Waterproofing of hydraulic structures with geomembranes

Hydraulic infrastructures need waterproofing barriers that are deformable, able to withstand displacements, and durable. Equally important are construction, freedom from routine maintenance and durability.

Geomembranes offer a number of advantages.

Geomembranes protect structures from water infiltration, which is detrimental to their life and safety, and prevent water leakage into slopes from affecting their stability and, ultimately, the integrity of structures.

They resist ground settlement, differential movements between adjacent blocks of the structure, or between deformable parts and rigid appurtenances, which exert very high stresses.

The installation of geomembranes involves lighter logistics and shorter construction times than conventional waterproofing solutions, such as concrete/asphalt facings or clay/asphalt concrete cores.

Geomembranes allow the use of local materials, avoid treatment and reduce the volume of fill. The environmental impact is considerably reduced.

Geomembranes do not require routine maintenance. Accidental damage can be repaired underwater, with no downtime costs.

Carpi, our geomembrane specialist subsidiary

Within the Freyssinet Group, the major specialist in waterproofing geomembranes is Carpi, which is a Swiss-based subsidiary with extremely international activities.

Carpi geomembrane waterproofing solutions differ depending on the type of structure, the loads involved and the specific requirements of each project. The geomembrane installed over the entire surface of the structure in contact with water can be fully exposed, partially or fully covered, or installed as an external water stop at the joints.

For fully exposed geomembranes, we offer a range of face anchorage systems, some of which are patented, placed along parallel lines or at specific points. Ballast layers can be made of concrete, reinforced concrete, shotcrete or granular materials.

  • 48
    New dams
  • 13
    New reservoirs
  • 40
    New traffic tunnels

Why choose Carpi geomembranes for your project

01. Expertise of a specialist since 1963

More than 300 new hydraulic structures worldwide have been waterproofed using Carpi geomembranes.

02. Durable watertightness

The watertightness of our geomembranes is checked during production and is not affected by the climatic conditions on site. The watertightness of the joints and perimeter seals is tested by standardised procedures.

03. High resistance to loads

The tensile performance of our geomembranes and a bespoke design allow them to withstand high stresses resulting from differential movements and settlements.

04. Quick installation

Thanks to simple site organisation, equipment and installation procedures, the waterproofing system can be installed quickly and cost-effectively, enabling rapid commissioning.
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Carpi, the Freyssinet's waterproofing specialist

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Exposed drained geomembranes

Exposed drained geomembranes are the most widely used solution for waterproofing hydraulic infrastructures, due to their rapid installation, ease of inspection, accessibility and reparability if necessary, even under water, during the whole life of the system. The geomembrane is fastened to the structure by various anchorage systems.

Exposed geomembrane with tensioning profiles

Tensioning profiles, developed and patented by Carpi, are used on rigid structures with a high pull-out resistance facing. They keep the geomembrane taut on the surface of the structure and act as upstream drains, collecting seepage water and preventing it from seeping into the structure.
  • High durability
  • Excellent resistance to
    high water pressure
    and high water speed
  • Effective drainage system

Exposed geomembrane with anchor trenches

The face anchorage of the geomembrane is made in vertical trenches cut into the granular facing during construction and compaction. Various configurations, including patented tensioning trenches, are available. The anchorage system and the perimeter seals allow for settlements and differential movements.
  • Resists settlements
    and differential movements
  • Quick construction,
    early commissioning
  • Low environmental footprint

Exposed geomembrane with anchor wings

In this patented solution, the face anchorage of the geomembrane is made by welding it on the geomembrane anchoring wings embedded in the facing during its construction, which reduces the installation time of the waterproofing system, and obtains a deformable anchoring system adapting to settlements. The perimeter seals are designed to accommodate differential movements.
  • Resists settlements
    and differential movements
  • Quick construction,
    early commissioning
  • Cost-effective solution

Exposed geomembranes with deep point anchors

Where the structure in contact with the water does not have the necessary pull-out resistance, such as embankments or weak subgrades, special anchors must be used to ensure that water or wind action does not lift the geomembrane. The face anchorage of the geomembrane is carried out at points, by a patented system of deep anchors, grouted or earth anchor type, embedded in the compacted granular facing. The perimeter seals are designed to adapt to differential movements.
  • Ensure stability on subgrades
    with low pull-out strength
  • Resists settlements
    and differential movements
  • Low environmental footprint

Covered geomembranes

When specific project design conditions require it, the geomembrane can be fixed to the structure by ballasting, installing a cover layer.

The following options are available:

  • concrete panels in which the geomembrane is embedded – for RCC dam facings
  • reinforced concrete for hydrotunnels, transport tunnels and shafts
  • granular materials for embankments.

In some cases, the cover layer is applied partially to sections that require it, or to fit a part of a structure of different design.

The design of the perimeter seals is site specific, the installation closely follows the construction schedule.

Covered geomembranes - Heavy and rigid covers

One of the possible ballasting solutions is a concrete cover. The concrete can be installed as reinforced slabs cast in situ, or as precast elements. These covers are often placed on a geotextile cushion.
  • Total protection
  • Proven technique
  • Can be used for partial covers

Covered geomembranes - Granular covers

Granular covers are used in embankments, either to ballast an upstream geomembrane, or to embed a geomembrane waterproofing barrier, placed in a central zigzag core, or as inclined upstream core A cushioning geotextile is placed on the geomembrane to protect it from puncturing.
  • Total protection
  • Environmentally friendly
  • Resist settlements
    and differential movements

External water stops

External water stops

Traditional embedded water stops can fail due to insufficient elongation capacity or poor placement. Carpi's patented external water stop, with a highly deformable watertight geomembrane supported by appropriate geosynthetics, resists multiaxial movements of contiguous blocks and large differential movements at the deformable body/rigid concrete appurtenance interface.
  • Resist differential movements
  • No interference with
    the construction of the structure
  • Can be inspected at all times

Carpi, the Freyssinet's waterproofing specialist

Visit their website

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