Flexible base materials that meet TxDOT specifications are getting more difficult to purchase in many TxDOT Districts. As a result, higher quality materials have to be hauled long distances, sometimes from other States. This act would significantly increase the costs associated with the construction of roads and subsequent maintenance and rehabilitation of them. Lower quality (i.e., out-of-specification) materials are normally available. If through appropriate modifications of the materials (adjusting the gradation or/and stabilization) or structural design (specifying thicker layers of base and/or hot mix) the use of the local materials can be permitted, the construction can be accelerated and significant monetary benefits can be realized. Under the current specifications (Item 247), a material can be considered out-of-specification (low-quality) for a variety of reasons (inadequate gradation, inadequate plasticity, inadequate strength etc.). In many cases, the local flexible base supplies miss the standard specifications by a small margin. Since the criteria set in Item 247 are experienced-based, some of the parameters used to classify a base may be less significant than others. In this project, we propose to evaluate the lower quality flexible base/subbase materials from local pits to determine whether, when and how the out-of-specification material can be used on a low-volume roadway and still get a quality foundation layer.
