Abstract
At present, many mines adopt the filling method. It is particularly important to solve the problem of the long-distance transportation of slurry during the filling process. Based on the high-density filling material of Sanning mine, the experiments were designed to add sodium abietate (SA), triterpene saponin (SJ) and sodium dodecyl sulfonate (K12) with concentrations of 0.0%, 0.2%, 0.4% and 0.6%, respectively, which were used as air entraining agents (AEA). The filling body with the curing age of 7 and 28 days was prepared for various tests, including nuclear magnetic resonance (NMR), and alternating current (AC) impedance tests. The effects of the air entraining agent and curing time on the physical properties, pore structure and AC impedance properties of the filling were obtained. The results show that: (1) within the frequency range of 10−1–105 Hz, the variation trend of AC impedance of the filling body cannot be changed by adding the air entraining agent, and the filling body with the same ratio had a similar topological structure. (2) The filling body with different AEA and curing times can be represented by the same equivalent circuit model, while the maximum chi-square coefficient was 0.46%. (3) Under the condition of a high frequency of 105 Hz, the porosity and uniaxial compressive strength of the filling body with 7 day curing age were linearly correlated with the AC impedance. However, the porosity and uniaxial compressive strengths of the filling body with 28 days curing time were affected by the type of AEA at a high frequency of 105 Hz.
Highlights
Similar to other rock masses, backfill has a complex internal structure
air entraining agents (AEA) is the maximum for the same frequency
When the curing ages for the filling body with the same AEA were 7 days and days, the equivalent circuit diagrams remained the same, and the chi-square coefficient had the maximum value of 0.46%
Summary
Similar to other rock masses, backfill has a complex internal structure. Cement tailings or macadam cement tailings consolidation fill has solid particles, and has water and air. The radius of the semicircle in the high-frequency zone can indirectly reflect the concentration of OH- ions in the pore solution of the cement slurry [9,10] conducted electrochemical impedance analysis on the hydration process of cement with different particle sizes, and showed that the pore diameter was smaller when the particles’ gradation was small. Cruz et al (2013) [6] studied the degree of hydration reaction of cement mortar through AC impedance parameters based on a three-branch circuit equivalent model, and quantified the electrochemical properties of hydration products located at the solid–liquid interface. Electrochemical AC impedance technology has been used in some studies to analyze the internal structure and equivalent circuit model of cement materials. The influence of AEA on the performance of cemented backfill was studied, which provided a reasonable method for AEA to improve the strength and fluidity of cemented backfill
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