Freeze–Thaw-Induced Deterioration and Failure Mechanisms of Permeable Concrete in Cold Regions

To investigate the performance degradation patterns and underlying damage mechanisms of permeable concrete under freeze–thaw cycles in cold regions, permeable concrete with varying porosities was selected as the research subject. A total of 120 rapid low-temperature freeze–thaw cycles were conducted. The evolution of porosity, mass loss, skid resistance, permeability, and compressive strength was systematically analyzed. Exploratory numerical simulations, conducted under idealized assumptions, suggest that rising porosity may reduce effective thermal conductivity, extend phase-change duration, and amplify internal temperature gradients—trends that are consistent with the observed porosity-dependent frost damage but require experimental temperature validation for quantitative confirmation. With the increase in freeze–thaw cycles, mass loss and porosity continuously increase, while compressive strength and permeability gradually decrease. After 120 cycles, the mass loss of all specimen groups was below 1%, with compressive strength decreasing by 5.5% to 12.9%. Despite this, the specimens maintained good permeability and skid resistance. Numerical simulations indicate that permeable concrete exhibits a three-stage temperature response during both freezing and thawing processes. An increase in porosity reduces the material’s effective thermal conductivity, prolongs the phase transition duration, and intensifies the internal temperature gradient, thereby amplifying the thermo–mechanical coupling damage effects. Therefore, optimizing the pore structure is crucial for improving the long-term service performance of permeable pavements in cold regions.