For high-demand tiling installations in swimming pools, wet areas, and commercial floors, ARDEX X 18 Tile Adhesive provides a polymer-fortified, fibre-reinforced cement mortar with mastic-type properties. Formulated with integrated fibres to add structural strength to the tile bed, this non-slump adhesive accommodates the mechanical demands of large format tiling, fully vitrified and ceramic tiles, porcelain, mosaics, and non-moisture-sensitive natural stone.
ARDEX X 18 is classified as a C2 TE S1 adhesive under ISO 13007, delivering a minimum tensile adhesion strength of 1.0 MPa under dry, water-immersed, heat-aged, and freeze-thaw conditions. The low sand content produces a creamy, highly workable mortar with sag resistance for vertical wall tiling and an extended 30-minute open time to manage complex layout alignments. For high-stress applications such as heated floors or swimming pools, the adhesive can be mixed with ARDEX E90 admix to increase resilience against structural and thermal movement.
ARDEX X 18 bonds to a wide selection of internal and external wall and floor substrates, including:
Substrates must be clean, dry, firm, and prepared in accordance with AS 3958. Prime porous substrates with ARDEX Multiprime. For dense concrete above 35 MPa, steel-trowelled concrete, or existing ceramic tiles, the surface must be mechanically roughened to create a sufficient bonding key.
Mix one 20kg bag with 5 to 6 litres of clean water. Pour the powder into water while stirring vigorously, mix for 2 minutes, allow to stand for 5 minutes, and mix a second time for 2 minutes. Do not add extra water after mixing. Press tiles firmly into the freshly combed mortar bed and slide them at right angles to the notches to achieve 100% back coverage. For large format tiles (400mm or larger in any direction) and ribbed or keyed back profiles, back-butter the tile to prevent voids. Grouting can proceed after 24 hours at 23°C and 50% relative humidity; allow longer drying windows for dense tiles, non-porous substrates, high humidity, or cold conditions.
Yes, ARDEX X 18 is formulated for internal and external use in swimming pools and wet areas. It maintains a strong bond, with ≥1.0 MPa tensile adhesion after water immersion and freeze-thaw cycles, preventing common failures.
The C2 TE S1 classification confirms ARDEX X 18 as an improved, cementitious adhesive (C2) with extended open time (E) and no vertical slip (T), plus S1 for flexibility. This allows it to handle minor substrate movement, reducing the risk of tile cracking or delamination.
ARDEX X 18 is not for direct use over substrates subject to shrinkage and other movement, such as untreated timber. For timber floors, a Ceramic Tile Underlay (CTU) of at least 6mm is required over plywood or particleboard, fixed per manufacturer instructions and AS 3958.
This adhesive is suitable for fully vitrified, ceramic, porcelain, and mosaic tiles. It can also be used for natural stones, with the important exception of moisture-sensitive types, which require a specific ARDEX Natural Stone System.
ARDEX X 18 offers a 30-minute open time and a 30-minute adjustment time, with a pot life of approximately 3 hours. This extended window allows for efficient setting of tiles over larger areas, reducing rework and ensuring proper placement.
| Application | Key benefit | Primary trades |
|---|---|---|
| Swimming pools and permanently wet areas | Delivers durable, waterproof adhesion with ≥1.0 MPa tensile strength after water immersion and freeze-thaw, preventing critical failures. | Tilers, Waterproofers, Builders |
| External wall and floor tiling | Withstands environmental extremes, maintaining ≥1.0 MPa tensile adhesion after heat and freeze-thaw cycles, ensuring long-term stability. | Tilers, Landscapers, General builders |
| Large format and heavy tiles | Non-slump properties and fibre reinforcement prevent tile drop and provide strong support, crucial for achieving level, uniform installations. | Tilers |
| Green Building Council of Australia Green Star projects | Meets Green Star requirements for ceramic tile adhesives, offering confidence for specification and compliance on sustainable projects. | Architects, Specifiers, Green builders |
| Over early-age concrete, screeds, and render | Flexible formulation accommodates minor substrate movement, reducing the risk of cracking in newly constructed surfaces (concrete min. 7 days old). | Tilers, Concreters, Builders |
| Internal residential and commercial spaces | Extended 30-minute open time and excellent workability allow for efficient, precise placement across diverse internal applications, from bathrooms to showrooms. | Tilers, Renovators, Interior fit-out teams |
Ensure your substrate is structurally sound, clean, dry, and free from any contaminants like dust, oil, or curing agents. All preparation must comply with Australian Standard AS 3958. Prime porous surfaces with ARDEX Multiprime.
