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Concrete structures protection with mineral waterproofing slurries

Measuring of moisture in the floor substrate is a necessary preparatory step before tiling.

Crucial to know

28 days old concrete substrate

keep CR 65 moist for 24 h

the 2nd layer of CR 166 after 3 h


Tools needed

a brush & a trowel

a drill with a paddle mixer

protection foil

Step 1

Mineral slurries general info

Features of cementitious slurries

There are two types of cementitious slurries: rigid (Ceresit CR 65) and flexible (Ceresit CR 166). Both contain modifiers and hydrophobic agents. Both are suitable for dump and wet mineral surfaces. Both mixing and application properties are easy to handle while some preparation steps must be followed. The main differences are:

  • rigid slurries are not crack bridging whereas flexible ones have crack bridging ability,
  • rigid slurries should be applied only on non-shrinking, non-deformable substrates, while flexible slurries are suitable also for deformable substrates (e.g. terraces, balconies, heated floors).

Ceresit CR 166 flexible 2-component waterproofing slurry has even more benefits – it is very high resistant to positive & negative water pressure, it is reinforced with fibres and compatible with sealing tapes.

    Step 2

    Preparing the substrate

    Substrate preparation

    Mineral slurries Ceresit CR 65 and Ceresit CR 166 require pre-wetting of the substrate before application, avoiding formation of puddles. When waterproofing foundation in the case of rear penetration of moisture, pre-treat the areas with CO 81 Silicifying Fluid.

    CR 65 and CR 166 adheres to load-bearing, solid and clean surfaces, free from any substances that decrease adhesion (such as grease, bitumen, dust), namely: concrete (over 28 days old), cement screeds (over 28 days old), rapid-hardening cement screeds Ceresit CN 87 (over 3 days old).

    Cracks of more than 0.5 mm width should be widened and then filled with Ceresit CX 5 cement. Uneven surfaces should also be levelled with cement mortar. For inner corner concave molding with radius of 4 cm should be done (alternatively sealing tape might be fixed in a slurry).

    Step 3

    Preparation & application of Ceresit CR 65

    Application of CR 65 Slurry

    Ceresit CR 65 one-component slurry should be stirred until it forms a homogeneous mixture, free of lumps. Wait about 5 minutes and stir the material shortly again. Application of two layers of the slurry is recommended. Avoid application of too thick layer in single operation while it may lead to crack of material and extend drying time.

    The first layer should always be applied with a brush on wet substrate, while the next layers can be applied by a float or with a brush. When the first layer has reached sufficient surface strength, pre-wet the substrate again and then spread the waterproofing slurry with a float or apply two thin slurry coats with a brush. The maximum layer thickness of each coat applied is 5 mm. Protect the waterproofed surface against too rapid drying; keep it moist for at least 24 hours.

    Keep the freshly applied coating in the wet conditions for at least 3 days (e.g. by periodic gently water spraying or wetting with a wet brush, using protection against draughts and direct sunlight). Protect against rain for at least 24 hours. Ceramic tiles, plasters or flooring can be applied on a layer of CR 65 after 7 days at the earliest from drying out too quickly, frost and precipitation.

    Step 4

    Preparation & application of ceresit CR 166

    Ceresit CR 166 two-component slurry should be stirred until it forms a homogeneous mixture, free of lumps. Wait about 5 minutes and stir the material shortly again.

    The first layer of CR 166 should always be applied with a brush on wet substrate, while the next layers can be applied by a trowel or with a brush. The fresh layer should be protected with foil sheets against drying out too quickly. Under average conditions, the next layer of CR 166 can be applied after 3 hours, when the previous layer is hardened but still damp.

    Consistency of the mortar should be adjusted to the application method:

    • application by brush – pour compound B (liquid) into a container, add 2 litres of water and add compound A (powder) whilst stirring,
    • application by trowel – pour compound B (liquid) into a container and add compound A (powder) whilst stirring.

    For horizontal damp-proofing barrier on wall footing, it is recommended to embed a reinforcement fleece (60 g/m2) between layers of CR 166.

    Tips & Tricks

    For professionals

    The Hydroslide Effect with CR 65 and CR 166

    The Hydroslide Effect creates an immediate water-repellent effect, providing a stronger reduction of capillary absorption of water vs. other standard slurries. It leads to a stronger reduction of aggressive substances dissolved in water (e.g. chlorides and de-icing salt) ensuring an excellent adhesion of subsequent layers.


    products used

    • ${/content/heliux/adhesive/ceresit/com/en/products/flooring/central-pdp#/ceresit-cn-87/SAP_0201TBC014A2/searchResult.productFields.MainImageAltText}
      CERESIT CN 87
      Mortar for the creation of fast-curing cement screeds in layer thicknesses from 10 to 80 mm, suitable for permanently wet areas. 
    • ${/content/heliux/adhesive/ceresit/com/en/products/waterproofing/central-pdp#/ceresit-co-81/SAP_0201WQC014A5/searchResult.productFields.MainImageAltText}
      CERESIT CO 81
      For sealing existing brickwork against capillary rise of moisture. Seals capillaries and fine cracks of up. 
    • ${/content/heliux/adhesive/ceresit/com/en/products/waterproofing/central-pdp#/ceresit-cr-166/SAP_0201WJC014B9/searchResult.productFields.MainImageAltText}
      CERESIT CR 166
      2-component flexible slurry, strengthened with fibres and designed for waterproofing and damp-proofing on deformable and non-deformable mineral substrates. 
    • ${/content/heliux/adhesive/ceresit/com/en/products/waterproofing/central-pdp#/ceresit-cr-65/SAP_0201WHC014C3/searchResult.productFields.MainImageAltText}
      CERESIT CR 65
      1-component cementitious waterproofing slurry, perfect to improve concrete substrate resistance on cementitious substrates that are ready for coating and non-shrinking, non-deformable, and salt-free. 
    • ${/content/heliux/adhesive/ceresit/com/en/products/mortars-and-auxiliaries/central-pdp#/ceresit-cx-5/SAP_0201VBC014O4/searchResult.productFields.MainImageAltText}
      CERESIT CX 5
      Universal fast-setting mortar for quick, easy and strong fixing and assembling with perfect consistency for horizontal and vertical substrates (indoor & outdoor applications). 

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