An expansive subgrade beneath a newly constructed roadway in Central Texas was instrumented using volumetric moisture content and matric suction sensors. Sensors were installed during construction, facilitating an evaluation of the hydraulic behavior in the subgrade beneath a temporary flexible base with a prime coat and a final asphalt surface. Monitoring indicated that the two surfaces had differing hydraulic boundary conditions. The asphalt surface acted as an impervious layer that reduced the infiltration of moisture into the subgrade, while the flexible base surface did not appear to provide a hydraulic barrier and allowed for more rapid moisture fluctuations through the entire subgrade. Additionally, monitoring of the pavement surface via total station surveying verified this behavior with the profile of the roadway undergoing differential movement at the edge for the asphalt surface but not for the flexible base surface. Overall, the hydraulic moisture fluctuations of the subgrade were affected by the different pavement surfaces, and total station technology was able to characterize the surficial profile movement.
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