Manufacture of reinforced concrete pool basins
In the world practice, construction of large reservoirs, which are also referred to as tanks, often involves concrete casting technologies. Reinforced concrete pool basins have long established themselves as a leading choice not only in the field of swimming pool construction, but also in creation of tanks for fish and mammals. And it is no wonder, because using reinforcement and concrete gives an opportunity to create a tank of any desired shape and size.
Our company also maintained the position of application of reinforced concrete technologies in the construction of swimming pools, as well as large ocean tanks for oceanariums and dolphinariums. The latter can hold more than hundreds tons, therefore using reinforced concrete for such volumes is of the optimum economic benefit. It is worth remembering that upon the construction completion the tanks will contain large sea mammals (dolphins and killer whales). Tanks of aqua stadiums often serve both as scaffolds and stage for spectacular and breathtaking water shows.
Thus, before proceeding with the construction of this magnificent structure, our experts carry out project design work, taking into account not only architectural concepts, but also the peculiarities of the construction site. Pool basins are designed for a specific type of fish, reptiles or mammals, which determines their shape and size. Our experts strive to achieve the optimal result that is the pool basins blend perfectly with the landscape and harmonize with the buildings designed or already built on the site.
The application of reinforced concrete technologies provides the illusion of shapeless and blurring form of the pool, which reminds the typical water view in natural environment, and gives sophisticated look to it.
This very feature provides a great scope for imagination as regards arrangement of space around the pool, placement of flora, Alpine rock gardens, cliffs and so on. Everything depends on the customer’s desires and capabilities.
As an illustrative example, we’ll calculate parameters for a rectangular pool (3×5×1.5). These dimensions are mostly wanted by the families of 3-4 members. Our calculations are divided into 2 parts:
- calculation for the structure footing of reinforced concrete pool basin;
- calculation for the walls of reinforced concrete pool basin.
Foundation calculation. First of all, the geologic survey of the place, where installation works will take place, has to be reviewed. The foundation type will depend on the soil characteristics within the given territory.
The ground water level is quite low in gravel, rocky and sandy grounds. This allows for installing reservoirs or basins of any configuration without additional labour-intensive and time-consuming efforts due to the fact that the reservoirs will not be deteriorated by soil heave.
Clay grounds, on the contrary, require that installed reservoirs have either flexible and water-proof walls and bottom, or floor thermal insulation layer in order to prevent from concrete deterioration and protect the walls against soil heave in winter.
There are also cases that piled foundation is the only alternative to use judging from the bad condition of the soil. However, grounds are tolerable more often than not so a foundation pad is enough. We’ll take this kind of foundation for our illustrative calculation as they are more common.
Foundation pad thickness can vary from 300 mm to 500 mm. It depends on the geological examination and the reservoir volume, i.e. floor load.
In our case, the base slab thickness is determined as 300 mm to bear the protective coating (the distance between the lower surface of foundation and bottom level fittings is not less than 50 mm; the distance between the upper surface of foundation and top level fittings is not less than 40 mm). Additional structural protection is provided by concrete blinding which is not less than 100 mm thick.
To reinforce the upper and lower levels of foundation pad, we take А-500С reinforcement with design resistance to tensile stress of 4500 kg/m².
The calculation of the foundation slab is similar to that of the multispan beam without fixed end restraint, taking into account the pressure under the foundation pad which is 3,13 tn/m. This figure is equal to the plate load, and the walls represent supports.
The maximum span between the walls: Ms max=9.8 tn×m
Select the reinforcement cross section in the lower part. Calculate the А0 coefficient, when b=1 m.
Calculate the total area of reinforcement (А500С)
The main reinforcement in the lower area: Ø12А500С, rod spacing – 200 m (АS=5.65cm2). The reinforcement in the upper area of foundation pad: Ø12А500С, rod spacing – 200 mm (АS=5.65cm2).
Walls calculation. Further, we proceed to calculations of reinforced concrete basin walls. Ordinary wall reinforcement: ∅10А400С, rod spacing – 200 mm (in case the basin has partitions); outer wall reinforcement: ∅16А400С, rod spacing – 200 mm.
