CM 420 Offshore

CM 420 Offshore is a pumpable self-levelling underlayment intended for substrates of steel or sheet metal on ships, ferries, oil drilling platforms, etc.

Recommended application thickness is 3–30 mm.

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Product specification

Technical data

Release of corrsive substances

CT (as per Marine directive 96/98/EC)

Compressive strength class

C20 (as per Marine directive 96/98/EC)

Compressive strength average

35 MPa (as per Marine directive 96/98/EC)

Flexural strength class

F4 (as per Marine directive 96/98/EC)

Flexural strength average

10 MPa (as per Marine directive 96/98/EC)

Fire resistance class

A2fl-s1 (as per Marine directive 96/98/EC)


100 (as per Marine directive 96/98/EC)


550 (as per Marine directive 96/98/EC)

Adhesion to surface

> 1,5 MPa (as per Marine directive 96/98/EC)

Thickness 1

3–30 mm

Grain size

< 0.5 mm

Material consumption

1.1 kg/m²/mm

Weight (dry state)

1100 kg/m³

Water requirements

4,3 l/15 kg

Flow rate

max 145 mm

Workplace temperature

10–25 °C

Mixing time

3 min

Working time

approx. 60 min

Final set

> 4 hrs

Coverable (tiles)

24 hrs


1–3 days


approx. 11

Water damage resistant


Surface Tensile Bond Strength, 28 days (sanded, loaded surface)

> 1,5 MPa


0.04–0.06 %

TVOC 28 days

30 μg/m² h



15 kg




The substrate should be clean and free of dust, cement skin, grease and other impurities that can prevent adhesion. Adhesion and surface resistance of the substrate should be no less than 0.5 MPa. Always prime the underlying substrate with PP600 and allow to dry before pouring. In terms of the primer forming a film and the curing of the self-leveling, the temperature of the substrate must not fall below 10 °C. For best results, the ambient temperature in the work area should be between 10 and 25 °C.


Mix CM 420 Offshore with max 4.3 liters of water (max 29 %) per 15 kg bag. Create the mixture with a drilling machine and a whisk, or a mixing pump intended for this purpose. The correct water mixture can be tested using a slump test with a cylinder with Ø 30 mm and a height of 50 mm on a 300 x 300 mm plexiglas plate. With the correct water mixture, the spread should be max 145 mm. The slump test also checks that the material is well blended and that there is no separation.


The mixed material is applied by hand, or pumped out onto the substrate in lengths and leveled with a toothed smoother. Each new ribbon is added to the old one as soon as possible so that the material can blend together and create an even surface. The width of the ribbons can be adjusted to the capacity of thwe mixing pump and the thickness of the covering. Use the Combimix form foam for edging. In order to avoid drainage pipes from getting clogged, always make sure the drains are properly sealed before pouring.

Post-treatment and curing

You can easily shape or cut the semi-hardened self-leveling underlayment material before it fully dries. Always make sure that the material is sufficiently dry before installing flooring. The drying time is 1–3 days for the product to be carpetable. The guiding value assumes a curing temperature of approximately 20 °C, 40 % RH and proper air flow. Newly produced surfaces must be protected against wind, sun and rain.

Consumption calculator

CM 420 Offshore

Consumption calculator


+46 171 46 65 90

Call our order department

Contact us

  • Verkstadsvägen 6
  • 746 40 Bålsta, Sweden
  • Tel. +46 171 46 65 90
  • E-mail: [email protected]


Combimix develops and manufactures mineral-based products for the construction industry. Our product range includes products for floor levelling, façade plastering, rendering, concrete resurfacing and restoration mortar for cultural buildings. We conduct sales in Europe and USA.

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