Recycled materials and industrial byproducts are being used in transportation applications with increasing frequency. There is a growing body of experience showing that these materials work well in highway applications. This study gathers the experiences of transportation agencies in determining the relevant properties of recycled materials and industrial byproducts and the beneficial use for highway applications. Information for this study was acquired through a literature review, and surveys and interviews with state department of transportation staff. The report will serve as a guide to states revising the provisions of their materials specifications to incorporate the use of recycled materials and industrial byproducts, and should, thereby, assist producers and users in “leveling the playing field” for a wide range of dissimilar materials.

 Because of the abundance of material on the subject, this Synthesis has been divided into eight volumes, the first volume providing an overview of the recycled materials and industrial byproducts being used in highway applications, and volumes two through eight corresponding to each category of material or byproduct. Volume one is available as a printed document; volumes two through eight are web-only documents accessible on the TRB website. Each volume can be read as a singular document covering one particular material/byproduct.

The eight volumes are: