Koster SL Premium - Cement-based Levelling Underlayment

Manufacturer guidance

• The substrate has to be sound and solid as well as free of bond inhibiting agents such as grease and oil.
• Remove all bond breaking substances such as laitance, loose particles, dust, formwork release oil, etc.
• The substrate can be prepared according to need by shotblasting, grinding, or brushing.
• Concrete and screed substrates are primed with KÖSTER SL Primer to reduce absorption before application.

Non-absorbent tile substrates must be removed or ground down to an absorbent layer.

Manufacturer guidance

General:

• The pull-off strength of substrates which are to be trafficked or that are to be treated with KÖSTER VAP I 2000 coatings must have a min. tensile strength of 1.5 N/mm².
• Do not acid etch substrates or clean the substrate with chemicals.
• Do not apply over adhesive residue. Do not bridge expansion joints with the KÖSTER SL Premium.
• Expansion joints must be installed in accordance with local guidelines.
• Mix each 25 kg bag of KÖSTER SL Premium with 5.2 l of potable water.
• The water is placed in a clean mixing vessel and the powder added while constantly mixing.
• Use an electrical paddle mixer and mix intensively for 3 minutes until a flowable, lump free consistency is reached.
• Distribute the material in the desired layer thickness directly after mixing.
• Mix and distribute the material in a constant work flow to avoid visible work edges.
• The material is self levelling when working “fresh in fresh”.
• While working larger areas use a KÖSTER Gauging Rake to distribute the material.
• Rolling the surface with a KÖSTER Spiked Roller immediately after distribution creates a very smooth surface through better de-airing.
• Install the KÖSTER SL Premium within 20 minutes.
• Do not delay successive pours by more than 10 minutes to avoid visible work edges.
• The surface qualities of the underlayment depend on workmanship, layer thickness, and curing parameters so that variations from a sample surface may occur.
• Moisture sensitive floor coverings and sealers may not be applied before the material has fully cured.
• Depending on the temperature it may take between 24 and 72 hours for the material to attain a residual moisture content of less than 3 M%.

Plain concrete without KÖSTER VAP I 2000 vapor barrier:

• Concrete substrates are prepared by shot blasting, milling and/or sandblasting in order to achieve an absorbent, open pored substrate.
• The cleaned concrete substrate is primed with KÖSTER SL Primer according to the Technical Guideline.

Concrete coated with a KOSTER VAP I 2000 vapor barrier:

• When applying onto smooth, non-absorptive substrates such as KÖSTER VAP I 2000 systems, KÖSTER SL Premium can be applied in layers up to 12 mm.
• It is necessary to prime such substrates with KÖSTER VAP I 06, consumption approximately 50 - 70 g/m².
• Depressions in the substrate should be filled below the VAP I 2000 layer.
• The coating can be opened to foot traffic after 24 hours and to traffic after 72 hours.

After treatment:

• Curing can be aided by covering the hardened material with polyethylene sheets.
• This reduces surface shrinkage tension especially when the material has been applied in thick layers.

Manufacturer guidance

• Bulk density (powder): 1.3 g/cm³.
• Compressive strength (28 days): approx. 45 N/mm².
• Bending tensile strength (28 days): approx. 10 N/mm².
• Tensile strength (depending on substrate): up to 4 N/mm²
• Application temperature: min. + 5 °C to +30 °C.
• Ideal application temperature: + 15 °C.
• Pot life: 20 minutes (+ 20 °C).
• Resistant to foot traffic after 3 – 4 hours*.
• Can be tiled over after 4 – 6 hours*.
• Trafficable (soft tires) after 24 hours*
• Application of Parquet, carpet: after 24 – 72 hours*.
• Application of synthetic flooring: after 24 – 72 hours.
• Layer thickness (self-leveling), 5 to 15 mm in depressions up to 30 mm.
• Not self-leveling: 2 to 5 mm.
• Can be feathered out to 2 mm.

*depending on temperature.