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Ardex RA 88 Plus: A Technical Overview
Ardex RA 88 Plus is a high-performance, two-component epoxy adhesive engineered to be the ultimate problem-solver on site. For tilers and waterproofers, its standout feature is the exceptional non-drip and non-sag performance, making it the go-to solution for challenging vertical and overhead repairs. Whether you're patching spalled concrete, securing anchor bolts, or using it as a capping paste for crack injection systems, its trowelable consistency ensures it stays exactly where you put it. This multi-purpose formula delivers a superior structural bond to almost any building material, providing a rock-solid, reliable foundation for subsequent tiling and waterproofing work.
87 MPa
Compressive strength after 7 days, providing a repair that is significantly stronger than the concrete it's fixing and built to withstand extreme loads.
Core Features & Specifications
- Excellent Non-Sag Performance: Trowelable gel consistency holds its shape perfectly for clean and precise vertical and overhead applications.
- High Compressive Strength: Cures to a formidable 87 MPa, ensuring repairs are incredibly durable and load-bearing.
- Superior Bond Strength: Adheres tenaciously to concrete, metal, brick, wood, and stone for versatile repair and bonding applications.
- Fast Cure Profile: Becomes tack-free in just 3 hours (@24°C), allowing for rapid follow-on work like grinding or coating.
- Potable Water Approved: Compliant with AS/NZS 4020, making it safe for repairs in drinking water tanks and reservoirs.
- Multi-Purpose Formula: A single product for concrete patching, crack capping, anchoring bolts, and terminating waterproofing membranes.
The Ardex RA 88 Plus Advantage for Tilers
- Reliability: A repair that won't fail, even overhead. Its immense bond and compressive strength mean you can trust your substrate prep and avoid costly callbacks.
- Professional Performance: One versatile, high-performance product handles multiple jobs on site, from structural repairs to waterproofing details, saving time and space in the van.
- Innovation: The advanced non-drip formula allows for clean, precise work in the most challenging orientations without the need for complex formwork, increasing on-site efficiency.
Proactive Troubleshooting for Tilers
Scenario: Using the adhesive for large, deep repairs
Potential Outcome: Applying the product in a large mass (deeper than 16mm) will generate excessive heat during the cure. This exotherm can cause swelling, smoking, and even cracking of the repair itself, leading to a complete bond failure.
Adheseal Best Practice: Ardex RA 88 Plus is engineered for small patch repairs, anchoring, and adhesive applications. For deeper voids, use a dedicated bulk-fill repair mortar designed to manage heat. Using the right product for the scale of the job ensures a sound, reliable repair every time.
Applications in Practice: Tiler & Waterproofer Scenarios
For Tilers: Repairing Damaged Concrete Stair Nosing
The Tiler's Challenge
Spalled and damaged concrete edges on stairs or walls create an unsound, uneven surface that is impossible to tile over. The repair needs to be built up on a vertical face without slumping and be strong enough to handle foot traffic.
The Adheseal Solution
Use Ardex RA 88 Plus to build out the damaged area. Its non-sag, trowelable formula allows you to perfectly sculpt the repair to the required profile without formwork. It cures to a strength far exceeding the original concrete, creating a sharp, incredibly durable edge ready for grinding and tiling.
Best Practice Note
For a seamless finish, slightly overfill the repair area. Once it's tack-free (approx. 3 hours), it can be ground flush with the surrounding concrete for a perfect substrate.
For Waterproofers: Crack Capping & Membrane Terminations
The Waterproofer's Challenge
When preparing for epoxy crack injection, a reliable capping paste is needed to hold injection ports and seal the crack face. Likewise, terminating sheet membranes into a wall chase requires a robust, waterproof adhesive that won't slump.
The Adheseal Solution
Ardex RA 88 Plus is the ideal choice for both applications. Its thick consistency securely fastens injection ports (like ARDEX T-Ports) and seals crack faces for pressure injection. For membrane terminations, it completely fills the reglet, creating a permanent, watertight, and structural bond that locks the system in place.
Best Practice Note
When capping, ensure there are no pinholes left in the application to prevent leakage during injection. Trowel the surface smooth for a clean finish.
Frequently Asked Questions
Can I use Ardex RA 88 Plus for overhead repairs without it slumping?
Yes. Ardex RA 88 Plus is specifically formulated with a non-drip and non-sag consistency. This makes it perfect for vertical and overhead applications, as it will hold its shape without slumping or dripping when trowelled into place.
How long until I can grind or paint over a repair?
At an ambient temperature of 24°C, Ardex RA 88 Plus will be tack-free in approximately 3 hours. After this time, it is hard enough to be mechanically ground, sanded, or overcoated with a suitable water-based architectural coating.
Is this product safe for repairs inside a drinking water tank?
Yes. Ardex RA 88 Plus is fully compliant with AS/NZS 4020, which means it is certified as safe for use in contact with potable (drinking) water. It is an ideal choice for repairing cracks or spalls in concrete water tanks.
Can I use it to fill a large, deep hole in a concrete slab?
