The insulation and underfloor heating pipes had already been designed for the installation of a flowing screed and so the installation of the VELOSIT SC 245 flowing screed could begin at 8:30 am. KKL had loaded one of its Brinkmann Transmix 3200s with 16 tons of a specially formulated 0-4 mm screed sand mix and filled the binder silo with 7 tons of VELOSIT SC 245. After a few minutes, the amount of water was adjusted by checking the outlet dimension and the paving could begin. After less than 2 hours, a good 20 tons of screed had been pumped into the second floor. The installation is comparable to an anhydrite screed and saves mechanical compaction of the material as with an earth-moist cement screed.
The Transmix now had to be filled again and the surface on the second floor was then laid in the afternoon. At this point, the first surface was already walkable and pleasantly warm due to the heat of hydration. VELOSIT SC 245 very quickly develops high flexural and compressive strengths.
When the surface was inspected the next day, the compressive strength was already 22 MPa. The three partners Andreas Kückmann, René Krüger and Thorsten Lux from KKL were delighted with the very even and crack-free surface. The screed specialists from Delbrück see enormous potential for this system, especially when larger areas need to be ready for use again quickly, as is often the case in the renovation of industrial areas, for example.
By the following Monday, the surface had dried sufficiently for tiling in the first apartment, and the surface was so even and stable that it did not need to be sanded.
The high strengths also enable relatively thin screed structures. Despite the highly exothermic reaction, virtually no stress cracks occur. As VELOSIT SC 245-based flowing screeds have a similar thermal expansion behavior to concrete, the field sizes and design of edge connections must be dimensioned in the same way as for cement screeds.
Flowing screeds produced with VELOSIT SC 245 harden to form a water and frost-resistant screed slab. They can be installed in a bonded layer from 10 mm and on a separating layer from approx. 35 mm layer thickness. The heating protocol for the underfloor heating can be started after just 24 hours.
For smaller areas, the VELOSIT SC 244 ready-mixed screed is also available based on the same technology, which contains an optimally matched sand mixture in addition to the binder.
With VELOSIT flowing screeds, the processing advantages of an anhydrite flowing screed can be combined with those of a cementitious rapid screed. Easy to install, quick to lay and also suitable for permanently wet areas.
