Abstract:
Viscosity is a measure of a grout’ s resistance to flow due to the inter-particle forces. Viscosities of grout can be accurately measured using viscometers and advanced rheometers in laboratories; however, some of these equipment are not robust enough for utilization in the field. As such, onsite viscosity is often evaluated indirectly through index tests, with the Marsh Funnel being the method of choice in the grouting industry. The Marsh Funnel test consists of measuring the time required for a known amount of material to flow through the funnel nozzle. As a result, the viscosities are measured in time, yielding an apparent Marsh Funnel Viscosity (MFV) measurement. The Marsh Funnel was originally developed for measuring viscosities of drilling fluids for oil well drilling. These fluids are mostly Newtonian consisting of low concentration bentonite suspensions. However, most of the non-chemical grouts used in the field are non-Newtonian which raises concerns on the use of the Marsh Funnel for such material. This paper presents the results of a study comparing the MFV values to those measured by a Fann Viscometer (Fann Model 35) for four Newtonian fluids and seven suspensions. The results show that the Marsh Funnel does an excellent job estimating the viscosities of Newtonian fluids, as well as non-Newtonian grouts with minimal yield stress. However, the Marsh Funnel tends to underestimate the viscosity of grouts with higher yield stresses.