The Superpave volumetric design method contains no strength or 'proof' test for quality control and quality assurance of mixtures. Accelerated wheel tracking systems, such as the Asphalt Pavement Analyzer (APA) and the NCSU Wheel Tracking Device (WTD) may fulfill the need for a relatively simple and inexpensive performance test. It is imperative that the predictability of these test systems should correlate with the field performance. Moreover, several compaction methods are used to fabricate specimens for performance testing in the laboratory. The compaction methods adopted in the laboratory are expected to simulate the properties of the pavement in the field. It is essential that the laboratory compaction of specimens should be a true indicator of field performance. So, the effects of different compaction methods on the performance of mixtures have been investigated in this study. Laboratory compaction methods such as Superpave Gyratory Compaction (SGC) and Rolling Wheel Compaction (RWC) were compared with the field compaction. Four field sites had been selected for this purpose. The mixtures were identified as Auburn Coarse, Auburn Fine, Charlotte and Kinston. The Auburn mixtures were 12.5mm mixtures whereas the Charlotte and the Kinston mixtures were 9.5mm mixtures. The performance parameters of the mixtures include fatigue and rutting distresses. Various performance evaluation tests were conducted on the field cores and specimens fabricated using the Superpave Gyratory Compactor (SGC) and Rolling Wheel Compactor (RWC). Performance evaluation was done using test systems such as Shear tester, Asphalt Pavement Analyzer (APA) and NCSU Wheel Tracking Device.
The analysis of test results indicate that the laboratory compacted mixtures tend to be superior in their performance than the field cores. The mixtures compacted using the SGC and the RWC have higher stiffness values and lower shear strain values than the field cores. The Rolling Wheel Compaction (RWC) seems to simulate field compaction better than the SGC. The mixtures, which failed to satisfy the RSCH test criteria, had rut depths greater than 0.5 inch, as measured by the APA and NCSU WTD. The mixtures that passed the RSCH tests had rut depths less than 0.5 inch. The APA test and the NCSU WTD test can be used as a simulator to examine the rutting susceptibility of a mixture. It is suggested that a rut depth of 0.5 inch could be prescribed in the APA test and the NCSU WTD test as ""pass/fail"" or ""go no-go"" criteria.
