| Summary: | 碩士 === 中原大學 === 土木工程學系 === 88 === Recent years, as citizens in Taiwan struggle to raise their standard of living, traffic grows with the increasing number of population and vehicles and, it make quality control of pavement maintenance of highway turn to difficult to be commanded. Generally, for the reason of keeping traffic passing smoothly, the overlay works of pavement maintenance were pressed to perform through midnight to next morning, and that way makes the asphalt concrete can not get a sufficient time lag to gain an anticipated strength. Because of insufficient time lag before opening to driving vehicle, the overlaid asphalt concrete has not yet gained an anticipated strength to prevent plastic deformation from wheel loads for pavement subjected to heavy traffic. Therefore, it is important to study the optimum time lag for vehicle admittance during the overlay works performed.
In this study, the specimens used for wheel trace tests were made in the condition of optimum asphalt content which derived from marshal’s mix design. And then these specimens were tested at a series of temperature conditions (80oC, 70oC, 60oC, 50oC, 40oC) to simulate the after-final-rolling field condition of temperature descending and the corresponding rut failure of an overlaid asphalt concrete course which subjected to wheels loading of trucks. And the intent of sufficient time lag for a newly overlaid asphalt concrete course is to determine an adequate temperature with respect to a time lag of temperature descending which admitting traffic passing without plastic deformation.
The results of this study indicate that the mechanism of rut failure of asphalt concrete is dominated by higher viscosity of asphalt at the temperature of 50oC. While at the temperature higher than 60oC, the mechanism of rut failure of asphalt concrete turn to the aggregate interlock control gradually. According to the results of this study, for a newly overlaid course, the descending temperature adequate for opening to driving vehicle is 50oC and, the optimum time lag with respect to temperature-time descending curve is 108~126 min for winter, 126~144 min for spring, 162~180 min for summer and 144~162 min for autumn.
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