Effects of Anisotropy on Performance of HMA Specimens Due to Roller Compaction

Abstract

The segmented roller compactor is a standardized method to produce HMA-slabs in the lab. Specimens are cored and cut from the slabs for further testing. The relation between the direction of compaction and testing in the laboratory is not always the same relation as it is between the direction of compaction and actual loading in the field. The paper presents research on the influence of the compaction direction on performance characteristics of roller compacted HMA specimens. Performance parameters of a base layer mix are obtained, including high-temperature, stiffness, fatigue and low-temperature tests. The relation between direction of compaction and testing is varied in all three dimensions to find relevant influences. It can be concluded from the results that all obtained performance parameters are sensitive to the material anisotropy due to compaction, especially for stiffness and fatigue performance. For the high temperature performance specimens from path- and force-controlled compaction were compared. The applied compaction work rather than the compaction method is linked to the difference in the regarding results. The uniformity of the compaction in terms of the variation of bulk density of the specimens reflects on the scattering of test results.