A green store of great value

Nynas Bitumen’s Steve Harris explains how one of the most sustainable of all construction materials has always been beneath our feet and the wheels of our vehicles.

“The asphalt sector focus, up until now, has been on developing more environmentally friendly products”
-Steve Harris

Asphalt has high sustainability credentials, higher than any other paving material, despite containing oil-based products. Despite its predominately black colour (although for years it has been available in almost any hue), asphalt has always been relatively ‘green’ in an environmental sense. As a result of efforts across the asphalt sector, it is getting greener still.

The recognition that sustainability has to govern the world’s approach to how its raw materials are used is forcing fresh appraisals of all construction materials and techniques.  But all industries are still struggling towards definitions of what precisely sustainability should mean for them; early blunt measures like carbon content are being jettisoned for more sophisticated approaches recognising that sustainability has social and economic as well as environmental implications.

For roads and other paved surfaces this includes making roads and the products that go into their creation as environmentally friendly as possible. This is being done through all the measures that would be expected, such as careful design, development of longer lasting new products, and continuously lowering emissions in the manufacturing stages. There have been numerous examples of sustainability improvements over the years from both the individual company level and from across industry co-operation.

The social and economic factors that enter the sustainability equation include recognising that roads are needed for efficient operation of modern economies, that they permit a multitude of other environmentally beneficial activities to take place.

The problem in coming up with a definition of sustainability and just what targets manufacturers and contractors should aim at can be seen in the lack of agreement on which parameters should be included in a sustainability assessment, and the relative weighting to give to the environmental, social and economic factors. There are sometimes conflicting pressures – within the European community there are national governments calling for major reductions in carbon emissions as strategic goals, with local authorities placing more value on social aspects.

The asphalt sector focus, up until now, has been on developing more environmentally friendly products. Among the technical advances made in recent years are quieter road surfaces, more durable surfaces, low temperature asphalts, skid resistant surfacing and cold mix designs already allow a reduction of some 30 percent in the energy used in manufacturing and the industry will continue to improve on that. And, as climate change occurs, products better able to cope with particular conditions are already available.

It is now possible to take advantage of the temperatures generated on road surfaces by the sun to heat water. There are existing development projects where water stored in tanks under roads can be heated by sunlight, cutting CO2 emissions by 50 percent compared to conventional heating systems, minimising the use of environmentally damaging salt to combat icy roads. Environmental concerns are possibly the most important but not the only parameter to define sustainability. 

The most obvious sustainability plus is that asphalt and the bitumen that coats most of it is infinitely recyclable – no asphalt product need ever be sent to landfill, and it can easily be re-used over and over again as it will always have a value because of its stone and bitumen content. The technology to use recycled material is well understood, readily available and proven on numerous projects. So all of the asphalt currently in use across the world can be looked on as a store of value for future generations.

There are other sustainability related factors to consider when choosing between asphalt and an alternative surfacing material, and when choosing between different asphalt products. For example, asphalt scores very high on durability measures and it is known that extra upfront investment can bring the benefits of long life pavements. These will use hot mix asphalts, but the extra years of in service life far outweigh the energy used and emissions generated.

Steve Harris is a civil engineer who originally studied concrete technology and soil mechanics. However, during his 30-year career within the construction industry he has specialised in asphalt engineering, including pavement design and bitumen technology.

Over the last 10 years he has branched into marketing now working as the Product Strategy Manager for Nynas Bitumen. In this role Harris is responsible for co-ordinating product related strategic development across Nynas’ European business.