Aggregate Physical Properties Affecting Modulus and Deformation Characteristics of Unsurfaced Pavements
Publication: Journal of Materials in Civil Engineering
Volume 24, Issue 9
Abstract
This paper presents findings from a recently completed research study at the University of Illinois aimed at investigating the effects of aggregate type and quality on mechanistic pavement response and rutting performance with implications to over 2.6 million km (1.6 million miles) of unsurfaced roads in the United States. Three aggregate types, crushed limestone, crushed dolomite, and uncrushed gravel, were tested in the laboratory for resilient modulus () and permanent deformation characteristics at different factorial combinations of selected aggregate physical properties. Aggregate properties studied included particle shape and surface texture, type and amount of fines, and moisture and density in relation to required compaction conditions. Stress-dependent material characterization models determined from the laboratory tests were used in a nonlinear axisymmetric finite-element analysis program to compute the vertical compressive stress on top of the subgrade as a critical pavement response. The adequacy of the aggregate layer to carry wheel loads and prevent subgrade rutting was evaluated using the concept of the subgrade stress ratio (SSR), defined as the ratio between the vertical stress on top of the subgrade and the subgrade unconfined compressive strength. The laboratory testing and modeling showed that the aggregate physical properties had significant influences on both the modulus and permanent deformation behavior of unbound aggregates. In addition to protecting the subgrade from rutting by means of placing stiff (high ) aggregate layers on top, a properly designed unsurfaced pavement system should also evaluate the susceptibility of the aggregate cover itself to excessive rutting, preferably through permanent deformation testing of the aggregates. The findings clearly highlighted the importance of considering both the load spreading and rut resistance aspects of the unbound aggregate layer in the design of unsurfaced pavements. The significance of different aggregate properties affecting modulus and permanent deformation model parameters was identified through statistical analyses of variance (ANOVA) conducted on the laboratory test results.
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Acknowledgements
This paper is based on the results of ICT R27-1 and ICT R27-81 research studies. Both projects were conducted at the Illinois Center for Transportation (ICT) in cooperation with the Illinois Department of Transportation, Division of Highways, and the U.S. Department of Transportation, Federal Highway Administration.
The contents of this paper reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Illinois Department of Transportation or the Federal Highway Administration. This paper does not constitute a standard, specification, or regulation.
References
AASHTO. (2011a ). “Standard method of test for determining the resilient modulus of soils and aggregate materials.” T307-99 (R2007), Standard specifications for transportation materials and methods of sampling and testing, 31st Ed., and Provisional standards, Washington, DC.
AASHTO. (2011b ). “Standard method of test for moisture-density relations of soils using a 2.5 kg (5.5-lb) rammer and a 305-mm (12-in.) drop.” T99-2010, Standard specifications for transportation materials and methods of sampling and testing, 31st Ed., and Provisional standards, Washington, DC.
Allen, J. J. (1973). “The effect of non-constant lateral pressures on the resilient response of granular materials.” Ph.D. thesis, Univ. of Illinois at Urbana-Champaign, Urbana, IL.
Barksdale, R. D., and Itani, S. Y. (1989). “Influence of aggregate shape on base behavior.” Transportation Research Record 1227, Transportation Research Board, Washington, DC, 173–182.
Hicks, R. G., and Monismith, C. L. (1971). “Factors influencing the resilient response of granular materials.” Highway Research Record 345, Highway Research Board, Washington, DC, 15–31.
Jorenby, B. N., and Hicks, R. G. (1986). “Base course contamination limits.” Transportation Research Record 1095, Transportation Research Board, Washington, DC, 86–101.
Lekarp, F., Isacsson, U., and Dawson, A. (2000). “State of the Art. I: Resilient response of unbound aggregates.” J. Transp. Eng., 126(1), 66–75.
Mechanistic-Empirical Pavement Design Guide (MEPDG). (2004). “Guide for mechanistic empirical design of new and rehabilitated pavement structures.” NCHRP Rep. 1-37A, Final Rep., National Cooperative Highway Research Program, Transportation Research Board, National Research Council, Washington, DC.
