Compaction of Longitudinal Joints
Constructing high quality longitudinal joints was the topic in the most recent RoadReady newsletter . One of the critical steps to constructing a quality joint is compacting the joint properly. Below is an animation illustrating proper placement of the roller.
- BEST PRACTICE: Rolling from the hot side 6 inches (150 mm) away from the joint. The first roller pass is done in vibratory mode with the entire roller wheel on the hot lane about 6 inches (150 mm) from the joint. This compaction technique pushes the material between the roller and joint towards the joint during the initial roller pass, which crowds the mix at the joint yielding a an opportunity to achieve better density during the 2nd pass when the roller compacts the joint directly.
- Rolling from the hot side. NOT RECOMMENDED. The first roller pass occurs in vibratory mode with the majority of the roller wheel on the hot lane and overlapped onto the cold lane by about 6 inches (150 mm). Because part of the weight of the roller is supported by the previously compacted cold lane, it can cause a situation where the roller “bridges” over the joint or leaves it only partially compacted.
- Rolling from the cold side. NOT RECOMMENDED. The first roller pass occurs in the static mode with the majority of the roller wheel on the cold lane and overlapped onto the hot lane by about 6 inches (150 mm). This technique is believed to pinch the joint together. The reason this is not a recommended technique is because the timing in this type of rolling is critical. When the roller is operated on the cold side of the joint, the hot side undergoes cooling which makes it difficult to achieve the desired compaction level before the hot side reaches cessation temperature.
Here are some additional resources if you want to learn more about longitudinal joint construction, performance data and best practice:
- The Pavement Interactive Longitudinal Joint Construction article gives lots of practical construction solutions.
- NCAT’s Evaluation of Eight Longitudinal Joint Construction Techniques for Asphalt Pavements in Pennsylvania has performance data on joints in roadways constructed in several popular ways.
- We mentioned that we don’t recommend using handwork unless you have well trained and experienced crews. Here are some resources to help get your crews the knowledge they need: the Pavement Interactive HMA Placement Considerations article and our Paving Handwork course.
Tags: Longitudinal Joint Construction, Paving Training, Resources