The effect of ultra-fine admixture on the rheological property of cement paste

The effect of ultra-fine admixtures (UA), such as blast furnace slag (BFS), silica fume (SF), fly ash (FA), limestone (LS) and anhydrous gypsum (AG), upon the rheological property of cement paste is researched. The results show that the yield stress value of cement paste is generally decreased with the increase of the UA quantity added, but the viscosity varies greatly with different types and quantity of UA. Ultra-fine LS, SF, FA and slag can decrease the viscosity of cement paste, whereas AG can increase it when the UA quantity is smaller than or equal to 15%. The viscosity and the yield stress of cement paste are decreased obviously with the increase of the UA quantity added, in which the effect of ultra-fine slag is the most significant when the UA quantity is more than 15%. The viscosity and the yield stress can be decreased by a respective addition of 10% ultra-fine LS, SF, FA or a single addition of 35% ultra-fine slag. The acting effect is ranged as: slag>LS>SF >FA. The viscosity and the yield stress of cement paste can be raised significantly by a single addition of 10% ultra-fine AG.