Dynamic deterioration of strength, durability, and microstructure of pavement concrete under fatigue load

摘要

To investigate the dynamic deterioration rules of pavement concrete during the service period, the strength, durability, and pore structure parameters under phased fatigue loading tests were tested. The variation trends of the performance with loading times were analyzed, and the evolution process of the microstructure under fatigue load was observed. The results show that the attenuation tendency of the bending strength under fatigue load is parabolic, and the bending strength increases slightly in the early stage of loading owing to the compaction effect at a stress ratio of 0.5. The attenuation degrees of impermeability of pavement concrete in the later period of fatigue loading at stress ratios of 0.5 and 0.8 are approximately equal owing to the different attenuation rates. The fatigue load changes the turning point of mass loss and dynamic elastic modulus decay under freeze-thaw cycles, thereby accelerating the deterioration of frost resistance. The evolution of the pore structure under fatigue load involves squeezing, expansion, and splitting, accompanied by the generation and propagation of microcracks.