Shotcrete or gunite is a heavy slurry of concrete, pumped through a hose using compressed air. It is also called sprayed concrete. Shotcrete requires a small crew to apply and trim and only a few pieces of equipment to set up. It can reach the strength of normal concrete which is more than sufficient in most situations. The working condition, though, is tough.
Working for shotcrete
Shotcrete surface on the diaphragm wall for water tightness