Two young fish set off in the morning to find breakfast. On the way an older fish swims past and says: ‘Morning, how’s the water?’ The two young fish nod politely and swim on until after a while one turns to the other and asks: ‘What the hell is water?’
The story highlights the nature, and the danger, of a paradigm, and what it means to have a paradigm shift.
Around the turn of the century, the now general manager for bitumen technology at Shell, Professor John Read (who turns 49 this month), asked his research team at Shell a revolutionary question: what other uses could a road have? Which is another way of asking: what is a road? What if the answer was a means of generating electricity, or a source of light or a sustainable urban drainage system? What if the deformation of a road was measured in terms of electrical output not potholes, and the measure of the state of our road network was not governed by a 10-year asset management plan, but a 150-year asphalt recycling plan?
The first generation of smart roads has been in gestation in the minds and research labs at Shell for close on a generation. In Shell and elsewhere – plastic roads in Cumbria for instance or solar roads in France – the concept is now being born. And it is a changing culture more than passing time that has nurtured it to life.
By as early as 2005, Prof Read’s team had developed a system using photochromic pigments in a synthetic bitumen called Mexphalte C [C for colour], which absorbs light during daytime and gives out light during hours of darkness. At the same time his team developed a range of other systems: conductive asphalt for generating electricity using the Peltier effect (see box); ‘Active Asphalt’ for cleaning PM10 particulates out of the air and another system that would remove nitrous oxides.
Prof John Read, general manager for bitumen technology at Shell
Prof Read says: ‘We were going to the market to try and find interest and to see if we could carry out demonstration trials. Everywhere we went there was a very silo-based thinking. We got no joy in the UK at all. By 2007/8, we decided to pull the plug on these products. There was no route to market for us so we withdrew. In the last two or three years we have seen far more joined up thinking by governments around the world.’
He points out it is not just governments that have changed, they have been led by society and its greater environmental awareness.
‘Now is really the right time to relook at these things. Society needs everything we do to have an impact. We have put all these technologies back into our research and development programme. We have had some further thoughts about how to refine them. To make them simpler, quicker to apply, cheaper. Our intent is to run three demonstration projects on Shell sites this year.’
Shell certainly intends to put them through their paces. The technologies will be tested in near desert conditions at its research centre in Houston, Texas, another in the tropical climate at its manufacturing campus in Bangkok, Thailand, and another set will undergo monsoon conditions at its research facility in Bangalore, India.
‘There are theoretical cost savings and income, based on the assumption that the systems last at least as long as an existing road, but because we have not trialled them with real traffic going over them we can’t make a true life-cycle assessment.
‘I would say it will take about two years to know – two full seasons – if the durability is there and see if they stand up under traffic. I would certainly hope that by the time we get to 2020 these are fully commercial products.’
Up and running
Some ideas are up already up and running. Shell has worked with Pavegen, a company that has invented kinetic tiles to capture the energy of footsteps and convert it into electricity. Together they have created the world’s first kinetic and solar powered football pitches in Rio and Lagos.
Shell says the team is now collaborating with Pavegen to help install kinetic tiles in a US city regeneration project.
And the ideas themselves have evolved; for instance the team is developing a road that changes colour when it freezes to warn people of ice. Another idea is for phosphorescent asphalt that can be used to imprint signs on a road.
In Active Asphalt, Shell uses a special fibre to change the polarity of the road surface to attract the PM10 particulates. ‘We also know that if we lay a current through that fibre we can attract those particulates far quicker. In theory the road can send back data. Every passing wheel generates an electric pulse, which could go back to the battery and some telematics, once you have electricity flowing from the connected cell.
‘Lots of damage such as rutting happens at high temperatures, and happens relatively quickly. It would be great if when the road temperature gets too high, the lane sent out a distress signal to divert traffic.’
Another twist on the kinetic paving would be to use the kinetic energy cell to send information about deformities in the road surface.
‘As roads fail and crack you would be able to read higher levels of electrical output. We had the idea that as the electricity started to increase because the road started to fail it would automatically tell the highways authority, so the road itself would tell you it was starting to fail.’
