Fracture Characterization of Reclaimed Asphalt Pavement Mixtures under Aging Conditions Based on Semicircular Bending and Digital Image Correlation

ABSTRACT The usage of reclaimed asphalt pavement (RAP) in pavement presents a sustainable solution for pollution caused by landfilled construction waste but raises concerns regarding the fracture resistance of RAP-incorporated asphalt pavement. This study evaluates the effects of coarse RAP content (particle size ranges from 10 to 16 mm), thermal oxygen aging, and environmental temperature on the fracture behavior of asphalt mixtures using semicircular bending tests and digital image correlation (DIC). Asphalt mixture specimens with coarse RAP contents ranging from 0 to 100 % were prepared and subjected to thermal oxygen aging conditioning. Results demonstrate that increasing coarse RAP content significantly impairs fracture resistance of asphalt mixture. Fracture energy (Gf) and fracture toughness (KIC) decrease by 47.0 % and 18.6 % for warm mix asphalt mixture (WMA) when the coarse RAP content is raised from 0 to 100 %. The negative influence of thermal oxygen aging on the fracture resistance of asphalt mixture gradually diminishes when the coarse RAP content exceeds 50 %. Warm mix additive notably mitigates the fracture resistance degradation of asphalt mixture by improving asphalt-aggregate interfacial bonding and delaying crack initiation, especially with a high coarse RAP content. The DIC test result reveals that a higher RAP content leads to increased linearity of crack path, lower crack tortuosity, and reduced horizontal deformation capacity in asphalt mixture during the cracking process. When the coarse RAP content is increased from 0 to 100 %, the maximum horizontal strain of the WMA mixture and the hot mix asphalt mixture decreased by 29.1 % and 38.2 %, respectively. The study provides deeper insight into the fracture behavior of RAP mixture, supporting the optimized usage of RAP in sustainable pavement engineering.