ARDEX S28 - Flexible adhesive for large format tiles

Flexible cement-based adhesive for large format tiles with MICROTEC® technology and Ardurapid® effect. For thin-bed or medium-bed fixing of large tiles, natural stone without stains and building materials. Grey colour. Interior. Certified EN 12004: C2 FTE S1. EC1 Very low dispersion.

Color ES
  • Gray
Packaging format
Tax excluded


C2FTES1   Marcado CE   Efecto Ardurapid    ISO 9001

Flexible tile adhesive for large-format tiles with MICROTEC® technology and Ardurapid® effect. For thin-bed or medium-bed fixing of large tiles, natural stone without stains and building materials. Grey colour. Interior. Certified EN 12004: C2 FTE S1. EC1 Very low dispersion.

Field of application:

Interior. Walls and floors.

Generates a flexible mortar bed of soft consistency that allows the total embedding of the pieces at the time of laying.

Stain and efflorescence-free laying of natural stone, terracotta slabs (Cotto), ceramics and building materials.

Ideal for the installation of large-format tiles. Ideal for installation on moisture-sensitive substrates (plaster, plasterboard, anhydrite, wood,...).

Ideal for the installation of polymeric quartz tiles.

Tiling and flooring of ceramic tiles on concrete and masonry work (brickwork) at least 3 months old.

Suitable for use over underfloor heating.

Product description:

Powder containing special cements, additives and flexible polymers. When mixed with water, it results in a flexible, mouldable, plastic mortar that hardens by the 'Ardurapid Effect (by hydration with complete crystallisation of the water).

Preparation of the substrate:

The substrate must be dry, strong and able to support weights, torsion-proof, free of dust, dirt or loose particles.

Gypsum or absorbent or polished anhydrite substrates must be dry and primed with ARDEX P 51, diluted 1:3 with water.

Anhydrite screeds must be prepared according to the BEB guidelines "Hinwise zur Beurteilung und Vorbereitung der Oberfläche von Anhydrite screeds" all surfaces must be vacuumed. Non-porous substrates such as metal, glass, lacquer paints, similar coatings must be primed with ARDEX P 82.

If the substrate is ceramic, it must also be primed with ARDEX P 82 or Ardex P4.

The laying of tiles with ARDEX X30 on bonding bridges, primers or waterproofing shall always be carried out after these have dried.

Instructions for use:

Pour clear water into a clean mixing bowl and mix a corresponding quantity of ARDEX S28 powder until a smooth, lump-free mortar is obtained.

The mortar should be stirred again before application on the substrate to improve its workability.

Approximately 7.5-9.0 litres of water is required to mix 25 kg of ARDEX S28 powder. For wall application the amount of water to be used is 7.0-8.0 litres.

The consistency of the mortar may vary slightly in each case, depending on the type, size and weight of the coatings to be applied.

ARDEX S28 powder is mixed with ARDEX E 90, diluted with water at a mixing ratio of 1:2, to achieve a special adhesive with high deformability and water-repellent properties.

The mixing ratio is approx:

25 kg ARDEX S28 powder

3.3 kg of ARDEX E 90

6.7 litres of water

This system is only recommended when laying ceramic or natural stone that is not sensitive to moisture. Otherwise, due to the delay in drying, staining may occur.

The ARDEX S28 mortar is applied to the substrate and combed with a notched trowel in such a way as to ensure adhesion of the tiles over the entire surface. The choice of notched trowel is determined by the type, size and back of the tiles.

In the case of heavily stressed surfaces, it is recommended that the tiles be laid using the double bonding system to achieve maximum adhesion.

Rough and uneven substrates can be levelled with ARDEX S28. Once the levelling layer has dried, tiling can be carried out.

Tile fixing surfaces should not be larger than the established application time allows, and should be laid on a damp, pasty bed.

Tiles can be corrected up to 20 minutes after laying. Areas that have already been tiled can be walked on and grouted after approx. 4 hours.

If in doubt, carry out a preliminary test.

ARDEX S28 should be used at room temperatures between +5ºC and +30ºC.

Higher temperatures shorten processing and laying times, lower temperatures lengthen them.


We recommend using ARDEX waterproofing products for preliminary waterproofing work.

When laying parts on concrete slabs and plasterboard, mineral fibre or wood slabs, it must be ensured that the slabs have sufficient support and stability with the internal substrate.

ARDEX S28 must not be used in permanently wet areas or in swimming pools. It is recommended for interior use only.

For grouting marble tiles and other moisture-sensitive natural stone slabs, ARDEX MG marble grout should be used.

When laying tiles on floors in the shrinking phase, the field dimensions must be limited by laying expansion joints.

For the installation of translucent natural stone, it is advisable to apply a continuous layer on the entire back of the tile with ARDEX S27W.

On large format pieces it is advisable to use the double gluing method to ensure the most solid installation possible.


Contains cement, reacts alkaline, therefore protect skin and eyes. In case of contact, wash thoroughly with water.

thoroughly with water. In case of eye contact, also consult a doctor.

Wear appropriate protective equipment, e.g. safety goggles, gloves.

Physiologically and ecologically harmless after setting.

Giscode ZP1 = product containing cement, low chromate content.

Technical data

Mixing ratio:

Floors: 7 ½ - 9 litres of water for 25 kg of powder.

Walls: 7 - 8 litres of water for 25 kg of powder.

Density: Approx. 1.1 kg/l.

Density of mortar when fresh: approx. 1.4 kg/l.


on smooth substrates:

approx... 1.2 kg/m² powder with 3 x 3 x 3 mm notched trowel.

approx. 1.9 kg/m² powder with a notched trowel 6 x 6 x 6 x 6 mm

approx. 2.4 kg /m² powder with a notched trowel 8 x 8 x 8 x 8 mm

approx. 2.9 kg /m² powder with notched trowel 10 x 10 x 10 x 10 mm

approx. 3.4 kg /m² powder with a notched trowel 12 x 12 x 12 x 12 mm

Working time (20°C): approx. 75 min.

Setting time (20°C): (open time) approx. 45 minutes (measured with fresh mortar).

Setting time (20°C): Approx. 20 minutes.

Workability (20°C): After approx. 4 hours, after which the joints can be sealed.

Suitable for underfloor heating: Yes.

Packaging: 25 kg bags.

Storage: Approx. 12 months in dry place in closed original packaging.

Product Details

Single component
Floor and wall
25 kg
Normative UNE
UNE 12004 C2 FTE S1
UNE 12004 - Type
C - Cementitious adhesive
UNE 12004 - Adherence
C2 - High adhesion
UNE 12004 - Drying time
F - Quick dry
UNE 12004 - Slipping
T - Reduced slip
UNE 12004 - Open time
E - Long open time
UNE 12004 - Deformability
S1 - Deformable
Drying time
Fast - Ardurapid effect
EC1 Plus
Marked CE
Quality certificate
ISO 9001 - LLoyds Register Quality Assurance Limited


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