Description
Mapei’s Keraflex Maxi S1 is a high-performance, deformable cementitious adhesive with extended open time and no vertical slip, purpose-built for large format porcelain tiles and natural stone. Its highly thixotropic formulation is what stops heavy, large tiles sagging on a vertical wall while the adhesive sets — a genuine failure risk with a standard adhesive once tile size and weight climb.
It’s classified C2TES1 to ISO 13007-1: improved, slip-resistant, extended open time, deformable. That deformability lets the adhesive accommodate a small amount of substrate movement rather than cracking rigidly, which matters on cementitious screeds, underfloor heating installations, and floors carrying heavy traffic.
Technical Specifications
| Classification | C2TES1 to ISO 13007-1 and EN 12004 |
|---|---|
| Colour | Grey or white powder |
| Bulk density | 1,400 kg/m³ |
| Mixing ratio | 100 parts powder to 28-30 parts water by weight (grey); 27-29 parts (white) |
| Density of mix | 1,500 kg/m³ |
| pH of mix | Over 12 |
| Pot life | Over 8 hours |
| Open time | Over 30 minutes (EN 1346) |
| Adjustability time | Approx. 60 minutes |
| Application temperature | +5°C to +35°C |
| Ready for grouting — walls | 4-8 hours, depending on thickness |
| Ready for grouting — floors | 24 hours |
| Set to light foot traffic | 24 hours |
| Ready for use | 14 days |
| Packaging | 20kg bags |
Where to Use
- Large format porcelain tiles and natural stone, floors and walls, up to 15mm thick
- Vertical surfaces where a standard adhesive risks slump
- Cementitious screeds and underfloor heating and cooling installations
- Substrates waterproofed with Mapelastic AquaDefense, Mapelastic Smart or Mapegum WPS
- Floors subjected to heavy traffic
How to Apply
- Prepare the substrate — it must be dry, structurally sound, free of dust, loose material and anti-adhesive film.
- Mix — while stirring, add the powder to potable water at 28-30 parts water per 100 parts powder (grey), or 27-29 parts (white), to a pasty consistency.
- Comb and place tiles — spread with a suitable notched trowel and press tiles into the wet ridges within the open time.
- Check for full contact — particularly with large format tiles, ensure complete coverage across the back of the tile.
- Grout when ready — walls after 4-8 hours, floors after 24 hours.
Important Notes
- Open time can vary with temperature, humidity and substrate absorbency — strong sun, drying wind or high heat will shorten it.
- Only mix as much adhesive as can be covered within the open time while maintaining good transfer to the tile.
- The substrate must be sufficiently dry; excessive residual moisture affects bond.
- Low VOC formulation contributes toward Green Star credits under the Green Building Council of Australia.
