Stone Mastic Asphalt Placed on Fort
(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
Reprinted with permission from Better Roads magazine
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