Steady viscous flow of some commercial Andean volcanic Portland cement pastes

Three commercial Ecuadorian cements, obtained from crushing a mix of clinker and a mixture of pumice powder and volcanic ash, were selected to perform studies on steady viscous flow behaviour. Steady flow curves were obtained during the dormant period. All pastes showed non-linear viscoplastic behaviour. A modified Bingham model was fitted to the experimental data. The yield stress was found to increase and plastic viscosity decreased with clinker substitution. These results were justified by using a model that considers fresh volcanic cement paste as a suspension of particles (cement and volcanic powder) dispersed in a liquid phase, formed by water, and a gel part, formed from the cement–water chemical reaction.