Add a 20kg bag of Ardex X 18 powder to 5-6 litres of clean water in a container. Mix with a mechanical stirrer for at least 2 minutes until a lump-free, creamy mortar is achieved. Let it stand for 5 minutes, then remix for a final 2 minutes.
Apply the adhesive to the substrate with a notched trowel suitable for the tile size. Spread only enough adhesive that can be tiled within the 30-minute open time. For large format tiles (>400mm) or tiles with ribbed backs, also butter the back of the tile to ensure 100% coverage and eliminate voids.
Press tiles firmly into the mortar bed with a sliding motion at a right angle to the notches. Periodically lift a tile to confirm full coverage has been achieved.
Signal Word: Danger
Wear protective gloves (e.g., elbow-length PVC, neoprene, nitrile), protective clothing (overalls, PVC apron), safety glasses with side shields or chemical goggles, and a face shield. For dust exposure, use an approved dust respirator (Type P1/N95).
Use only outdoors or in a well-ventilated area. Avoid breathing dust or fumes. Prevent dust concentration in hollows and sumps.
Store locked up in original, securely sealed containers in a cool, dry area, protected from environmental extremes. Keep away from incompatible materials such as strong acids, oxidising agents, copper, and aluminium alloys. Dispose of contents and container to an authorised hazardous or special waste collection point according to local regulations. Avoid contamination of drains or waterways.
Proper surface preparation is crucial for achieving a durable bond and preventing tile failure. Follow these guidelines for specific substrates before applying ARDEX X 18.
Surface prep: Concrete must be at least 7 days old and 20 MPa. Remove sealers or curing compounds. Mechanically roughen steel trowel finished or dense concrete (>35 MPa) to remove laitance and create a key. Ensure the surface is true, level, and pitched to drains where required.
Primer: Prime porous concrete with ARDEX Multiprime.
Surface prep: Finish new renders and screeds with a wood float to achieve the required regularity. Allow at least 24 hours to cure for bonded screeds, or 7 days for unbonded screeds, before tiling.
Primer: Prime porous renders and screeds with ARDEX Multiprime.
Surface prep: Boards must be firmly and rigidly fixed as per the manufacturer's instructions. Ensure they can adequately support the tile bed weight.
Primer: Priming is recommended for fibre-cement sheet. Plasterboard typically does not require priming unless jointing compound has been used.
Surface prep: Existing tiles must be sound, clean, firm, and stable. Roughen the surface mechanically to remove at least 80% of the glaze. Clean off all contamination and dust before tiling. Not recommended for immersed applications.
Primer: Prime with ARDEX Multiprime or ARDEX P9.
| Property | Value |
|---|---|
| Colour | White or Grey |
| Mixing Ratio | 5 - 6 litres water per 20kg powder |
| Classification | C2 TE S1 |
| Open Time | 30 mins |
| Adjustment Time | 30 mins |
| Pot Life | 3 hours |
| Grouting Time | 24 hours |
| Sagging | None |
| Underfloor Heating | Yes |
| Tensile Adhesion 28 Days Dry | ≥1.0 MPa |
| Tensile Adhesion Water Immersion | ≥1.0 MPa |
| Tensile Adhesion Heat | ≥1.0 MPa |
| Tensile Adhesion Freeze Thaw | ≥1.0 MPa |
Here are some common examples on where Ardex X 18 Tile Adhesive used by our customers.
