I have acquired a 3000lb air compressor and will begin shot-crete/mortar testing forthwith. If it turns out I can atomize with a large volume of air at only 50 psi then I could conceivably use a large, cheaply purchased turbo which I also own and I've heard generates 50-60 psi. So I guess what I learned literally just this moment is that I should have tested the turbo before buying a gigantic compressor but whatever.