Shell Bitumen is playing its role in a more sustainable future
How Shell Bitumen technology can help play a part in more sustainable paving solutions.
A roundabout to represent circular economy
We’re proud to have reached an incredible milestone of being in business for one hundred years.
At Shell Bitumen we have decades of experience innovating more resource-efficient products and finding new and improved solutions for the road pavement industry. As we look to the future there’s an opportunity to introduce new ways of working which include approaches like the circular economy.
Roads are an important fixture of our landscapes, moving people and goods to where they are needed. To do that well, roads require ongoing maintenance, repair and eventually, replacement.
But what might not be such common knowledge is that asphalt is actually one of the world’s most recycled materials and is a great example of the circular economy in action within the pavement industry.
The increasing interest in asphalt recycling and the use of Reclaimed Asphalt Pavement (RAP) is rooted in benefits that are well-documented. In addition to reducing construction costs, recycling asphalt can also help to conserve resources. For example, impressive efforts in countries like Germany have shown it’s possible to reclaim up to 90%2 of asphalt and use it to construct new roads or to maintain existing ones.
Sustainable construction practices are also on the increase in other countries, as society looks to design waste out of the system and keep products and materials in use. China, for example, has mandated new regenerative systems at all levels in society to reduce waste and increase resource efficiency.
Embracing the circular economy and maximising the volumes of RAP in new road construction is clearly becoming a global priority, but this is only half the story. Sustainable, modern roads must be able to withstand ever-increasing traffic loads, changes in climate and be built with quality and end-performance in mind. This durability is largely affected by the quantity and quality of the binder used in the asphalt mixture.
To meet the increasing demands of everyday road users in a cost-effective and resource-saving way, reclaimed asphalt needs to be used in combination with conventional bitumen, low temperature bitumen, or polymer modified bitumen. However, when using higher quantities of RAP in the asphalt mixture, there are factors that shouldn’t be overlooked.
First, as bitumen ages in the pavement it becomes progressively more viscous, so to achieve the required rheology a lower viscosity bitumen is required. In fact, higher RAP contents will require progressively lower viscosity bitumen in order for the mix to meet the required final bitumen grade.
Greater levels of RAP can also make asphalt mixtures more challenging to compact, which can sometimes lead to increased mixing temperatures, which are less sustainable. Lower mixing temperatures can be achieved by using binders with special additives resulting in reduced CO2 emissions during mixing. The lower temperatures also mean that the surface cools faster, so roads can reopen sooner, reducing disruption for drivers.
Achieving lower temperatures by using binders with special additives
Shell has spent years researching and testing bitumen and RAP blends. The result is the development of a special polymer-modified bitumen, Shell Cariphalte® RC, designed for the application and usage of RAP in high-quality surfacing materials. The product not only improves workability but promotes better adhesion and resistance to moisture damage when compared to conventional bitumen grades, providing greater durability of the finished asphalt.
Used in combination with RAP in base, binder and surface course layers, Shell Cariphalte® RC and other premium products in Shell’s portfolio are being adapted by Shell’s global bitumen R&D centre to render the solutions fit to meet both current and future challenges.
As pressures on road use grow and the circular economy becomes an engrained approach to doing business, contractors, highway agencies and governments will increasingly seek solutions that maximise how effectively reclaimed asphalt is used. The latest technology and bespoke bitumen solutions can already support road constructors in the quest for making sustainable roads more cost-effective, without having to compromise the road’s performance.
Construction worker laying asphalt
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