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Ardex X 18: A Technical Overview
Ardex X 18 is a high-performance, polymer-fortified cement-based tile adhesive engineered specifically for tilers and waterproofers. Formulated with specially developed synthetic fibres, it delivers superior strength and flexibility (S1) for wall and floor applications where reliability is non-negotiable. Its excellent non-slump properties make it the ideal choice for heavy, large-format tiles on vertical surfaces, preventing slippage and ensuring a perfect finish. With an extended open time and mastic-like workability, Ardex X 18 provides the control and performance needed for complex residential and commercial jobs, including fully immersed areas like swimming pools.
≥1.0 MPa
Tensile Adhesion Strength Dry, Wet, and After Heat/Freeze-Thaw Cycles for a Permanent, High-Strength Bond You Can Trust.
Core Features & Specifications
- Fibre Reinforced: Integrated synthetic fibres add flexural strength and toughness to the adhesive bed, resisting movement and preventing tile failure.
- Non-Slump Performance: Mastic-like consistency holds large format and heavy tiles in place on walls, eliminating slippage and the need for supports.
- Extended Open Time: A 30-minute open and adjustment time gives you the control to perfectly position tiles, ensuring flawless layouts on complex jobs.
- Early Age Concrete Compatibility: Can be applied to concrete just 7 days old, accelerating project timelines without compromising the bond.
- Versatile Substrate Adhesion: Achieves a high-strength bond to concrete, renders, screeds, fibre-cement sheets, and approved ARDEX waterproofing membranes.
- Immersed Applications: Excellent water resistance makes it suitable for demanding wet areas, including swimming pools and shower walls.
The Ardex X 18 Advantage for Tilers
- Reliability: Delivers a tenacious, permanent bond that exceeds 1.0 MPa in all conditions, preventing delamination and callbacks, even in fully immersed environments.
- Innovation: The fibre-reinforced formula provides a modern solution for tiling over challenging substrates, adding a level of security that standard adhesives can't match.
- Professional Performance: With a C2 TE S1 classification, Ardex X 18 meets the highest technical demands, giving you the confidence to tackle any commercial or high-end residential tiling project.
Proactive Troubleshooting for Tilers
Scenario: Tiling Over Contaminated or Unprepared Surfaces
Potential Outcome: Applying adhesive over dust, curing compounds, or laitance will severely compromise the bond, leading to tile delamination, costly repairs, and reputational damage.
Adheseal Best Practice: Always ensure the substrate is clean, firm, and mechanically prepared. Steel-trowelled concrete must be ground to remove laitance. This guarantees the adhesive bonds directly to the substrate, delivering the permanent result your clients expect. Get it right the first time.
Applications in Practice: Tiler & Waterproofer Scenarios
For Tilers (Installer): Fixing Large Format Porcelain Tiles to a Bathroom Wall
The Tiler's Challenge
Fixing heavy, large format (e.g., 600x1200mm) porcelain tiles vertically requires an adhesive with immediate grab and zero slump. Any slippage can ruin the layout and lead to time-consuming rework.
The Adheseal Solution
The non-slump properties of Ardex X 18 are engineered for this exact task. Mix to a thick, creamy consistency and apply using a 10-12mm notched trowel. Butter the back of each tile to ensure 100% coverage. The adhesive will hold the tile firmly in place from the moment of contact, delivering confidence and professional performance.
Best Practice Note
Press each tile firmly into the adhesive bed and slide it perpendicular to the trowel lines to collapse the notches. This technique guarantees full contact for a bond that meets AS 3958 requirements.
For Waterproofers (Applicator): Ensuring Tile System Integrity Over Membranes
The Waterproofer's Challenge
After applying a liquid waterproofing membrane, the success of the entire system depends on the tile adhesive's ability to form a permanent, compatible bond without compromising the waterproof layer.
The Adheseal Solution
Ardex X 18 is formulated for direct application over fully cured ARDEX liquid undertile waterproofing membranes. Its polymer-fortified nature ensures excellent adhesion, creating a unified, reliable system. This provides a seamless transition from waterproofing to tiling, guaranteeing a leak-proof result for the client.
Best Practice Note
Always ensure the membrane is thoroughly dry and free of any contaminants before tiling. Follow the membrane's specified cure times, especially in cool or humid conditions, to ensure system integrity.
Frequently Asked Questions
How soon can I tile on new concrete or screed with Ardex X 18?
Ardex X 18's innovative formula allows you to tile over concrete after only 7 days and new cement screeds after just 24 hours. This significantly accelerates project schedules compared to traditional adhesives, allowing you to move onto the next stage of the job faster.
Is Ardex X 18 suitable for tiling a swimming pool?
Yes, it's engineered for fully immersed applications. For maximum performance and resilience in pools, mix Ardex X 18 with ARDEX E 90 admixture as specified in the datasheet. This creates an incredibly durable, water-resistant bond that withstands pool chemicals and constant immersion.
