Early properties and modeling of cemented superfine tailings backfill containing sodium dodecyl sulfate: Microstructure, mechanics, and acoustics

Abstract

Primary microcracks exist within brittle materials such as cemented superfine tailings backfill (CSTB), and these microcracks control the damage mechanism and determine the structural strength of the brittle material. The early damage evolution mechanism and the constitutive model of CSTB under the consideration of initial defects are analyzed and discussed from macroscopic and microscopic viewpoints by using acoustic emission (AE), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) techniques. It is demonstrated that AEA inclusion can slow the hydration reaction inside the CSTB, reducing the number of hydration products and hence the density of the CSTB's internal structure. The amount of AEA incorporated was correlated with the elastic modulus, and the initial damage to the CSTB was quantified as a result. As the initial damage increases, the effective contact area inside the CSTB decreases, and the damage form of the CSTB changes from predominantly tensile damage to predominantly flaking areas in patches, accompanied by a weakening of the AE signal. Analyzed from the perspective of the AE energy rate, the incorporation of AEA reduces the energy storage capacity of CSTB, and with the increase in AEA content, it further leads to a sharp decrease in the energy released from CSTB. The early damage constitutive model of CSTB with different initial damage proposed in this paper agrees well with the experimental data and can provide a reference for the design of CSTB in structural filling.