For Gunite and Shotcrete, the subs are responsible for shooting the concrete that will form the shell for your pool. The concrete that they use is a low-slump (low moisture) six-sack mix that is pneumatically applied (delivered by compressed air) at 100-150 psi pressure. The compressive strength of the concrete is 3000 psi when its delivered and rises to 4000-5000 psi after 28 days of curing. Concrete with low water-cement ratios improves its strength.

This is highly desirable as it makes it more resistant to shrinkage/cracking, freezing, thawing, permeability, and wear in general.  The concrete is applied to the walls of the excavation over the steel rebar reinforcement. Fibermesh is typically added to the concrete when the floor is shot.  The fibermesh helps to prevent these cracks from becoming too large during the drying/curing process. Your pool builder will recommend applying either a shotcrete or gunite concrete material for you based on your unique soil conditions and year-around climate.

After the electrical inspection the reinforcing steel is covered with concrete. Your contractor may use ready-mix delivered to your site in ready-mix trucks. A pump at the street then pumps the concrete into the pool. This method is also referred to as shotcrete. Another method is to deliver dry sand and cement to the site then pump dry material through the hose adding water at the discharge nozzle. This method is called gunite.

Regardless of method, the pool concrete is trimmed and shaped to the exact contours required. This includes all spas, benches and steps. After the placement of the concrete, you will need to keep the material wet. Spray the surface with a hose spraying a mist of water 3 to 5 times per day for 7-10 days. Water curing is usually the responsibility of the homeowner.

Concreting of swimming pools is normally carried out using a spray concrete. The special spray concrete mix is delivered in to a concrete pump which pumps the concrete to a nozzle which uses compressed air to blast the concrete on to the earth & build up a thick wall encompassing the steel. (see photo)
When spray concreting is being carried out, there is always the possibility of over spray.

It is necessary to cover any nearby garden, paths, house walls & windows etc so that the strong, cement rich concrete does not get on to these items.

The spraying of the concrete is always carried out by professional concrete sprayers.

Once the concrete has been sprayed on & cut to the finished shape.
The concrete must be cured for a minimum of seven days.
This is usually carried out by wetting the surface every 3-4 hours with a garden hose.
This is ok but it is better to fully cover & tape in place a complete thin plastic cover hard against the concrete.
This must be taped at the joints to stop air entering & drying the concrete.