What is the open time and pot life of Ardex X 18?
Ardex X 18 gives you a generous 30-minute open time for tile adjustment and a pot life of approximately 3 hours at 23°C. This provides professional tilers with excellent workability and enough time to achieve precise layouts without the mortar skinning over prematurely.
Can I use this adhesive for large format wall tiles?
Absolutely. Ardex X 18 is specifically designed with non-slump properties, making it the perfect choice for heavy and large format wall tiles. It provides exceptional grab, preventing any sag or slippage during installation for a perfect finish.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Wall & Floor Tiling | Fibre-reinforced S1 flexibility and non-slump properties for reliable fixing of all tile types. | Tilers |
| Swimming Pools & Wet Areas | Excellent water resistance and high bond strength ensure durability in immersed conditions. | Tilers, Waterproofers |
| Large Format Tile Installation | Superior non-slump performance prevents slippage of heavy tiles on vertical surfaces. | Tilers |
| Tiling Over Early-Age Concrete | Can be used on concrete after 7 days, speeding up project timelines. | Tilers |
| Internal & External Applications | Versatile formulation is suitable for both interior and exterior use on floors and walls. | Tilers |
Applying Ardex X 18: Professional Protocol
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Step 1: Substrate Preparation
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.
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Step 2: Mixing
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.
Pro Tip: Do not add extra water after the initial mixing, as this will compromise the adhesive's non-slump properties and final bond strength. -
Step 3: Application & Fixing
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.
Fixing Technique
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.
Grouting: Allow the adhesive to set for approximately 24 hours before grouting. This can be longer in cool or humid conditions.
Limitations & Safety
Product Limitations
Temperature: Do not apply at temperatures below 5°C or on substrates with frozen water.
Moisture Sensitive Stone: Not suitable for fixing moisture-sensitive natural stones. Refer to the ARDEX Natural Stone System for these applications.
Substrate Movement: Not for use over substrates subject to significant shrinkage or movement, such as timber floors. Not for use over metal.
Deflection: Do not use on floors with deflection greater than joist span divided by 500 (for tiles <600mm) or 700 (for tiles >600mm).
Safety & Handling
Personal Protective Equipment
Always wear protective gloves, safety goggles/face shield, and appropriate dust mask (P2/N95) when mixing and handling the powder. Wear long sleeves and trousers to avoid skin contact.
Ventilation & Handling
Use only in well-ventilated areas. Avoid breathing in dust. When mixed, wet cement is alkaline and can cause skin irritation or burns. Wash hands thoroughly after handling.
Emergency First Aid
Eyes
Rinse immediately and cautiously with water for several minutes. Remove contact lenses if present. Continue rinsing and call a POISON CENTER or doctor immediately.
Skin
Wash with plenty of soap and water. If skin irritation or a rash occurs, seek medical advice. Wash contaminated clothing before reuse.
Inhaled
Remove person to fresh air and keep comfortable for breathing. Call a doctor if you feel unwell.
Ingested
Rinse mouth with water. Do NOT induce vomiting. Seek immediate medical advice.
Substrate Adhesion & Preparation Guide
Concrete, Renders & Screeds
Surface Preparation
Ensure surfaces are firm, clean, and free of laitance, curing compounds, or grease. New concrete must be at least 7 days old. Mechanically roughen steel-trowelled or dense concrete (>35 MPa) to create a key. New renders/screeds should be wood-float finished and cured for at least 24 hours.
Primer Requirements
Primer recommended for porous surfaces
To prevent water loss into porous substrates and ensure a stronger bond, prime with ARDEX Multiprime before applying the adhesive.
ARDEX MultiprimeFibre-Cement Sheet & Plasterboard
Surface Preparation
Boards must be rigidly fixed according to the manufacturer's instructions to support the tile weight. Ensure surfaces are clean and free from dust. For floor applications, use compressed fibre-cement sheets and follow AS 3958 guidelines.
Primer Requirements
Primer recommended for fibre-cement
Priming is recommended for fibre-cement sheets to minimise water absorption. Plasterboard does not typically require priming unless jointing compound is present.
ARDEX MultiprimeExisting Ceramic Tiles (Internal Dry Areas)
Surface Preparation
Existing tiles must be sound, stable, and clean. The glazed surface must be mechanically roughened to remove at least 80% of the glaze, creating a sufficient key for the new adhesive to bond to. This method is not suitable for immersed or wet areas.
Primer Requirements
Primer required
After roughening the surface, clean off all dust and apply a coat of ARDEX Multiprime or ARDEX P 9 to ensure a tenacious bond between the old tile surface and the new adhesive.
ARDEX Multiprime- Choosing a selection results in a full page refresh.