In 1990, a team of State, industry, and Federal engineers from the U.S. participated in a European Asphalt Study Tour. Their mission was to identify promising asphalt technologies. Of the asphalt mixture technologies studied, Stone-Matrix asphalt (SMA) had great promise for use in this country. SMA is an asphalt mixture developed in the 1980s in Germany to provide a rut-resistant pavement surface layer. Its proven performance is attributed to a "gap graded" aggregate gradation that provides a stone-to-stone structure held together by a durable asphalt cement, mineral filler, and fiber matrix. SMA is routinely used in many parts of Europe.

The goal of this project was to test and evaluate the use of Stone-Matrix asphalt (SMA) on test sections of U.S. highways to determine its construction feasibility and cost-effective performance. DP-90's mobile asphalt laboratories, its staff, and the Turner-Fairbank Highway Research Center staff are assisted other States with SMA mix design information, while the mobile asphalt laboratories provided materials analysis on-site and support quality control and compliance.

Interest in SMA remains strong. To date, project presentations have been made at over 100 locations to thousands of government and industry individuals interested in the various aspects of material selection, design, construction, and performance. Continuing interest in SMA is evidenced by the increasing number of States participating and the tonnage of SMA used in projects.

Telephone and on-site assistance, speakers, mix design assistance (based on laboratory availability), and mobile laboratory (subject to long-range planning)

SMA Model Materials Selection and Construction Guidelines are available through the Office of Technology Applications and are also being distributed by the industry. Copies of materials on European SMA Synthesis also are available upon request.

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HIGHWAYTECHNET   VIRTUAL EXPO   PAVEMENTS INDEX

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U.S. Department of Transportation
Federal Highway Administration