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In order to investigate the dynamic mechanical properties of polyphosphoric acid (PPA) and SBS co-modified asphalt mixtures, uniaxial compression dynamic modulus tests were conducted. The influences of temperature and frequency on the dynamic modulus and phase angle were analyzed. Additionally, dynamic modulus and phase angle master curves were constructed based on the modified Havriliak-Negami (HN) model. A comparative analysis was also performed with SBS-modified asphalt mixtures. The results indicate that both types of asphalt mixtures exhibit similar trends in dynamic modulus and phase angle variations with changes in temperature and frequency. The HN model accurately fits the master curves of dynamic modulus and phase angle for both asphalt mixtures. In comparison to SBS-modified asphalt mixtures, the phase angle of PPA+SBS co-modified asphalt mixtures decreases at -10, 20, and 50 °C, while the dynamic modulus decreases at -10 °C, changes minorly at 20 °C, and increases at 50 °C. Over a wide frequency range, PPA+SBS co-modified asphalt mixtures exhibit increased dynamic modulus and decreased phase angle at high temperatures and low frequencies, while they show decreased dynamic modulus and relatively stable phase angle at low temperatures and high frequencies. These findings suggest that PPA+SBS comodification endows asphalt mixtures superior dynamic mechanical properties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Jiangsu University (Natural Science Edition) / Jiangsu Daxue Xuebao (Ziran Kexue Ban) is the property of Editorial Department of Journal of Jiangsu University (Natural Science Edition) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To scientifically select and evaluate ultra-thin wearing course asphalt mixture, three types of asphalt mixture, SMA-10, UTAC-10 and NovaChip Type-C were selected to study the performance evaluation indicator. The low temperature performance of mixture was evaluated by use of thermal stress rest rained specimen test, and the surface performance was evaluated by permeable coefficient test and anti-slide performance test. A kind of indoor abrasion test was designed to evaluate the skid resistance attenuation property of asphalt mixture, and a set of dispersion tests under three conditions was designed combining with freeze-thaw splitting test to evaluate water damage resistance performance of asphalt mixture. The results show that the frozen broken temperature and frozen broken strength can effectively evaluate the low temperature performance of ultra-thin wearing course asphalt mixture. It is scientific to use initial value of BPN and sliding attenuation degree to evaluate skid resistance performance of ultra-thin wearing course. Freeze-thaw splitting strength ratio and freeze-thaw splitting strength should be combined to evaluate resistance water damage performance. [ABSTRACT FROM AUTHOR]

In order to research the fatigue performance of asphalt pavement under repeated load considering the fatigue damage and healing of asphalt mixtures, the discrete element model of asphalt pavement was used to calculate the tensile stress and strain at the bottom of the asphalt layer. Considering the random dynamic loads of vehicle, the influence of load magnitude, rest period Of repeated load and loading sequence on fatigue performance of the asphalt layer was studied. Results show that the tensile stress and strain at the bottom of the asphalt layer fluctuate according to the repeated load. With the increase of rest period of repeated load, the level of stress or strain at the bottom of the asphalt layer is reduced evidently and the amplitude of stress or strain is increased with a certain extent. Different fatigue performances of the asphalt layer are caused by different loading sequences. The fatigue damage of asphalt pavement caused by the sequence from heavy load to light load is more serious than that from light load to heavy load. [ABSTRACT FROM AUTHOR]

The controlling efficiency of permeable asphalt pavement to runoff pollutant has been studied from materials and structures of permeable pavement based on determining the main value indices of runoff pollutant. Experimental results show that the materials of layers with different structures in the permeable pavement can remove COD to a certain degree. The surface and base with binder materials exhibit better removal rate of SS, however, loose aggregate reservoir bed and sand-gravel filtration layer without binder materials will increase the content of SS. Fiber can be used in the subbed course to filtrate the suspended solids to improve the removal rate of SS. Furthermore, the physical mechanism of controlling pollutant by adopting different materials and structures of permeable pavement is clarified and the key points in the design of material and structure for permeable pavement are put forward. [ABSTRACT FROM AUTHOR]

To analyze the similarity of stress state between rutting test and asphalt pavement, finite element simulation was carried out to modify the rutting test model based on similarity theory. Firstly, the relationship between structure of asphalt pavement and parameters of the modified rutting test model was deduced through similarity theory. Then the affected areas for three typical pavement structure under loading of wheel load were obtained by finite element simulation with ABAQUS, and the model size of the entire structure was achieved by dint of similarity theory. According to the principle of mechanical response equivalency, parameters of indoor rutting test model for the multiple board structure were determined, and the correctness of multiple board rutting model was verified by rutting test. [ABSTRACT FROM AUTHOR]

By adopting the digital speckle correlation method (DICM), the tensile strain researches in the indirect tension test of asphalt mixture sample are preceded in this paper. Simulation on the tension of speckle diagram shows that the DICM is available, and its accuracy is high. Furthermore, the efficiency of DICM is proved by the comparison and analysis with the gauge measuring and calculating method. It is concluded that DICM is feasible in measuring the indirect tensile strain. [ABSTRACT FROM AUTHOR]

The microwave thermal induced healing properties of asphalt mixture with different dosage of Fe3O4-SiC were studied. Firstly, the effect of Fe3O4-SiC on the microwave heating efficiency of asphalt mixture was studied by microwave heating. Then, the fluidity of asphalt was characterized by frequency scanning and temperature scanning tests of DSR, and the healing effect of asphalt was evaluated by LAS tests of loading-intermittent loading mode. Finally, the healing effect of asphalt mixture was studied by SCB test of destruction-healing-failure mode. The experimental results show that with the increase of Fe3O4-SiC content, the microwave heating efficiency of asphalt mixture is improved, and the heating rate of 25%, 50% and 75% is increased by 27.41%, 43.44% and 77.26% compared with the blank group, respectively. Frequency scanning, temperature scanning and LAS tests show that high temperature promotes asphalt flow and is beneficial to healing. SCB test results show that when the content of Fe3O4-SiC is 50%, it is more suitable for microwave heat-induced healing of asphalt mixture, which not only reduces the heating time, but also maintains a certain healing effect. [ABSTRACT FROM AUTHOR]

Isocyanate modified liquid was prepared by isocyanate and diluted asphalt. Then, isocyanate modified asphalt cold patch asphalt mixture was prepared by combining isocyanate modified liquid with aggregates. Crosslinking reaction was used to improve the performance of cold patch asphalt mixture. The experimental results show that the modified liquid exhibits good short-term storage stability. By adjusting the dosage of PM-200 and PPU-1102 isocyanate, the viscosity and the reactivity of the system can be effectively regulated, from which the mechanical properties and water damage resistance of the cold patch asphalt mixture can be well adjusted. When the proportion of diluted asphalt, PM-200 and PPU-1102 in the modified liquid are 50%, 10% and 40%, respectively, the Marshall stability and the residual stability of the cold patch asphalt mixture with 6% liquid content reaches 24.8kN and 86.1%, respectively, which are close to those of the hot asphalt mixture. Field experiments show that compared with traditional material, the isocyanate modified cold patch asphalt mixture exhibits higher durability. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)