Empirical and Fundamental Methods for Measuring Rheological Properties of Cement-Based Materials

Abstract

Work has been conducted on comparing different methods for measuring rheological properties of cement based materials. These properties are used to describe the effect of superplasticizing admixtures. A concentric cylinder viscometer and rheometer will bob-cup geometry were used to measure the viscosity and yield point of cement paste, and mini-slump for measuring the flow and flow retention of mortar. The coaxial cylinder viscometer and the mini-slump gives empirical results, whereas the rheometer gives a fundamental value describing the viscosity. It is important to be aware of the sensitivity cement based materials have to experimental set-up because of the degree of structural breakdown this will induce in the matrix. Both cement paste's and mortar's rheological properties were measured with different amounts of plasticizing admixtures based on lignsoulphonate, at a water to cement ratio of 0.5. The results show correlation between the viscometer and the rheometer. Mini-slump results follow the same trends.