ABSTRACT
This chapter focuses on selection of the appropriate equipment for any given shotcrete application. The first part deals with the dry-mix shotcrete process. Initially, double pressure chamber guns were used, but nowadays most dry-mix shotcrete is applied with either rotary barrel or rotary bowl-type guns. Discussion is provided regarding the selection of a suitable air compressor size (CFM or m3/min) and material hose size (inside diameter, mm) to match the size of the rotor in the gun. In addition, the water pressure for the water added at the nozzle (bar or psi), should be sufficiently high to create a water curtain that will thoroughly wet out the shotcrete material as it passes through the nozzle. Discussion is also provided on the use of a hydromix nozzle, where water is added at a water ring up to 3 m before the exit from the hose. For wet-mix shotcrete, there is discussion on the selection of an appropriately sized pump to suit the work at hand. Small hand-applied shotcrete repair projects may only require pumps rated at 5–10 m3/h, whereas hand-applied shotcrete on large structural shotcrete walls may require pumps with rated capacities of as much as 15–18 m3/h. Information is also provided on selection of wet-mix shotcrete hoses and nozzles and equipment for accelerator addition at the nozzle.
