Gunite is a mixture of dry cement and sand. It is sprayed on a surface with a gunite gun, which is a cement gun that forces air through a tube attached to a nozzle that hydrates the gunite. This makes a dense, durable material that adheres to a form such as a swimming pool structure.
Swimming pool contractors have been using sprayed gunite for over 30 years, and it is still used today. Sprayed gunite when finished has between 6,000 to 7,000 pounds of force per square inch (PSI). This is twice as much as cast concrete. Due to its strength and ability to adhere to unusual shapes, gunite can be used for any size or shape of swimming pool.
How to Spray a Pool with Gunite
Install reinforcement bars (rebar) of steel mesh over a base of crushed stone on the base of your excavated pool area. Then using a ready mix concrete, spread it over the rebar and stone to form the base of the pool.
Run rebar of steel mesh up the sides of the excavated pool area. Additional rebar should be added in areas where water depth will be greater than 5 feet.
Rent a gunite machine that will feed dry sand and cement concrete through a hose, mixing it and hydrating it. The machine will come with a large air compressor that blows the gunite material through the hose.
Spray the gunite evenly and thoroughly over the concrete pool bottom. Then using a trowel, spread the gunite and smooth it over the bottom of the pool area. Let it dry completely.
Spray gunite over the rebar on the walls of the pool. Use a trowel to smooth it. You will need to apply additional layers to the walls until they are 6 to 9 inches thick. If you’ve constructed areas for steps or benches in your pool, you should spray the gunite in this area as well.