New method of testing the flowability of grout

Abstract

Various flow-cone methods are widely used to determine the flowability of grout. The methods involve the use of a cone-type viscometer, the purpose of which is to determine indirectly the kinematic viscosity of Newtonian fluids. However, grout is generally accepted to be a Bingham-like fluid. Thus we have investigated whether flow cone methods are appropriate for testing the flowability of grout. That is, an energy equation was applied to the flow condition of the fluid surface in the flow cone and to the outlet of the discharge tube at the bottom of the flow cone. The average outflow velocity offluid was determined both theoretically and experimentally to clarify the effect on the measured values of differences in the shape of the flow cone and in the length of the discharge tube. As a result, an inclined-pipe testing method based on the principle of capillary viscometers was proposed. In this method the discharge tube was lengthened and inclination o/the discharge tube was near to horizontal, in order to obtain a steady flow of grout through the discharge tube. The flow velocities measured using this apparatus agreed with those measured using a rotation viscometer. The inclined-pipe method gave accurate measurements of differences in the physical properties of grouts according to their mix proportions and the ambient temperature. Furthermore, as a practical application of this method, a procedure is proposed for calculating the load on a grout pump when pumping a predetermined quantity of grout through a pumping pipeline in a grouting works.