Volume 38, Issue 4 (July 2010)
A Full Scale In Situ Evaluation of Strain Characteristics at Highway Flexible Pavement Sections
The objective of this study was to evaluate the strain characteristics in asphalt pavements with respect to five in situ factors: Layer thickness, vehicle speed, axle weight, pavement temperature, and lateral distance between loading tire and sensor (i.e., loading offset). Two sets of moving load tests have been performed at three asphalt sections (A14, A5, and A8) selected from the Korea Highway Corporation Test Road. Design variables for those sections included base thickness (80, 180, and 280 mm) and base type (BB1, BB3, and aggregate). A three-axle (single-tandem) dump truck was adopted as a loading source, and steel plates were added to simulate heavy axle loads. Each pavement section was loaded at different speeds ranging from 20 to 80 km/h and was tested in different seasons from 2003 to 2004. In addition, the effect of loading offset was investigated with seven loading courses in one of the sections in 2006. This study first demonstrated that the rank between longitudinal and transverse strains can be changed as pavement ages under different temperatures. With multiple regression analysis on 123 data collected, a relation between field testing variables and the maximum strains in both directions was created to further understand statistical contributions of individual variables to stain anisotropy characteristics. As a result, both pavement temperature and layer thickness were found to be the most significant field variables.