Shuttle Buggy® MTVs for Better Longitudinal Joints
Roadtec’s Shuttle Buggy® Material Transfer Vehicle is outfitted with features designed to help create stronger longitudinal joints in paving projects. From improving mix quality to facilitating echelon paving, Roadtec’s innovative machine will help you construct joints that last longer.
An Ideal Mix
It’s well known that mix design, transportation methods and material handling are some of the main variables that play into mat quality. Running a mix through a Shuttle Buggy® Material Transfer Vehicle ensures that the mix has little to no segregation as it reaches the paver.
After the material reaches the paver’s hopper, Roadtec’s exclusive tractor design smoothly conveys it back under flow gates towards the screed. The flow gates strike off the material to prevent asphalt from flooding the conveyor tunnel to allow for better material control. Once the asphalt arrives at the end of the conveyor, an auger distributes the material across the width of the screed. At this point, it is crucial to have the material halfway up the augers and for the screed to be properly set up to allow material flow. There needs to be a proper angle of attack placed into the screed to allow efficient material flow under the screed. These steps prevent segregation in the mix.
When trying to match a joint, it is necessary to make sure that the augers efficiently distribute material out to the end gates. Material should not be allowed to roll out to the sides of the screed since this encourages rock to roll down the pile creating segregation. When the auger distributes the material towards the end gate, it should distribute it right up to the end gate. Ideally, the end gate should be heated and only overlap the joint about one inch so that enough material can be placed into the joint.
An excellent option for constructing joints is Carlson’s vibratory tapered notch that attaches directly to the screed’s extension. By using this tapered notch, a compacted stepped joint is created that will be easier to match with the paver’s second pass. An added benefit to the stepped joint is that it is compacted which provides an excellent base for the second pass, thereby creating the longitudinal joint.
The best way to construct a longitudinal joint is when both sides of the joint contain hot mix. This can be done by using Roadtec’s Shuttle Buggy® Material Transfer Vehicle to feed two pavers at the same time. Both pavers will be slightly offset from one another while they pave, and the Shuttle Buggy® will swing the C3 conveyor to discharge material to both pavers. This keeps both pavers continually working to create an excellent longitudinal joint through a method known as echelon paving. This allows the joint to be rolled along with the rest of the mat, resulting in a superior, longer-lasting joint.
Product Manager – MTVs & Pavers