InfraStructures - October 2005 - Canadian Heat for the White House

Canadian Heat for the White House

Robert Kieswetter, Heat Design Equipment Inc.
Special Collaboration

Our road infrastructure is deteriorating faster than repairs can be made, and a major contributor to the problem is the quality of the longitudinal joint (centerline joint). It is commonly the first sign of failure of a road surface, and leads to a much-reduced life of a pavement surface. The problem is attributed to an uncompacted edge of the first lane of pavement where there is no edge support to allow compaction. This uncompacted strip absorbs water and quickly ravels and opens up as a crack, especially under freeze/thaw conditions.

The technology of a Canadian company, that has been used in Quebec since 1995 to ensure construction of a better joint, was recently chosen as the method of repair of poor longitudinal joints on a new rustic pavement surface on Pennsylvania Ave at the White House, Washington DC.

A honey colored polymer binder and colored aggregate surface course was laid on the six lane three block section in front of the White House in October 2004. Lanes paved in echelon resulted in satisfactory joint appearance, but two cold joints running the entire length of the project displayed early raveling and unacceptable appearance problems.

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. After reheating, new material would be added to the joint, leveled and recompacted.

The general contractor for the project was The Lane Construction Corporation, Meriden, CT.

The specifying authority for the project, Federal Highway Administration, Eastern Federal Lands Highway Division, suggested a test repair on one of the project's original test sites at Rock Creek Park in Washington DC.

Last May, an HDE JMH 400 T - a standard longitudinal joint heater - was used to reheat a test joint. The joint heater has four heaters each 4 ft long by 18 in. wide, each heater capable of being adjusted from a low infrared emission using 60 000 BTU/hr to a high of 110 000 BTU/hr. Various procedures were tried and final approval was given to using the infrared heating equipment and test material the contractor had left over for the original project.

During reheating test sections, overheating the synthetic resin with the lower softening point than conventional asphalt bitumen was a concern, since it would burn and blacken. Repair protocol for the White House site was decided, to heat at low heat with the infrared heaters placed at a higher elevation than conventionally.

To avoid segregation problems due to hand raking required at the joint the contractor proposed removing the plus 1/4 in. size from the test mix and add 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 added to remove the coarser material. The synthetic resin was than added to the finer mix and the hot mix placed in individual cardboard boxes and allowed to cool for use on the White House project. Approximately 2 ton of repair mix was produced.

On June 13 and 14th, 2005, some 1000 feet of longitudinal joint was reheated. Aggregate Industries then did all repair work.

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 1/3 cubic foot storage area below.

The longitudinal joint was reheated at the rate of about 4 feet/minute, new hot material added to the joint, then luted. Recompaction of the joint was done in 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 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.

Heat Design Equipment Inc. manufactures infrared heating equipment for new asphalt pavement construction as well as repairs. The unique patented design allows for a high infrared emission over a large area, reheating asphalt in place quickly without an open flame that would damage the asphalt. The particular design ensures fast uniform penetration of the asphalt, making it possible to reheat longitudinal joints without slowing the paving operation. Using larger heating equipment it has been possible to economically reheat the entire base mat of asphalt during cold weather paving to ensure a good bond and compaction.