Investigating the Sensitivity of Aggregate Size within Sand Mastic by Modeling the Microstructure of an Asphalt Mixture
Publication: Journal of Materials in Civil Engineering
Volume 23, Issue 5
Abstract
The objective of this study is to investigate the sensitivity of aggregate size within sand mastic by modeling the microstructure of an asphalt mixture. The sensitivity of the maximum aggregate size on the sand mastic phase is investigated through discrete-element simulations. A three-dimensional (3D) discrete-element model of asphalt mixture was prepared from X-ray computed tomography (X-ray CT) images. In the discrete-element model, an asphalt mixture is divided into aggregate, sand mastic, and air void phases. In this study, the sand mastic is defined as fines and fine aggregates mixed with asphalt binder. Three different nominal maximum aggregate sizes (NMASs) of sand mastic, namely, 1.18 mm, 0.6 mm, and 0.3 mm, were used in the 3D model to investigate the best gradation of sand mastic. The dynamic moduli of three different NMASs of sand mastic were measured for use in the 3D discrete-element modeling simulation. Laboratory-measured dynamic moduli of asphalt mixtures were compared with prediction results. The sand mastics with NMASs of 1.18 mm and 0.6 mm could be used to predict the asphalt mixture modulus across a range of temperatures and loading frequencies with good accuracy. The sand mastic with a NMAS of 0.3 mm overpredicted at high and low temperatures. The overprediction resulted from the difficulty of proper visualization of the smaller aggregate size in the model.
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Acknowledgments
This material is based in part upon work supported by the National Science Foundation under Grant NSF0701264. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. This research could not have been completed without the significant contributions of Drs. M. Emin Kutay, Qingli Dai, and Thomas Van Dam.
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Published In
Journal of Materials in Civil Engineering
Volume 23 • Issue 5 • May 2011
Pages: 580 - 586
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Oct 27, 2008
Accepted: Oct 22, 2010
Published online: Oct 27, 2010
Published in print: May 1, 2011
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