Lógica simbólica

The bituminizes is a substance made up of a mixture of Hydrocarbure S, very viscous (even solid) with the room temperature and of color Noir E.

Industrially the bitumens are manufactured starting from crude oil from where one extracts, au préalable, the lightest fractions. Remaining part, consisted viscous oils, one separates the bitumen with desired hardness. Certain varieties are prepared starting from a filler cracked, others are obtained by oxidation “blowing”.

In the language running, one often confuses it with the Goudron of carboniferous origin , or with the asphalts of which it is only one component.

More generally, the bitumen indicates any mixture of Hydrocarbure S extracted the Pétrole by Fractionnement which, in form pasty or solid is liquefiable hot and adheres on the supports to which one applies it.

Introduction

The bitumen, known since highest Antiquity in natural form, comes, nowadays, almost exclusively of the distillation of crude oils.

Its physical and chemical qualities made a material of very first importance of it.

It has a great agglomerating capacity because it adheres in the majority of usual materials: hone, concrete, wood, metal, glass.

It is an excellent heat insulator and dielectric.

It is light, ductile and flexible. From the mechanical point of view, it behaves like a plastic or elastic material.

It is insoluble in water, but one can obtain from them solutions in many organic solvents. It is practically inert with respect to the majority of the usual chemical agents.

Its not very current properties and the complexity of its composition initially resulted in introducing empirical tests intended to locate the various varieties obtained, but the importance and the multiplicity of the applications which are made by it then brought producing and users studied it more completely.

The modern means of investigation made it possible to analyze the influence of the composition on the physical properties and to be thus directed worms of qualities meeting the user's needs better. The study of the viscoelastic properties made it possible to include/understand the significance of empirical tests used hitherto and to connect them to basic concepts. It also allowed the calculation of the mechanical behavior of the bitumens as well as that of other construction materials, such as the concrete or metals.

It is known that the bitumens are industrially manufactured starting from crude oils from where one extracts, au préalable, the lightest fractions. Remaining part, consisted viscous oils, one separates a bitumen from desired hardness. Certain varieties are prepared starting from a cracked filler, others are obtained by oxidation (blowing).

Physicochemical structure

The bitumens are mixtures of hydrocarbons has raised molecular weight being able to belong to the three following groups:

The group Oléfinique is meeting in certain cracked bitumens.

The use, like selective solvent, of a light hydrocarbon in great excess, makes it possible to split a bitumen in two parts (The properties off Asphaltic Bitumen, J.Pfeiffer, Elsevier).

  • the dissolved part - the Maltènes - with the aspect of a viscous oil of dark color;
  • the precipitated fraction - the Asphaltenes - is consisted bodies of very high molecular weight being appeared as a solid substance and noirâtre.

There is no discontinuity between maltenes and asphaltenes, fractionation obtained depend on solvent employed. One a long time used the ether of oil, now replaces by the normal Heptane.

It is noted that the maltenes behave like a perfectly viscous fluid (Newtonian fluid). The presence of asphaltenes confers on the bitumens index properties of the colloidal state.

Asphaltenes tend to absorb the aromatic fraction heaviest of maltenes and thus form complex corpuscles - the Micelles - which are in suspension in a continuous phase formed by maltenes of low molecular weight.

If the maltenes contain sufficient aromatic so that absorption powers of asphaltenes are saturated, the micelles are completely mobile in the middle of the dispersing phase: they are peptisées. The colloidal solution is then with the state of ground.

If there are not sufficient aromatic, the micelles, attract each other; mutually, become less mobile and form a network in the middle of the phase intermicellaire This structure, which confers on the bitumen elastic properties, is indicated under the name of freezing.

Use

One uses practically the bitumens thus prepared in three different forms:

  • such as they are;

  • in the form of cut-backs: cut-backs cut-back by addition of solvents birds;
  • in the form of aqueous emulsion or emulsion of bitumen.

The combination of these various processes makes it possible to obtain a very wide range of products being able to fulfill the varied requirements of very different uses.

Mixed with fine elements (as sand), it is used like joint-sealing compound in the building or the Civil engineering.

Antiquity with the Industrial revolution

It was known at that time, for this use (sealing), under the name of “Bitume of Judaea” in particular of the Égyptien S, Hebrew X and Sumériens because there existed in a natural state on the edges of the Dead Sea (but also of the Caspian Sea). It had already multiple employment:
  • Binder;
  • produced pharmaceutical S - being used in particular for the conservation of the Egyptian Mummy S - and cosmetologic S;
  • but especially, and this in all the Mediterranean basin, with the Caulking of the ships.
  • It is also thanks to the Bitumen of Judaea that Nicéphore Niépce will invent photography with Saint-Wolf of Varennes in 1824. (http://maison.niepce.museum)

In 1627, a letter patent authorized its commercial exploitation with Pechelbronn, in Alsace, of a source which produced a “stone oil” considered for its therapeutic properties. In 1741 was made up the first oil company of the history, to exploit beside the source a vein of bituminous Sable from which one drew a grease ready to replace the “old COInG” and tallow. The king Louis XV, conscious of the interest of this exploitation, entrusted it by letter patent of the August 5th 1772 to certain the Beautiful one. This company will create Antar in 1927.

Nowadays

In road construction , it is used as binder for the realization of materials coated hot , such as the asphaltic concretes or the serious S bitumens. It also enters the manufacture of surface dressings in the form of emulsion or fluxed by a Solvant.

The physical characteristics of the bitumens are generally described by various parameters of which the temperature of softening (the " method ball-anneau" or the method Kraemer-Sarnow) and the Hardness (method of the Penetration).

All the bitumens are entirely dissolved by the Carbon bisulphide.

The bitumen is transported at sea on the Bitumier S.

Research and development

In 2007, the Arkema company presented an additive, which, mixed with the bitumen, makes it possible to decrease by approximately 50°C the temperature to which the bitumen is run, thus improving the conditions of handling of the personnel. Its main advantage lies thus in the harmful energy saving and the reduction of the gas emissions (mainly the Carbon monoxide, with economies being able to reach the 50% compared to an installation using of the traditional bitumen. According to Arkema, the use of this additive on the whole of the infrastructures of the European territory (estimated at 350 million tons of bitumen per annum) would allow a saving in 700.000 tons of fuel each year, which represents the yearly consumption in heating of a town of 2,5 million inhabitants (example of Paris). On the environmental level, it would be an abstention from emissions of 1,8 million tons of Carbon dioxide in the atmosphere.

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