Joint Heating

 HDE JMH 400 TRAILER MODEL

The HDE JMH 400 T will preheat the surface of the asphalt at the joint in the cold lane just prior to placing the new asphalt strip. At standard operating pressure of 35 psi, the heater has an input of 400,000 BTU, capable of raising the surface temperature of the joint to a satisfactory range of 100°C (212°F) to 120°C (250°F). Paving speeds of up to 35’ per minute can be acheived under ideal conditions. For colder temperatures or higher paving speeds, the pressure can be increased to 50 PSI, changing the input of the machine to 470,000 BTU. 


TRAILER EXTENSION

The trailer model has an attachment that adds another 3 heaters, increasing the maximum input to 825,000BTU. The use of a paver booster heater has also proven successful in eliminating the loss of heat from cooling between the heater and paver. One 4’ HDE 100 asphalt heater is attached to the side of the paver and operates on vapour propane which mounts on the top of the heater or onto the paver 


PAVER ATTACHMENT

The HDE paver attachment is available in three standard models 

HDE JMH 300-PA - 12’ 300,000 BTU 

HDE JMH 400-PA - 16’ 400,000 BTU

HDE JMH 500-PA - 20’ 500,000 BTU

HDE joint heaters are designed to be expanded depending on paving requirments. Slower paver speeds may require an HDE 300-PA, withing 10 minutes it can be canged into a HDE 500-PA for highway paving. After the initial instalation the JMH-PA can attach to any brand of paver within 10 minutes, as all electrical and propane connections are quick connect. Each unit is pre-wired for electronic igniton and both manual and automatic modes. When operating on automatic, the heater will switch from operating pressure (35 psi) to low pressure (5 - 10 psi) If there is a delay in the paving operation and the paver has to stop, the unit will switch to low and heat the joint slowly without burning it. When the paving operation commences the heat will switch to operating pressure. The heaters width can be adjusted based on paving width by sliding the heater on the 2” chrome shaft.

 

HISTORY OF JOINT HEATING

Construction of longitudinal joints is recognized as one of the most significant asphalt paving construction problems today. At the Swift Airport Conference in Calgary a presentation on longitudinal joints was given by Mr. Rob McClure P. Eng of Hatch, Mott, Macdonald. The presentation outlined the problems of consructing a good longitudinal joint using a case study of a paving project done in 2007 at the DFC Shearwater Heliport in Dartmouth, N.S., Canada. The specifications required cutting and removal of the edge of the cold lane prior to tacking and butting up the new pavement lane. The paving contractor requested and received approval for using an alternate method using a HDE longitudinal joint heater. 

The joint heating proved very effective, saving the contractor money in material, labour, and project time. All the test results using the joint heater met the required compaction, whereas the specified technique of cut joints had failures. The appearance of the joint was excellent. The cost was reported to be in the area of $0.15 per lineal meter ($ 0.05 cents per foot), which is considerably under any other longitudinal joint construction technique cost, even considerably under any joint repair technique. The 2008 project specifications were changed to include joint heating.


JOINT REPAIR

The HDE JMH can also be used for longitudinal joint repair to ensure a better watertight joint and prevent accelerated deterioration. It is particularly cost effective when the joint has widened to such an extent,that joint filler will not stay, or when the cracks have spread to the adjacent joint. By re-heating the asphalt it can be reworked, asphalt can then be added to fill in any voids in the pavement. This process creates a lasting seamless repair

Heat Design Equipment Inc. has been promoting the idea of a re-heated joint since 1995, and have been supplying equipment to meet a hot joint specifications in the Province of Quebec since it was enacted in 1995. HDE’s joint heaters have been used on numerous projects since then, both in Canada and the United States. The Shearwater project could be considered the best documented project. Using the joint heater allows the contractor to heat the cold, un-compacted edge to temperatures of +100C (212F) at regular paving speeds in conventional paving temperatures. For faster speeds and colder weather, additional heaters can easily be added so the contractor has the opportunity to re-compact the edge, making a seamless, watertight joint.

A comparable project in Toronto, Ontario, Canada, involved heating 2200 feet (700 meters) of unacceptable joint paved the previous fall. Salt and sand had penetrated the joint and the authority required complete removal of the joint 4” (100mm) on either side of the joint or the contract alternative to the repair which was grinding and removal of the entire lane. Removal of the joint was easily done after heating, new asphalt was then placed and compacted. The authority required an extension of the warranty on the joint for one year, and prior to expiry requested further repair on just 20 ft (6 meters). At that point it was difficult to identify where the joint was. 

A 2005 joint repair of 1000 feet of ravelled joint at The White House on Pennsylvania Avenue confirmed that joints can be reheated efficiently and structurally repaired with no physical damage to the properties of the asphalt. The unique synthetic asphalt with a clear resin and two colored aggregate exhibited properties similar to polymer modified asphalt, with a lower softening point. Making a good longitudinal joint without echelon paving proved challenging to the contractor. Two 500 foot joints were not acceptable. Joints were repaired by the contractor using the HDE JMH 400T to reheat the joint and an HDE mini recycler was used to reheat material required to fil the gap in the joint. The work was done to the satisfaction of the Federal Highways and after three years the repairs remain in good condition. In 2008 HDE was invited back to repair additional areas that had failed due to cracking of the joint.

One of our previous projects for the Ministry of Transport of Ontario was in 1997 on the Queen Elizabeth Way, where after 11 years “ the longitudinal joints continue to perform well.” 

While the idea of a hot joint is not new, echelon paving is recognized as the best way to achieve a good longitudinal joint. However, at HDE we believe that joint heating is the next best thing, providing it can be done efficiently, without overheating the asphalt. Our clients have been successfully using our joint heaters in Quebec, Ontario, Nova Scotia , newfoundland, Tennessee, Mississippi, Delaware, Michigan and Washington DC (The White House) on actual projects.