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Cold calling

Roads Profile

One of Britain's leading experts in environmentally friendly cold mix asphalt technology is Jean Walter, a Frenchman with distinct American tendencies.

Where others lead in pavement materials design and production, the UK tends to follow. High tech thin surfacings for example, so successful on British roads, have their origins mainly in mainland European research and development. Technology transfer has been mainly one way but this is likely to change, specifically in the area of cold mix asphalts.

'My remit is to help establish a European centre of excellence in cold mix technology in the north west of England, ' says Jean Walter, a Frenchman whose masters degree in civil engineering comes from the Oregon State University.

'I see no irony in my role. If I can help the British reverse the flow of pavement materials knowledge, then that is good for my company.'

Walter works for Nynas Bitumen, a Europe-wide bitumen specialist with a strong UK operation. It is within the laboratories of Nynas' Eastham refinery near Liverpool that Walter is endeavouring to build on an existing body of cold product and process expertise, and focus this 'further downstream' to concentrate more on end user needs.

'Cold mix systems are entirely sensible, ' he says.

Asphalt mixed and laid cold, or at least cool compared to conventional hot mix asphalt, has a lot to commend it, both environmentally and from a safety point of view. For starters, it requires less energy to heat and lends itself to recycling old pavement.

But the mechanics of cold mix are very different to those of hot mix. 'The aggregate and bitumen binder together do not work in the same way. And the binder is particularly complex, polymer modified for strength and also emulsified to temporarily maintain viscosity.' Making sure the binder emulsion 'breaks' - ie the water evaporates properly - completely and at the right time to set the mix, is also a complex matter, he says.

Because of this, people in Europe are wary of cold mix asphalts and their use has never really taken off, despite official European Union encouragement. Nynas has 'a very nice family' of emulsions and a lead over many competitors.

'But we need more knowledge to advance the processes.

We want Nynas UK to become the company in Europe which leads the way, to where the applicators and users of asphalt can turn for problem solving and developing leading edge products.'

So Walter is a man with a mission. His interest in civil engineering, and road building in particular, began in adolescence when he helped gain access to a remote farm near Poitiers which his parents, teachers in Paris, acquired in search of the good life in the late 1960s.

'We built a 2km long drive to the farmhouse, me, my father and his tractor, ' he says. Gravel was used to smooth out the path over rock and across soft clay, the tractor's wheel tracks filled with loose stone from the fields.

'Some years later, after a materials lecture, I wrote to my father from university that we could have made a much better job of it by obtaining hydrated lime and ploughing this in, to bind the stone.'

He read civil engineering at Poitiers University and following a summer spent in the US after graduation, applied to the Oregon State University to do a masters in pavement technology. This majored on structural design, materials mix formulation, surfacing technology and stabilisation techniques.

'Stabilisation was of great interest to me. In the US they tend to build their roads with whatever materials are to hand locally, a bit like my father and me at the farm. They make the materials work.'

Walter spent most of his twenties in America, returning to France to work in the international department of construction and materials giant Screg. He soon found himself back in the US, however, prospecting for partners to market Screg-developed polymer modified products.

He returned to Paris, later working with Exxon Chemicals as a consultant, before moving to Toronto in Canada and then spending time at Quebec's Laval University. 'Most of my work related to polymer modified bitumens and cold mix, ' he says.

'I had some success in developing and marketing cold in-place recycling, helping create a boom in this technique in Toronto and Ontario.'

Back in France last year on sabbatical, he heard of Nynas' plans for a centre of excellence in Eastham. 'It sounded just what I wanted to do.'

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