The best information on this subject can be found in ACI 506R-05, “Guide to Shotcrete,” and likely in past articles in Shotcrete magazine. The distance that can be pumped is a function of too many parameters to fit a rule of thumb. The distance that can be pumped is influenced by the equipment being used, the vertical lift, the available compressed air, and other factors. We would suggest that you consult with one of our corporate members (www.shotcrete.org/BuyersGuide) in the area of the project and get their input.