ARDEX X 78 S MICROTEC® Flexible Rapid Set Semi-Pourable Floor Tile Adhesive Grey 20kg


£47.58 inc. VAT
£39.65 ex. VAT

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  • Product ID: 18331
  • Suitable For: adhering floor tiles
  • Area of use: INT & EXT
  • Application Method: trowel
  • Time to full cure: 90 minutes
  • Volume: 20kg
  • Container Type: bag
  • Type: adhesive
  • Colour: grey
  • Brand: Ardex
  • Manufactuer: Ardex
  • Box Size: 1

 

ARDEX X 78 S grey is a MICROTEC fibre-reinforced, ultra-rapid setting, cement-based floor tile adhesive that can be walked on and grouted within just 90 minutes. Formulated for superior adhesion and flexibility, it features a semi-pourable consistency that is ideal for fixing large format floor tiles. ARDEX X 78 S is particularly suited for fully vitrified or porcelain tiles, as well as glass mosaics, terrazzo, and other low-porosity tiles. Classified under BS EN 12004 as a C2 FE S1 adhesive, it offers fast setting, deformability, and extended open time. Its tensile adhesion strength exceeds 1 N/mm², even under conditions like water immersion, heat aging, and freeze-thaw cycles, making it suitable for both internal and external applications, including swimming pools. The adhesive reaches the EN 12004 standard of 0.5 N/mm² within just 6 hours and provides excellent adhesion to materials like concrete, screeds, and existing tiled surfaces.

 

Key Points:

  • Ultra-rapid setting adhesive, walkable and groutable after 90 minutes.
  • Semi-pourable consistency, ideal for large format and low-porosity tiles.
  • Meets BS EN 12004 C2 FE S1 standards for fast setting, deformability, and extended open time.
  • Strong adhesion in challenging conditions, suitable for both internal and external applications, including swimming pools.

 

Coverage: A 20kg bag of ARDEX X 78 S produces approximately 16.5 litres of mortar, using around 1.2kg of powder per m² for each mm of adhesive thickness. Actual coverage may vary based on the tile’s back profile, trowel type, and bedding technique. For example, using a 5mm x 5mm square-toothed notched trowel, a 20kg bag of ARDEX X 78 S will cover approximately 9.4m².

Storage and Shelf Life: ARDEX X 78 S contains a reducing agent to manage the level of Chromium VI when mixed. It should be stored in unopened packaging, off the ground, in cool, dry conditions, and protected from draughts. When stored correctly and used within 6 months of the date on the packaging, the reducing agent will remain active, ensuring the product contains no more than 0.0002% (2ppm) of soluble Chromium VI by dry weight when mixed with water. Using ARDEX X 78 S beyond the declared storage period may increase the risk of allergic reactions, and the product should not be used after this period.

 

 

 

For more in our range of tile adhesives, please click here, and for more in our range from Ardex, click here.

Alternatively, you can visit the Ardex website here.

 

 

ARDEX X 78 S is specifically designed for fixing fully vitrified and porcelain tiles, as well as other low-porosity materials like glass and porcelain mosaics and terrazzo. Classified under BS EN 12004 as C2 FE S1, it is an improved fast-setting deformable cementitious adhesive with extended open time. It has excellent tensile adhesion strength of over 1 N/mm², maintaining this performance even after water immersion, heat aging, and freeze-thaw cycles, making it ideal for both internal and external applications, including swimming pools. With enhanced setting and hardening properties, ARDEX X 78 S reaches the EN 12004 standard of 0.5 N/mm² after just 6 hours. The semi-pourable consistency ensures easy application for large format floor tiles, and it bonds well to various surfaces such as concrete, cement screeds, heated sub-floors, anhydrite screeds, and existing ceramic tiles.

 

Surface Preparation
The surfaces and backgrounds for tiling must be clean, firm, and free from dust, dirt, oil, grease, or any other materials that could interfere with adhesion. Ensure that the background has had sufficient drying time as specified in BS 5385-3 before tiling. Install tiles in accordance with BS 5385 and BS 8000: Part 11 Workmanship on Building Sites. Backgrounds for ceramic tiles should meet Surface Regularity 1, meaning any gap under a 2m straight edge should not exceed 3mm. ARDEX X 78 S can be applied to both dry and moist surfaces, but moisture-sensitive materials must be dry and remain dry after fixing. For additional protection in wet areas, the ARDEX WPC Waterproof Protection System can be applied to create a waterproof barrier, protecting moisture-sensitive backgrounds from water damage.

Mixing
ARDEX X 78 S powder should be mixed with clean water in a clean container, stirring thoroughly to create a semi-pourable, workable mortar. Using an ARDEX mixing paddle with a 10mm chuck and a variable-speed electric drill will make mixing easier. The recommended mix ratio by volume is approximately 2¾ parts ARDEX X 78 S powder to 1 part water. A 20kg bag requires up to 7.0 litres of water—do not exceed this maximum. Adjust the adhesive consistency to suit site conditions and materials. The mortar should be applied when temperatures are above 5°C, and its pot life is about 30 minutes at 20°C.

Application
Apply the mixed mortar to the prepared surface using a trowel, and comb it through with a suitably sized notched trowel to create straight ribs for a ribbed mortar bed. Tiles should be fixed within the adhesive’s open time, using a twisting and sliding action to ensure solid bed fixing. ARDEX X 78 S has an open time of up to 30 minutes when freshly mixed, as per BS EN 12004. For best results, tiles should be fixed within 20 minutes and can be adjusted for up to 15 minutes at 20°C.

Grouting
Grouting can begin once the tile bed has hardened sufficiently to prevent tile displacement. For floor tiles, ARDEX X 78 S typically hardens enough to allow foot traffic after 90 minutes at 20°C, depending on the tile and background porosity. Higher temperatures will reduce, and lower temperatures will extend this time. Grout the tile joints with ARDEX-FLEX Tile Grout, or use ARDEX Epoxy Grout in areas where chemical resistance and hygienic joints are needed, such as commercial food preparation areas.

 

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Elementlength
up to
1,5 m
up to
2,5 m
up to
3,5 m
up to
4,5 m
up to
2,5 m
up to
3,5 m
up to
4,5 m
Type of window frame material Minimum witdth of joints
for a butled mounting b in mm
Minimum witdth of joints
for a inner mounting b in mm
Hard PVC (white) 10 15 20 25 10 10 15
Hard PVC and PMMA (dark)
(colour extruded)
15 20 25 30 10 15 20
Hard PUR integral foam 10 10 15 20 10 10 15
Wood-aluminium-window 10 10 15 20 10 10 15
Aluminium-plastic sandwich
frame (bright)
10 10 15 20 10 10 15
Aluminium-plastic sandwich
frame (dark)
10 15 20 25 10 10 15
Wooden window frame 10 10 10 10 10 10 10

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