Publication Number: FHWA-RD-01-066
Date: August 2001

New Standard Adopted for Recycled Glass in Pavements

The use of recycled materials in pavements has received a boost with the adoption of a new national specification for recycling glass in soil aggregate base courses. The specification, entitled "Glass Cullet Use for Soil Aggregate Base Course," was adopted by the American Association of State Highway and Transportation Officials (AASHTO) in December 2000 and will be published in the next edition of AASHTO's Standard Specifications for Transportation Materials of Sampling and Testing.

The specification notes that, "When properly processed and mixed with natural or crushed aggregate, hauled to, and properly spread and compacted on a prepared grade to appropriate density standards, glass cullet can be expected to provide adequate stability and load support for use as road or highway bases."

The new standard was developed as part of a research project conducted by the Recycled Materials Resource Center (RMRC) at the University of New Hampshire. This project is designed to investigate the properties of selected recycled materials and to develop guidance specifications for highway construction applications in an AASHTO format. Overseeing the effort is a technical advisory group composed of representatives from 15 State departments of transportation (DOT).

"The new AASHTO specification conforms nicely with what we're doing in Minnesota," says Roger Olson of the Minnesota DOT and a member of the Technical Advisory Group. Minnesota's specification allows for up to 10 percent glass cullet use in base courses.

"The specification makes it easier for States," says Frank Palise of New Jersey DOT and also a member of the Technical Advisory Group. "Without a specification, it is particularly hard for county or municipal engineers to try something new. Having an AASHTO specification makes it easier for States to give the stamp of approval."

According to Taylor Eighmy of the RMRC, "The glass cullet specification was one that many States were asking for. There was a lot of interest in it. We're now actively working with States to develop the additional specifications that they need."

The five additional specifications currently being developed by the RMRC research project are:

• Recycled Concrete Pavement as an Aggregate Substitute Material in Granular Base
• Recycled Concrete Pavement as an Aggregate Substitute in Portland Cement Concrete Pavements
• Recycled Asphalt Pavement Used in Hot-Mix Asphalt (HMA) at Hot-Mix Plants
• Use of Asphalt Shingles as Asphalt Cement Replacment in HMA
• Coal Fly Ash Use in Embankments

The glass cullet specification can be downloaded from the Web at www.rmrc.unh.edu/Research/Rprojects/project13/Specs/AASHTO-Rev-03-13-01.pdf. For more information on the specification, contact Taylor Eighmy at 603-862-1065 (fax: 603-862-3957; email: t.eighmy@rmrc.unh.edu).

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