Effect of temperature on time-dependent rheological and compressive strength of fresh cemented paste backfill containing flocculants

Abstract

Temperature significantly affects the transportability and strength of fresh cemented paste backfill (CPB). In this study, experiments are performed to investigate the effect of temperature on the time-dependent fluidity and compressive strength of CPB samples containing different flocculants dosages (anionic-type polyacrylamide). Rheological tests are conducted on fresh CPB samples containing 0, 55, 75, and 85 g/t flocculants, which are then are cured for 0, 20, 40 and 60 min, respectively. Subsequently, mechanical tests are performed on the CPB samples cured at 2 °C, 20 °C and 50 °C for 3, 7, and 28 d, respectively. Moreover, microstructural analysis and zeta potential measurements are performed to evaluate the effect of curing temperature and flocculants dosage on the microstructure and zeta potential of fresh CPB mixtures. The results show that the time-dependent rheological of the fresh CPB mixtures are significantly affected by the curing temperature and flocculants dosage. Both the yield stress and viscosity increase steadily as the curing time elapses, and an increase in the curing temperature and flocculants dosage results in a higher yield stress and viscosity. The uniaxial compressive strength of the CPB samples is enhanced by the curing temperature but decrease with increasing flocculants dosage. The CPB samples with flocculants exhibit a looser and more heterogeneous structure than the flocculants-free CPB samples. The findings of this study provide guidance for the design and application of CPB in deep mines.