EVALUATION AND THE USE OF WASTE AND RECLAIMED MATERIALS IN ROADBASE CONSTRUCTION

This report summarizes the following: (1) Material location and availability survey of commercial sources; (2) the Waste and Reclaimed Materials (WRMs) evaluation system; and (3) the results of the laboratory testing undertaken to develop specifications. A close examination of the data presented in Report 1348-1 indicated the need for a survey of commercial sources of waste materials in Texas. The survey of commercial sources was considered important, inasmuch as the Texas Department of Transportation (TxDOT) has ownership of only two of the reported materials, namely, reclaimed asphalt pavement (RAP) and reclaimed portland cement pavement (RPCP); moreover, TxDOT district personnel could not provide firm estimates of materials available in commercial stockpiles and, hence, recommended a survey of relevant sources. As to the technology, WRMs cannot match natural aggregate material in technical properties. Technical studies that have been used in the past to evaluate WRMs also fail to take into account the socioeconomic and environmental benefits of using these materials, which in our opinion is an oversight. To overcome this problem, a WRM evaluation method was developed that considers the socioeconomic and environmental benefits, in addition to the technical and economic aspects. An initial screening method was also incorporated to screen out materials having low or no utilization potential. All the available WRMs were subjected to this evaluation method and, based on objective data, a rational decision was made to select RAP, RPCP, and electric arc furnace slag (EAFS) for detailed laboratory testing (only materials showing high potential were subjected to such extensive technical studies). The detailed laboratory studies are summarized and the resulting specifications are presented in this report.