This overview article, written by Mr. Alain Le Corroler, Chairman of the International Bitumen Emulsion Federation, aims to present a picture of the current European market of Bitumen Emulsions.

1800 years ago, GALIEN prepared the first ever man made emulsion : it was for a cosmetic application.

17 Centuries later, Europe became also the birthplace of Bitumen Emulsion.

As soon as 1902, a Swiss physical doctor and an early environmentalist, put together an association aimed at promoting the coating of road surfaces with hydrocarbons along the Mediterranean shoreline of Monaco and organised an international Symposium on that matter ; the purpose of this early surface dressings was to stabilize the dust produced by the traffic ; these hydrocarbons were emulsified using a soap based on ammonium. The first production of bitumen emulsion in a dedicated plant was made in 1905 in Elsass, in the city of Lutterbach by a chemist named Emile FEIGEL.

However, significant utilisation actually started during the end of the Twenties with the process patented by a British chemist, MAC KAY, in 1922. This patent defined the anionic emulsion and deposited the Trade Mark : Cold Spray which was modified into COLd ASphalt in 1925, and later on contracted into COLAS. Another significant breakthrough was the development of cationic emulsion initiated by ESSO in France in 1951.

Since the first years of emulsion utilisation in some countries, the tonnage increased steadily over Europe and, with the exception of a set back during the last years in some countries, is still developing after 70 years of history. This is not matched by any other technique and is due to the versatility of emulsion which allows it to adapt to the variations of the demand as this is illustrated by the table below, describing the French example of application variations over the last 30 years.

Europe still occupies a prominent position in the use of bitumen emulsion, since 5 of the 10 major producing countries are located in this continent (see table below).

BITUMEN EMULSION CONSUMPTION IN MAJOR EMULSION PRODUCING COUNTRIES

Some other European countries produce a significant amount of bitumen emulsion such as: Portugal (86.000 T) - Turkey 85.000 T) - Sweden (70.000 T) - Netherlands (30.000 T) - Austria (23.000 T) Belgium (20.000 T) - Denmark (20.000 T) ; very little information is available from Central Europe where the use of bitumen emulsion is still limited but very likely to develop fast. Among the European countries, one of them has a very specific position, FRANCE, where about 50% of the total production of the continent is manufactured and used.

Such an extensive utilisation needs to be explained. The first reason probably lays in the structure of the French Network which comprises a larger amount of secondary and rural roads, 1.300.000 km's or 75% of the total length, aimed at serving every corner of the French Territory, even though the traffic level may be very limited on most sections. It was therefore a necessity to develop reliable, flexible and non expensive techniques to pave these roads, hence the extensive use of penetration.

Now, that most roads in this category are paved, it is necessary to maintain them, while keeping in mind the same objectives of cost limitation, efficiency and flexibility. Of course, surface dressings made with emulsion perfectly match this requirement while on the limited length of these road sections which still require rehabilitation or new construction, an intermediate solution was developed, consisting of three layer surface dressings on top of an unbound crushed aggregates base course while grave emulsion is used for reprofiling deformed old pavements.

This experience gained by French contractors and road authorities on these secondary roads led them naturally to extend the use of bitumen emulsion to roads bearing higher traffic levels.

This new field of application required the development of more sophisticated techniques such as the use of polymers or of fibres and a better definition of the mix formulas, dosage of binder and grading of aggregates. This in turn, was made possible, thanks to the second reason behind the development of emulsion in France : a confident co-operation between engineers from the private sector and from the authorities. This is illustrated for instance, by the procedure enforced for delivering the technical agreements of proprietary products developed by French contractors ; as a matter of fact, these agreements are delivered by a joint committee grouping the same number of engineers from the road authority and from the private sector.

Common actions were also undertaken to develop the knowledge in some specific fields, such as the signing in December 1996 of an agreement between the directorate of roads and the association of road industries (USIRF). This agreement is aimed at developing a method for characterising the behaviour of cold mix asphalt for base courses. This method will be established from jointly operated laboratory research, execution of test sections and measurement carried out on these test sections to be correlated with the lab results. The final target is to define tests relevant to cold mixes which will make it possible to determine the formulation and dimensioning specific to these materials mixed with emulsion.

France is already familiar with such co-operation agreements, which can be signed on an international basis, such as the "Protocole Franco Suédois" called SAMARBETSSAVTAL - MELLAU for a research program on "grave emulsion", another family of cold mix. This contract was signed in Stockholm on 13 June 1996 by the Swedish director of Roads on one hand and by the chairman of USIRF and the French director of roads on the other hand. The French part of this agreement is operated jointly by the association of French road contractors and the LCPC (Central Research Laboratory of the Road Authorities).

