“Gunite is the dry spray method of spraying concreteto create a single cast shell and iswidely regarded as a leading method of construction for high quality, luxury swimming pools” according to Jack Harding, Director of luxury swimming pool company, Guncast Swimming Pools. Guncast takes its name from Gunite, having perfected the technique over thirty years of luxury pool design and construction.
Gunite is a small aggregate and cement, mechanically mixed together and fed, in a dry state, into the hopper of a ‘gun’. The mixture is forced by air, supplied by a 600cfm compressor, to the nozzle, when water is added, and the wet mixture is sprayed at high velocity on to the surface to be ‘gunited’.
Other methods of concrete construction include Shotcrete, a ‘wet spray’ method of spraying a high cement content, small aggregate ready mix concrete, at velocity onto the shuttering and reinforcement. The Poured Concrete, or ‘Shutter and Pour’ method involves pouring concrete into conventional wooden forms and inmasonry block pools the walls are constructed with concrete blocks.
“The Gunite method is more commonly used in our luxury swimming pool builds than poured concrete due to its many benefits” says Jack. “To do it properly however, requires a high level of skill and experience, as getting it wrong could lead to problems, such as leaks, later.”
1. No Joints, No Cracks
Due to the way in which the concrete is applied, through a spraying method that typically builds up in layers, the Gunite pool shell is a complete, continuous shape, containing no joints, which is important to create a strong pool shell, as Jack explains. “Joints can give concern for leaks and potential cracking due to movement.”
Other materials used to construct pools include fibreglass, plastic and metal, but Gunite sprayed concrete creates a strong layered shell, which is extremely hard and dense, making it stronger than normal concrete. From this tough foundation, the pool can then be finished to create a highly durable, luxury swimming pool.
2. New Depths
“A pool’s depth can often depend upon the selected method of construction” says Jack. Some concrete pools are created using hollow blocks, which are filled with a concrete mix to form a solid wall. Pools built in this way however, have limitations on vertical wall depth, in order to withstand the stresses of containing several tons ofwater and the external soil pressure. Gunite pools can be made to be much deeper because of the high strengths achieved with the method and have no limitations on steel and concrete design.
3. Flexibility of Shape
The Gunite spraying method of construction is ideal for pools with an intricate shape, as the technique provides the flexibility to design and create a pool to any desired shape. “A key element for consideration when creating a luxury swimming pool is that the pool must be designed in harmony with the property and its surroundings, to enhance the space and reflect the style” explains Jack. “Gunite gives the flexibility to create a pool to any shape allowing more flexibility and creativity in the design.”
4. Economical
“For larger pools, where reinforced concrete would be used, a Gunite sprayed pool would almost certainly be a cheaper alternative” says Jack.
The Gunite method is faster to complete than the conventional shutter and pour method, which helps to speed up the entire construction process.
“With less expenditure on the construction of the pool shell, the budget can also be focused on the finish of the pool, such as tiles, or stone, as well as any extras, including lighting or moving furniture” he adds.
5. Personnel and Work Space
Gunite requires only a small team of operators, which includes the Nozzleman,responsible for placing the concrete and controlling its hydration, the Gunman, who regulates the supply of the mix and the air from the gun and the Mixer Operator who ensures the sand and cement are correctly proportioned and of good quality.
The Gunite method is also useful for working on difficult access sites, as the operators require only a 50mm diameter hose to reach the working area, which can be up to 80 metres away from the plant and materials so less space is required during the construction process.
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