A contribution to understanding the rheological measurement, yielding mechanism and structural evolution of fresh cemented paste backfill

Cemented paste backfill (CPB) is an efficient and sustainable technology for the disposal of tailings in mining industry. However, the flowability of CPB is not completely clear due to the lack of robust characterization methods and sufficient studies. In this study, the effects of pre-shear rate and time, resting time, and shear protocol on the rheological measurements of fresh CPB were examined. Additionally, a yielding model was built, and the 2-h structural evolution was investigated. The structural evolution of CPB was observed using the oscillatory shear rheology method. The underlying mechanisms were investigated using zeta potential, thermogravimetry, ionic concentration, focused beam reflectance measurement, and 1H nuclear magnetic resonance. The pre-shear rate of 100 s−1, pre-shear time of 100 s, pre-shear resting period of 150 s and the stress ramp-up protocol were all recommended by the results. The dual yielding properties of CPB are adequately represented by the proposed model. It is possible to categorize the structural evolution of CPB at rest into three stages, each of which can be attributed to flocculation brought on by particle interactions, packing density enhancement from the massive formation of rigid links, and an increase in the volume fraction of solid, respectively.