Investigation of the field aging behavior and gradient characteristics of asphalt pavement of cement bridge deck

The aging of asphalt pavement over prolonged use affects its safety and durability. Differences in external factors and forces between the asphalt layer and traditional pavement make it necessary to analyze the specific aging characteristics of the asphalt layer. In this study, a 15-year-old asphalt mixture was obtained from cement concrete via in-situ core drilling. Semi-circular bending test samples were extracted, and the asphalt mixture's cracking resistance and fatigue properties were analyzed. Field-aged asphalt was obtained through rotary evaporation extraction, and its rheological parameters were determined using a dynamic shear rheometer (DSR). The aging mechanisms of the field-aged asphalt were further investigated using infrared spectroscopy and atomic force microscopy. The results showed that the cracking resistance of the top layer was inferior to that of the bottom layer at-10 degrees C. However, at 15 degrees C, the bottom layer exhibited poorer cracking resistance. Linear amplitude sweep (LAS) tests revealed variations in fatigue life across the asphalt layers, with the surface layer having the shortest fatigue life, making it more susceptible to fatigue damage. Infrared spectroscopy aging indices indicated that aging was most severe at S1. Micromechanical tests showed that S1 had the highest modulus and lowest adhesion, while S3 had the lowest modulus and adhesion. The relationship between aging and depth was found to be nonlinear.