Study on the Damage Mechanism of Concrete after Freeze-Thaw Cycles

Concrete, the most widely used artificial building material, is highly susceptible to damage from freeze-thaw cycles in cold regions. Grounded in practical engineering applications, this study investigates the damage and failure mechanisms of concrete subjected to freeze-thaw cycles. Freeze-thaw cycle tests and numerical simulations were conducted to investigate the mechanical behavior of the material. The experiments focused on changes in surface morphology and mass loss rate, with uniaxial compression tests providing stress-strain curves. A two-dimensional, four-phase mesoscale concrete model incorporating the coarse aggregate, mortar, interfacial transition zone (ITZ), and pores was developed using Python and implemented in ABAQUS for thermomechanical coupling analysis. The results show that as the number of freeze-thaw cycles increases, the freezing and thawing of pore water causes expansion and contraction, which promotes crack propagation. This significantly accelerates the accumulation of internal damage, resulting in higher mass-loss rates and reduced compressive strength. Additionally, an increase in the coarse aggregate content was found to effectively improve the frost resistance of concrete. The simulation results align well with the experimental data, providing a theoretical basis for optimizing concrete performance in freeze-thaw environments.