No, Ardex RA 88 Plus is designed for small patch repairs with a maximum depth of 16mm. Using it in a larger, deeper mass will generate excessive heat during curing (exotherm), which can cause the repair to crack or fail. For larger voids, a dedicated bulk-fill repair mortar should be used.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Vertical & Overhead Concrete Repair | Non-sag formula holds its shape without formwork, perfect for spalls and defects. | Tilers, Concrete Repairers |
| Capping Paste for Crack Injection | Trowelable consistency securely seals cracks and holds injection ports in place. | Tilers, Waterproofers |
| Waterproofing Membrane Termination | Creates a durable, watertight, and powerfully adhesive seal for membrane edges in reglets. | Waterproofers |
| Multi-Material Structural Adhesive | Delivers a superior bond for concrete, metal, wood, stone, brick, and block. | Tilers, General Trades |
| Anchor Bolt & Dowel Installation | High compressive strength provides a rock-solid, permanent anchor for structural fixings. | Tilers, Concrete Repairers |
Applying Ardex RA 88 Plus: Protocols & Best Practices
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Surface Preparation
All substrates must be sound, clean, dry, and free of any contaminants. A roughened surface is critical for good adhesion.
For Concrete Repairs
Use a grinder to cut the repair area to a minimum depth of 13mm, ensuring clean, square edges. Avoid feather-edging. Roughen the internal surface mechanically.
For Bonding Surfaces
Mechanically abrade smooth surfaces like metal or stone with a wire brush or sandpaper to create a textured profile for the adhesive to key into.
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Cartridge Setup & Mixing
Correct cartridge setup ensures a perfect 1:1 mix ratio and optimal performance.
Purge Cartridge
Before attaching the nozzle, place the cartridge in the caulking gun and dispense a small amount until both components flow evenly.
Attach Nozzle & Purge Again
Attach the mixing nozzle and dispense material until a consistent, streak-free grey colour is achieved. Discard this initial amount.
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Application
Apply the mixed epoxy to the prepared substrate using the appropriate method for the job.
For Patching & Repairs
Apply the adhesive to the repair area, slightly overfilling it. Use a trowel to smooth the material flush with the surrounding surface.
For Bonding & Anchoring
Apply a sufficient amount of adhesive to one of the surfaces to ensure complete coverage and fill any gaps when the two parts are brought together.
Working Time: You have approximately 45 minutes of working time at 24°C. In hotter conditions (40°C), this is reduced to 20 minutes. -
Curing
Allow the material to cure before subjecting it to traffic or mechanical finishing.
Cure Time: The repair will be tack-free and ready for grinding or over-coating in approximately 3 hours at 24°C. Allow for longer cure times in colder temperatures.
Limitations & Safety
Product Limitations
For Small Patches Only: Designed for repairs up to 16mm deep. Use in larger/deeper masses can cause an exothermic reaction, generating excessive heat and potential failure.
UV Exposure: Product may discolour upon exposure to UV light. If aesthetics are critical, overcoating with a suitable UV-stable paint is recommended.
Not for Moving Cracks: This product cures to a rigid solid and is not intended for repairing cracks or joints that are subject to movement.
Do Not Thin: Never add solvents to the product, as this will prevent it from curing correctly and will compromise performance.
Safety & Handling Requirements
Personal Protective Equipment
Critical: This product causes severe skin burns and eye damage and may cause an allergic reaction. Always wear protective gloves, clothing, and eye/face protection. Avoid all direct contact.
Handling & Ventilation
Use only in a well-ventilated area. Avoid breathing in any mists, vapours, or spray. Wash hands thoroughly after handling. Contaminated work clothing should not be allowed out of the workplace.
Emergency First Aid
Eyes:
Rinse cautiously with water for several minutes. Remove contact lenses if present and easy to do. Continue rinsing and call a POISON CENTER or doctor immediately.
Skin:
Take off immediately all contaminated clothing. Rinse skin with water or shower. Wash contaminated clothing before reuse.
Inhaled:
Remove person to fresh air and keep comfortable for breathing. Call a POISON CENTER or doctor if you feel unwell.
Swallowed:
Rinse mouth. Do NOT induce vomiting. Immediately call a POISON CENTER (13 11 26) or doctor.
Substrate Preparation Guide
Concrete & Masonry
Surface Preparation
The substrate must be structurally sound, clean, and dry. Remove all dust, oil, grease, curing compounds, or any other contaminants. New concrete must be cured for at least 28 days. A roughened surface profile is essential for a strong bond.
Primer Requirements
Primer not required
No primer is needed. Ardex RA 88 Plus is designed to bond directly to correctly prepared concrete and masonry surfaces.
Metal, Wood & Stone
Surface Preparation
All surfaces must be clean, dry, and free from contaminants. Mechanically roughen smooth surfaces with a wire brush or sandpaper to create a key for the adhesive. For metal, ensure all rust, scale, and oils are removed.
Primer Requirements
Primer not required
Ardex RA 88 Plus achieves a superior bond directly to these materials without a primer, provided the surface has been properly cleaned and abraded.
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