Installing large-format tiles, especially on vertical surfaces, demands an adhesive that holds its position and accommodates movement. Keraflex Maxi S1 provides that confidence. It ensures heavy and oversized tiles stay exactly where placed, without sag, while offering the flexibility needed to prevent common cracking from minor substrate shifts. This product secures challenging installations, delivering a durable, level, and crack-free finish.
Keraflex Maxi S1 is a high-performance, deformable cementitious adhesive specifically formulated for demanding tile installations. Developed by MAPEI, its composition of cement, fine graded sands, and a high quantity of synthetic resins with special additives provides essential characteristics for modern tiling. It is engineered for large-format and heavy tiles, ensuring they remain fixed without vertical slip, and accommodates movement in challenging environments. This distinct formulation separates it from rigid or non-thixotropic adhesives not suitable for complex and heavy-duty applications.
Classified as a C2TES1 adhesive under ISO 13007-1, Keraflex Maxi S1 offers critical performance advantages. The 'C2' indicates improved adhesion, vital for securing heavy tiles. 'T' denotes no vertical slip, ensuring that even large, heavy tiles on walls won't sag during installation. 'E' signifies an extended open time of over 30 minutes, allowing trades to work efficiently and adjust tiles for up to 60 minutes before the adhesive skins. Most critically, 'S1' confirms its deformability, meaning it can accommodate substrate movement up to 2.5 mm. This flexibility is essential for preventing cracks in tiles or grout lines, particularly on substrates subject to minor deformation, such as those with underfloor heating.
The final tensile adhesion strength of 2.6 N/mm² (initial) and robust performance after heat ageing (2.5 N/mm²), water immersion (1.1 N/mm²), and freeze/thaw cycles (1.3 N/mm²) underscore its durability in diverse conditions. With an 8-hour pot life, the mixed adhesive remains workable for an entire shift, reducing material waste on site.
Keraflex Maxi S1 mixes easily with water to a low-viscosity, lump-free paste. After a 5-minute rest and re-mix, it's ready for up to 8 hours of use. For application, first spread a thin layer to the substrate with the straight edge of a notched trowel, then apply the full thickness. For outdoor installations, tiles larger than 900 cm², or heavy-traffic areas, back-buttering the tile is essential for complete coverage. Tiles do not typically require wetting prior to installation, except for very dusty backs. Position tiles firmly to ensure good contact within the 30-minute open time and 60-minute adjustability window.
Protect newly installed tiles from running water, rain, frost, and strong sunlight for at least 24 hours (for rain/water) and 5-7 days (for frost/sunlight). Grouting walls can begin after 4-8 hours, and floors after 24 hours. For cementitious grouts, consider Keracolor FF for narrow joints or Keracolor GG for wider joints, or Ultracolor Plus for advanced performance. If chemical resistance is required, use an epoxy grout like Kerapoxy or Kerapoxy Design. For elastic expansion joints, use MAPESIL AC silicone sealant.
Keraflex Maxi S1 functions as the critical primary adhesive in high-performance tile installations. It is typically the first step after substrate preparation, laying the foundation for the entire tile system. In real-world specifications, this adhesive is commonly selected for its C2TES1 characteristics, particularly when followed by durable grouts. For example, it is documented as the initial adhesive in systems that later specify a chemical-resistant epoxy grout like Kerapoxy Adhesive, particularly in commercial kitchens or areas requiring high durability and resistance.
Yes, Keraflex Maxi S1 is designed for this. Its highly thixotropic nature ensures no vertical slip, allowing large and heavy tiles to be installed from the top down without support. This aligns with its C2TE S1 classification.
Yes, Keraflex Maxi S1 is rated for both interior and exterior use on floors and walls. It maintains adhesion and deformability across temperatures from -30°C to +90°C, making it suitable for floors under heavy traffic.
C2TE S1 means it's a high-performance (C2) cementitious adhesive with extended open time (E), no vertical slip (T), and S1 deformability. This provides flexibility to accommodate substrate movement, prevents tile sag on walls, and offers a longer working time of over 30 minutes, crucial for precise placement of large tiles.
Yes, gypsum substrates and anhydrite screeds must be perfectly dry and treated with Primer G or Mapeprim SP. This prepares the surface and ensures proper adhesion, preventing potential bond failure.
| Application | Key benefit | Primary trades |
|---|---|---|
| Installing large-format porcelain tiles on walls | No vertical slip (T rating) prevents heavy tiles from sagging, allowing top-down installation without pegs. | Tilers, Architects |
| Bonding ceramic or natural stone to exterior floors | S1 deformability accommodates substrate movement and temperature extremes (-30°C to +90°C), preventing cracks and delamination. | Tilers, Landscapers |
| Tiling floors subject to heavy foot traffic | High tensile adhesion strength (2.6 N/mm² initial) ensures durability and long-term bond in commercial or public spaces. | Commercial Tilers, Builders |
| Installing tiles on uneven interior substrates up to 15mm thick | Allows thick-bed application without prior levelling, saving time and materials on site prep. | Tilers, Renovation Specialists |
| Tiling over Mapei waterproofing membranes | Compatible with Mapelastic and Mapegum WPS systems, ensuring a cohesive and warrantable wet area installation. | Waterproofers, Tilers |
| Spot-bonding insulating panels (e.g., polystyrene, rock wool) | Strong adherence to various insulating materials, simplifying acoustic or thermal panel installation. | Drywallers, Insulators |
Pour powder into clean water while mixing at low speed; rest 5 min and re-mix to a smooth paste.
