6. Plaster sand – grain size composition 2 - 4 mm 1 - 2 mm 0,5 - 1 mm 0,25 - 0,5 mm 0,125 - 0,25 mm < 0,125 mm (“dust”) dust is a must in the mixture in order to receive pumpable material 5 - 10% 5 - 10% 15 - 20% 12 - 18% 10 - 15% 30 - 40%
7. Washed sand dust particles are missing => mortar is not pumpable! Washed sand, e.g. river sand 2 - 4 mm 1 - 2 mm 0,5 - 1 mm 0,25 - 0,5 mm 0,125 - 0,25 mm
8.
9. Grain size composition of 4mm plaster sand The content of the fine particles (fillers, clay, dust) is very important for the pumpability! But, if it is too much, cracks may occure due to the higher shrinkage.