چكيده به لاتين
Moisture damage and fatigue cracking are the distresses that are directly related to the properties of cohesion and adhesion of materials. Asphalt binder aging is an irreversible process that reduces pavement durability and leads to early damage and an increase in repair and maintenance costs. This process begins with the production of the asphalt mixture in the factory and develops in asphalt over time, finally leading to the destruction and fragility of the asphalt mixture. Therefore, in this research, the effect of short-term and long-term aging on the moisture susceptibility of asphalt mixtures has been investigated using mechanical and thermodynamic methods. The two basic types of bitumen used in this study were applied to the short-term and long-term aging condition and then tested for Pull-off adhesion test and contact angle test using sessile drop method. Different combinations of asphalt mixtures made with limestone and granite aggregates with different hydrophilic potential, were exposed to short-term and long-term aging conditions by SHRP M-007 method. Then, the moisture conditions were applied on samples by AASHTO T283 method. Furthermore, the fatigue life of asphalt mixtures was measured by indirect tensile fatigue test. According to the results of Pull-off test, in samples made with limestone aggregates, aging has reduced the moisture susceptibility and In samples made with granite aggregate, aging has been associated with increased moisture susceptibility by reducing the amount of POTS wet to dry ratio. Analysis of fatigue life in dry and wet conditions showed that mixtures made with 60-70 asphalt-binder have more fatigue life than mixtures made with 85-100 asphalt-binder. In dry conditions, aging increases the acidic and basic components of surface free energy of bitumen, which increases fatigue life in all asphalt mixtures. In wet conditions, aging increases the fatigue life of mixtures made with limestone and decreases fatigue life of granite mixtures, which shows the role of chemical structure of bitumens and aggregates in cohesion and adhesion parameters of asphalt binder and analysis of moisture damage and fatigue life of asphalt mixtures. Among different thermodynamic parameters related to moisture damage, the debonding energy parameter with coefficient R2 of 0.68 and 0.85, respectively, have the highest correlation with the results of the ratio of fatigue life and POTS in wet to dry conditions.
