The construction of concrete pools is one of the worlds oldest professions. After all, the Romans were building concrete pools over 2000 years ago and some of them still stand today.
A designed concrete pool allow you the versatility of being able to include the features that are important to you. You will also know that it will fit into the space that you
have for it.
A well built concrete pool will require dedicated experienced crews to methodically complete each stage of construction to a high standard. This will achieve the best outcome - a water
feature you can swim in.
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The process usually begins with an excavation, although some pools are built in partial excavations due to sloping sites. Others are built above the ground often to meet an elevated deck or similar.
Most commonly the excavation required will be undertaken using our own excavator and tippers to remove the soil from the site. Good access will be a minimum width of 3.0 metres with no height restrictions or sharp turns required. This will allow the tippers to be loaded directly by the excavator. If it is not possible to get the tippers close enough, we will use our Bobcat to move the excavated soil from the pool site to the tippers. The excavation is usually completed within 8 to 10 hours provided there is no delays.
If rock excavation is necessary a hydraulic rock hammer is used to break up the rock. This is an additional cost and can delay the completion of the excavation by several days. Fortunately, the need for rock excavation is not as common in Darwin as many might think.
The movement of heavy machinery and trucks into and out of your yard will cause some damage to lawns and can also do damage to unprotected paving and concrete.
Most concrete pools are built to finish at least 150mm above natural ground level which helps to control the amount of debris and stormwater that can end up in the pool during a wet
season. Some pools are built well above ground level for a variety of different reasons. Without the walls of an excavation to retain the concrete, formwork must be erected to contain the concrete. The formwork must not only be constructed to the shape of the pool, but also be able to support the considerable weight of the concrete.
In some cases, where the excavated pool walls are unstable or have collapsed during excavation, it is necessary to install “lost formwork” to recreate what would have been the excavated wall. It is called "lost formwork" because it is not recovered after the concrete has been placed. The cost of materials and labour to construct and then strip formwork, is an additional cost that is allowed for in the preparation of the pool quote.
Steel and Plumbing
The reinforcement of a concrete structure is achieved by placing steel bars centrally in the concrete walls and floor. A typical 9 metre domestic pool will have more than a tonne of
12mm deformed steel bar. It is cut, bent and tied both ways to create an oversized mesh framework which will precisely reflect the shape of the pool. “ Steel fixing” is an art of its own. On completion of the steel work within the excavation, you almost feel that it’s a pity that it will be lost when covered with concrete.
Pre-plumbing is the installation of specialised fittings such as skimmers, main drains, spa jets, pool returns and light buckets, all of which are precisely positioned and secured to the steel. The pipework that will connect these items to the pool’s filtration unit are run behind the steel and out of the pool.
The final stage of the pool shell construction is the all important placement of the concrete. A special concrete mix called spraymix is used in pool building. Spraymix uses smaller aggregate, a higher cement ratio, lower water ratio and a range of concrete additives, all of which combine to create a very strong waterproof concrete.
The concrete is pneumatically placed, which means the concrete is sprayed at high pressure onto the walls and floor of the pool using a concrete pump and a compressor. The use of a concrete pump allows for pools to be constructed in areas where a concrete truck would never be able to gain access.
Once sprayed onto the pool walls the surface of the concrete is “cut” and shaped to the desired wall thickness which is usually a minimum of 150mm. Once the concrete spraying starts it must continue until the pool shell is completed. For the next two weeks the concrete is left to cure. The curing process is slowed by adding water to the concrete shell as often as possible. The slower the cure, the stronger the concrete.
Now that the concrete shell has been constructed and the concrete allowed to cure, the pool is ready to be finished. A concrete pool can be finished with a huge variety of materials depending on your budget and the look you want to achieve.
Years ago concrete pools would typically have a mosaic tile installed around the waterline and the interior would be cement rendered and painted blue or white. The optimum alternative to a painted interior was a pool that was fully tiled throughout. These days a fully tiled pool is still considered to be the premium finish and as such is also the most expensive option. There is now an increasing number of specialised pool renders which are available in a range of colours that offer a much more durable alternative to painted interiors.
These specialised pool renders are products such a Quartzon, Beadcrete, Rainbow Quartz, Koreltex, just to name a few.
Pool renders are recommended to be installed in conjunction with a waterline tile which is much easier to keep clean and far less likely to stain. The most popular and possibly the most durable and cost effective pool interior is pebblecrete. Pebblecrete is simply a blend of natural pebbles mixed with neat cement which when applied by a skilled team will offer a very attractive, durable, non slip surface. Pebblecrete is the most versatile of all pool finishes because it is the only one suitable to be used throughout the pool. Pebblecrete can be finished up to a waterline tile, it can be finished up to the underside of a coping (top of the pool) tile or it can be “rolled over” where it goes over the top of the pool and back down to ground level on the outside of the pool coping.
The coping is the part of the pool most visible and susceptible to the harshest conditions. If you are not opting for a rollover pebblecrete finish, you will need to select a coping tile. The range of coping tiles is enormous since nearly any paver or tile can be used. The only restriction is if salt is to used in the pool, you need to ensure that the coping tile
selected is salt resistant. Some tiles may need to have a sealer applied prior to installation or after installation to protect them against staining. Remember that once you start sealing you must continue to re-seal. Many clients prefer to use a bullnosed tile on the pool coping which is more user friendly. Increasingly clients are also looking to have a “pool deck”
constructed which is a concreted area outside of the pool coping which is finished at the same height and with the same tiles as the coping.
The pool filtration system is the heart of the pool. It cleans and sanitizes the pool water keeping it looking good and making it safe to swim in. Domestic pool filtration should be of sufficient size to be able to cycle the entire volume of the pool within an 8 hour period. However, because of the much warmer water temperatures in Darwin, Pool Concepts believes that the filtration and chlorination system specified should be far more efficient. Other factors also need to be considered such as environment and expected useage. A leafy environment and a high useage will have a substanially higher chlorine demand.
There are different types of filters as well as different filter medias that all have their uses. Flow rates for pumps must also take into account the demand created by spa jets and water features without compromising the warranty on the filter tank by exceeding the maximum flow rate. Pool pumps are probably the hardest working appliance in your house and yet they receive the least amount of care and consideration of duty cycle.