Assessment of the Effectiveness of a Vertical Moisture Barrier

The rehabilitation of a section of Interstate Highway 37 in San Antonio, Texas, was undertaken to correct a chronic expansive clay roughness problem. A vertical moisture barrier was placed down to a depth of 2.44m along the outside shoulders of the north and south bound lanes. Several types of measurements have been made subsequently to evaluate the effectiveness of the moisture barrier. These include: field monitoring of the 'in situ' matrix potential using thermal block sensors, pavement surface profile measurements with the GM profilometer, photologging, and service ability surveys. The subsurface soils are characterized with routine engineering classification tests.