USE OF DIESEL-CONTAMINATED SOIL IN RECYCLED COLD-MIX PAVEMENT

The United States military, working with the state and the EPA, combined a contaminated asphalt cement and a reclaimed asphalt pavement (RAP) to produce an asphalt paving material suitable for containing diesel-contaminated soil. The project involved the use of various contaminated and waste materials, including a diesel-contaminated soil, a stockpile of asphalt cement, and a stockpile of RAP. These materials were combined and, depending on their location in the pavement structure, were stabilized with an emulsified asphalt cement to produce an improved roadway pavement. Prior to construction, a laboratory analysis was conducted to determine if the asphalt mixture containing the contaminated soil would leach petroleum materials. Toxicity characteristic leaching procedure (TCLP) extract tests on mixtures with and without contaminated materials showed that unacceptable levels of leaching would not occur under the conditions simulated in the laboratory. The RAP material was processed with a crusher to obtain a uniform-sized material. The crushed RAP was then mixed with the contaminated soil and an asphalt emulsion in a pugmill. This mixture was then placed and compacted using conventional asphalt-concrete paving equipment. The use of the materials at this site for pavement construction resulted in substantial savings when considering costs for removal and disposal of these materials. These contaminated materials provided a structurally satisfactory material for pavement construction; the roadway continues to perform satisfactorily since its placement, almost four years ago.