An Experimental Study on the Performance of Recycled Stone Matrix Asphalt Pavement

In 1991, the Wisconsin Department of Transportation and the asphalt paving industry in the state decided to construct a trial installation of an asphalt paving technology that had piqued the interest of a group of professionals who had recently toured Europe. The success of that initial trial was the basis of the decision to conduct a thorough evaluation of stone matrix asphalt (SMA). Subsequently, six projects were constructed at various locations around the state. Each project contained six test sections utilizing various fiber and polymer-modified SMA mixes. Besides evaluating the various types of SMAs, this research effort also contained elements for evaluating the impact of aggregate size and aggregate hardness on the effectiveness of the SMA mixes. These projects were constructed over a period of 3 years; the last one was constructed in 1994. All the projects were evaluated from the standpoint of ease of construction and performance. Although the ease of construction was to be evaluated mostly on a subjective basis, the performance measures were established to be objective and measurable. The performance measures were amount of cracking, friction characteristics, overall pavement distress, amount of rutting, noise impacts, and ride. Although the data collected so far are limited because of the short time the pavements have been in place, they point to an asphalt pavement that resists cracking and rutting, while providing a good ride and excellent frictional qualities. The SMAs demonstrate promise of being a durable and long-lasting asphalt pavement.

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Evaluation of Two Compaction Levels for Designing Stone Matrix Asphalt

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198105192900118 ◽

2005 ◽

Vol 1929 (1) ◽

pp. 149-156 ◽

Cited By ~ 1

Author(s):

Hongbin Xie ◽

Donald E. Watson ◽

E. Ray Brown

Keyword(s):

Asphalt Pavement ◽

Design Guidelines ◽

Mineral Aggregate ◽

Rutting Resistance ◽

Stone Matrix Asphalt ◽

Aggregate Breakdown ◽

Successful Design ◽

Asphalt Content ◽

Stone Matrix

Current stone matrix asphalt (SMA) design guidelines list two compaction options to design SMA, 50 blows Marshall or 100 gyrations with the Superpave® gyratory compactor (SGC). However, some states have found that 100 gyrations with the SGC is excessive for their materials. In this study a lower compaction level of 65 gyrations was used to compare with the standard 100 gyrations to design SMA mixtures. Results showed that mixtures designed by 65 gyrations had an average of 0.7% higher optimum asphalt content and 1.5% higher voids in mineral aggregate (VMA) than those designed by 100 gyrations. All mixtures designed by 65 gyrations met the minimum asphalt content and VMA requirements for SMA, whereas only eight of 15 mixtures designed by 100 gyrations met those two requirements. Compaction at 100 gyrations resulted in an additional 0.62% average aggregate breakdown at the critical sieve as compared with 65 gyrations. SMA mixtures designed by 65 gyrations and 100 gyrations had an average asphalt pavement analyzer rut depth of 3.9 mm and 3.1 mm, respectively. Thirteen of 15 mixtures designed by 65 gyrations performed well if 5.0 mm was set as the maximum allowed rut depth. On the basis of this study, 65 gyrations can be used to design a more durable SMA mixture, while still maintaining the good rutting resistance that SMA mixtures are noted for. The successful design by 65 gyrations for all five aggregates in this study indicates that a lower design compaction level may allow the use of more aggregate sources for SMA mixtures.

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