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Ardex RA 142: A Technical Overview
Ardex RA 142 is a professional-grade, super low viscosity epoxy engineered for the structural repair of concrete cracks. For tilers and waterproofers, this isn't just a crack filler; it's the foundation for a flawless installation. By injecting deep into hairline cracks (from 0.05mm to 3mm), it restores the monolithic strength of the substrate, eliminating a key failure point for tile and membrane systems. Its 100% solids, solvent-free formula ensures a permanent, high-strength bond, providing the flat, stable, and reliable surface required for demanding wet-area tiling projects. This is the trade-focused solution for ensuring the substrate won't undermine your work.
70 MPa
Compressive strength after 7 days, ensuring a structural repair that exceeds the strength of most concrete and provides a rock-solid base for tiling.
Core Features & Specifications
- Super Low Viscosity (190 cps): Ensures deep and complete penetration into the finest hairline cracks for a true structural bond.
- 100% Solids Formula: Provides a solvent-free, low VOC system with negligible shrinkage, guaranteeing a stable, permanent repair.
- Rapid Cure Profile: Achieves full cure in 24 hours, allowing for next-day waterproofing or tiling to keep the job moving.
- High-Strength Performance: Delivers exceptional compressive (70 MPa) and tensile (50 MPa) strength for repairs you can trust.
- Versatile Application: Suitable for both pressure injection in vertical cracks and simple gravity-feeding for horizontal slabs.
- Epoxy Mortar Binder: Can be mixed with aggregate to create a high-strength, trowelable mortar for durable spall repairs.
The Ardex RA 142 Advantage for Tilers
- Reliability: Creates a permanent, structural bond that eliminates substrate cracks as a point of failure, preventing tile delamination and costly callbacks.
- Professional Performance: Delivers compressive strength greater than concrete itself, ensuring your tiling work is built on a foundation that will not fail.
- Innovation: The ultra-low viscosity formula leverages advanced epoxy technology to penetrate and seal cracks that other products can't reach, ensuring a complete repair.
Proactive Troubleshooting for Tilers
Scenario: Injecting into an active (moving) crack
Potential Outcome: The rigid epoxy bond will fail as the structure continues to move. This will cause the repair to crack, reflecting through the waterproofing and newly laid tiles, resulting in a complete failure and an expensive callback.
Adheseal Best Practice: Always determine if a crack is active or dormant before starting work. Ardex RA 142 is designed exclusively for repairing stable, dormant cracks. For moving joints, a flexible sealant system is required. Get the diagnosis right the first time to guarantee a permanent repair.
Applications in Practice: Tiler & Waterproofer Scenarios
For Tilers: Preparing a Cracked Balcony Slab for Large Format Tiles
The Tiler's Challenge
A concrete balcony has developed fine hairline cracks. Tiling directly over them, especially with expensive large format tiles, risks the cracks reflecting through and ruining the finish, compromising the entire job.
The Adheseal Solution
Use Ardex RA 142 to gravity-feed into the horizontal cracks. Its super-low viscosity ensures it penetrates the full depth of the slab, structurally bonding the concrete back together. This creates a solid, monolithic substrate, eliminating the risk of reflective cracking and providing a reliable base for the waterproofing and tiling system.
Best Practice Note
For best results, use a grinder with a diamond blade to chase the crack, creating a small 'V' groove. This acts as a reservoir and helps guide the epoxy deep into the crack for a guaranteed fill.
For Waterproofers: Securing a Substrate Before Membrane Application
The Waterproofer's Challenge
Applying a waterproofing membrane over a cracked concrete substrate is a guaranteed failure. Even fine cracks will move and tear the membrane over time, leading to water ingress and catastrophic damage.
The Adheseal Solution
Pressure inject Ardex RA 142 into all dormant cracks prior to any membrane application. By restoring the structural integrity of the slab, you create a stable, sound, and continuous surface. This ensures the waterproofing membrane has a solid foundation, critical for achieving a fully compliant and leak-proof system ready for tiling.
Best Practice Note
For vertical wall cracks, use injection ports spaced 15-30cm apart and seal the crack face with Ardex RA 88 Capping Paste. This ensures the low-viscosity epoxy stays within the crack to achieve a full-depth cure.
Frequently Asked Questions
How fine a crack can Ardex RA 142 actually penetrate?
Ardex RA 142 is engineered with a super-low viscosity to penetrate and structurally repair dormant hairline cracks as fine as 0.05mm. This ensures a complete, full-depth repair, not just a surface seal.
Can I use Ardex RA 142 on a damp or wet crack?
No. For a reliable structural bond, the concrete substrate and the inside of the crack must be completely dry. Use clean, oil-free compressed air to blow out any dust and moisture before application to ensure maximum adhesion and performance.
How long before I can tile or waterproof over an Ardex RA 142 repair?
Ardex RA 142 is fully cured in 24 hours at 24°C. After this period, the repair will have achieved its full structural strength, and you can proceed with grinding, waterproofing, or tiling, keeping your project on schedule.
What is the best method for repairing vertical cracks in a concrete wall?
