Influence of the addition of dispersed fine polymineral calcined clays on the properties of Portland cement paste

The addition of certain types of polymineral clays containing 40–62% or 0% without kaolinite, calcined at 400–800°C and ground to 250–800 m2/kg, was found to increase the strength, density and water resistance of hardened Portland cement paste relative to the addition of metakaolin and silica fume. Increased research in this field could provide a scientific and technological basis for the standardised manufacture of effective pozzolans based on polymineral clays in different countries and regions. Effective pozzolanic additives based on calcined polymineral clays with high pozzolanic activity can be produced by calcination at lower temperatures (400–600°C) and with a lower fineness than metakaolin.