Type of Document	Master's Thesis
Author	Appea, Alexander Kwasi
Author's Email Address	Alexander.Appea@dot.state.fl.us
URN	etd-111297-153911
Title	In-Situ Behavior of Geosynthetically Stabilized Flexible Pavement
Degree	Master of Science
Department	Civil Engineering
Advisory Committee	Advisor Name Title Al-Qadi, Imadeddin L. Committee Chair Brandon, Thomas L. Committee Member Coree, Brian J. D. Committee Member
Keywords	flexible pavement dynamic loading stabilization geogrid geotextiles geosynthetics falling weight deflectometer
Date of Defense	1997-06-20
Availability	unrestricted
Abstract The purpose of a geotextile separator beneath a granular base, or subbase in a flexible pavement system is to prevent the road aggregate and the underlying subgrade from intermixing. It has been hypothesized that in the absence of a geotextile, intermixing between base course aggregate and soft subgrade occurs. Nine heavily instrumented flexible pavement test sections were built in Bedford County Virginia to investigate the benefits of geosynthetic stabilization in flexible pavements. Three groups of different base course thicknesses (100, 150 and 200mm) test sections were constructed with either geotextile or geogrid stabilization or no stabilization. Woven geotextile was used in sections 2, 5 and 8. Geogrids were used in sections 3, 6 and 9, and sections 1, 4 and 7 were controls. Six Falling weight deflectometer (FWD) tests were performed on all the nine sections over 30 months. The nine sections were subjected to at least 5 load drops with wide loading range each time. The measured deflections were analyzed using the MODULUS back-calculation program to determine layer moduli. The measured deflections were used together with elastic, viscoelastic and the MODULUS program to determine the extent of intermixing at base-subgrade interface. The study concluded that a transition layer would develop when a separator is absent, especially in the weak sections (designed to fail in three years). Other measurements such as in-situ stresses, rut depth, and subsurface profiling (using ground penetrating radar) support the conclusion of the development of a transition layer.
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