For vertical surfaces, a pressure injection system is required. Use injection ports spaced approximately 15-30cm apart along the crack. Seal the surface of the crack between the ports with Ardex RA 88 Capping Paste to prevent the low-viscosity epoxy from running out before it cures.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Structural Crack Repair (0.05-3mm) | Restores monolithic strength to concrete, preventing crack reflection through tiles and membranes. | Tilers, Waterproofers |
| Gravity-Feed of Horizontal Slabs | Super-low viscosity ensures deep penetration into fine cracks for a complete, reliable repair. | Tilers |
| High-Strength Spall Repair Mortar | Creates an extremely durable, high-impact repair when mixed with aggregate for damaged concrete. | Tilers |
| Substrate Prep for Wet Areas | Provides a stable, structurally sound base essential for the long-term performance of waterproofing systems. | Waterproofers, Tilers |
Applying Ardex RA 142: Protocols & Best Practices
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Crack & Surface Preparation
A successful repair starts with proper preparation. Ensure the concrete is sound, clean, and completely dry. New concrete must be cured for at least 28 days.
Crack Cleaning
Use a wire brush to clean the crack surface. Blow out all dust, debris, and contaminants from within the crack using clean, oil-free compressed air. This step is critical for achieving a full structural bond.
Crack Chasing (Optional)
For hairline cracks in horizontal slabs, consider using a grinder with a diamond blade to cut a V-groove. This creates a small reservoir, making it easier to gravity-feed the epoxy and ensuring a complete fill.
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Cartridge Setup & Purging
Proper cartridge preparation prevents mix issues and ensures consistent performance.
Prepare and Purge
Place the 470mL cartridge into the dispenser gun. Remove the plastic cap and plug, then dispense a small amount of material into a disposable container until both Part A and Part B are flowing evenly.
Attach Nozzle
Attach the static mixing nozzle to the cartridge. Dispense and discard the first 1-2 trigger pulls of material to ensure a perfectly mixed product from the start.
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Application & Injection
Select the application method based on the crack's orientation.
Horizontal Cracks (Gravity Feed)
Slowly dispense the mixed epoxy directly into the prepared crack or V-groove. Allow the product's self-levelling properties to fill the void completely. Re-apply if necessary to ensure the crack is filled flush to the surface.
Vertical Cracks (Pressure Injection)
Securely attach injection ports along the crack and seal the crack face with Ardex RA 88 Capping Paste. Start injecting at the lowest port and continue until epoxy flows from the port above. Plug the first port and move to the next, repeating until the entire crack is filled.
Pro Tip: The gel time is approximately 20 minutes at 24°C. Work in manageable sections and replace the nozzle if the epoxy begins to gel. Do not try to force gelled product. -
Curing and Finishing
Allow the repair to achieve full strength before proceeding.
Curing Time: Ardex RA 142 is fully cured and ready for grinding or over-coating in 24 hours. Once cured, any capping paste and injection ports can be removed with a chisel or grinder.
Limitations & Safety
Product Limitations
For Dormant Cracks Only: Do not use to repair active, moving cracks or expansion joints. This product cures to a rigid, high-strength solid and will fail if subjected to substrate movement.
Temperature Sensitive: Apply only when substrate and ambient temperatures are between 10°C and 35°C. Colder temperatures will significantly slow the cure time.
Not for Water Stopping: This product is not designed to stop actively seeping or flowing water. Cracks must be dry prior to application.
Professional Use: This is a hazardous chemical system intended for professional trade use only. It is not suitable for DIY applications due to its complex handling and safety requirements.
Safety & Handling Requirements
Personal Protective Equipment
Critical: This product can cause severe skin burns, eye damage, and allergic reactions. Always wear chemical-resistant gloves (e.g., PVC), safety goggles, and protective clothing. Avoid all contact with skin and eyes.
Ventilation & Handling
Use in a well-ventilated area. Avoid breathing vapours or mists. Keep containers sealed when not in use. Do not eat, drink, or smoke when handling this product.
Emergency First Aid
Eyes:
Immediately hold eyelids apart and flush continuously with running water for at least 15 minutes. Seek immediate medical attention.
Skin:
Immediately remove all contaminated clothing. Flush skin and hair with running water. Seek medical attention if irritation or a rash occurs.
Inhaled:
Move to fresh air. If breathing is difficult, seek urgent medical attention.
Swallowed:
Rinse mouth. Do NOT induce vomiting. Contact a Poisons Information Centre (13 11 26) or a doctor immediately.
Substrate Preparation Guide
Concrete Slabs
Surface Preparation
Ensure concrete is structurally sound, clean, and completely dry. New concrete must be cured for a minimum of 28 days. The crack and surrounding surfaces must be free of dust, oil, grease, or any other contaminants. Use oil-free compressed air to blow out the crack thoroughly.
Primer Requirements
Primer not required
No primer is needed for the crack injection itself. Ardex RA 142 is a self-priming epoxy that bonds directly to correctly prepared concrete.
Masonry & Blockwork
Surface Preparation
The masonry surface must be clean, sound, and dry. Use a wire brush to remove any loose debris from the crack face. Thoroughly blow out all dust and contaminants from within the crack using oil-free compressed air before injection.
Primer Requirements
Primer not required
Ardex RA 142 achieves a powerful structural bond directly to prepared masonry without the need for a separate primer.
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