Determination of master curves for asphalt mixtures by means of IT-CY tests
The concept of ecologically conscious and energy saving roads must be expanded to the performance of the asphalt mixtures as well as to the test related to it. This paper investigates the tests focusing on a better description of the behaviour of asphalts as well as on a deeper revelation of the impact of different compositions. Based on the international experiences the recording of the asphalt´s complex module over the entire temperature range by the determination and evaluation of the mater-curves appeared as a possible solution for more precise description of the asphalt behaviour.
Evaluation of Application of Thin HMA Overlay on the Existing Flexible Pavement for High-Traffic-Volume Rural Highways
Thin hot mix asphalt (HMA) overlay of flexible pavement is a conventional method for preventive maintenance of the existing flexible pavements especially in  high-traffic-volume rural roads. In this research, MEPDG software is used to  investigate the effects of thin HMA overlay on the pavement performance improvement by considering various scenarios for applying overlay layer under dierent climatic  conditions. These scenarios consist of applying dense graded asphalt concrete  (DGAC) and gap graded asphalt rubber concrete (GGARC) as thin overlay layer with and without thin milling the existing asphalt concrete layer. The analyses are made for the climatic conditions of three cities in Iran. According to the obtained results, the effect of mean annual air temperature on thin HMA overlay performance is more than rainfall. The results also indicate that the performance of GGARC in retention of fatigue cracking is better than DGAC. Furthermore, the results suggest that thin HMA overlay remarkably increases the service life of existing flexible pavement for heavy trac rural highways.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.