Finely Ground Quartz Sand and Plasticizing Admixtures Influence on Rheological Properties of Portland Cement Paste

Abstract

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.