Falling Weight Deflectometer for Estimating Subgrade Elastic Moduli
Publication: Journal of Transportation Engineering
Volume 129, Issue 1
Abstract
Subgrade soil characterization in terms of resilient modulus is essential for pavement design/evaluation. Due to the complexity of the laboratory test procedure, highway agencies have been exploring nondestructive tests, such as the falling weight deflectometer. In this study, 12 test sections with subgrade reflecting a range of soil types (fine- and coarse-grain soils) were tested. Falling weight deflector measurements were conducted directly on the prepared subgrade, followed by thin-wall Shelby tube samples from depths up to 1.5 m for laboratory tests. Deflection measurements were repeated at the same locations after completion of pavement construction. Results showed that the backcalculated moduli of the prepared subgrade are in good agreement with the laboratory values. Due primarily to confinement and overburden pressure, the backcalculated subgrade modulus, based on deflection measurements on the finished pavement, increases approximately 40 and 100% for fine- and coarse-grain soil, respectively. The modulus increase is substantiated by complementary studies of 20 Mississippi long-term pavement performance sections. In light of these results, the AASHTO factor of 0.33 to adjust for the backcalculated moduli, computed from deflection measurements on finished pavements, warrants further scrutiny and revision.
Get full access to this article
View all available purchase options and get full access to this article.
References
AASHTO. (1993). AASHTO guide for design of pavement structures, Washington, D.C.
AASHTO. (1998). AASHTO provisional standards, Washington, D.C.
Ali, N. A., and Khosla, N. P. (1987). “Determination of layer moduli using a falling weight deflectometer.” Transportation Research Record 1117, Transportation Research Board, Washington, D.C., 1–10.
Burnham, T., and Johnson, D. (1993). “In-situ characterization using the dynamic cone penetrometer.” Rep. MN-93/05, Minnesota Dept. of Transportation, Maplewood, Minn.
Chai, G., and Roslie, N. (1998). “The structural response and behavior prediction of subgrade soils using falling weight deflectometer in pavement construction.” Proc., 3rd Int. Conf. on Road and Airfield Pavement Technology, China.
Chen, Bilyeu, and He. (1998). “Comparison of Resilient Moduli Between Field and Laboratory Testing: A Case Study.” Proc., 76th Annual Meeting of Transportation Research Board (CD-Rom), Washington, D.C.
Chou, Y. J., and Lytton, R. L. (1991). “Accuracy and consistency of backcalculated pavement layer moduli.” Transportation Research Record 1293, Transportation Research Board, Washington, D.C., 72–85.
Colleman, H. W., and Steele, W. G. (1989). Experimentation and uncertainty analysis for engineers, Wiley, New York.
Davies, T. G., and Mamlouk, M. S. (1985). “Theoretical response of multilayer pavement system to dynamic nondestructive testing.” Transportation Research Record 1022, Transportation Research Board, Washington, D.C., 1–7.
Hassan, A. (1996). “The effect of material parameters on dynamic cone penetrometer results for fine-grained soils and granular materials.” PhD dissertation, Oklahoma State Univ., Stillwater, Okla.
Heukelom, W., and Klomp, A. J. G. (1962). “Dynamic testing as a means of controlling pavements during and after construction.” Proc., 1st Int. Conf. on Structural Design of Asphalt Pavements, Univ. of Michigan, Ann Arbor, Mich.
Houston, S. L., and Perera, R.(1991). “Impact of natural site variability on nondestructive test deflection basins.” J. Transp. Eng., 117(5), 550–565.
Houston, W. N., Mamlouk, M. S., and Perera, R. W. S.(1992). “Laboratory versus nondestructive testing for pavement design.” J. Transp. Eng., 118(2), 207–222.
Huang, Y. H. (1993). Pavement analysis and design, Prentice-Hall, Englewood Cliffs, N.J.
Neter, J., Wasserman, W. and Whitmore, G. A. (1988). Applied statistics, Allyn and Bacon, Needham Heights, Mass.
Newcomb, D. E.(1987). “Comparison of field and laboratory estimated resilient moduli of pavement materials.” Asphalt Paving Technol., 56, 91–106.
Newcomb, D. E., Chadbourn, B. A., Van Deusen, D. A., and Burnham, T. R. (1995). “Initial characterization of subgrade soils and granular base materials at the Minnesota Road research project.” Report No. MN/RC-96/19, Minnesota Dept. of Transportation, St. Paul, Minn.
Parker, F. (1991). “Estimation of paving materials design moduli for falling weight deflectometer measurements.” Transportation Research Record 1293, Transportation Research Board, Washington, D.C., 42–51.
Roesset, J. M., and Shao, K-Y. (1991). “Dynamic interpretation of dynaflect and falling weight deflectometer tests.” Transportation Research Record 1022, Transportation Research Board, Washington, D.C., 7–16.
Scullion, T., Uzan, J., and Paredes, M. (1990). “MODULUS: A microcomputer-based backcalculation system.” Transportation Research Record 1260, Transportation Research Board, Washington, D.C., 180–191.
Snedecor, G. W., and Cochran, W. G. (1980). Statistical methods, Iowa State University Press, Ames, Iowa.
Von Quintus, H. L., and Killingsworth, B. M. (1997). “Design pamphlet for the backcalculation for pavement layer moduli in support of the 1993 AASHTO guide for the design of pavement structures.” FHWA-RD-97-076, Brent Rauhut Engineering, Austin, Tex.
Von Quintus, H. L., and Killingsworth, B. M. (1998). “Comparison of laboratory and in-situ determined elastic layer moduli.” Proc., 76th Annual Meeting of the Transportation Research Board (CD-Rom), Washington, D.C.
Information & Authors
Information
Published In
Copyright
Copyright © 2003 American Society of Civil Engineers.
History
Received: Feb 13, 2001
Accepted: Dec 3, 2001
Published online: Dec 13, 2002
Published in print: Jan 2003
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.