When traces of lignite are present within the screed, we would recommend contacting the manufacturer of the subfloors to confirm this and seek assurances from them that this will not hinder the performance of the subfloors.
Due to what we suspect is lignite present within the subfloors, we would recommend that the subfloors are dry before applying any ARDEX products, and that, once dry, an epoxy primer should be used to avoid disturbing the lignite with moisture, as moisture can cause the lignite to swell and pop out from the surface of the screed.
Moisture tests should be carried out in accordance with BS 8203 and the presence of a functioning DPM is confirmed.
Once it has been confirmed that the new subfloors are dry i.e., below 75% RH and suitably prepared, ARDEX R 3 E Primer, sand blinded with ARDEX Fine Aggregate can be applied.
Once dry the floor can be smoothed with ARDITEX NA or CL+.
For more information contact the Technical support team on 01440 714 939.