ASPHALTopics | Summer 2014 | VOL 27 | NO3

“It’s much more economical to pay a
premium up front now, than to have to pay
even more later for a failed pavement that
has to be repaired or replaced.”
– Mark Eby
heavy traffic. The Ministry plans, however, to tender select
contracts over the next few years to evaluate the use of
the MSCR acceptance criteria in place of high temperature
grade bump-ups. Other AC tests used by MTO include the
Ash Content, Double Edge Notched Tension (DENT) test,
and Extended Bending Beam Rheometer (ExBBR) test.
Both the MTO and Ontario municipalities have had
performance issues with Superpave designs in recent
years, and are looking to improved specifications to
extend the life of pavements and minimize costly repairs
and replacements. Some municipalities have incorporated
MSCR testing for select projects in their road construction
programs. In the Region of Waterloo, an urban road
expansion on the west side of Kitchener/Waterloo is
including the MGAC specification. On a three kilometre
stretch of arterial roadway, two lanes are being expanded
to four lanes and the work is being completed in separate
stages; the first phase of the work is being constructed
with conventional paving specifications and the second
phase is being constructed using the MGAC specification.
The project is expected to be completed before the end
of this year’s paving season.
“Premature cracking has shown up in pavements that
were constructed only two or three years ago,” says Gary
MacDonald, Head of Transportation Rehabilitation for
the Region of Waterloo. “Last winter certainly exacerbated
cracking, but there are inherent performance issues. There
are a number of tests out there, and we want to verify that
this is the best testing method. It will likely take a number of
years to conclusively assess and compare the performance
of the paving that we’re completing this year.”
In Wellington County, one project using the MGAC
specification has been completed and another one is
underway. On Wellington Road 124, for a span of five
kilometres between Guelph and Eramosa, MGAC graded
asphalt cement was used for an additional surface lift once
base repairs were completed. Increased volumes of car
and truck traffic would benefit from the addition of an
elastomer in the AC, which created ideal conditions to
use the MGAC specification.
A second MGAC project, north of Guelph on Wellington
Road 7, is the construction of two passing lanes for each
direction of the road. The project requires 16,000 tonnes
of HMA to construct the base and surface layers for a
section of the roadway that spans three kilometres. The
MGAC includes an elastomer so that the pavement will
have the necessary flexibility to perform better under
heavy traffic conditions.
“The MGAC is more expensive than PG graded asphalt
cement, but it is worth it in the long run,” says Mark Eby,
Construction Manager for Wellington County. “For the
Wellington Road 7 project, the premium was between
$1.75 and $4.55 per tonne, which is reasonable. An
additional $50,000 for a $2.4 million project is a minor
increase if the pavement will perform better. It’s much
more economical to pay a premium up front now, than
to have to pay even more later for a failed pavement
that has to be repaired or replaced.”
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