Repsol YPF

Geomembranes

Waterproofed sheets manufactured with synthetic plastic materials are called geomembranes. The main and common characteristic in all types is their low permeability to water with the use of a much lower thickness than with traditional waterproofing materials.

The characteristics that should be found in a good geomembrane, which will depend on the field of application, can be summarised as follows:

• Very low permeability to water
• Good mechanical properties
• Resistance to traction
• Expansion of rupture by traction
•  Resistance to shattering
•  Easiness of union (weldability, gluing,...)
•  Adaptability to the terrain
•  High duration (useful life)
•  Low cost of the geomembrane and of its installation            

The useful life of a geomembrane depends on its resistance to the aggressions to which it is subject while in service.

Factors determining the geomembrane's stability in time are the following:

• Resistance to the outdoors
• Effects of solar radiation
• Thermal effects, as much for high and low temperatures as for the combined effect of cold-hot cycles
• Attacks by ozone in the atmosphere
•  Resistance to chemical products
•  Resistance to microorganisms
•  Resistance to perforation   

Numerous polymers are used in the making of geomembranes. The projected European norm on waterproofing groups the polymeric materials used in three categories, Thermoplastics, Thermoplastic Rubber and Elastomers.            

More information on the European and Spanish norms.

Chart 1 summarizes the polymers used in waterproofing.

Application materials can be used in situ but the synthetic materials used for the most part in waterproofing are the so-called "prefabricated" ones that have sheet shape.

Repsol is present in the market of geomembranes of high-density polyethylene.