Ruggedness Testing of the Factors Affecting the Permanent Deformation Behavior Studied under the Modified Wheel Tracker (MWT)

Rutting or the accumulation of permanent deformations has long been a major mode of failure for the flexible pavements. While researchers have developed multiple tests to characterize this phenomenon in asphalt concrete pavements, little information is available on how each factor or parameter or their combinations from these tests affect the permanent deformation behavior of asphalt concrete pavements when it comes to the prediction of the actual field performance. This paper focuses on the ruggedness testing of the factors affecting the permanent deformation behavior utilizing the modified wheel tracker (MWT). These factors are percentage of air voids in the compacted mix (%VTM), nominal maximum aggregate size (NMAS), binder type, and test temperature. The analysis involved these factors, each at two levels. The study utilized half-factorial design in accordance with ASTM E1169-20. The parameters which have a significant effect on permanent deformation were determined through statistical analysis. All the test parameters except the Mix NMAS were found to be significant with VTM imposing the greatest effect followed by test temperature and binder type. Regression models were proposed to predict the flow numbers based on vertical and horizontal deformations, FN_V and FN_H, respectively. Although the NMAS did not seem to be significant in this analysis, its interaction with binder type proved to be significant. In addition, sensitivity analysis was undertaken as an attempt to provide reasonable tolerance limits for the test parameters.