<p>To investigate the compactness, electrical conductivity, and strength characteristics of fly ash subjected to varying freezing temperatures, a series of experiments including wave velocity detection, resistivity measurement, and uniaxial compression tests were conducted on fly ash samples with different moisture contents at various temperatures. Dynamic resistivity changes were also monitored throughout the process. The findings reveal that the longitudinal wave velocity of fly ash initially increases and subsequently decreases as the temperature drops, with the increase being more pronounced at higher moisture contents, reaching an overall peak at − 15&#xa0;°C. Moisture content significantly influences the resistivity of fly ash, which decreases with increasing moisture content and increases with prolonged freezing time. Under varying moisture content conditions, the peak stress in the uniaxial compression stress–strain curve of fly ash escalates with increased moisture content, and the resistivity undergoes three distinct stages of change. During compression, the rate of resistivity decline is greater in samples with higher moisture content. Additionally, the mechanical and electrical properties of the samples are influenced by the pressure melting effect and ice cracks observed in the uniaxial compression tests. These research outcomes elucidate the mechanical and electrical conductivity behaviors of fly ash under load, providing critical insights for monitoring its stability in freeze environments. This is particularly significant for ensuring the safety of road engineering in cold regions where fly ash is used as a subgrade material and for mitigating environmental pollution.</p>