Effect of Radial Inhomogeneity on Shear Properties of Asphalt Mixtures
Publication: Journal of Materials in Civil Engineering
Volume 17, Issue 1
Abstract
Radial inhomogeneity is often observed in superpave gyratory compacted specimens because of the rotational movement of the gyratory and the boundary condition imposed by the gyratory mold. The effect of the inhomogeneity on mechanical properties of asphalt mixtures is not known. To study this effect, laboratory specimens of asphalt mixtures with known levels of aggregate inhomogeneity were fabricated. Nondestructive X-ray computed tomography was used to scan cross-sectional images of the specimens. A statistical index was developed to evaluate the scanned images for radial inhomogeneity. The results clearly show that the index can distinguish between levels of inhomogeneity. By means of frequency sweep at constant height (FSCH) test, the shear stiffness and the fatigue susceptibility at test temperature of and the shear stiffness and rutting susceptibility at test temperature of were evaluated. The resistance of the material to cumulative shear deformation was measured using the repeated shear at constant height (RSCH) test at . The effects of radial inhomogeneity on the shear properties of the specimens were investigated at the two test temperatures. As indicated from the FSCH test, the shear modulus increases, the rutting susceptibility, and the fatigue susceptibility in thick layers decreases, and the fatigue susceptibility in thin layers increases with increasing radial inhomogeneity. The correlation between the shear properties from the FSCH test and the inhomogeneity index is greater at the test temperature of than at the test temperature of . Although the RSCH test is conducted at , the permanent deformations resulted from the test shows the highest correlation with the level of inhomogeneity. The permanent strain decreases significantly with the increase in the level of inhomogeneity. The results of this study indicate that predicting the performance of the same material in the field based on the properties of laboratory-made specimens will lead to overprediction of the field performance and as a result underdesign of pavements.
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Acknowledgments
This study was supported by the FHWA, McLean Va. Special thanks to Mr. Thomas Harman, the pavement materials and construction team leader, for his support throughout this study. The work of Mr. Scott Parobeck and Mr. Frank Davis in the preparation and testing of the specimens is greatly appreciated.
References
American Association of State Highway and Transportation Officials (AASHTO). (1998a). “Method for determining the permanent deformation and fatigue cracking characteristics of hot mix asphalt (HMA) using the simple shear test (SST) device.” TP7-94, Washington, D.C.
American Association of State Highway and Transportation Officials (AASHTO). (1998b). “Method for preparing and determining the density of hot mix asphalt (HMA) specimens by means of the sharp gyratory compactor.” TP4-00, Washington, D.C.
Ansell, P., and Brown, S. F. (1978). “Cyclic simple shear apparatus for dry granular materials.” Geotech. Test. J., 1(2), 92–91.
Christensen, D. W. (2001). “Requirements for voids in mineral aggregate for Superpave mixtures.” Interim Rep No. NCHRP 90-25, National Cooperative Highway Research Program (NCHRP), Washington, D.C.
Duncan, J. M., and Dunlop, P. (1969). “Behavior of soils in simple shear tests.” Proc., Int. Conf. On Soil Mechanics and Foundation Engineering, Mexico, 101–109.
Image-Pro Plus Version 4.1. (2001). Media Cybernetics, Silver Spring, Md.
Instrotek Incorporated. (2001). Corelok Operator Guide, Version 10, Raleigh, N.C.
Kandhal, P. S., Foo, K. Y., and Mallick, R. B. (1997). “Critical review of voids in mineral aggregate requirements in Superpave.” Transportation Research Record 1609, Transportation Research Board, Washington, D.C., 21–27.
Ketcham, R. A., and Carlson, W. D. (2000). “Quantitative characterization of asphalt concretes using high-resolution x-ray computed tomography (CT).” NCHRP-IDEA Program Project Final Rep. No. NCHRP-IDEA Project 64, Transportation Research Board, Washington, D.C.
Khedaywi, T. S., and White, T. D. (1994). “Development and analysis of laboratory techniques for simulating segregation.” Transportation Research Record 1492, Transportation Research Board, Washington, D.C., 36–45.
Masad, E., and Bahia, H. (2002). “Effect of loading configuration and material properties on non-linear response of asphalt mixtures.” Proc., AAPT, 71, 575–607.
Masad, E., Muhunthan, B., Shashidhar, N., and Harman, T. (1998). “Aggregate orientation and segregation in asphalt concrete.” Proc., Application of Geotechnical Principles in Pavement Engineering, Geotechnical Special Publication 85, ASCE, Reston, Va., 69–80.
McCuen, R. H., and Azari, H. (2001). “Assessment of asphalt specimen homogeneity.” J. Transp. Eng., 127(5), 363–369.
Mendenhall, W., and Sincich, T. (1992). Statistics for engineering and the sciences, Dellen, San Francisco.
Stuart, K. D. (2000). “On the superpave asphalt binder specification for fatigue cracking performance.” In-House FHWA Technical Memorandum, Federal Highway Administration, McLean, Va.
Stuart, K. D., Mogawer, W. S., and Romero, P. (2000). “Validation of asphalt binder and mixture tests that measure rutting susceptibility using the accelerated loading facility.” In-House Rep. No. FHWA-RD-99-204, Federal Highway Administration, McLean, Va.
Tashman L., Masad, E., D’Angelo, J., Bukowski, J., and Harman, T. (2002). “X-ray tomography to characterize air void distribution in superpave gyratory compacted specimens.” Int. J. Pavement, 3(1), 19–28.
Tashman, L., Masad, E., Peterson, R., and Saleh, H. (2001). “Internal structure analysis of asphalt mixes to improve the simulation of superpave gyratory compaction to field conditions.” Proc. AAPT, 70, 605–634.
Wang, L. B., Wang, Y. P., Mohammed, L., and Harman, T. (2002). “Voids distribution and performance of asphalt concrete.” Int. J. Pavement, 1(3), 22–33.
Williams, R. C., Duncan, G., Jr., and White, T. D. (1996). “Hot-mix asphalt segregation: Measurement and effects.” Transportation Research Record 1543, Transportation Research Board, Washington, D.C., 97–105.
Yue, Z. Q., Bekking W., and Morin, I. (1995). “Application of digital image processing to quantitative study of asphalt concrete microstructure.” Transportation Research Record 1492, Transportation Research Board, Washington, D.C., 53–60.
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© 2005 ASCE.
History
Received: Apr 2, 2003
Accepted: Mar 26, 2004
Published online: Feb 1, 2005
Published in print: Feb 2005
Notes
Note. Associate Editor: Mary Stroup-Gardiner
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