A Performance Baseline for Stone-Matrix Asphalt: Fid-Bau Portal

A Performance Baseline for Stone-Matrix Asphalt

McGhee, Kevin K. / Clark, Trenton M. / Reid, Robert A.

In 2003, Virginia launched an expanded commitment to stone-matrix asphalt (SMA). By the end of 2004, contracts that encompassed nearly 400,000 tons of SMA had been awarded for this two-year period. This paper documents many aspects of Virginia's 2003/2004 SMA "implementation initiative." It summarizes and presents detailed information on costs and quantities, volumetric properties, compaction, permeability, and initial functional characteristics (ride & friction) for SMA pavements placed during the two-year timeframe. The data presented in this work will be used to form the baseline for future pavement and material evaluations. Among the significant findings and conclusions are the higher initial costs for SMA, $10 to $20 per ton more than for the nearest equivalent dense-graded surface mixes. Further, the average daily production of SMA was approximately 900 tons, although as much as 1,500 tons per day (night) appeared achievable for nearly every mix (with "typical" project constraints). The SMA surface mixes had generally good (i.e., low) permeability characteristics, and production compaction results were generally within specification limits. In addition, the achieved smoothness levels for SMA improved slightly from 2003 to 2004. Finally, early-age friction improved rapidly under traffic for SMA. Then, the SMA tended to exhibit prototypical seasonal variation for friction, with the lowest test results in the summer months. Building on these findings, anticipated follow-up research will examine the economic differences between SMA and Superpave in more detail. Additional research to monitor functional characteristics over time and to support selection and use criteria for SMA is also recommended.