Natural Lime concrete screed for heated floors
The lime concrete has to reach a density of above 2200 kg x m3.
To achieve this use an aggregate of 10mm down to 0.150.
You might have to mix 3mm down, well graded sharp sand with fine gravel (up to 10mm) in a 50/50 mix. The dosage of lime (NHL 5) will be 400/450kg. per m3 of aggregate (1:2 by volume).
80mm thick screed: lay first 40mm (semi dry mix), level and compact well. Cure for 1 week with light water mist 2 times a day. Once sufficiently hard fix the heating elements on this layer. Put heating elements under pressure to check for leakages. Once satisfied that there are no leakages, apply the remaining 40mm of mortar, level and compact. Light spray the surface with clean water as soon as you have finished to compact.
Curing: with a light water mist 3 times a day for at least 2 weeks.
Do not use heating for minimum 3 weeks.
For further Guidance, contact your St Astier Distributor.