Measuring Directional Stiffnesses in Pavement Base Material

Unbound aggregate base layers in a quarry haul road in Georgia were characterized using embedded sensors and in-situ seismic testing. Two sections of the road were constructed as inverted pavements, one using a South African Roads Board method and the other using a conventional Georgia Department of Transportation method. A third was constructed using a traditional method. Horizontally propagating compression and shear waves were measured under varying loading conditions to determine the stiffnesses. It was found that the Georgia section was as good as the South African Section. Surprisingly, the traditional section was found to be somewhat stiffer than the other sections. This higher stiffness is thought to be due to a prolonged period of compaction prior to construction of the unbound aggregate base layer. Additionally, the negative pore-water pressures in the partially saturated granular base had a significant impact on the stiffness of the UAB layer, especially under small load levels.Naval Postgraduate School Monterey CA is the author of 'Measuring Directional Stiffnesses in Pavement Base Material', published 2002 under ISBN 9781423506362 and ISBN 1423506367.