Swimming pool waterproofing with flexible cementitious continuous membrane with ceramic coating

Descripción sistema

Municipal complex in Argentona (Barcelona) consisting of two swimming pools in which waterproofing and subsequent ceramic coating has been carried out. Correct waterproofing of the pool basin is essential if the aim is to avoid water level losses and to ensure optimum operation of the installation during its useful life.

The use of continuous cementitious flexible membranes is the ideal solution for this purpose, as it not only offers the usual advantages over discontinuous membranes (elimination of overlaps, welds, etc.) but also guarantees total compatibility with the cementitious adhesive that will be used to lay the ceramic tiles.

In addition, they are able to withstand both positive and negative pressure or back pressure and offer a high resistance to movements caused by thermal shocks due to their high flexibility.

Reason for the intervention

“Need to waterproof the main pool and cover it with a ceramic coating.
“New adjacent pool for children’s use with the same treatment.

Challenges and constraints

“Provide an application surface with a correct planimetry prior to waterproofing.
“Apply a continuous flexible cementitious membrane, which guarantees the waterproofing of both pool basins.
“Apply an adhesive that allows easy, safe and quick fixing of the ceramic tiles.
“Use a grout that ensures the waterproofing of the installation joint.

Molins Solution

“Use PROPAM® RECRECIDO PRONTO screed mortar to level the surface and create the necessary slopes for water drainage.
“Make half-rounds at all wall-to-wall and wall-to-slab junctions with PROPAM® REPAR TECHNO repair mortar.
“Apply the flexible continuous waterproofing cementitious membrane FLEXITEC.
“Lay the tiles with VAT® FLEXIBLE flexible cementitious adhesive.
“Grout with the special BORADA® PORCELANIC WHITE POLAR cementitious joint mortar.

Execution

“Cleaning and sanitising of the concrete vessels, which must be firm, clean, free of loose particles, compact, free of grease, oil, paint, etc.
“Regularisation and levelling of the screed with PROPAM® RECRECIDO PRONTO (CT-C30-F6) normal setting mortar for the execution of quick-drying screeds in thicknesses of 10 to 80 mm.
“3. Production of half-rounds with PROPAM® REPAR TECHNO repair mortar, thixotropic cementitious mortar with fibres, rapid setting and compensated shrinkage (meets the requirements of standards EN 1504-3 class R4, EN 1504-2 and EN 1504-7). The morphology of the half-round allows to reduce the stresses on the membrane at the joints between the wall and the paving.

“Before applying the waterproofing it is necessary to slightly dampen the substrate.
” 5. Apply a first coat of FLEXITEC, a flexible two-component cementitious waterproofing mortar (complies with the requirements of EN 1504-2), on the dampened surface, using a brush or roller in one direction without spreading the material excessively. After 4 hours, apply a second coat in a cross direction with respect to the previous one. The final thickness of the film should be in the order of 3-4 mm to guarantee the waterproofing of the tank.
“6. 4 days after the application of the FLEXITEC flexible cementitious membrane, the ceramic tiles are laid with the VAT® FLEXIBLE adhesive (C2TES1 according to EN 12004 standard) using a notched trowel, and the tiles should be properly bedded.

“After 24/48 hours from the laying of the ceramic tiles, these pieces are grouted with the special cementitious grout for ceramic joints of up to 4mm BORADA® PORCELÁNICA (CG2WA according to EN 13888).

“Finally, the pools are filled 21 days after grouting.

Technical note

The correct waterproofing of a pool shell is a fundamental operation that must not be neglected if the installation is to function optimally throughout its useful life.
The demanding conditions of use in a swimming pool put the materials used to the test. The settling of the pool, the pressure and back pressure of the water put the tiles under considerable stress. Whether full or empty, the pool shell is always under stress, either from the hydrostatic pressure of the water (positive pressure) or from the back pressure exerted by the ground (negative pressure).

POSITIVE hydrostatic pressure
When the water pressure is exerted directly on the waterproofing layer, favouring its adherence to the substrate (this is the pressure exerted by the water that fills the pool).

NEGATIVE hydrostatic pressure or counter pressure
This occurs when the waterproofing layer is applied on the opposite side of the wall, and the water pressure tends to tear it off (this is the pressure exerted by the ground water against the pool shell).

To ensure waterproofing in swimming pools, a waterproofing mortar with high adhesion and flexibility must be used, capable of withstanding hydrostatic pressure and counter-pressure and movements caused by thermal shocks.