When design works and calculations has been completed, we proceed directly to the preparatory works and concreting of the basin.
Form handling. This is the most crucial step in the basin processing. The concreting itself will depend upon it. The major defects of incorrect formwork:
- bulging of the forms
- non-conformity to the design dimensions, inaccuracy in building
10 mm thick plywood is recommended for the formwork. Of course, using metal formwork is more profitable in the economical point of view, because it can be re-used. But every reservoir or swimming pool is a unique project with specific shape, bottom profile, dimensions, so we recommend using a disposable formwork in this case.
Reinforcement cage is mounted over groundwater waterproofing. To protect waterproofing system against any damage, cement covering is carried out).
Basic issues in reinforcing:
1. Under no circumstances welding is used for reinforcement cage processing:
а) weld area is a potential area of metal corrosion
b) metal structure is damaged
c) the process of concreting is accompanied by locked-up welding stress
Foundation pad reinforcement
Cast-in-situ wall reinforcement
2. Fittings are set on special plastic bar spacers in the bottom and walls (the so-called support chairs and doughnuts).
3. When reinforcing, pipework should be carried out in the places which will not be available later.
4. After reinforcement completion, the hidden works acceptance statement is filled in and signed.
Concreting. Correctly performed concreting is a guarantee of structural strength and durability, and, which is of great importance, will help to avoid additional expenditures for leveling works and corresponding materials. Since we deal with mega-aquariums and oceanariums, we are aware of how to make monolithic structures that would meet the raised requirements and exclusive standards. Tanks for dolphinariums and mega-aquariums are made of high quality concrete. The composition of the mortar mix and fittings are subject to special requirements. As a rule, a mega-aquarium or the main tank in an oceanarium has a curved complex shape, so the processing of formwork should also be paid much attention.
The concreted surface should be flat and smooth, without any cracks and cavities. Injection systems are well recommended for cold joints, which have to be very few.
But one of the main issues is glazing quarters, and our specialists are perfect at it. The project budget directly depends on the accuracy of the quarters implementation. It is not surprising, because pretty expensive acrylic transparent panels are imported ready-made from abroad. It is necessary to remember about the pipelines in the bottom and walls of concrete tanks, which are closely associated with technological part of a project report. Properly embedded fittings of pipelines will guarantee trouble-free installation later on. There are cases, when a customer carries on all concrete works independently, being sure that there is nothing complicated about it. But it usually results in that our experts correct his mistakes, which is a waste of time and resources.
The main principles:
1. Concrete should be of M350 (В25 W6) grade and higher.
2. It is recommended to perform concrete works, when the temperature falls between +5 and +25 °C. The temperatures up to -5°C require that the antifreeze agents are added to the mixture. Still, working at such temperatures is possible, but not recommended.
3. There are two main methods of concreting: continuous casting and two steps casting (using cold joint waterproofing)..
4. Concrete mix compaction by means of a concrete vibrator.
Waterproofing. After having obtained flat and smooth surface, don’t hurry to install the tanks – it is worth thinking of another important question, waterproofing. It allows for protecting the pool or other reservoir against deformations and damage. This measure lessens the number of repair operations.
High quality waterproofing will protect the construction against the harmful effects of water, and this will increase its operating life. Waterproofing is carried out both on the inside and outside.
External waterproofing prevents the penetration of groundwaters. In order to perform this membrane waterproofing, the basin is processed with rolled material. At the same time, internal waterproofing protects against the water contained in the tank – for this purpose various waterproofing plasticizing agents are used.
Waterproofing can be performed with the help of coating materials, too. But before applying corresponding mastic, the surface should be treated with a primer.
Summing up, it should be noted that the production of reinforced concrete basins, preparation of concrete quarters and installation of acrylic panels, followed by sealing, constitute a complex process, and any mistakes in the implementation will have consequences. Strict observing of technological process and the high quality of performed work provides the safety of visitors and saves your money and time.
It is an undoubted fact that Planeta Neptuna Company due to the obtained experience is an expert in this field.