Mishra, D., and Tutumluer, E. (2011). “Aggregate physical properties affecting modulus and deformation characteristics of unsurfaced pavements.” TRB 90th Annual Meeting Compendium of Papers (DVD), Transportation Research Board, Washington, DC.
Mishra, D., Tutumluer, E., and Butt, A. A. (2010). “Quantifying effects of particle shape and type and amount of fines on unbound aggregate performance through controlled gradation.” Transportation Research Record 2167, Transportation Research Board, Washington, DC, 61–71.
Mishra, D., Tutumluer, E., Kern, J., and Butt, A. A. (2009). “Characterizing aggregate permanent deformation behavior based on types and amounts of fines.” Proc., 8th Int. Conf. on Bearing Capacity of Roads, Railways, and Airfields, Tutumluer, E., and Al-Qadi, I. L., eds., CRC Press/Balkema, Leiden, Netherlands, 237–246.
Monismith, C. L., Ogawa, N., and Freeme, C. R. (1985). “Permanent deformation characteristics of subgrade soils due to repeated loading.” Transportation Research Record 537, Transportation Research Board, Washington, DC, 1–17.
Puppala, A. J., Mohammad, L. N., and Allen, A. (1999). “Permanent deformation characterization of subgrade soils from RLT tests.” J. Mater. Civ. Eng., 11(4), 274–282.
Puppala, A. J., Saride, S., and Chomtid, S. (2009). “Experimental and modeling studies of permanent strains of subgrade soils.” J. Geotech. Geoenviron. Eng., 135(10), 1379–1389.
Rada, G., and Witczak, M. W. (1981). “Comprehensive evaluation of laboratory resilient moduli results for granular material.” Transportation Research Record 810, Transportation Research Board, Washington, DC, 23–33.
Rao, C., Tutumluer, E., and Kim, I. T. (2002). “Quantification of coarse aggregate angularity based on image analysis.” Transportation Research Record 1787, Transportation Research Board, Washington, DC, 117–124.
Seyhan, U., and Tutumluer, E. (2002). “Anisotropic modular ratios as unbound aggregate performance indicators.” J. Mater. Civ. Eng., 14(5), 409–416.
Skorseth, K., and Selim, A. A. (2000). “Gravel roads: Maintenance and design manual.” U.S. Dept. of Transportation, Federal Highway Administration, Washington, DC.
Thompson, M. R., Kinney, T. C., Traylor, M. L., Bullard, J. R., and Figueroa, J. L. (1977). “Subgrade stability: Final report.”, Illinois Cooperative Highway and Transportation Research Program, Dept. of Civil Engineering, Univ. of Illinois at Urbana-Champaign, Urbana, IL.
Thompson, M. R., and Smith, K. L. (1990). “Repeated triaxial characterization of granular bases.” Transportation Research Record 1278, Transportation Research Board, Washington, DC, 7–17.
Thompson, M. R., Tutumluer, E., and Bejarano, M. (1998). “Final report: Granular material and soil moduli review of the literature.”, Center of Excellence for Airport Pavement Research, Dept. of Civil Engineering, Univ. of Illinois at Urbana-Champaign, Urbana, IL.
Tutumluer, E. (1995). “Predicting behavior of flexible pavements with granular bases.” Ph.D. thesis, Georgia Institute of Technology, Atlanta.
Tutumluer, E., and Barksdale, R. D. (1995). “Behavior of pavements with granular bases—Prediction and performance.” Unbound Aggregates in Roads: Proc., 4th Int. Symp. on Unbound Aggregates in Roads (UNBAR4), Dawson, A., and Jones, R., eds., Dept. of Civil Engineering, University of Nottingham, Nottingham, UK, 173–183.
Tutumluer, E., Mishra, D., and Butt, A. A. (2009). “Characterization of Illinois aggregates for subgrade replacement and subbase.”, Illinois Center for Transportation, Univ. of Illinois at Urbana-Champaign, IL.
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Information
Published In
Journal of Materials in Civil Engineering
Volume 24 • Issue 9 • September 2012
Pages: 1144 - 1152
Copyright
© 2012 American Society of Civil Engineers.
History
Received: Mar 6, 2011
Accepted: Feb 1, 2012
Published online: Feb 3, 2012
Published in print: Sep 1, 2012
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