Moisture Variation...

Water enters a pavement structure from a variety of sources.  This water may drain away from the pavement or pond in or under the pavement layers, weakening the pavement and causing premature failure.  Tracking the presence of moisture or the variation of moisture within a pavement structure allows pavement engineers to correct the source of the water and/or repair the distressed area.  Moisture variation is determined by first establishing a benchmark from the driest pavement.  Geophysical methods will then locate changes from this benchmark, and they can also be useful in identifying where to look for an appropriate benchmark location, itself.

Techniques Recommended

Surface NDT Methods:

• Ground penetrating radar (GPR).
• Percometer (point data collection).

While other methods are available or under development, the ones listed above provide cost-effective ways to screen for locations with suspect moisture variation which can then be verified by other means, including in-situ sampling and laboratory testing-or instrumentation of suspect sites that are identified using a screening tool, such as GPR.

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