patch whole again. This whole process
was done over a period of five years until
last year when the runway was repaved.
What is noteworthy is that the combination
of infrared heat and a premium cold
mix was sufficient to meet a repair standard
that involved 737 jets landing and
taking off!”
There are no-heat options for asphalt
pavement repair.
“If you don’t have an asphalt heater
available, a contractor can saw cut and replace
the damaged area,” Strassman said.
“Saw cut just outside of the area to be repaired,
finding a decent edge, remove old
asphalt and replace, level and compact
with fresh HMA. However, a saw cut creates
a seam and lacks the ability for thermal
bonding of the old and new asphalt.”
There are asphalt repair projects where
it is best to not use reheat technology.
“An infrared reheat system penetrates
into the asphalt one inch to an inch-anda-half,
so any type of obvious base failure
will not be a great candidate for an infrared
repair,” Blake said. “Depending on
the severity of the base failure, infrared
can be used as a temporary fix but will
not be a permanent solution.”
Additionally, Kieswetter stated: “Infrared
heaters should not be used on pavements
that are rolling out of grade. This
means the water penetration has gotten
into a plastic subgrade and the vehicle
loading and/or frost conditions have allowed
the silt to pump up and destroy
the granular layer. If the pavement is repaired
without fixing the granular layers
the pavement structure will not continue
to perform.”
If infrared technology cannot be used
on a specific repair area, the most common
repair methods would be to saw cut
remove and replace the damaged area
complete a mill-and-fill operation.
To perform a repair using infrared,
Blake outlined the following steps:
1. Allow 7-10 minutes for the repair area
to heat and gain 1- to 11/2-inch penetration
into the asphalt surface.
2. Move in 3-inches from the outside of
the heated area and “picture frame” the
repair area. Proceed to completely scarify
the entire area.
3. Apply rejuvenator and lute the entire
area removing large stone and aggregate.
4. Compact the area starting with the
outside edges and gradually working your
way in. Compaction is one of the most
important steps so ensure the repair area
is at a high temperature to get optimal
compaction density.
As with any reheat project, the contractor
needs to be aware of heating too
much. Once the asphalt is heated to more
than 360°F, it is possible to start burning
the asphalt cement—the glue. This can
happen if a contractor is trying to heat
too deep, too fast. The top layer can be
heated to 360°F and getting two-inches
down into the asphalt should be at about
300°F or more to make it soft and pliable.
The easiest way contractors can prevent
burning the asphalt is by watching for
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September 2020