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Bitumen for paving applications

16/08/2017 16:40

The Bridge Builder

Nynas’ highly modified special bitumen has proven to be ideal for surfaces on some of the biggest bridges in Northern Europe.

One of the most vulnerable parts of the traffic system is the heavily trafficked bridges. Maintaining a stable, consistent flow of traffic requires careful management, operation and maintenance, not least when it comes to the asphalt surface.

This is an area on which Nynas has been focusing for many years, one of the results of which has been the development of Nynas Endura F2. This is a polymer-modified binder (PMB) with a high degree of flexibility and good resistance to deformation, which is ideal for the surface course on bridges. 

One example is the Öresund Bridge that connects Sweden and Denmark. The link, which was officially opened in summer 2000, consists of a bridge extending almost 8 kilometres, which passes via the artificial island of Peberholm and becomes a 3.5 kilometre long tunnel as far as the Danish coast.

No fewer than 100 million vehicles have driven over the Öresund Bridge since it was opened to traffic 17 years ago. Yet the original asphalt surface still remains untouched, which is remarkable in view of the intensive traffic. In round figures, 30,000 vehicles travel in both directions every day.

Complex projects

Nynas Endura F2 has also been used as a binder for two other major bridge projects in Sweden – the High Coast Bridge and the Sundsvall Bridge.

The High Coast Bridge over the Ångerman River is one of the biggest suspension bridges in the world. The geographical location creates tough demands, as the average temperature in winter is around minus 20 degrees, dropping to minus 40 degrees at times, while in the summer the thermometer can go as high as 30 degrees or so.

To prevent any future crack formation, the road authority decided to lay a new surface course on the bridge in 2012. Just as in 1997, when the bridge was completed, Nynas supplied the polymer-modified binder. 

December 2014 saw the official opening of the 2,109 metre long bridge over the Sundsvall Fjord, at the time the biggest bridge construction project under way in Europe. By using Nynas’ polymer-modified binder, the contractor wanted to make sure that the surface would withstand not only the intensity of the traffic, but also the high proportion of studded tyres and the use of salt in the winter.

The special feature of Nynas Endura F2 is the fact that the asphalt mass is extremely elastic, almost like a rubber band. This is a major advantage, as bridges move a lot. With a conventional asphalt mass, there is a greater risk of cracks and of stones coming loose from the surface.

Further reading

Better roads = improved competitiveness

The upgrading and maintenance of road networks are effective tools for countries wishing to improve their competitiveness. Roberto Crotti from the World Economic Forum explains why.

Read more about Better roads = improved competitiveness

Keeping cool when it’s needed

Bitumen is handled at elevated temperatures. There are many important precautions that need to be taken to minimise the risk of burn injuries.

Read more about Keeping cool when it’s needed

Rheology rethink

A proposed new method for studying the rheology of bitumen and binders at low temperatures proves promising. Hilde Soenen explains the method’s potential.

Read more about Rheology rethink