 |
|
This infrared heater was used to make repairs where
longitudinal joint cracks formed in a new pavement surface on Pennsylvania
Avenue.
|
The paving contractor for the rustic pavement
surface course, Aggregate Industries of Greenbelt, Maryland, proposed
reheating the longitudinal joints using unique infrared heating equipment
manufactured by Heat Design Equipment Inc. of Kitchener, Ontario, Canada.
After reheating, new material would be added to the joint, leveled, and then
re-compacted.
The specifying authority for the project, the
Federal Highway Administration, Eastern Federal Lands Highway Division,
suggested a test repair be done on one of the project’s original test sites
at Rock Creek Park in Washington DC.
The job
On May 2, 2005, the general contractor for the
project, The Lane Construction Corporation, Meriden, Connecticut, used an
HDE JMH 400 T, a standard longitudinal joint heater, to reheat a test joint.
The joint heater has four heaters, each 4-foot long by 18-inches wide,
capable of being adjusted from a low infrared emission using 60,000 BTU/hour
to a high of 110,000 BTU/hour. Vari-ous procedures were tried and final
approval was given for using the infrared heating equipment and test
material the contractor had left over from the original project.
During the reheating of test sections, overheating
the synthetic resin with a lower softening point than conventional asphalt
bitumen was a concern, since it would burn and blacken if overheated. So, it
was decided to heat the joints at low heat with the infrared heaters placed
at a higher elevation than usual.
To avoid segregation problems due to hand raking
required at the joint, the contractor proposed removing aggregate larger
than 0.25 inches from the test mix and adding more binder to improve on the
workability and richness of the mix and the final surface appearance.
The contractor reheated the test mix using an HDE
mini recycler with an additional screen to remove the coarser material. The
synthetic resin was then added to the finer mix and the hot mix placed in
individual cardboard boxes and allowed to cool. Approximately 2 tons of
repair mix was produced.
On June 13th and 14th, some 1,000 feet of
longitudinal joint was reheated and the repair work done.
The prepared blocks of repair material were once
again reheated in the HDE mini recycler. The blocks were placed on the
2-inch-square screen deck just below an HDE 100 infrared heater that forms
the top of the recycler, and within minutes the material was soft enough to
fall through the screen to the 0.333-cubic foot storage area below.
The longitudinal joint was reheated at the rate of
about 4 feet/minute, new hot material was added to the joint, and then it
was luted. Re-compaction of the joint was done perpendicular to the joint
using an Ingersoll Rand DD-24 dual-drum vibratory roller. A final rolling
for smoothness was done parallel to the joint.
The result
The reheating and repair resulted in considerable
improvement in the visual appearance of the joint. The process is being
considered for repair of future utility cuts that may be required, since it
would provide a sealed joint ensuring a longer pavement life, and would meet
the appearance criteria of the original design. |
Click here for copyright permissions!
