ARDEX S 21 Rapid Setting Floor Tile Bedding Mortar Grey 22kg
£45.88 inc. VAT
£38.23 ex. VAT
- Product ID: 18320
- Suitable For: bedding floor tiles
- Area of use: INT & EXT
- Application Method: trowel
- Volume: 22kg
- Container Type: bag
- Type: mortar
- Colour: grey
- Brand: Ardex
- Manufactuer: Ardex
- Box Size: 1
ARDEX S 21 is a high-performance, fast-setting cementitious adhesive classified under the BS EN 12004 C1 F standard. This designation indicates that the adhesive is designed for quick setting and is ideal for situations where time is a factor. Once tiles are set with ARDEX S 21, they can be grouted and subjected to normal use within just 3 hours at standard temperatures. This makes it particularly useful for projects that require rapid turnaround or for environments where lower temperatures could slow down the setting of traditional cement-based adhesives.
ARDEX S 21 is a grey powder composed of special cements, high-quality synthetic resins, and fillers. When mixed with water, it creates an easy-to-apply mortar with a working time of approximately 30 minutes. This mortar provides strong adhesion to cementitious surfaces such as concrete and cement/sand screeds. For optimal results with large, flat-backed tiles and dense materials like porcelain or vitreous mosaics, it is recommended to use ARDEX E 90 admix. This admixture also supports tile installation over underfloor heating systems.
Key Points:
- Fast Setting: Tiles set with ARDEX S 21 can be grouted and used within 3 hours at normal temperatures, making it ideal for projects with tight timelines.
- Versatile Use: Suitable for both internal and external locations, ARDEX S 21 is effective for fixing a variety of tile types, including large tiles, ceramic pavers, terrazzo, and natural stone.
- Strong Adhesion: The adhesive provides excellent bonding to cementitious surfaces like concrete and cement/sand screeds, ensuring a reliable installation.
- Enhanced Performance: For fixing large, flat-backed, and dense tiles, and for installations on underfloor heating, using ARDEX E 90 admix with ARDEX S 21 is recommended for improved results.
For specific advice on fixing tiles to fully commissioned underfloor heating systems, consult with the heating system manufacturers or contact the ARDEX Technical Support Team.
Coverage: ARDEX S 21 provides coverage of approximately 1.8 kg of powder per square meter per millimeter of thickness. For example, a 22 kg bag will cover about 2.5 square meters with a 5 mm bed thickness, or approximately 4 square meters with a 3 mm bed thickness.
Storage and Shelf Life: Store ARDEX S 21 in its unopened packaging, in a cool, dry place, and off the ground. Protect it from drafts to maintain its quality. When stored under these conditions, the adhesive has a shelf life of 12 months from the date indicated on the packaging.
For more in our range of mortars, please click here. For our full range of Ardex products, click here.
Alternatively, you can visit the Ardex wesite by clicking here.
ARDEX S 21 is a specialized, fast-setting pourable mortar designed for bedding floor tiles both indoors and outdoors. It is particularly effective for installing large tiles, ceramic and brick pavers, terrazzo tiles, and natural stone.
Surface Preparation
ARDEX S 21 can be applied to both dry and damp subfloors, including cement and sand screeds or concrete, provided these surfaces are solid, clean, and free from dust, dirt, oil, grease, and other substances that could hinder adhesion. Concrete surfaces may need mechanical preparation to expose the aggregate. For dense, smooth surfaces like terrazzo, priming with ARDEX P 82 or ARDEX P 4 is recommended before applying ARDEX S 21. In wet or external areas, use ARDEX S 21 with ARDEX E 90 directly on the cleaned surface. Always follow the guidelines in BS 5385: Part 3 regarding the age of backgrounds before tiling or levelling.
Mixing
To mix ARDEX S 21, add the powder to clean water in a clean container, stirring thoroughly to achieve a smooth, slump-free mortar. Using an ARDEX mixing paddle or a cage-type mixer with a 10mm chuck and variable speed drill makes mixing easier. The standard mix ratio is approximately 4.5 parts powder to 1 part water by volume. For a 22kg bag, use about 3.5 liters of water. If using ARDEX E 90, mix 2kg with 2 liters of water; up to 0.5 liters extra water may be needed for large tiles. The mortar’s consistency can be adjusted to suit the application, and up to 4.5 liters of water may be used for sub-floor levelling. ARDEX S 21 should be applied at temperatures above 5°C.
Thickness
ARDEX S 21 is suitable for bed thicknesses between 2mm and 3mm, depending on the size of the notched trowel used. For thicker applications, such as pre-levelling or forming falls, up to 30mm thickness can be achieved by mixing the mortar with sand or aggregate as needed. For layers up to 10mm, use ARDEX S 21 in its standard form. For thicknesses between 10mm and 30mm, mix with 1 part screeding sand (0-5mm) by volume, approximately 20kg of sand per bag of ARDEX S 21. Ensure no water film forms on the surface of the fresh mortar. If the base is porous, dampen it with water before applying the mortar.
Application
ARDEX S 21 can be applied from a trowel in a single operation, eliminating the need for buttering tiles. Apply the mortar to the prepared surface with a trowel, then comb it with a square-toothed notched trowel to create a ribbed mortar bed. The open time is at least 10 minutes, and tiles should be fixed within this period for optimal performance. Once the mortar begins to firm up, discard it—do not add more water after it has started setting. For levelling and forming falls, ARDEX S 21 can be used with or without sand/aggregate to achieve the desired level. A bonding coat of ARDEX S 21 should be applied before adding sand-filled mortar. The surface should be allowed to set and harden before fixing tiles.
Grouting
Tiles installed with ARDEX S 21 can be grouted and subjected to foot traffic after three hours at 20°C.
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| Elementlength | |||||||
| up to 1,5 m |
up to 2,5 m |
up to 3,5 m |
up to 4,5 m |
up to 2,5 m |
up to 3,5 m |
up to 4,5 m |
|
| Type of window frame material |
Minimum witdth of joints for a butled mounting b in mm |
Minimum witdth of joints for a inner mounting b in mm |
|||||
| Hard PVC (white) | 10 | 15 | 20 | 25 | 10 | 10 | 15 |
| Hard PVC and PMMA (dark) (colour extruded) |
15 | 20 | 25 | 30 | 10 | 15 | 20 |
| Hard PUR integral foam | 10 | 10 | 15 | 20 | 10 | 10 | 15 |
| Wood-aluminium-window | 10 | 10 | 15 | 20 | 10 | 10 | 15 |
| Aluminium-plastic sandwich frame (bright) |
10 | 10 | 15 | 20 | 10 | 10 | 15 |
| Aluminium-plastic sandwich frame (dark) |
10 | 15 | 20 | 25 | 10 | 10 | 15 |
| Wooden window frame | 10 | 10 | 10 | 10 | 10 | 10 | 10 |
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