The following measures, among others, will be carried out as part of the construction work: the construction of central reservation crossings, the construction and dismantling of emergency stop bays, the dismantling of the concrete ceilings, as well as the construction of an asphalt surface layer in DSH-V construction on the open road, as well as on three building approaches. In addition, an asphalt surface layer made of mastic asphalt will be produced on three motorway structures after the asphalt superstructure has been milled off in layers. The renewal of verges, rainwater sewers, the renewal of collecting sewers using underground pipe jacking, induction loops and signage are also included in the scope of the contract.
Paving thin layers requires great care and experience
DSH-V stands for ‘thin asphalt layers in hot construction on seal’. ‘This method is a fast and environmentally-friendly process for maintaining roads in need of repair. Compared to stone mastic asphalt and asphalt concrete, up to 50 per cent less material is required. However, the installation requires absolutely precise work and a lot of experience,’ explains project manager Christoph Ritze. “PORR transport route engineering is a member of the DSH-V quality association and is therefore also involved in the continuous further development of the construction method and the quality assurance process,” he continues.
High demands on evenness
As with all thin-layer surfaces, a good evenness of the base and in particular of the asphalt binder layer is absolutely necessary for this project in order to ensure an optimal load-bearing capacity and longevity of the road, as well as optimal water drainage.
After dismantling the old concrete surface, the subsoil must be profiled over an area of 81,350 m2. The new layers on the open stretch consist of a 35 cm thick gravel base layer, a 20.5 cm thick asphalt base layer, a 9.5 cm thick asphalt binder layer, as well as a 2 cm thick asphalt surface layer made of asphalt mix DSH-V 5, covering a total area of 74,750 m2. A polymer-modified bitumen emulsion, applied to a thickness of just a few millimetres, serves as a sealing layer and bonding agent. It is applied evenly over the entire surface and must not be damaged under any circumstances. For this reason, the pavers are designed with a special spraying device so that the bitumen film is not driven on after spraying. Sealing and paving of the asphalt surface course are carried out in a single pass.
