ARDEX B12 - Thin layer plastering and repair mortar

Thin layer plastering and repair mortar for filling and levelling of irregularities. Smoothing of concrete walls and finishes. Thickness up to 5mm. Exterior and interior.

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45 8% €190.08


Marcado CE

Field of application:

Repairing, levelling and smoothing walls, concrete ceilings, plaster and exposed brickwork.

Filling cracks, holes, large surfaces and irregularities in walls and ceilings.

Smoothing of walls and light concrete finishes.

For exteriors and interiors.


Grey cement-based product.

When mixed with water it becomes a paste-like, stable mortar that is very easy to work with and hardens by hydration and drying, resulting in a tension-free, breathable, waterproof and weather-resistant mass. It adheres to practically any surface.

Preparation of the substrate:

The substrate may be dry or damp but must nevertheless be rough and free of dust, dirt or other separating elements.

Old paints, plaster residues, plaster splashes, etc. must be removed.

Metals should have a corrosion protection layer that serves at the same time as an adhesion bridge.

Instructions for use:

Pour clear water into a clean container and mix, stirring vigorously, the required amount of powder until a homogeneous, lump-free, pasty mortar is obtained.

For the mixing of 25 kg. ARDEX B12 approximately 8.5 litres of water are required.

The mortar can be used for approx. 45 minutes at a temperature of 18-20°C and can be applied in a single pass over several millimetres. At normal temperatures it sets within 2 hours by hydration and drying so that a subsequent finishing application with the ARDEX B12 product itself is possible.

For layers over 5 mm use ARDEX B12 extended with 0-4 mm washed sand up to one third of the mortar volume.

To match the colour of the concrete to be treated, the grey cement in ARDEX B12 can be lightened with ARDEX F11, facade paste (white) or with cement pigments. ARDEX F11 can be mixed in any quantity with ARDEX B12. The pigments should first be mixed with water and then added to the ARDEX B12 as a paste. The pigment can be used in a ratio of up to 5% of the weight of ARDEX B12.

Cracks can be closed with ARDEX B12. Fine cracks in plaster should be widened before repair with ARDEX B12 mortar. Subsequent cracks may be caused by movement of the substrate itself.

In case of doubt, a preliminary test is recommended.

Apply ARDEX B12 outdoors and indoors at a temperature above 5°C.


Once dry, ARDEX B12 can be painted with either silicate paint, pliolite, plastic and stone coating. The drying time depends on the thickness of the applied layer and the ambient conditions on site. A still wet undercoat can cause efflorescence.

The recommendations of the paint manufacturer for application on concrete substrates must be observed.

The recommendations indicated by the paint manufacturer for application on concrete substrates must be observed, whether for use on large surfaces or only on partial surfaces.


Contains cement, irritating to eyes and skin. Keep out of the reach of children. Avoid contact with eyes and skin. In case of contact with eyes rinse immediately with clean water and seek medical advice. Wear suitable gloves.

After drying has no physiological or ecological effects.

GISCODE ZP 1 = Product containing chrome-poor cement.

Technical data

  • Mixing ratio: Approx. 8.5 litres of water : 25 kg of powder representing approx. 1 vol. water : 2 ¾ vol. powder.
  • Density: Approx. 1.1 Kg/litre.
  • Density of the mortar when fresh: Approx. 1.7 Kg/litre.
  • Yield: Approx. 1.2 Kg of powder/m²/mm.
  • Workability time (20°C): Approx. 45 minutes.
  • Compressive strength: 
  • After 7 days approx. 8 N/mm².
  • After 28 days approx. 10 N/mm².
  • Flexural strength: After 7 days approx. 3 N/mm² After 7 days approx. 3 N/mm².
  • After 28 days approx. 5 N/mm².
  • pH-value: approx. 12
  • Corrosion behaviour: Contains no metal-corrosive elements.
  • Packaging: 25 kg bags.
  • Storage: Approx. 12 months in a dry place in closed original packaging.

Product Details

Indoor and outdoor
Single component
Wall and ceiling
Drying time


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