The effect of fine pozzolanic and other particles on the hydration of C3S

Abstract

The effect of a range offine particles on the hydration of C3S has been studied. Graphite and α-alumina particles had no effect and titania only a slight effect, but amorphous silica, clays and γ-alumina had marked effects. Silica produced a strong acceleration of C3S hydration and a reduction in the CH content of the paste. The acceleration of C3S hydration was independent of the surface area of the silica in the range 380–50 m2/g but, in contrast, the removal of CH was markedly accelerated by a reduction in particle size. Clay particles caused less acceleration and had little effect on the CH content of C3S pastes. Particles of γ-alumina in some circumstances produced a marked retardation of C3S hydration. The effects are discussed in terms of the mechanism of C3S hydration.