Shotcrete is concrete that is shot at high velocity pneumatically through a high pressure hose into a surface to facilitate construction. It is usually reinforced by steel rods, mesh or other fibers. Steel or synthetic fiber reinforcement is used for slope applications, particularly when engaged in slope tunneling.
The shotcrete can be either of a wet or dry mix concrete in most construction applications. Specific to pool construction, the term is always a reference to wet mix concrete while the dry mix concrete is refered to as gunite. However, in other application the term gunite can’t be seen as the same as all dry mix concrete.
Using a high pressure nozzle, shotcrete is introduced, placed and compacted at the same time. Shotcrete has a multiplicity of uses ranging from being shot into conventionally graded surfaces or soils, directly overhead, vertically, or into nearly every surface type imaginable.
When using dry mix concrete, the ingredients are placed in a hopper. The mixture is carried pneumatically through high pressure hoses. A nozzleman oversees the introduction of water to the dry mix. The skill this entails is important as the mixture must come together as it hits the surface. This process is more difficult on thick surfaces or when there has been heavy reinforcement. Instant adjustment of the water mix is an advantage conveyed by a skillful nozzleman with the dry mix process. This is particularly important when engaged with overhead or vertical applications in which accelerators are commonly used. The frequent stopping needed in the repair process is also made easier due to the fact that the dry elements in the mix can be easily expelled from the hose.
Wet mix shotcrete involves the use of previously prepped and treated concrete pumped through the nozzle. Ready mix concrete is most commonly used in this process. Compressed air sends the mixture through the hose onto the surface area. There is less wasted material falling to the floor when utilizing wet mix and also less rebound or dust. A clear advantage of wet mix application is that a lot more material can be introduced much faster. The mix with water and other additives is quicker and more effective.