During 1994 and 1995, asphalt overlay performance problems in the form of disintegration, rutting, and raveling were experienced in the Atlanta District of the Texas Department of Transportation (TxDOT). An investigation of the damage by TxDOT engineers in Atlanta identified the cause as extreme moisture susceptibility of asphalt mixtures containing locally available crushed gravel. A task force was assembled to identify tests and specifications to allow use of local gravel aggregates while, at the same time, precluding future moisture damage problems. The resources of the South Central Superpave Center were mobilized to assess whether Superpave mix design tests and criteria would have identified the mixtures as troublesome in ways other than moisture sensitivity. Because TxDOT already uses a moisture damage test very similar to the Superpave moisture sensitivity evaluation, no Superpave moisture damage tests were conducted. The Superpave mix design evaluation indicated that one or more Superpave aggregate tests, gradation requirements, and volumetric and compaction properties would have precluded use of the materials.