To give you an idea of why a revolution in roads is needed, first picture the sheer size of the world’s network. Prof Read suggests around 2 billion tonnes of asphalt are laid every year, and the number is growing.
‘Utilising waste plastic is absolutely right, or using rubber from tyres as a modifier in the roads, just as we should be recycling as much of the road itself as possible, but they aren’t going to replace bitumen. The volumes required are too big. The industry as a whole supplies 110 million tonnes of bitumen a year and it’s growing. China is still building its road network, India has only just started really building its road network, then comes Africa. If you look at demand, we will need all of these technologies in order to help us meet the demand alongside at least as much bitumen, maybe more.’
Shell and Pavegen's kinetic paving being tried out...for fun
Could bitumen be replaced with a biological material? The answer, like everything Prof Read says on the subject, is a massive eye opener. ‘When anyone talks about “bio”, they think of it being intrinsically safe and good for the environment. We have looked at bio binders, using second generation feedstocks so we don’t impact the food chain. From a rheological standpoint we were able to mimic bitumen. The fact is when we tested the bio bitumen we created it was more carcinogenic than tar. We looked at a number of different feedstocks and different manufacturing methods, we found it much, much more harmful to human health – 10 times as bad as tar, and tar is a thousand times worse than bitumen.
‘In the future I think biochemistry will become very important, not only working in conjunction with bitumen, but also to give us unique properties and chemistries we can’t achieve today.’
Recycling is no panacea
Sadly, Prof Read says recycling asphalt will also not provide a panacea.
‘There is a view, and I believe it is misguided, that you can just recycle asphalt ad infinitum. We have done research that shows it does get to a certain point where you can no longer recycle the material back into the same use. I don’t know how many times, but you can’t do it an infinite number. We need to do some work in this area to make sure that inadvertently we don’t create a legacy problem for the future.
‘Increasing the amount of recycled material is a good thing. In the UK, it’s about 15-18% and most asphalt plants without any modification could quite happily go to 30%, but around the world we recycle less than 10%.
That’s still 200 million tonnes recycled back into asphalt every year; I read somewhere that it is the most recycled material in the world. We could do more and we will need to do more.’
One way to do more is to re-engineer the properties of bitumen itself.
‘I can start to take apart the bitumen. I can model it and I can look at what parts give which properties, and therefore enhance elements. There are about 13 deficiencies we have identified that you commonly see in bitumen. We are working towards being able to engineer all of those deficiencies out. I would say we probably cracked about eight of the 13.’
‘Asphaltenes are the big heavy compounds which we have known for a long time are connected to aging and adhesion in bitumen. Working with IBM, looking at the structures in asphalt and using supercomputing molecular modelling, we have created models of what an asphaltene looks like. It is made up of parallel plates, interconnected by carbonal chains.
‘When you have lots of entanglements of all these carbonal chains the plates can no longer slide over one another, and if they can’t slide you end up with a very brittle bitumen. If you can control the amount of chains and their entanglement you can control the amount the plates can slide over one another, and hence increase or decrease the ductile nature of the bitumen. This is what we are doing at a molecular level.’
Finally, we had to ask, what is the perfect road?
‘For me the ideal road structure would be a thick, structural layer at the bottom to make it a perpetual pavement. This would use high levels of recycled product and a hard modified binder. On top of that I would have a double layer of porous asphalt, a base course and a wearing course. I would make the road essentially a sustainable urban drainage system, a huge reservoir that can absorb water and then attenuate the flow out to the drains. Being porous asphalt it would be very quiet to drive on, it would reduce glare, with no spray. You would plane it out every 10 years and replace it.
‘I would also identify all of the sources of high PSV stones and only use them in the surface course, making the roads safer, so we get very good micro and macro texture in both dry and wet skid resistance.’
After all these years, we need to ask the question more than ever – what is a road? Shell is starting to answer that question in new and incredible ways. For now we can say the answer is, it’s changing. Our roads are changing.
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