What is the longitudinal joint?
When a section of roadway is paved it most often requires several passes to be able to cover the entire width of the travel way, with each pass the paver creates a joint that runs the length of the road. This is the longitudinal joint and it is most often recognized by the crack that quickly forms in the center of the road.
Why is the longitudinal joint important?
The longitudinal joint is often considered the weakest part of a roadway and is prone to early deterioration if not constructed properly. A poor longitudinal joint can show signs of failure within a years time and can easily reduce the lifespan of the road by several years. Once the joint begins to fail it will require constant maintenance to prevent further damage the roadway below the cracked area. This maintenance is very costly and is often short lived due to the freeze thaw cycles in northern climates.
What causes the longitudinal joint to fail?
The most common reason for joint failure is due to low density at the joint. This is often due to the way a multi-lane roadway is paved with one lane being paved before the other. When the first lane is compacted with a roller there is an area at the edge of the paving mat that is not supported from the sides, this material will not receive adequate compaction and will not only be weaker than the surrounding pavement but it will also allow water to permeate through the surface, which allows for additional deterioration through freeze thaw cycles. The image below illustrates the unconfined edge under the roller.
The paving crew makes the second pass along the side of the first lane, which is where the area of low density is. This is what causes the joint to fail and deteriorate in a short period of time. The image below illustrates the location of the low density zone and where the longitudinal joint is formed.
Studies show that the life of the pavement can be directly related to densities.
How do we prevent the longitudinal joint from deteriorating?
The goal is simple, remove the low density zone and allow for adequate bonding between the two lanes of pavement. There are several methods of removing the low density zone, some actually require removing the edge of the new pavement with saws and milling machines, but this is expensive and wasteful and a cut edge will not provide an ideal bonding surface for the adjacent lane.
A more economical method is to reheat the low density zone to bring that pavement back to a pliable temperature where additional compaction can be achieved. Many studies show that paving against a hot joint will provide numerous benefits and increase the strength of the longitudinal joint. The problem is to safely heat the material to a high enough temperature for effective compaction without burning or harming the pavement.
What will a solid longitudinal joint with increased compaction provide?
A solid longitudinal joint with higher compaction will provide numerous benefits to motorists, taxpayers and agencies.
- Safer roadway for motorists
- Fewer maintenance delays
- Reduction in cost for maintenance
- Reduction in cost for vehicle repair
- longer lifespan for the roadway
- Increased budget for other projects
What can Seam Sealing Systems offer for a solution?
The technology we use at Seam Sealing Systems is capable of heating the asphalt surface to any selected temperature. The heating of the material is automated and monitored at all times providing safe, effective and consistent heating to higher temperatures without the risk of damaging the pavement materials. Our equipment utilizes electric infrared elements that offer a very controllable and adaptive heat heat source for any surface material. We can heat the low density zone of the pavement, increase the bonding strength between the two lanes and provide a solid watertight joint that will stand the test of time.
Why Seam Sealing Systems with electric infrared?
The characteristics of pavement change with the amount of heat that is applied, if the pavement is too cold then it is stiff and effective compaction can not be achieved, if the material is too hot then the pavement components begin to burn and boil away leaving a damaged material that will not last long. The temperature of the pavement must be monitored in a heating process to allow for the optimum temperature range and the heat source must be even, consistent and adaptable to provide effective results. With an electric infrared system the surface temperature is constantly monitored and the heat is automatically adjusted to maintain the ideal temperature. Electric heating elements provide a completely even heat source that is fast acting, fully adjustable, and independent of weather conditions. With these features we can provide safe, reliable and consistent heat to the pavement to allow for ideal conditions while compacting the longitudinal joint.
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