A multi-stage triaxial test for cemented paste backfill

In this study two series of uniaxial compression and indirect tensile (Brazilian) tests, as well as a multi-stage triaxial compression test were performed in order to determine the mechanical properties and to develop a shear failure criterion for a particular Cemented Paste Backfill (CPB). CPB is used in underground mines for backfilling excavated stopes. This practice provides ground support to adjacent stopes, thereby permitting mining of the surrounding ore (i.e., increased ore recovery). It is a high-density, non-segregating, low-plasticity mixture of mine tailings, binder, and water which typically contains 70%–85% solids. The multistage triaxial test has been adopted as an alternative to a series of single-stage triaxial tests to determine engineering material parameters of rocks, whereas three single-stage triaxial tests are required to obtain a complete failure envelope, one multi-stage triaxial test may give the complete failure envelope. This paper mainly focuses on the experimental development of a shear failure criterion using just one multi-stage triaxial test of a CPB consisting of carbonate sand with grain size ≤ 250 μm instead of mine tailings, Portland cement as a binder and tap water.