Page 35 - ConcreCem - State of the Art

11.6 Pumpable Self-leveling Floor Screed in Ireland
In Ireland and the UK, sand-cement floor screed emplacement has historically been a very labor intensive process, with a four man crew capable of laying 15m3 per day of screed, at thicknesses of between 75-100mm.
CEM Ltd studied this process and decided to initiate lab trials on the design of a pumpable, self-leveling sand/cement screed, which, would not crack, suffer shrinkage nor suffer edge curl-up, and give sufficient integrity to perform as the traditional dry screed.
It was decided to include ConcreCem in the pumpable screed to negate the perceived problems above. ConcreCem was introduced in the trials at 0,3% of the cement content (330 kg/m3) and a high water/cement ratio of 0,85 was decided on to give the desired slump/flow of 260-280mm. Compressive strength results at 28 days of between 12-18 Mpa, dictated the need for field trials.
Two small floors of circa 20m2 have been poured. The process time for these from pumping, to leveling, to vacating the site has been in the order of 20 minutes for 1.5m3 of screed. This would give us typical single pumpable day rates of 120 m3. Pumping was carried out in 6 minutes.
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