Nondestructive evaluation of surface texture conditions in dense-graded asphalt concrete

Abstract

The research objective is to evaluate the texture conditions in dense-graded asphalt concrete. The research scope is to collect various plant-mixed DGAC mixtures, compact mixtures to slabs, polish the slabs, and evaluate the texture. The testing slabs were polished step-wisely by the wheel-tracking polishing device. WTPD runs in a circle of 284mm in diameter and wears off the surface textures through a standard of procedures, namely 0, 3,000, 6,000, 12,000, 25,000, 50,000、100,000 rounds of polishing efforts. The circular track meter or CTM in lieu of ASTM E2157 was employed to assess the surface texture, non-destructively. The measurement of macro- and micro-texture of the slab surface is the mean profile depth or MPD and as such is a highly accurate yet repeatable texture data, due to the one-micron resolution laser source equipped with CTM. In this study, four DGAC mixtures collected from different regions were examined. MPD data decrease in the first thousands of polishing rounds, due to possible local compaction induced by the repeated wheel loading. MPD data thereafter increase to a maximum between 12,000 to 50,000 polishing rounds and start to decrease. It is possible that the asphalt mixtures were worn off and the texture of aggregates activate to involve in the overall texture condition. More polishing rounds and more repetition tests are recommended to gather more information to be analyzed in the future.