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The majority of roadways in the United States are low volume. Pavement structures for low-volume roads (LVRs) are designed according to empirical procedures that are sometimes verified by a mechanistic-based design process. The flexible pavement structure for an LVR consists of a relatively thin asphalt–concrete wearing course and an aggregate base course constructed on subgrade. An asphalt wearing course provides a good riding surface and moisture protection for the base course. Service life of a thin asphalt pavement depends on material quality and thickness of granular layers. A compelling need now exists for reducing the cost of building and maintaining the national transportation infrastructure. The limited lifespan of most construction materials due to continuing wear and tear requires more creative, innovative, economical, and sustainable roadway design techniques. Geogrid reinforcements in LVRs are seen as a particularly promising solution because they can be designed to provide an equivalent service life through use of less material. The combination of the aggregate and geogrid materials creates an improved or mechanically stabilized layer (MSL) with a significantly increased resilient modulus. The objective of this study was to use existing testing protocol to determine and to evaluate material design parameters for an unbound and a geogrid MSL. To determine the effects of an MSL, a test combination that included AASHTO T307 and NCHRP 598 was conducted on both unbound and mechanically stabilized aggregate specimens.

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The measurement of deflection characteristics is a key feature in the evaluation of pavements. Deflections are used to evaluate pavement moduli, relative stiffness, load transfer, and, when used periodically, a rate of deterioration and remaining life. The comprehensive deflection testing program conducted on Runways 9L/27R and 8R/26L, both jointed concrete pavements, at the Hartsfield Atlanta International Airport is described. A heavy-weight deflectometer was used to measure deflections at discrete locations on slab interiors, transverse joints, longitudinal joints, and slab corners. A rolling dynamic deflectometer was used to measure continuous deflection profiles along three longitudinal lines on both runways. Before fall 2001, all pavement deflection testing was performed using a falling-weight deflectometer. Comparisons of the equipment, loading mechanisms, and measured deflections are presented.