Research On The Aging Characteristics And Mechanism Of TLA Modified Asphalt And Its Mixture

Trinidad lake asphalt (TLA) is a natural formed substance and it has been fully oxidized and precipitated due to millions of years effect of earth’s crust pressure and temperature, therefore it has steady quality. The incorporation of TLA has significant effect on improving pavement performance (high temperature stability, low temperature crack resistance and water stability) of common asphalt mixture. However, there is less research on the aging resistance of TLA asphalt and its mixture, and the applicability of existing aging evaluation system for the TLA modified asphalt needs further discussion. Therefore, in order to improve the service life, and further promote the application and development of TLA modified asphalt, this paper further researches on the aging characteristics and mechanism of TLA modified asphalt and its mixture.By using the rolling thin film oven test (RTFOT) and pressure aging vessel (PAV) to study the variation of three basic indicators, rotary viscosity and rheological properties of TLA modified asphalt at different aging temperatures, aging time, and aging modes.The results show that three aging factors all have significant effect on the performance of TLA modified asphalt, and its aging resistance is better than that of base asphalt under different aging modes.By using the dynamic shear rheometer (DSR) to test the dynamic rheological properties of the asphalt pre-and post aging, and then the aging dynamic equation of asphalt is established with the parameter of 64℃ complex modulus to find the difference of aging resistance by thermodynamic method. The results show that TLA modified asphalt has a higher activation energy, which increases by 12.8% when mixing with 25%TLA. Therefore, the TLA modified asphalt is more stable due to the reaction rate of TLA modified asphalt is smaller than that of base asphalt.The changes of chemical structure of the TLA modified asphalt pre-and post aging are analyzed by infrared spectral analysis technology, and hence studying the aging mechanism of TLA modified asphalt. The results show that the incorporation of TLA is physical modification and does not produce any new characteristic absorption peak, naphthalene and quaternary ammonium functional group which the TLA contains have significant effect on improving the oxidation resistance of asphalt, preparation process of TLA modified asphalt exists a certain degree of aging, the aging carbonyl and sulfoxide index increases with the deepening of aging, but the increasing extent of TLA modified asphalt is smaller than that of base asphalt.Starting with the immersion marshall test and indirect tensile fatigue test, the influence of aging time, aging temperature and coarse aggregate percentage on aging performance of asphalt mixture are researched. The results show that three factors all have significant effect on the performance of water stability and fatigue property of asphalt mixture, while the mixture with more coarse aggregate percentage can accelerate the aging effect, and fatigue cracks tend to develop along the internal voids.