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Tackling tiling projects over substrates prone to movement, within immersed areas like swimming pools, or directly over underfloor heating systems demands a specific type of adhesive. RLA Flex Pro delivers the required high flexibility and bond strength. It ensures tiles remain secure, even when conditions challenge rigid systems, providing a lasting finish in demanding internal and external environments.
RLA Flex Pro is a high-performance, cement-based tile adhesive engineered for applications where flexibility and robust adhesion are critical. It allows tilers to confidently fix ceramic, porcelain, and natural stone tiles to floors and walls. This formulation specifically addresses the challenges of dynamic environments, accommodating the movement that often leads to tile failure in less adaptable adhesives.
Tensile Adhesion Strength of over 1.5 MPa ensures tiles remain firmly fixed. This robust bond strength resists shear and pull-off forces, even in high-traffic or externally exposed areas. An open time of 20-30 minutes provides a practical window for efficient tile placement, particularly useful for larger format tiles or complex layouts.
Critical for wall tiling and facades, a “no vertical slip” rating holds tiles in position immediately after placement, preventing sag and ensuring alignment during installation. Furthermore, foot traffic is permissible in 24 hours, allowing for quicker project progression and enabling subsequent trades to access the area sooner.
RLA Flex Pro mixes easily with clean water to a smooth, lump-free consistency using a mechanical mixer. After a brief 5-minute stand time, the adhesive is ready to apply with a notched trowel. Optimal coverage requires ensuring full adhesive contact to the tile back, pressing tiles firmly into the adhesive bed with a twisting motion. Prompt cleaning of excess adhesive from tile surfaces and grout joints during application simplifies cleanup. For porous substrates, RLA Universal Primer prepares the surface, ensuring consistent bond and performance.
Both RLA Flex Pro and RLA Polymastic Primer are high-performance, flexible tile adhesives from the RLA family, but they serve different project needs. RLA Flex Pro is a cement-based adhesive designed for demanding internal and external tiling applications, offering excellent adhesion and flexibility over movement-prone substrates, including immersed areas like swimming pools and over underfloor heating systems. In contrast, RLA Polymastic is a polymer-modified cement-based adhesive known for its superior bond strength and flexibility, particularly for large format tiles and challenging substrates that require enhanced adhesion, such as some external and commercial projects. Choose RLA Flex Pro when your project demands a high-flexibility cementitious adhesive for general internal and external areas, wet areas, or underfloor heating. Opt for RLA Polymastic for those critical applications needing the highest possible bond strength and maximum flexibility for oversized tiles or extremely demanding conditions.
Q: How does Flex-Pro MS handle the high movement in concrete expansion joints compared to a standard sealant?
A: RLA Flex Pro MS is engineered with 400% elongation at break, providing significantly more movement capability than many standard sealants. This superior elasticity allows it to repeatedly stretch and compress during thermal cycles without splitting or losing its bond, ensuring the long-term integrity of the joint.
Q: As a waterproofer, can I confidently use this as a bond breaker under RLA's acrylic membranes?
A: Yes, absolutely. RLA Flex Pro MS is specified for use as a compatible bond breaker for all RLA acrylic membranes. Its formulation ensures it will not react with or compromise the membrane, allowing you to create a fully compliant Class III membrane system where the bond breaker facilitates correct movement.
Q: Is this sealant truly paintable, and are there any special precautions needed for a perfect finish?
A: Yes, it is fully paintable once cured. The key is to allow the sealant to cure completely (typically 3mm per 24 hours). Because some solvent-based paints can react with flexible sealants, we always recommend conducting a small field test with your chosen coating to ensure perfect compatibility and prevent any crazing or tackiness.
Q: What is the main advantage of this MS Polymer technology over a standard polyurethane sealant?
A: The primary engineering advantage is its isocyanate-free chemistry, which enhances workplace safety. From a performance standpoint, MS Polymers typically offer superior UV resistance—meaning less yellowing and degradation—and broader substrate adhesion, often without needing a primer where a polyurethane would require one.
Q: Can I apply RLA Flex Pro MS in damp conditions?
A: The product is moisture-cured and can be applied to moist, non-porous surfaces. This is a significant advantage in unpredictable weather. However, you should not apply it to visibly wet surfaces or if rain is imminent, as this can affect the initial cure and tooling finish. For porous substrates, ensure they are dry to avoid trapped moisture causing issues.
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Expansion & Construction Joints | High Movement Capability (400% Elongation) | Builders, Concreters, Remedial Contractors |
| Perimeter Sealing (Windows/Doors) | Excellent UV/Weather Resistance & Adhesion | Glaziers, Carpenters, Builders, Façade Installers |
| Waterproofing Bond Breaker | System Compatibility & Permanent Flexibility | Waterproofers, Tilers |
| Sealing Penetrations (Pipes/Ducts) | Acoustic Damping & Flexible Sealing | Plumbers, HVAC Technicians, Electricians, Builders |
| Sanitary & Kitchen Applications | Fungal Resistance & Non-Staining | Plumbers, Joiners, Tilers, Builders |
| Bonding Metals, Stone & Ceramics | High-Strength Adhesive Properties | Stonemasons, Metalworkers, Builders, Landscapers |
The Engineering Challenge: Pre-cast panel joints are subject to significant thermal expansion and contraction, requiring a sealant with high movement capability to prevent failure. Adhesion to concrete without extensive priming is critical for efficiency.
The System-Based Solution with RLA Flex Pro MS: RLA Flex Pro MS provides 400% elongation, easily handling the dynamic movement of large panels. It bonds directly to clean concrete, while its 3mm/24hr cure rate ensures a robust seal develops efficiently. Its service temperature range of -50°C to +120°C guarantees performance year-round.
Best Practice Note: For joints over 12mm wide, maintain a 2:1 width-to-depth ratio. Use an open-cell polyurethane backer rod to allow moisture to access the back of the joint, enabling a faster, more uniform cure.
The Engineering Challenge: Creating a durable, weatherproof seal between dissimilar materials like anodised aluminium or PVC frames and masonry or timber surrounds. The seal must resist constant UV exposure without yellowing or cracking.
The System-Based Solution with RLA Flex Pro MS: FLEX-PRO MS excels with its primerless adhesion to both porous (brick, timber) and non-porous (aluminium, PVC) substrates. Its excellent UV stability ensures it won't break down, and its paintability allows for a clean, integrated finish that matches the facade.
Best Practice Note: For window frames, ensure a minimum joint width of 10mm. After application, tool the sealant to a concave profile to ensure positive water shedding and maximum adhesion to the sides of the joint.
| Property | Value |
|---|---|
| Base Chemistry | Silane Modified Polymer |
| Appearance | Paste |
| Colour | Black |
| Density | 1490 kg/m³ |
| Tensile Strength | 1.2 MPa |
| Elongation | 400% (ASTM D 412) |
| Shore Hardness | 32 |
| Modulus | 0.45 MPa |
| Shrinkage | <1.5% (ISO-0563) |
| Deformability | 60% |
| Skin Time | Approx. 30 minutes (@23°C & 50% RH) |
| Application Temperature | +5°C to +35°C |
| Service Temperature | -50°C to +120°C |
| Humidity Range | 5mm per 5 Days |
| UV Resistance | No change (dry UV 300 w, 25 cm distance, 6-week test) |
| Packaging | 600ml Sausages |
| Shelf Life | 12 months |
Here are some common examples on where RLA Flex Pro used by our customers.
