Ardex K 55 Fast - Cementitious Subfloor Levelling

A single-pack compound designed for time-sensitive projects. It provides rapid hardening and drying, making it ideal for high-traffic areas and fast-track installations. Once mixed with water, it forms a smooth, self-levelling mortar that can be applied from feather edge to 10mm thickness. This product’s excellent flow characteristics ensure superior levelling, making it walkable within 30 minutes and ready for floor coverings in as little as 60 minutes.

Applications and Compatibility

This product is designed for smoothing uneven subfloors, such as in-situ concrete, screeds, and other porous substrates. It is not intended as a wearing surface and should not be used on asphalt subfloors or directly on subfloors without an effective damp proof membrane (DPM). It is highly recommended to use appropriate primers, such as Ardex P 82 for non-absorbent subfloors, or Ardex P 51 for porous substrates, to maximise adhesion and performance.

Primers and Associated Products

Ardex K 55 Fast works best when paired with the appropriate primer. For absorbent substrates, Ardex P 51 Primer is recommended to prevent air bubbles and ensure smooth application. For non-absorbent substrates, Ardex P 82 Primer ensures excellent adhesion. Additionally, the use of Ardex AF 2575 Plus adhesive can allow floor coverings to be installed even if Ardex K 55 Fast appears damp, provided the surface is sufficiently hard.

Limitations and Precautions

Do not apply Ardex K 55 Fast on asphalt subfloors, outdoor surfaces, or subfloors exposed to moisture without a damp proof membrane. It should also not be applied over old adhesive residues or directly to ground-based subfloors without an effective DPM. For installations over underfloor heating, ensure the system is correctly commissioned and turned down to room temperature before applying the compound.

Mixing and Application

Mix Ardex K 55 Fast with 4-4.2 litres of water per 20kg bag using a slow-speed drill. The mixture should be used immediately as it has a working time of approximately 10 minutes. For best results, apply the product within this time window. It can be applied using a smoothing trowel or spiked roller to achieve a flat finish. This product is suitable for internal use only and should not be exposed to heavy loads for at least 48 hours following installation.

Coverage

Each 20kg bag covers approximately 6.2m² at a thickness of 2mm. For optimal flow properties, a thickness of 2mm or more is recommended on non-absorbent subfloors.

Health and Safety

Ardex K 55 Fast does not contain Diisocyanates and is classified as non-hazardous for transport (UN number: N/A). Avoid inhalation of dust, and use appropriate protective equipment during handling. For detailed safety information, always refer to the safety data sheet.