Summer vacation roads, Tour de France roads, country roads…, France’s road network spans almost one million kilometers. Except for freeways and highways, virtually every road is constructed and maintained using bitumen emulsion techniques (see definition), i.e. a liquid blend at ambient temperature (between 20°C and 70°C) instead of traditional molten bitumen (between 140°C and 170°C). And the manufacture of this bitumen emulsion that makes up road surfacing requires emulsifiers: this range of additives is manufactured by CECA and sold under the tradenames Dinoram®, Polyram®, Stabiram® and Emulsamine®.
Less energy and greenhouse gas
The benefits of bitumen emulsion are that it can be custom-manufactured, and requires no heating equipment on the road construction site. This emulsion can be stored and used a few days after manufacture, which makes for more flexible working. Finally, a road that has been renovated using bitumen emulsion can be reopened to traffic virtually immediately. With no smoke and no dust, the emulsion technique, light and easy to apply, is therefore highly suited to small road construction and maintenance sites.
Ecologically speaking, bitumen emulsions (or cold techniques) offer a raft of benefits compared to the hot bitumen process. First of all in terms of energy consumption: to manufacture one metric ton of hot aggregate (blend of bitumen and gravel of a certain size), you need around 700 megajoules of power, whereas to manufacture the same amount of aggregate emulsion, i.e. cold, requires around half the energy. Furthermore, the manufacture of one metric ton of hot aggregate bitumen releases 50 kilograms of greenhouse gases into the air, whereas the preparation of one metric ton of aggregate emulsion releases a mere 30 kilograms ! Additionally, the emulsion technique makes for easy recycling of road materials and hence easier reuse.
CECA’s asset: technical support
CECA, however, is not just about manufacturing and selling emulsifiers. "The technical expertise, the know-how which we offer our customers help them develop their activities. This in turn generates new demands upon CECA, explains Guillaume Legouis, in charge of the activity. "Technical assistance is now the added value which helps CECA conquer new markets."
CECA surfaces the roads of the planet
Although CECA sells its additives around the world, China and the United States are the countries that will generate its growth.
On the other side of the Atlantic, the authorities are gradually coming to realize that a road prevention and maintenance policy is preferable to the major refurbishment work needed when roads have to be taken out of service. In this field, CECA works in partnership with an American laboratory in charge of finetuning the additives’ formulations to customers’ requirements.
Another approach has been adopted in China, whereby CECA has opted to set up its own laboratory. Indeed, « the Chinese road network is in full construction. As local companies are not familiar enough with techniques using bitumen emulsions, we are bringing them our experience », explains Jean-Marc Lefebvre, Development Engineer in charge of road additives for Asia.
CECA is not satisfied just with the ecological benefits of bitumen used as an emulsion, as the company is now involved in developing additives for hot bitumen; the objective is to reduce manufacturing temperature, and therefore cut down the quantity of energy needed, as well as the emission of greenhouse gases resulting from this technique, which still prevails on road construction sites around the world. After bitumen emulsions, CECA is also intent on making hot bitumen more ecological, a market with a promising future.
The event that triggered the renovation of France’s road network… a particularly harsh winter.
Following the particularly severe winter of 1962, almost 80 % of France’s road network had to be repaired. Since then, France has undertaken a preventive renovation policy for its road network: the idea is not to wait until the road has deteriorated irreversibly before taking action, but to carry out constant maintenance work. This prevention policy is unique in the world, and has allowed the country to take the lead in cold techniques. And yet this technique is not new, as « the first bitumen emulsion patent dates back to 1922 », comments Serge Roncen, Development Engineer in charge of bitumen additives for Northern Europe.
Road = 5 % bitumen + 95 % aggregate< /STRONG >
Bitumen is a material that has been used since Antiquity. It consists of hydrocarbons and their nitrogen, sulfur and oxygenated derivatives, residues from the distillation of oil. It has now become the most cost-effective material for road construction. It helps bond the aggregate into road surfacing. Its sought-after qualities include adhesion and cohesion.
Take the example of a road’s top layer: the bitumen has to be liquid to be applied and to allow the aggregate to adhere to the highway foundation. To this end, two techniques are available: you either heat up the bitumen above its melting point, or you manufacture a bitumen emulsion. In the latter case, the emulsion is laid onto the road. For the blend to adhere to the aggregate, the emulsion has to be broken down, i.e. all traces of water have to be removed. This is achieved through compacting.
Emulsion
A bitumen emulsion is a dispersion of bitumen in water. However, in the same way as water and oil do not mix easily, water and bitumen together do not get on. To produce a bitumen emulsion, you therefore need to add a chemical substance which will promote the blend and especially make it stable: this is an emulsifier. This additive helps impart the same electical charge to every bitumen particle present in the blend. As a result, the particles repel each other evenly, and this in turn ensures a stable and fluid blend.
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