ASPHALTopics | Spring 2014 | VOL 27 | NO 1

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the Percent Recovery portion of the Multiple Stress Creep
Recovery (MSCR) procedure (using equipment introduced
in the early 1990s). Based on research carried out both
here in Ontario and in the United States, the newer
MSCR Percent Recovery test is a much more reliable
and accurate testing procedure.
These tests help to determine if elastomeric polymers
have been used in the formulation of modified asphalt
cement. Both tests are being evaluated on 33 contracts
in an industry/MTO partnership, testing asphalt cement
√ Bulk Lubricant Dispensing
√ Fluid Inventory Control & Management
√ Workbench Tanks
√ Oil & Grease Pumps
√ Control Valves & Dispensing Meters
√ Hose Reels
grades ranging from PGAC 52-40 to PGAC 70-34
all across Ontario. These test sections are full MTO
reconstruction projects, not just trials. The field work
for these projects started in 2010. Now that some of
the contracts are three years old, field inspection of
pavements will be starting. The objective is to look at
the performance over seven to eight years of the initial
pavement life. The monitoring of all the trial sections
will be completed in about five years.
While field performance hasn’t been evaluated yet,
there have been some interesting
conclusions from the laboratory
testing carried out to date. The
conclusion seems to be that it
doesn’t matter which of the additional
procedures (MSCR or DENT) you
specify for acceptance — when you
ask for one value, you also get the
other. Given that finding, in 2012 MTO
adopted a new specification that
includes the MCSR Percent Recovery
for all their projects.
In the meantime, if municipalities
wish to modify their specifications,
any asphalt cement supplier in Ontario
can and will supply material to local
contractors that meets MTO’s Percent
Recovery criteria under MSCR for
modified grades (any grades other
than PG 58-28 or PG 52-34 which
are considered unmodified grades
for lower service pavements). It may
cost a bit more and the performance
advantage hasn’t been fully
determined yet, but the industry is
ready and has been supplying material
meeting that specification for three
or four years.
For Total Lube Solutions,
Master Distributor for:
Tel 1.800.668.5458 sales@flocomponents.com www.flocomponents.com
Finally, one modifier that may be
used in some grades of asphalt
cement is derived from recycled
and re-refined engine oil. Known as
Re-refined Heavy Vacuum Distillate
Oil residue (RHVDO), this product
comes from a refinery where engine
oil for your car is recycled. This not
the sludge collected from the local
garage, but rather a processed
material that meets engineering
and environmental guidelines.
Using recycled and refined engine
oil residue is a sound environmental
practice instead of burning or
36 OHMPA | ASPHALTOPICS