Parchem Vandex Cemelast

Flexible, sulphate-resisting, cement-based waterproofing render suitable for live cracks and negative hydrostatic pressure

Vandex Cemelast is a ready-mixed, two component, polymer modified, cementitious, waterproofing membrane which is made by mixing Vandex BB75-Z with Vandex Cemelast liquid. The BB75-Z powder component consists of grey sulphate resistant cement, graded quartz sands and inorganic additives. The Cemelast liquid is the polymer component. Vandex Cemelast is waterproof and has been tested to a pressure of 1.5 bar (15m water head). The initial and final bonding capability of Cemelast is excellent, making it suitable for application to both vertical and horizontal surfaces. It is durable, resistant to frost and heat after setting and remains permeable to water vapour.
  • Overview


  • Description


    Waterproofing of concrete and masonry structures both new and old where live cracks are present. Vandex Cemelast is a flexible cementitious membrane and does not rely on crystal growth to achieve its waterproofing. As a result, Cemelast can be used on most masonry surfaces, including sandstone, provided that the surfaces are adequately prepared.

    Vandex Cemelast has been formulated using sulphate resisting cement making it ideal for application in pH aggressive water. It can be applied to either the pressure or non-pressure faces of the concrete or masonry.

    Vandex Cemelast is excellent for solving the problem of water seepage through concrete and masonry where live cracks are present in both new and old structures.

    Vandex Cemelast is ideal for application in potable water structures.

    It can also be used in applications where live crack movement up to 0.3 mm exists.


    • Permanently flexible and accommodates dynamic crack movement up to 0.3 mm
    • Applied to either the pressure or non pressure face of concrete
    • Tested to withstand a water head of 15 metres
    • Based on sulphate resisting cement making it suitable for use in tanks containing pH aggressive water
    • Works on masonry, brick, stone and concrete blocks where crystal growth treatments are not effective
    • Applied to damp concrete
    • Non-toxic
    • Suitable for use in potable water (AS 4020 compliant)
    • Protects concrete against aggressive water, sea water, aggressive ground water and a range of chemical solutions


    Surfaces treated with Vandex products which are to be coated or painted should be left to cure for at least 28 days. Coatings on top of a Vandex treatment have to be alkali resistant. Decorative coatings applied on the passive (negative) water pressure side are recommended to be water vapour permeable.

    *In negative side applications, do not apply Vandex Cemelast to substrates that are weeping. Use Vandex Plug to stop all water seepage before applying Cemelast.

    Sewerage processing applications
    Vandex Cemelast is only suitable for use in open headed sewerage processing tanks. Consult Parchem for specific advise on the use of Vandex Cemelast in closed sewerage environments where sulphuric acid concentrations may be high.

    Potable water applications
    Where potable water will be in contact with Vandex products, care must be taken to insure the surface has had adequate time to cure prior to filling. If the area is returned to service too soon ‘water taint’ may occur. Once adequate curing time has been left, it is good practice to complete a thorough washing down of the lining with clean water prior to the first filling. Variable atmospheric conditions will dictate how long to leave the surface prior to the wash down. As a guide please refer to the table below:

    5 - 10°C = 14 days,
    10 - 15°C = 10 days
    15 - 25ºC = 7 days
    25 - 30°C = 5 days


  • Performance

  • Compliances and Accreditations


    • AS 4020
  • Systems & Installation


    Priming is not required on good quality concrete substrates, however all surfaces must be pre-watered before applying Vandex Cemelast.

    In most waterproofing applications, Vandex Cemelast is applied in 2 coats by trowel or spray at a total thickness of 2.5 mm. Note: The maximum total thickness of all coats of the Vandex Cemelast system must not exceed 4 mm.

  • Compatible Products

    Parchem Vandex BB75-Z

    Surface applied, cement based render, waterproofing barrier for positive and negative water pressure applications

  • Spec Clause

    Spec Clause

    Where so designated on the drawings, surfaces to be waterproofed shall have a surface applied, flexible cementitious waterproofing membrane installed. The waterproofing product will be produced by mixing a cementitious powder component with a liquid polymer component. The waterproofing must form an impermeable layer on the surface of the substrate and must not rely on crystal growth within the substrate in order to be effective. The waterproofing treatment must be flexible and be capable of accommodating long term cyclic crack movement up to 0.3 mm without any loss of waterproofing integrity. It must have a proven capability of sustaining pressures of 1.5 bar (15 metre water head) even after sustaining 0.3 mm cyclic crack movement.

    The cementitious waterproofing membrane must be non toxic and be capable of being applied to concrete and masonry surfaces by trowel or spray application through a fine mortar spray machine.

    Vandex Cemelast supplied by Parchem is such a product.

  • Projects & Installers

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  • Downloads

    Parchem Vandex Cemelast

    Surface applied, cement based render, waterproofing barrier for positive and negative water pressure applications

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