Progressive failure mechanism of water glass modified recycled rock-filled concrete based on radon monitoring and resistivity monitoring

The extent of damage during the progressive failure process of concrete typically is reflected in changes in radon exhalation concentration and electrical resistivity. In this study, radon monitoring, resistivity monitoring, and low-field nuclear magnetic resonance (NMR) techniques were employed to investigate the radon exhalation concentration, resistivity, pore structure, and pore fractal dimensions of recycled rock-filled concrete (RRFC) and water glass-modified recycled rock-filled concrete under different stress levels. The study elucidated the characteristics of resistivity variation and the radon exhalation mechanism during the progressive failure of RRFC. A three-dimensional geometric model of RRFC was developed using multi-view three-dimensional reconstruction technology. The influence of specimen size on the electrical resistivity of RRFC was assessed by integrating experimental data with numerical simulation results. The findings indicate that the modification of recycled rock-fill aggregates with a water glass solution effectively reduces total porosity and radon exhalation concentration while enhancing the compressive strength and initial resistivity of RRFC. As the stress level increases, the radon exhalation concentration initially decreases before subsequently increasing, whereas the resistivity exhibits a continuous decline. At peak stress, the radon exhalation concentration and resistivity reach their maximum and minimum values, respectively. The evolution of the internal pore structure is found to be closely correlated with both resistivity and radon exhalation rate. Furthermore, the electrical resistivity of RRFC is not significantly affected by specimen size.