Insight into the isothermal multiphysics processes in cemented paste backfill: Effect of curing time and cement-to-tailings ratio

Abstract

Due to the complexity of multiphysics processes, cemented paste backfill (CPB) materials begin the “black box” curing period after placement into underground stopes. Moreover, due to the limited interference in the thermal process, CPB materials may experience locally isothermal curing conditions in underground excavations. Therefore, to yield an optimal design of CPB, it is necessary to investigate the isothermal multiphysics processes in CPB. In this study, the evolution and characteristics of isothermal multiphysics processes of CPB under the different cement-to-tailings ratios are studied. Through SEM, XRD, TGA, and MIP micro-analysis, the hydration products and pore structure of CPB at different curing times and cement-to-tailings ratios are analyzed. Moreover, an isothermal multiphysics monitoring program is implemented to quantitatively study the evolution of matric suction, volumetric water content, and electrical conductivity at various curing conditions. Based on the measured data, it has been found that the mechanical strength of CPB shows a strong dependency on matric suction, volumetric water content, and electrical conductivity. The correlation among multiphysics processes under isothermal conditions is established through regression analysis on the measured data. The findings have the potentials to improve the understanding of the complex field behavior of CPB and contribute to its optimal design.