18.5 x 21.5 slab. About the max I can handle in one shot is a 9.5 x 5 section, that takes about 20, 60 pound bags or about 1300lbs. It will take 8 of them give or take a few inches. 2nd go round is still not pretty, but it least will be more smooth, with out the pitting.
The calculator I used missed by about 4 1/2 bags, so the 1st section had to be done in 2 stages, that will not happen again!
Finally all finished and we can order shed!