Maximum Quality in Next to No Time
Roland Schug, Anja Sehr
Special Collaboration
A spectacular construction project took place at Bremen City Airport, in Germany. The airport's only runway was in urgent need of rehabilitation as it was over 20 years old and pitted with holes and cracks. The parties responsible had only one option – to close the airport for the duration of the pavement rehabilitation work. This made it even more important to reduce the actual construction time to an absolute minimum.
The contract for the works was awarded to Heitkamp Erd- und Straßenbau GmbH, who already had experience in runway rehabilitation projects. One of the tasks involved was the pavement rehabilitation at Zweibrücken Airport. At first, Wirtgen milling machines moved onto the runway. Five large W 220 and two W 150 milling machines were put to work on the 45 m wide and 2,045 m long section. The machines milled away 12 cm of the existing pavement in preparation for the challenging asphalt paving. This first stage of the project was successfully completed after 30 hours of non-stop work.
Pavers Achieve High Level of Pre-Compaction
Actually replacing the asphalt layers was a logistical masterstroke made possible by months of planning and an impressive fleet of vehicles: a total of 60 trucks shuttled between the mixing plant and the job site. The first thing they delivered was the mix for the binder course, of which 19,000 t were required. Three Vögele pavers placed the material in an 8 cm thick layer. The pavers used were two SUPER 1800-2 and a SUPER 2100-2. In order to achieve maximum pre-compaction, the pavers were combined with AB 600 Extending Screeds in the TP1 version, i.e. equipped with a high-compacting pressure bar.
 Precisely Laid Binder Course
Laying the binder course already called for the utmost precision. To ensure outstanding results, paving was carried out "hot to hot" in two sets of three strips. This contributed greatly to achieving a uniform and durable layer. The Vögele 3D control system NAVITRONIC Plus was used when paving the two inner strips so as to achieve an extremely even and accurate profile. This resulted in an absolutely precise binder course – the ideal basis for the surfacing. The unique NAVITRONIC Plus system makes it possible to perform the paving work on the basis of existing survey data. The system controls the pave width, the layer thickness and also the longitudinal route fully automatically.
Paving "Hot to Hot" Produces Perfect Joints
A veritable armada of Vögele pavers was tasked with placing the surface course of asphaltic concrete: six SUPER 1800-2 and SUPER 2100-2 pavers built the new layer to a thickness of 4 cm in strips with a pave width of 7.5 m. The "hot to hot" method was employed in order to achieve optimal interlocking of the adjacent strips and to produce perfect asphalt joints. After all, the airport's quality requirements were extremely high. Consequently, Heitkamp not only had to achieve an evenness of 3 mm over a longitudinal distance of 4 m, but also had to produce precisely positioned rain channels. To ensure that rainwater can reliably drain from the runway, the inner strips were paved with a transverse slope of 1.5%, while the outer strips were provided with a slope of 1%.
MT 3000-2 Offset for Uninterrupted Paving
In other words: a perfect and highly durable pavement was required – one that could once again withstand the tremendous loads of aircraft weighing several tonnes and last far into the future. When a project is as challenging as this, it is all the more important that the mix supply runs smoothly. To accomplish this, the six pavers were supplied with mix by two Vögele MT 3000-2 Offset material feeders and two MT 1000-1 feeders. The extremely efficient MT 3000-2 Offset can transfer up to 1,200 t of mix to the paver per hour and the maximum capacity in the overall system of material feeder and paver is 40 t of asphalt. Potential interruptions in the flow of mix from the feed lorry to the paver can thus be avoided. What is more, uninterrupted paving has a very positive impact on the attainable evenness of the pavement. And thanks to its enormous capacity, one MT 3000-2 Offset with its pivoting offset conveyor can even feed paving material to two pavers simultaneously.
High Degree of Longitudinal Surface Accuracy
To achieve the high specified evenness in the longitudinal direction, too, all six pavers were equipped with NIVELTRONIC Plus, the Vögele System for automated grade and slope control in combination with the “Big MultiPlex Ski”. Measuring up to 13 m in length, the ski has three sonic sensors that level out irregularities in the base precisely by calculating a mean value.
The machines and technology of Vögele interacted perfectly to achieve top-quality pavement rehabilitation in next to no time: the airport was closed for just 149 hours, after which flight operations were recommenced as planned. The first aircraft started at 7:30 in the morning. And beneath their undercarriages was a brand new, extremely even and stable asphalt pavement – the ideal basis for safe take-offs and landings. |
