Noninvasive Measurement of Three-Dimensional Permanent Strains in Asphalt Concrete with X-Ray Tomography Imaging

Abstract

Because of the stiffness differences between aggregates and mastics, permanent deformation of asphalt concrete is localized mainly in the soft mastics. Therefore, studies on the microresponse of the aggregates and mastics could provide a better understanding of the macrobehavior of asphalt concrete. A method is presented to measure the deformations in the mastics; this was correlated with the permanent deformation resulting from the asphalt pavement analyzer test. An automated procedure with tomography images to reconstruct three-dimensional particles was developed. The translations of the particles can be obtained from the coordinate differences of the mass centers before and after testing. The microstrains in the mastics and macrostrains in the mixture can be calculated on the basis of particle translations. The procedures described have significance for future study on how the aggregated shape, size, and arrangement affect the macroresponse of the mixture in three dimensions and how the relative stiffness of aggregates and mastics affects rutting potential.

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