5.6–6.0 L water per 20 kg (28–30%).
5.4–5.8 L water per 20 kg (27–29%).
Key in a contact coat, then comb fresh ribs with a suitable notch. Back-butter large or profiled tiles to achieve ≥95% contact (wet areas/immersed) and ≥80% minimum elsewhere.
Use larger notch; up to 15 mm bed to correct minor irregularities.
Exploit high thixotropy; set from top-down without spacers, checking plumb.
Protect fresh work from rain, frost, and strong sun. Honor movement joints and seal appropriately.
Walls 4–8 h; floors ~24 h. Use Keracolor FF/GG, Ultracolor Plus, or Kerapoxy where chemical resistance is required.
Seal with Mapesil AC; consult for heavy-traffic joint design.
Keraflex Maxi S1 contains cement and free crystalline silica. Prolonged exposure to respirable crystalline silica dust can cause silicosis. Cement contact with body fluids can cause irritation or burns.
Wear close-fitting safety goggles for eye protection. Use protective gloves made of polychloroprene (CR), nitrile rubber (NBR), butyl rubber (IIR), or fluorinated rubber (FKM) with a minimum thickness of 0.35mm and breakthrough time of 480 minutes. Wear clothing that provides comprehensive skin protection, such as cotton, rubber, or PVC. Use appropriate respiratory protection where ventilation is insufficient or dust exposure levels exceed workplace limits, referencing AS/NZS 1715-1716.
Use only outdoors or in a well-ventilated area. Implement localized ventilation systems to minimise dust inhalation. Avoid breathing dust.
Store in dry conditions in original, unopened bags for up to 12 months. Keep in a well-ventilated, cool place, away from food and drink. Dispose of contents and packaging in accordance with local environmental protection and waste disposal regulations. Avoid dispersal of spilled material into drains or waterways.
Proper substrate preparation is critical for Keraflex Maxi S1 performance, ensuring optimal bond and preventing failures.
Surface prep: Substrates must be cured, mechanically sound, free of loose particles, grease, oil, paint, and wax. Cementitious screeds require at least 28 days cure, and renders 1 week per cm thickness, unless Mapei special binders were used. Keep surfaces cool if exposed to direct sunlight.
Primer: Not required for adequately cured cementitious substrates.
Surface prep: Ensure substrates are perfectly dry (max residual moisture 0.5%), hard, and dust-free. Firmly fix gypsum board. If in high moisture areas, consult Mapei Technical Services for a suitable moisture vapour barrier.
Primer: Required. Treat with Primer G or Mapeprim SP.
Surface prep: Ensure the waterproofing membrane (e.g., Mapelastic AquaDefense, Mapelastic Smart, Mapegum WPS) is fully cured and clean as per its technical data sheet.
Primer: Not required over Mapei waterproofing systems.
| Property | Value |
|---|---|
| Compliance | C2TE S1 (ISO 13007-1, EN 12004) |
| Type | Powder |
| Colour | Grey, White |
| Bulk Density | 1400 kg/m³ |
| Dry Solids Content | 100% |
| Consistency Of Mix | Pasty |
| Density Of The Mix | 1500 kg/m³ |
| pH Of Mix | Over 12 |
| Pot Life | Over 8 hours |
| Application Temperature | +5°C to +35°C |
| Open Time (EN 1346) | > 30 minutes |
| Adjustability Time | Approx. 60 minutes |
| Initial Tensile Adhesion Strength (28 days) | 2.6 N/mm² |
| Tensile Adhesion Strength After Heat Ageing | 2.5 N/mm² |
| Tensile Adhesion Strength After Water Immersion | 1.1 N/mm² |
| Tensile Adhesion Strength After Freeze/Thaw Cycles | 1.3 N/mm² |
| Resistance To Alkalis | Excellent |
| Resistance To Oils | Excellent (Poor to Vegetable Oils) |
| Resistance To Solvents | Excellent |
| Temperature When In Use | -30°C to +90°C |
| Deformability | S1 (Deformable) |
| Grouting On Walls | 4-8 hours |
| Grouting On Floors | 24 hours |
| Set To Light Foot Traffic | 24 hours |
| Ready For Use | 14 days |
| VOC Content (Rule 1168) | 5.4 g/l |
| Shelf Life | 12 months |
Here are some common examples on where Mapei Keraflex Maxi S1 Cementitious Adhesive used by our customers.
