Investigation into causes of in-place rutting in asphalt pavement

The field measurement and laboratory tests were conducted to investigate potential causes of in-place rutting. The results indicate that the major rutting is attributed to the decrease in thickness of middle and lower layer, and the driving lane shows a severer rutting. Inadequate compaction is a major cause for the final rutting depth. Also the aggregate gradation has a major contribution to rutting. The gradation between 1.18 and 4.75 mm in sieve size becomes finer for the three layers. The upper and middle layer show an increase in asphalt content, but the lower layer presents a decrease in asphalt content.