Deflection characteristics of Unbound Base Course During a Large Scale Model Experiment

Makhaly Ba, Meissa Fall, Oustasse Abdoulaye Sall


This paper evaluates de deflections (measured at the surface and/or at the top of the subgrade) of unbound pavement materials under cyclic loading. Deflections of three base course materials (Bakel Red Quartzite, Bakel Black Quartzite and Diack Basalt) were investigated using a large-scale model experiment (LSME). The LSME is a prototype-scale pavement test apparatus where cyclic loading is applied and deflections are measured. The LSME replicates field conditions and accounts for scale effects. The LSME results showed that the total, plastic and net plastic deflections of a pavement increase progressively as the number of loading cycles increases. The total deflection decreases as the thickness of the base layer increases. Plastics deflections at the top of the subgrade decrease progressively as the thickness of the base layer is increased. The elastic deflections of the surface and of the base layer decrease gradually with the increasing loading cycles. The elastic deflection at the top of the subgrade decreases with increasing thickness of the base layer. So, rutting can be limited by limiting the elastic deflection at the top of the subgrade. However, this criterion does not account for the rutting caused by the unbound base layers and that of the asphalt concrete.

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Ba M., Fall M., Samb F., Sarr D., Ndiaye M. (2011) Resilient Modulus of Unbound Aggregate Base Courses from Senegal (West Africa). Open Journal of Civil Engineering, Vol. 1, No. 1, 2011, pp. 1-6. doi:10.4236/ojce.2011.11001.

Ba M., Fall M., Sall O. A., Samb F. (2012) Effect of Compaction Moisture Content on the Resilient Modulus of Unbound Aggregates from Senegal (West Africa). Geomaterials, Vol. 1, No. 2, pp. 19-23. doi:10.4236/gm.2012.21003.

Ba, M., Nokkaew, K., Fall, M., Tinjum, J. M. (2013) - Effect of Matric Suction on Resilient Modulus of Compacted Aggregate Base Courses. Geotech Geol Eng, DOI 10.1007/s10706-013-9674-y.

BCEOM-CEBTP (1984). “Guide Pratique de dimensionnement dans les pays tropicaux, ’’ Ministère Français de la Coopération - 155 pages.

Harichandran, R. S., Baladi, G. Y., Yeh, M. (1989). “Development of a Computer Program for Design of Pavement Systems Consisting of Bound and Unbound Materials,” Dept. of Civil and Environmental Engineering, Michigan State University, Lansing, Michigan, 1989.

Kootstra, B. K. (2009). “Large Scale Model Experiments of Recycled Base Course Materials Stabilized with Cement and Cement Kiln Dust,” Master of Science Thesis / Final Report to Portland Cement Association. PCA R&D Serial No. SN3109.

Kootstra, B. R., Ebrahimi, A., Edil, T. B., and Benson, C. H. (2010) “Plastic Deformation of Recycled Base Materials,” Proc. GeoFlorida 2010, Advances in Analysis, Modeling and Design, ASCE Geo Institute, GSP 199, West Palm Beach, FL, 2682-2691.

Tanyu, B. F., Kim, W. H., Edil, T. B., and Benson, C. H., (2003). “Comparison of Laboratory Resilient Modulus with Back-Calculated Elastic Moduli from Large-Scale Model Experiments and FWD Tests on Granular Materials, ” Resilient Modulus Testing for Pavement Components, ASTM STP 1437, Paper ID 10911, G. N. Durham, A. W. Marr, and W. L. De Groff, Eds., ASTM International, West Conshohocken, PA.



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