IN-SITU BEHAVIOR OF GEOSYNTHETICALLY STABILIZED FLEXIBLE PAVEMENT

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
Dr. Imad L. Al-Qadi Committee Chair
Dr. Brian J. D. Coree Committee Member
Dr. Thomas Brandon 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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