Guidelines for the Design and Construction of Flexible Bases to Control Thermal Cracking in Pavements (1432-5F)

Many miles of pavements in Texas are constructed with aggregate bases. These pavements are typically comprised of a thin asphalt surface over a flexible or aggregate base layer. The base layer is, therefore, usually the primary structural layer. Thermal- and moisture-related effects can cause cracks and general distress within these layers, resulting in a general reduction in the serviceability and load-carrying capacity of the pavement. The cracks that may emanate from the flexible base will reflect through the hot mix asphalt surface and further compromise load-carrying capacity of the pavement. The complex and diverse environment within Texas provides a challenge to the proper design, construction, and maintenance of aggregate bases. This project identifies a simple and easy-to-use dielectric value measurement test as an aggregate is subjected to capillary soak as a primary tool for design and construction of acceptable bases. The dielectric value test, combined with an assessment of the effects of the environmental conditions (based on suction potential versus moisture content) at a specific location, can be used to improve the methods for design and construction of aggregate bases. A protocol for this approach to design and construction is presented. Finally, the report presents a protocol for field analysis of the structural capability and response of pavements containing distressed flexible bases. This field testing protocol is integrated with simple and direct lab testing to establish a method of flexible base rehabilitation and recycling alternatives.