Title: EFFECT OF NATURAL POZZOLANS ON PORTLAND CEMENT PASTE REOLOLOGY.

Author(s): Viviana F. Rahhal, César Pedrajas, Fabián Irassar y Rafael Talero.

Publication: IMCYC

Volume: 5

Issue: 2

Appears on pages(s): 2-11

Keywords: reology, cement pastes, natural pozzolans.

DOI:

Date: 1/1/2014

Abstract:
In this paper the influence of three spanish natural pozzolans of different chemical character were analyzed on twoportland cements with very different mineralogical composition (with opposite C3A and C3S content) and with different replacement percentages. All determinations were made at 25°C and just at the dormant periods of their hydration. The results showed that the cement with low C3A and high C3S, had higher shear stress than the cement with high C3A and low C3S; but its recovery was lower. In the pastes with natural pozzolans, the shear stress increased when the proportion of reactive alumina was higher for a particular replacement percentage. At the time the rotor stopped, the shear stress increase was more significant in the case of cement mixtures with high C3A. Finally as the shear stress increased, with higher percentage replacement for the pozzolans A and C; while for the pozzolan O it decreased, possibly due to its low adsorption.