Cemkey Concentrate

Cemix Cemkey Concentrate allows the laying of new concrete screeds and renders, without the need to mechanically roughen the existing surface to obtain a bond.
Typical Applications & Uses:
Cemix Cemkey Concentrate is used for bonding Portland cement screeds, and renders to brick, concrete and concrete masonry without any need to hack the surface to obtain a bond. May be used on new or old surfaces. Cemix Cemkey Concentrate can also be added to the mixing water to improve resistance to trace acids and alkali, as well as reducing surface dusting.
• No mechanical key required to obtain a bond.
• Can be used for new work or repair work.
• Will adhere to most sound surfaces.
• Faster application of screeds and renders.
• Resists trace acids and alkali.

1L, 2.5L, 5L, 20L & 210L

Substrate Preparation:

Ensure the substrate to be treated is structurally sound and free from oil, grease, paint and dirt which may interfere with the bond of the material.


Used as a bonding agent: Dilute 1 volume of Cemix® Cemkey Concentrate with 1 volume of clean water.

For use with mixing water: Dilute 1 volume of Cemix® Cemkey Concentrate with 5 volumes of clean water, e.g. 3L of Cemix® Cemkey Concentrate to 15L of water per 40kg bag of Portland cement.


Bonding agent for Portland cement screeds and renders:

Dilute Cemix® Cemkey Concentrate with equal volume of water. Apply Cemix® Cemkey Concentrate solution with a stiff brush, broom or squeegee, ensuring that the continuous coating covers the surface, without pools or puddling on horizontal surfaces. Two coats may be necessary. Allow the Cemix® Cemkey Concentrate coating to become tacky before laying the screed or render.

For use with mixing water:

Dilute Cemix® Cemkey Concentrate with 5 volumes of water as per the mixing instructions and use the solution as a total mixing liquid. Dry mix materials required. Add Cemix® Cemkey Concentrate solution and follow normal mixing and placing routine. Curing is essential to ensure that the screed or render reaches full strength, and this operation should be carried out as soon as the surface will allow.

NOTE: Floor screeds should have a minimum thickness of three times the diameter of the largest aggregate contained in the screed and should be correctly designed to withstand the workload to which they will be subjected. To increase the resistance of the screed or render to trace acids or alkali, use Cemix® Cemkey Concentrate diluted at the rate of 1 volume Cemix® Cemkey Concentrate to 2 volumes of clean water. Clean all tools in fresh water before material hardens or dries.


Agitate product thoroughly before use.

Technical Data:

Appearance – White

Yield / Coverage - Primer: 8m2/L - 12m2/L . Coverage is dependent on the roughness

and porosity of the existing surface.

The data shown above reflects typical results based on laboratory testing under controlled conditions. Reasonable variations may occur on site.


Cemix® Cemkey Concentrate is not a waterproof material, nor is it suitable for use under conditions where continuous water is present.


Cemix® Cemkey Concentrate can be stored for Twelve (12) months in original, unopened containers when stored in dry conditions between +5OC and +30OC. Keep containers closed in a well ventilated area when not in use. Do not expose to direct sunlight in storage.


Clean all tools with water & brush immediately after use.


Allow the Cemix® Cemkey Concentrate to become tacky before laying the screed or render.