Building bridges
The demands placed on the asphalt pavement on a bridge differ from those that apply for a normal road. Nynas high-performance PMB guarantees a high level of resistance to deformation.
The asphalt on a bridge must not only withstand deformations and cracks, but also protect and seal the underlying steel or concrete structure against water and road salt. There are also the strong loads that arise a consequence of vibrations and the effects of wind and weather. Another challenge is that extremely strong forces can build up in the interface between the asphalt surface and the bridge’s bearing structure.
To provide the surface of the bridge with sufficient resistance, it has now become common practice to use a polymer-modified bitumen (PMB) in both binder and surface course. And this was the starting point when the 930-metre-long Älvsborg Bridge in Gothenburg was renovated in order to guarantee the bridge’s functionality and extend its useful life. The final stage was completed in summer 2021, with a new pavement covering a total area of 17,000 m2.
The pavement consists of two layers. Underneath is a protective and binder course of 30 mm mastic asphalt with Nynas high-performance PMB as a binder, while the surface course is a stone mastic asphalt concrete, also with a polymer-modified binder. The polymer-modified binder in the surface on the Älvsborg Bridge is the same kind as the one used in several other major Swedish bridge projects, including the Öresund Bridge, the High Coast Bridge and the Sundsvall Bridge.
