To investigate the pore structure of graphene oxide modified polymer cement mortar (GOPM) under salt-freeze-thaw (SFT) coupling effects and its impact on deterioration, this study modifies polymer cement mortar (EMCM) with graphene oxide (GO). The micro-pore structure of GOPM is characterized using LF-NMR and SEM. Fractal theory is applied to calculate the fractal dimension of pore volume, and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores. The experimental results indicate that, after 25 salt-freeze-thaw cycles (SFTc), SO 4 2− ions penetrate the matrix, generating corrosion products that fill existing pores and enhance the compactness of the specimen. As the number of cycles increases, the ongoing formation and expansion of corrosion products within the matrix, combined with persistent freezing forces, and result in the degradation of the pore structure. Therefore, the mass loss rate (MLR) of the specimens shows a trend of first decreasing and then increasing, while the relative dynamic elastic modulus (RDEM) initially increases and then decreases. Compared to the PC group specimens, the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc. The fractal dimensions of the transition pores, capillary pores, and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases. Among them, the capillary pores show the highest correlation with MLR and RDEM, with correlation coefficients of 0.974 38 and 0.985 55, respectively.
