In-Roads – Bitumen technology moves ahead

By BP Bitumen

Bitumen may be something which is taken for granted driving along the highway. But it’s an increasingly sophisticated product – technical know-how stands right behind it.

As overall traffic volumes increase, the contribution from commercial vehicles with increased axle loads is growing, putting ever more strain on roads and highway maintenance budgets. Highway authorities are looking for products that will be able to cope better and are more cost effective over the life of a road. Technical innovation is the only way to answer this challenge effectively. A task BP’s bitumen specialists are well placed to tackle, especially with the opening this year of the company’s new technology centre in Gelsenkirchen, Germany. This opening – right in the heart of Europe – takes advantage of being close to some of the largest, most developed, and technically advanced bitumen markets in the world.

Increasingly, the properties of bitumen are being enhanced by blending it with polymer additives. In some markets up to 25% of asphalt roads are already built with asphalt mixtures using polymer modified bitumen (PMB) and this market is growing due to the improved performance that PMBs deliver: lower emissions, time savings, noise reduction and spray reduction to mention just some benefits. PMBs give road designers the option of applying special porous asphalt materials or using thinner layers of asphalt.

For example, the recent renewal of 1.6 km of the motorway from Munich to Nuremberg in Germany used BP’s Olexobit NV 25 polymer modified product. Olexobit NV is a range of polymer modified road binders with low viscosity and environmentally friendly aspects. The environmental benefits include mix production at lower temperatures – over 20°C lower than normal – not only saving on energy but also improving the working environment by reducing fumes and emissions during mixing and laying. Although the mixture is produced at lower temperature, workability is not compromised and asphalt stability is improved. Furthermore, lower application temperatures allow the new surfacing to be ready for traffic sooner thereby minimising disruption to traffic.

A more porous surface provides the dual benefits of reduced traffic noise and improved drainage. One recent BP Bitumen project focused on a busy motorway between Essen und Mühlheim in Germany, where heavy traffic rumbles past housing just 14 meters away, making noise reduction to a top priority. The BP binder Olexobit SMA has the right mechanical characteristics to achieve a durable porous surface with a void content around 24 per cent per volume, leading to substantial noise reduction. In addition, improved drainage from the surface – water can run inside the porous surface layer without any problems – results in less splash and spray, giving better driver visibility when it’s raining and hence safer driving conditions. Olexobit SMA is characterised by good adhesion to the aggregate as well as having well balanced viscoelastic behaviour.

The ability to opt for thinner asphalt layers with high performance PMBs can deliver material savings and corresponding cost benefit during construction, as well as reducing maintenance costs over the life of the road. “The initial cost per kilogram may be higher but the costs per unit area or the cost over the lifetime of the pavement can be lower,” says Carl Robertus, global technology manager for BP Bitumen.

BP Bitumen is continuing to develop PMBs with novel properties making technology an integral part of BP’s bitumen business as a primary ‘enabler’ supporting its customers. All aspects from feedstock selection, bitumen manufacturing, quality control, product application, and asphalt mix design are covered. “We are committed to understanding and quantifying factors that influence product quality and performance of bitumen and end use applications, such as road surfacings”, says Robertus. To improve understanding, extensive rheological characterisation of bitumen and extensive mechanical testing of the end product, the asphalt mixture, are undertaken. For example, understanding the way in which bitumen stiffness changes with temperature is important when designing roads for different climates. It takes one set of characteristics to prevent a road from melting in the heat of a Spanish summer, for instance, and quite another to prevent embrittlement and low-temperature cracking on a Norwegian motorway in winter or on an airport runway in northern Sweden. “It‘s our task to provide the right binder tailored to the local requirements”, Robertus notes.

The new bitumen technology centre, scheduled to open in winter 2008, will serve as the main site supporting the group’s bitumen businesses internationally, with further support coming from existing laboratories at BP’s technology centre in Naperville, USA, and in Altona, Australia.

The work at the new technology centre falls into three key areas. First, there’s the technical support service for BP’s customers. “Some road contractors just don’t have the necessary laboratory equipment, so we run tests that enable us to advise them how to manage their asphalt recipes”, says Robertus. “And if something does go wrong, BP can usually help to track down the reason, such as contamination or incorrect processing of the mixture.” The second area is research and development to improve the properties of bitumen and asphalt and to find answers to tomorrow’s challenges. One such area is ‘recycling’ which is a priority on everybody’s agenda nowadays. An enormous benefit of asphalt materials is that they are 100% recyclable. A PMB product that supports this is BP’s Olexobit RC. It is specifically designed to be used in combination with recycled asphalt materials. Finally, there’s the research to support the bitumen production process, with the laboratory supporting BP’s refineries by developing models to characterise crudes for selecting those which will make good bitumen. “Did you know that not every crude oil can be used to produce bitumen? It’s definitely not just black residue from the refinery to be got rid of. It’s actually a highly technical product”, says BP’s Bitumen manufacturing technology manager, Simon Watkins.

Robertus adds: “The new bitumen technology centre is a big move forward. While the centre will continue to provide technical support to customers at the level they are presently accustomed to, it will also provide a window offering views of the wider bitumen technology network across the globe.” Clearly the centre demonstrates BP’s long term commitment and dedication to support customers solve their problems and explore new opportunities together with them.

About BP Bitumen
BP Bitumen is part of the BP Group of companies and markets bitumen for roads and industrial applications around the world. BP Bitumen has a leading role in development, production and marketing of polymer modified bitumen (PMB) and other specialised products. PMBs are marketed under the brand of Olexobit by BP Bitumen in Europe especially in Germany, France, Spain and Sweden. Technical support is one of the key ‘enablers’ and this manifests itself in, for example the on-site customer support by graduated engineers. The central laboratory is moving to the BP refinery in Gelsenkirchen, Germany – right in the heart of Europe. This new technology centre, scheduled to open in winter 2008, will serve as the main site supporting the group’s bitumen businesses internationally.

Based on an article in BP Frontiers magazine. Click here to view the article in full.