Study On Temperature Adjustments For Deflection And Backcalculated Asphalt Moduli Of Pavement

Nondestructive deflection testing using falling weigh deflectometers (FWDs) is one element of the monitoring effort currently underway in the road engineering, but the investigation shows that asphalt concrete materials are temperature dependent in nature, in other words, the stiffness, or modulus, of asphalt concrete is very temperature-sensitive. Routine deflection test results must nearly always be adjusted to represent the deflection at a standard temperature or some other reference temperature that is need for analysis. Also, the backcalculated modulus must be adjusted to the modulus expected at some selected reference or characteristic temperature for the section being analyzed. This is named temperature adjustment; it is also the mostly work in this paper.The detail contents are summarized as follows:1. Taking the typical structure of bituminous pavement as the observation object, a kind of detailed method for temperature field research is put forward. Basing on the abundant measured temperature data, the regularities of distribution of asphalt pavement temperature field is studied in detail, and the dependency relation between the air temperature and temperature field is discussed with regression analysis.2. Thinking about the effect difference to asphalt pavement temperature field which is applied by temperature rise period and temperature fall period of air, the dependency relation between air temperature and different temperature changing periods are researched respectively, at last, the prediction models on asphalt pavement temperature which based on different temperature changing periods are established. The comparison between measured value and predicted asphalt pavement temperature indicates that these models are equipped with comprehensive applicability and excellent accuracy.3. According to the testing deflection basins measured using Falling Weight Deflectometer(FWD) of semi-rigid pavement on the experiment pavement, the structure layer moduli of asphalt pavement is backcalculated according to the principle of system identification method. The corresponding relation between the deflection, back-calculated moduli of asphalt pavement and mid-depth temperatures are analyzed, then the relevant temperature adjustment equations of deflection and back calculation moduli are developed.On the base of studying temperature field, this paper develops the correction relation between temperature and deflection, backcalculated of AC pavement, so this research findings...