Abstract
A brief review is made of the rheology of suspensions in general and cement slurries in particular. The factors influencing the flow behaviour of these systems are discussed. It is pointed out that the rheological properties of cement slurries can not be determined by theory alone from the original constituents, and experimental tests combined with empirical formulae are needed. The co-axial cylinder viscometer was used to characterise the rheological behaviour of the cement slurry used in this investigation, the slurry being made highly thixotropic by the use of additives, It is shown that no single flow model, however complex, can correctly fully describe the flow behaviour of such materials. The cement slurry used in this research programme had a structure which changed continuously with time and, when pumped through a pipe, formed a high water content slip layer on the pipe surface. An accurate theoretical solution for this type of pipe flow is lacking in the literature. A new method to predict the pressure gradient of such suspensions flowing in pipes is proposed and the technique was tested using a small pumping line and also with data extracted from the literature. The shear vane test, commonly used to measure shear strength of soils, was developed to measure gel strength of the cement slurry used in this investigation. It is shown that the gel strength measured with this technique is of considerable benefit when assessing the real material behaviour.