Let us now consider the current trends in terms of techniques used in Europe :

The percentage of emulsions used for Surface dressings is usually high in countries producing a large quantity of Emulsion, considering the country's size :

• United Kingdom 75%
• France and Germany 60%
• Spain 55%
• Netherlands 50%

Potential development of the emulsion market can therefore exist in this field of application, particularly in countries where a large network of secondary roads exist requiring reliable versatile and non expensive paving techniques. However, newly developed binders, such as polymer modified emulsion and controlled breaking emulsions now allow using surface dressings on pavements supporting higher traffic levels. This tendency is still enhanced by the implementation of modern surface dressing structures such as racked in or sandwich surface dressings, beside the traditional single course or double course.

These modern structures help better adapting to various kinds of substrates.

A good example, which also illustrates the versatility of the emulsion techniques, is given by the French market, where in 30 years, from 1967 to 1997, the percentage of emulsion used in surface dressing rose from 30% to 60%. This is due on one hand to the shortage of funds available for road maintenance, which led to replacing some asphalt overlays with surface dressings and to the other hand, to a lesser interest for penetration on secondary road network, which tends to be replaced with three course surface dressings.

Another technique, "Tack Coat" is becoming more and more popular as the wearing courses tend to become thinner and thinner. In most European countries, the percentage of emulsion used for this application ranges from 20 to 30% from one country to another with only a few exceptions, firstly in countries such as France, Spain and The United Kingdom where the extensive use of surface dressing limits the percentage of emulsion used for Tack Coats to about 15% and secondly in Italy where the market of emulsion does not seem to be as much developed as in neighbour countries, and where emulsion is almost exclusively used for Tack Coats (85%).

"Slurry Surfacing techniques" occupy a specific position on the European market. They represent a significant proportion of the emulsion production in only a few country (Belgium 30% - Germany 17% - Portugal 13%) and only of the order of 5% in the other major European Slurry Surfacing Countries(France, Italy, Spain, United Kingdom).

However, if we consider the surface laid, the situation becomes different in term of absolute quantities.

Spain ranks first with 18 Millions Square meters laid last years, followed by Germany and France with about 10 Millions sq.m and Italy, Belgium and the United Kingdom with 5 Millions of square meters each.

Theses figures can be compared with those corresponding to the largest markets outside Europe, with the exception of the United States which stands far beyond every other country ; the production of Spain is almost equivalent to that of Brazil, while France and Germany can compare with Mexico, Thailand or China.

In Europe, during the last decade, the use of Slurry Surfacing shifted globally from slurry seals to micro-surfacing. In the same periods, countries like France where most applications took place in urban environment, more and more apply micro surfacing on pavement bearing a high traffic volume such as motorway's which was already the case in Germany. It must also be noted that this market is not stable and does not move consistently from one country to another.

During the last five years, the German market almost collapsed, being divided by two, while the French market doubled and the Spanish market first rose by almost 50% in three years, before dropping back to its initial level.

Cold mixes also represent a significant part of the emulsion market but very variable from a country to another (3% in Germany, 5% in Italy, 15% in Spain, 20% in France, 43% in Portugal) ; this category in fact covers several different technologies among which open graded storable cold asphalt for patch working, combined cement/bitumen emulsion mixes, "Grave-Emulsion" and dense graded cold asphalt for wearing course. The two last categories deserve a special mention :

• "Grave-emulsion" was first developed in France where it is still a very popular technique and is now subject to a standard which considers three grades ; these grades are related to the formulas and field application (routine maintenance, reprofiling, or base course material) grave-emulsion is now currently used in several other countries.
• Researches are currently being carried out in several countries, mainly France and Spain, to develop reliable techniques for dense graded cold asphalt to be used as wearing courses. These researches look very promising and it is likely that in not too remote a future, this will become in some cases a valuable alternative to hot overlays. The cold process will then provide the advantages of a lower energy consumption and of complying more easily with the demands related to the preservation of environment.

Among the many other techniques, a special mention must be made to "Cold Recycling" (in stationary plant, or in situ) which also seems to be a very promising alternative in a world where the natural resources of materials tend to become scarcer.

While "Cold Recycling" is widely developed in the United States, it however does not yet correspond in Europe to more than a few percent of the total emulsion production in these country where it is being significantly developed : France, Portugal, Spain, Turkey (where it reaches 10%), United Kingdom.

To conclude this article, the fact is pointed out that the development of bitumen emulsion based applications in Europe, led to the definition of efficient European Standards by the CEN TC19/SC1/WG3 (16 standards available, 3 under completion) plus two standards available and 2 under completion by CEN TC227/WG1/TG1 (surface dressings) and 2 available and 2 under completion by CEN TC227/WG1/TG2 (slurring surfacing).