American Society of Civil Engineers


Discrete Element Modeling of Constant Strain Rate Compression Tests on Idealized Asphalt Mixture


by Junwei Wu, (Research Student, Nottingham Transportation Engineering Centre, Faculty of Engineering, Univ. of Nottingham, Nottingham NG7 2RD, U.K.), Andrew C. Collop, (Professor, Nottingham Transportation Engineering Centre, Faculty of Engineering, Univ. of Nottingham, Nottingham NG7 2RD, U.K.), and Glenn R. McDowell, (Professor, Nottingham Centre for Geomechanics, Faculty of Engineering, Univ. of Nottingham, Nottingham NG7 2RD, U.K.)

Journal of Materials in Civil Engineering, Vol. 23, No. 1, January 2011, pp. 2-11, (doi:  http://dx.doi.org/10.1061/(ASCE)MT.1943-5533.0000002)

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Document type: Journal Paper
Special Issue: Multiscale and Micromechanical Modeling of Asphalt Mixes
Abstract: Discrete element modeling has been used to simulate constant strain rate compressive tests for an idealized asphalt mixture comprising approximately single-sized sand particles. A range of constant strain-rate compressive tests to failure have been undertaken in the laboratory and the axial stress-strain response has been carefully measured. The peak stress (compressive strength) of the material was found to be as a power-law function of the equivalent (temperature compensated) strain rate in the viscoelastic region of behavior. The internal geometry of the idealized asphalt mixture has been reproduced in PFC-3D and internal damage (cracking) in the material was modeled by allowing bond breakage between adjacent particles. Elastic contact properties have been used to investigate the effect of random variations in internal sample geometry, the distribution of bond strengths between adjacent particles and the coefficient of friction between particles where the bond has broken. A simple viscoelastic Burger’s model was used to introduce time dependent shear and normal (tensile) contact stiffnesses and an elastic contact has been assumed for the compressive normal contact stiffness. To reduce the computation time, both viscosities in the Burger’s model were scaled which has been shown to have the same effect as scaling the loading velocity (strain rate) by the same factor. A strain rate dependent bond breakage criterion has been developed and model results were found to compare well with the experimental data.


ASCE Subject Headings:
Asphalts
Mixtures
Compression tests
Stress strain relations
Bonding

Author Keywords:
Discrete element modeling