The main advantage of concrete swimming pools is that they provide scope for customization. The shape and design limitations present in case of vinyl liner pools are not applicable to concrete variety. This allows you to build pools of any desired shape along with features like waterfalls and the like.
One more important benefit of opting for concrete swimming pools over vinyl lined ones is durability. The risk of tears, stains or leaks is much lower in case of concrete swimming pools compared to vinyl liner pools. Due to its durability, the pools in hotels or apartment complexes are usually of concrete variety. These pools can be lined with tiles to make them more attractive.
Cleaning and maintenance of concrete pools
Concrete swimming pools either have a concrete lining or a tile lining. In case of concrete lining, the pool has to be scraped with wire bristle brush to get rid of the dirt and algae from floor and surrounding walls of the pool. The best way to do this is to start on the shallow side of the pool and work your way towards the deeper end. After the debris settle, a pool vacuum cleaner can be used to clean it.
pools, the tiles need to be occasionally scrubbed clean using household tile cleaner. Chlorine is helpful in removing stains from concrete pools. In case of tougher stains, acid wash is a good option. Concrete pools can be drained completely without risk of collapse, this makes cleaning easier to some extent.
|Acid wash of Concrete
Pressure washing is not recommended for concrete swimming pools. Although pressure washing can effectively get rid of dirt, and clean the pool, it can cause peeling of the base of your concrete pool. Peeling of the base results in uneven surface and repairing uneven pool surface is a costly affair.
A most important issue in pool placement is safety, this aspect is particularly essential when you are concerned about children, elderly/pets or non-swimmers. If one select a deep swimming poll, it is mandatory to aware all swimmers about start point with depth. When hopper pool is selected, the start point of deeper end should be visibly identified. To ensure a safe pool, it should have under always supervision; in addition you can provide:
• Install fencing having gate that can be locked
• Install safety cover
• Provide some floating lifebuoys
• Provide some step units; in case of accidental falling into pool, the shallower steps can help one to come out of this pool.
• Pool should be located close to house and they visible from window (say kitchen window).
Site preparation and excavation:
Irrespective of size and shape of swimming pool, the instructions provided below will be virtually identical, but have some differences while setting out and digging. At first you have to determine dimensions of pool (width, length and depth). Once these are set, the inner dimensions of swimming pool have to be marked out over the ground; the excavation perimeter should be 0.5 m larger all over the sides of pools to accommodate the walls and necessary backfilling.
You can choose mechanical excavator to excavate soil which is more convenient and quicker than manual excavation. The excavator can be hired from local company; a JCB excavator can easily dig 30’X14’ pool in a day, if soil is not required to transport out of the site.
If excavated soil can be used to fill lower area around the house or utilized to elevate garden bank, it will be more cheaper and easier than to transport soil by truck or lorries to other location; obviously time of excavation will be extended too.
The final excavation level of pool is the matter of owner’s requirement as well as the length of shallow area, but it is recommended to keep more than one third of length of pool. However one can choose to start slope from shallow end and continue up to deep end wall taking wedge shaped pool.
It should remember that the pool should be dug 12” more than the finished depth to accommodate 9” thick concrete floor and a 3” (larger if required) of stone rejects. But when subsoil is found unmanageable and wet, a 3” thick layer of lean concrete (dry) can be laid over soil which is porous enough to permit water passage through it. Simultaneously it will offer a dry surface to continue construction work above it. The finished surface should have perfect shape. If any spot have been cut too deep, dry lean concrete should be used to fill depression to avoid any settlement.
If subsoil encountered has good draining strata like gravel or shale etc., you can avoid layer of rejects; thus concrete can be placed directly over the subsoil. In this case, a over excavation of 9” is considered enough, except along the perimeter of pool as pool walls must have concrete foundations of 12” thick. Please note that this is not completer guide for constructing swimming pool; all dimensions stated above considering pool build over stable subsoil in normal conditions. If ground is found unstable, you should consult with expert for specific instructions.
