Above: A small, streamlined swimming pool built using gunite
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Gunite Pools May be Built in Every Shape and Size
If you are going to be building a new swimming pool, have a look at all the different types including gunite pools, hand-packed concrete pools, vinyl-lined pools and fiberglass pools. Compare both the different building methods and prices, and then compare what features you will get for your money. Each type has its advantages, but it’s going to be up to you to decide which suits your needs the best.
The gunite, or shotcrete process, revolutionized the pool construction industry more than seven decades ago because it enabled pool builders to create gunite pools in every size and shape for a lot less than other methods of concrete construction which had been used until then.
The Origin of Gunite
Invented more than a century ago by an American taxidermist who used it to fill plaster models of animals, gunite involves spraying out dry material with compressed air, and then wetting it quickly just as it is applied. Strictly speaking, shotcrete describes a process during which the mix is sprayed on either dry or wet. Generally the mix for gunite pools should be made with a strong mortar mix (usually about 4:1 river sand and cement), but it might include a slightly bigger aggregate, in which case it would be classified as concrete (which always includes some type of stone, however fine).
The Gunite Process
One of the main advantages of building gunite pools is that the cement material mix can be applied to vertical surfaces. By comparison, when concrete is poured, the builders must rely on shuttering to hold it in shape. And when concrete is hand packed, it must be done gradually – by hand – making this a much more labor intensive process.
Neither vinyl-lined nor fiberglass pools can be directly compared to either concrete or gunite pools because the processes used for construction and installation are completely different.
When gunite pools are built, a hole is dug in the ground, and then steel reinforcing is put into place on the walls and floor. If steps are to be incorporated, then they are formed at the same time. There should also be a steel-reinforced ring beam around the perimeter, for basic strength.
Then the gunite machine is used to literally blast the strong cement:sand mixture onto the walls and floor of the swimming pool.
Specifications and Guidelines
When pool contractors build gunite pools they must construct them in accordance with any regulations laid down by the local authority or governing body. It is their responsibility to ensure that they specifications are met, not yours.
While the specifications for gunite pools may vary, generally guniting of an ordinary domestic swimming pool should be completed in a single day, without any disturbance to the steel reinforcement. The minimum thickness of the walls and floor of gunite pools should be between four and five inches, and the shell should be watered (just a light sprinkling with a hose pipe) every day for about five days, to allow the shell to cure correctly. Once this curing period is complete, the contractor will return and plaster the pool. Generally gunite pools are rendered with a marble plaster, but there are some other alternative finishes. Make sure you approve the finish in your contract.
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