Yield stress measurement of cemented and non-cemented paste backfill with the vane method and slump tests


Abdolreza S. Moghaddam, Ferri Hassani,

The transportation of mine tailings in the form of paste material through pipelines is one of the main stages of mine backfill operations and waste deposition. For the purpose of pipeline transportation design, rheological properties of paste backfill such as yield stress and viscosity must be determined. To measure the yield stress of paste backfill directly, a rheometer with a 6-bladed vane spindle was used in two modes, controlled shear rate and controlled shear stress. The results show a strong correlation (99%) between these two modes. The yield stress was also calculated from the empirical equations developed from standard conical and cylindrical slump tests. The comparison between the vane method and the slump tests indicates that the slump tests generally overestimate the yield stress values. Furthermore, the yield stress of cemented paste backfill was also compared with the non-cemented paste backfill at the same water content. Our study shows that cement has a direct effect on the increase of the yield stress of paste backfill while the percentage of increase depends on the properties of the materials.
Keywords: cemented paste backfill, the vane method, slump, yield stress measurement, Rheology