It is fond that cracking in pools are mostly due to adequate reinforcement. Though welded mesh of steel (8 mm dia) is found adequate for concrete swimming pools having four feet depth supported on good foundation, is not enough for deeper swimming pools. In such cases 10 mm MS bars are usually chosen and applied throughout the side wall.
Such bars can be bent easily to take the shape of pool; usually spaced at 9” intervals which cross the bars normal to them also placed at 9” intervals, thus a square of 9” sides are created. To keep the bars in shape crossing end of bars is wired by galvanized wire. To avoid corrosion of reinforcement, the fabrication are kept 50 mm apart from the sides of tank, in this purposes steel chairs can be used which keep the fabrication in place before concreting.
Before laying reinforcement and essentially before concreting, the pipework required for pool functionally must be placed on floor and quality earth bonding have to established for all metal works including reinforcement of concrete.
Placing main drain:
After fabrication and laying of reinforcement, at the middle of floor near deep end, main drain is placed keeping top 1.5” above finishing level of concrete slab so that after finishing it is flushed with pool finishing.Install pipe in the main drain penetrating concrete floor to outside of pool walls (to be constructed). This pipe is then bent to reach up to top of pool. To avoid possible blockage with debris of constriction, the open end of pipe are kept sealed.
The sump pot of main drain should be protected from entering concrete during placing. A collection tube having hydrostatic relief valve atop are installed in main drain.
With the completion of installation of main drain and placement of reinforcement, the concrete is placed on floor. It is preferable to place concrete at a time as this will result strongest floor. But if it is not possible, it can be carried out with construction joints followed by successive placing. Ready mix concrete is always preferred as it offers constant proportioning and convenient mixing properties to concrete. The slump of mix should be 2” and designed to have strength of 4500 psi. While concreting it is essential to place well under reinforcement which require significant amount of efforts including vibrating and leveling.
A vibrating poker is used to vibrate accumulated concrete on the floor to agitate concrete mix thoroughly to expel out air entrapped into concrete which will ensure a dense structure. This is done by pressing poker into mix; while vibrating water comes out to surface through cement making a circle of around 27”. Then it is made ready to receive necessary rendering; generally a good surface means textured it by brush to develop bond. Vibrating pokers are usually hired from local service providers.
In construction of walls, formwork is not required as concrete blocks are used to build two walls having a cavity of 6”. This cavity is concreted then placing required reinforcement. At first exterior walls are constructed with wall ties and wired reinforcement is placed. The lateral reinforcement are wired with normal bars to make an interval of 12”; it should remember that the reinforcing bars must have overlap of 20Xdb ( db=bar diameter). After fabrication of reinforcement, interior wall is constructed.
Any leak during concreting should be avoided. If water with some cement is leaked that not only make a weak concrete but also affects workability of the concrete.
Considerations for water tightness:
Following consideration should apply to reinforced concrete water tight pools:
After completion of RC body of pool, the water tightness can be verified by filling the pool with water (usually chlorinated water is used) for test to the rim level around the pool. Freestanding pools should not be water proofed on the outer side until the leak test is completed. Water tightness can be attained by
• Designing impermeable concrete
Making a mark of water level while testing for leaks provides us an sufficiently accurate reference line for placing ceramic accessories to account for overflow that don’t need additional care. The cured concrete must not contain any cracks. The following considerations should be considered while constructing pool:
• Optimum compaction of fresh concrete should be ensured using immersion of vibrator,
• Low water/cement ratio and appropriate composition of aggregates are required
• Pool walls and floors should have at least 10” thick. The upturn in front of drainage channel or behind it should be at least 6” thick when no additional sealing is provided.
• Appropriate curing of concrete by maintaining moist environment.
• A minimum strength of 3600 psi should be ensured.
• Adequate lapping of reinforcement as discussed in reinforcement section
• When it is suspected to have any aggressive agent in water like salt water, selection of bonding should be based on water analysis.
• Stop-end tape at joints must be placed at construction joint.
• It is expected to provide joints in floor and wall not at floor-wall joint, if it is possible.