Heavy Metal Content and Leaching Potential of Recycled Glass Beads Used in Pavement Markings: Executive Summary (TTI-2011-1)

This executive summary recaps a project that measured heavy metal content and leaching potential of recycled glass beads used in pavement markings. Recycled glass beads are incorporated into pavement marking systems to improve nighttime roadway delineation, marking visibility, and safety by retroreflecting vehicle headlights. Researchers tested samples from three different batches of glass beads to determine the composition of heavy metals in samples of recycled glass beads provided by the sponsor, and to investigate the leaching potential of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and lead (Pb) from the provided recycled glass bead samples under laboratory conditions. Researchers found that the fast initial metals release, coupled with the finding that smaller particle size fraction releases more metal into solution, indicates that leaching is occurring.