Shotcrete should not be applied directly to a dry, dusty or frozen rock surface. The
work area is usually sprayed with an air-water jet to remove loose rock and dust from
the surface to be shot. The damp rock will create a good surface on which to bond the
initial layer of shotcrete paste. The nozzleman commonly starts low on the wall and
moves the nozzle in small circles working his way up towards the back, or roof. Care
must be taken to avoid applying fresh materials on top of rebound or oversprayed
shotcrete. It is essential that the air supply is consistent and has sufficient capacity to
ensure the delivery of a steady stream of high velocity shotcrete to the rock face.
Shooting distances are ideally about 1 to 1.5 metres. Holding the nozzle further from
the rock face will result in a lower velocity flow of materials which leads to poor
compaction and a higher proportion of rebound.