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Stone Mastic Asphalt Placed on Fort Washington Way
(SMA Introduced to Southwest Ohio)

The reconstructed pavement for Fort Washington Way (I-71 and US 50) in Cincinnati was completed over the weekend of June 9-10, 2001 with the placement of the Stone Mastic Asphalt surface course. This is thought to be the first application of Stone Mastic Asphalt in southern Ohio.

Stone Mastic Asphalt (SMA), sometimes called Stone Matrix Asphalt, is a European development. The paving mixture consists of a nearly single sized coarse aggregate filled with a mastic of asphalt and filler. The mixture has gained wide acceptance because it combines many of the best performance features of different paving mixtures. It has much of the spray and noise reducing qualities of permeable, open-graded mixes along with the durability of impermeable, dense-graded mixes and outstanding rutting resistance.

The City of Cincinnati and their managing consultant, Parsons Brinckerhoff, selected SMA for the Fort Washington Way project surface because it could be expected to meet their project requirements of increasing durability and resistance to rutting, lowering noise and spray, and presenting a pleasing architectural appearance of different texture between the traveled lanes and paved shoulders.

The SMA was placed by the John R. Jurgensen Company as sub-contractor on the project. The SMA mix design was developed by the Jurgensen Company to meet the ODOT specification requirements of Supplemental Specification 856, and was approved by the ODOT laboratory. The binder was SBS polymer modified asphalt grading at PG70-22. 0.3% cellulose fibers were added to develop the heavy film thickness required. Aggregate was a blend of #78 and #8, 100% crushed gravel, #8 limestone, manufactured limestone sand and mineral filler to meet gradation and volumetric requirements of the mix design. Mixture properties and compaction requirements were verified with a test strip produced and placed at the Jurgensen Company's plant. This being the Jurgensen Company's first experience with SMA, they enlisted the counsel of Jim Scherocman, nationally known asphalt paving technology consultant, to assist with finalizing the design and placement techniques. The shoulders on Fort Washington Way were surfaced with a conventional type 1 mix, which had been designed for rutting resistance and proof-tested on the loaded wheel tester.

Through their application of the latest asphalt paving technology, the City of Cincinnati has achieved a beautiful and functional pavement surface that should give outstanding service for years to come.

Reprinted with permission from Better Roads™ magazine

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