Concrete screed for heated floors
with Saint-Astier® natural lime
The lime concrete has to reach a density of above 2,100-2,200 kg x m3.
To achieve this, use an aggregate between 10 and 0.150 mm.
Mixing
You might have to mix an under 3 mm well graded, sharp sand with fine gravel (up to 10 mm) in a 50/50 mix. Dosage should be 350-400 kg of Saint-Astier® NHL 5 or 300-350 HL 5 (Hourdex® or Tradiblanc®) per m3 of aggregates.
For a 80 mm thick screed
First lay 40 mm (semi-dry mix), level and compact well. Cure for 1 week dampening with a light water mist twice 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 40 mm of mortar, level and compact. Light spray the surface with clean water as soon as you have finished to further compact.
Curing
Spray a light water mist 3 times a day for at least 2 weeks.
Do not use heating for minimum 3 weeks.