Finely ground quartz sand and plasticizing admixtures influence on rheological properties of portland cement paste / ; Cemento tešlos su maltu kvarciniu smėliu ir plastifikuojančiais priedais reologinės savybės.

The effect of finely ground quartz sand and plasticizing admixtures on yield stress, viscosity and dilatancy of cement pastes was investigated experimentally. The studies revealed that the addition of quartz sand up to 5% of the cement without plasticizing admixtures reduces the yield stress of such cement paste, whereas higher content of quartz sand in the cement does not cause a further change in the yield stress of the cement paste. With the increase of plasticizing admixtures from 0.2 to 1.0% in the cement paste with quartz sand additive the yield stress of the paste decreases. When 5% of the cement is replaced by quartz sand the viscosity of the cement paste without plasticizing admixtures slightly reduces, whereas the raising of quartz sand content up to 20% does not have a further effect on the viscosity both at high and low shear rate. The quartz sand content up to 5% slightly increases the cement paste dilatancy, whereas the replacement for 20% cement does not change the dilatancy of the paste. The dilatancy of the cement paste increases with more quartz sand and different chemical composition plasticizing admixtures. The studies have proved that rheological parameters of the cement paste are affected by the percentage by weight of finely ground quartz in the cement paste and the particles shape of this additive.