Title: On the relationship of microstructure properties of asphalt mixtures to their constitutive behaviour

Authors: Shadi Saadeh, Eyad Masad

Addresses: Department of Civil Engineering and Construction Engineering Management, California State University, 1250 Bellflower Blvd., Long Beach, CA 90840, USA. ' Department of Civil Engineering and Texas Transportation Institute, Texas A&M University, 3135 TAMU, College Station TX 77843-3135, USA

Abstract: Asphalt mixtures are composite materials that consist of asphalt binder, air voids and aggregate particles that vary by orders of magnitude in size. Most constitutive models of asphalt mixtures are formulated based on macroscopic measurements. However, little effort has been spent in the past in determining the relevance of these macroscopic measurements to actual material response at the microstructural level. This paper presents an overview of a viscoelastic-viscoplastic model for asphalt mixtures that was developed previously by the authors. The model|s parameters were obtained in this paper by analysing triaxial repeated creep and recovery tests conducted at different confining and axial stresses. The microstructure characteristics of asphalt mixtures were determined by measuring aggregate physical characteristics, three-dimensional orientations of aggregates and air void distribution. The relationships of model|s parameters with these microstructure characteristics are discussed in this paper. The results are used to draw conclusions in regard to the influence of microstructure characteristics on asphalt mixture response in terms of hardening, softening and dilation. These results have also provided insight in regard to the suitability of some of the macroscopic measurements in reflecting the actual changes in the material microstructure during deformation.

Keywords: asphalt mixtures; microstructure; X-ray CT; anisotropy; damage; viscoelasticity; viscoplasticity; modelling; stress; deformation; hardening; softening; dilation; construction materials; road surfaces.

DOI: 10.1504/IJMSI.2010.035206

International Journal of Materials and Structural Integrity, 2010 Vol.4 No.2/3/4, pp.186 - 214

Published online: 14 Sep 2010 *

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