Force-electric characteristics of model rock-filled concrete under uniaxial compression with different curing ages and rock-filled ratios

By analyzing the force-electric properties of rock-filled concrete under uniaxial compression, the precursor information and characteristics of deformation and failure of rock-filled concrete can be mastered, and the reliability and safety of rock-filled concrete structures at an early age can be ensured. This study investigated four variations of model rock-filled concrete, each with a distinct rock-filled ratio. Using the two-electrode alternating current test method, we analyzed the electrical resistivity properties of rock-filled concrete under uniaxial compression at various curing ages (1 d, 3 d, 7 d, 14 d, and 28 d). Additionally, the microscopic pore structure was examined using low-field nuclear magnetic resonance technology. The results showed that with increasing curing age or rock-filled ratio, the compressive strength and electrical resistivity of rock-filled concrete showed a nonlinear growth trend. In contrast, the porosity showed a nonlinear decrease, with the internal pore structure gradually becoming more refined. A mathematical model was established to describe the electrical resistivity of rock-filled concrete at various curing ages and rock-filled ratios. During uniaxial compression, the electrical resistivity of rock-filled concrete followed a pattern of rapid decline, slow decline, stable, and slow increase with strain. These phases corresponded to the development of internal pores and cracks and changes in the crack resistance performance of the rockfill skeleton in the concrete. Moreover, a mathematical equation was formulated to elucidate the relationship among the damage variable, the rock-filled ratio, and the electrical resistivity of model rock-filled concrete, thereby enabling the prediction of the extent of damage to the model rock-filled concrete under stress conditions.