Ardex A18 – Screed Bonding Cement with Colour Indicator
Ardex A18 – Screed Bonding Cement with Colour Indicator is a green powder with aggregates and specially formulated additives which, when mixed with water,
produces a slurry ideal for bonding Ardex Screed Cements. The bonding slurry changes colour as it dries, indicating if it remains open to receive the Ardex Screed Cement.
Ardex A 18 is used for producing bonding slurries for application over concrete and cement/sand screeds. It is suitable for internal and external use, including swimming pools.
Ardex A 18 can also be used for joining daywork joints when a new bay is laid against a set and hardened screed, including screeds with underfloor heating systems.
Preparation of the substrate:
The substrate may be dry or damp (with no surface water) but must be rigid, clean and free of dust, grease and other barriers to adhesion. The use of Ardex DGR Degreaser is recommended for the removal of oils, waxes and any other barriers to adhesion, from the substrate. Concrete surfaces must be prepared using suitable mechanised equipment to expose the coarse aggregate and to remove all barriers to adhesion. All surface coatings must be removed prior to application.
Mixing Ardex A18 – Screed Bonding Cement with Colour Indicator:
Add the Ardex A 18 powder to clean water in a clean container, whilst stirring and mixing thoroughly to give a smooth, lump-free paste. The use of an Ardex
mixing paddle with a 10mm chuck variable speed electric drill makes light work of mixing. The mixing proportions by volume are: 3 parts Ardex A 18 powder to 1 part
water. A 25kg bag of Ardex A 18 powder requires approximately 5.75 litres of water. The mixed Ardex A 18 slurry has a working time of approximately 60 minutes. Once the mortar starts to stiffen/set, do not add additional water to the mix.
Application of Ardex A18 – Screed Bonding Cement with Colour Indicator:
Apply Ardex A 18 to the substrate with a brush to a minimum thickness of 1.5mm. The screed cement must then be placed and compacted ‘fresh in fresh’ whilst the bonding slurry is still wet and workable; this is indicated by a dark green colour. After approximately 15 minutes the colour changes to light green, indicating the slurry has dried and an additional application will be required. Apply Ardex A 18 at temperatures above 5°C.
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