Optimum Use of Local Material for Roadway Base and Subbase

Base materials that meet specifications are getting more difficult to get in many regions of the United States. As a result, higher quality materials have to be hauled long distances. This act would significantly increase the costs associated with roadway construction and subsequent maintenance and rehabilitation. Low quality or out-of-specification materials are usually available from local sources. If through appropriate treatment of the materials or/and structural design, the optimum use of local materials can be permitted, the construction can be accelerated and significant monetary benefits can be realized. Under many current specifications, a material can be considered low-quality for a variety of reasons such as inadequate gradation, inadequate plasticity, and inadequate strength. In many cases, the local base supplies miss the specifications by small margins. Since the criteria set in most of current specifications are experienced-based, some of the criteria used to classify a base material may be less significant than others. This paper presents a test protocol for the use of low quality flexible base materials based on the test results of materials from eight local pits in Texas to document how a low-quality material can be used on low-volume roads and still get a quality foundation layer.