Volume 1, Issue 1
Uniformity, Repeatability, and Permanent Deformation Resistance of Slabs Produced with the Linear Asphalt Compactor
Regardless of what method of compaction is used in the laboratory, specimen consistency and repeatability are important to produce useful test data. Ideally performance properties of laboratory compacted specimens will be representative of field compacted specimens, though the ideal is not typical even in the present day. This paper is a thorough investigation into the consistency and performance of slabs produced by the Linear Asphalt Compactor (LAC); rectangular LAC slabs are 29 cm by 62 cm with thicknesses from 4 cm to 10 cm. The LAC uses a combination of vertically aligned steel plates and a hydraulically actuated steel roller to create a kneading effect for asphalt compaction. A total of 173 asphalt slabs were produced with the LAC from 43 mixtures originating from multiple research projects; 184 gyratory compacted specimens were also produced from some of the mixtures. Effects of mold temperature variability were investigated using thermocouples. Statistical analyses of slab air void data were conducted to examine within slab variability (uniformity) and between slab variability (repeatability). Permanent deformation characteristics of slab compacted specimens were compared to Superpave gyratory compacted specimens with the Asphalt Pavement Analyzer. Results showed that uniformity of slabs produced by the LAC were as good as or better than reported in literature for other slab compactors. Repeatability of the LAC slab compaction process was reasonable after some modifications were performed. Rutting resistance of LAC compacted mixture appeared to be similar to or less than Superpave gyratory compacted mixture. Overall, the evaluation presented in this paper supports consideration of the LAC for preparation of performance test specimens.