METHOD OF INCREASING DURABILITY OF ASPHALT ROAD COATING

AND BITUMEN MASTIC

Background of the Invention

Various mechanical defects arise in the layer of asphalt on a road during exploitation. These defects are cracks, rifts, potholes, stripping and other non-uniformities of an asphalt cover.

A prevalent opinion is that the essential reason for the destruction of the asphalt covering upon the road is influenced by ultraviolet sun radiation. This author has calculated and has tested that ultraviolet light does not penetrate into depth practically more than one millimeter. Therefore, it cannot destroy the asphalt (or so-called asphalt- concrete) layer on a road, a thickness which is not less than several centimeters. To say the least, it cannot be the main reason for the asphalt coating destruction.

It has also been suggested that one of the main reasons for the asphalt-concrete destruction on roads is mechanical forces influenced by transport. In fact, asphalt- concrete destruction is apparent on a road with very intensive car motion, particularly if there is not enough qualitative base of a priming layer under the asphalt cover. However, it has been noticed that asphalt cover destroys quickly enough on roads with a low intensity of car motion, and also degenerates on roads with a full absence of car motion.

Presently, the basic way of increasing the duration of the asphalt surface is the repair of it by putting paths of a fresh material, via filling minor defects with bitumen sealant, or by melting the top layer of the covering. However, all these methods are connected with significant use of manual labor, are expensive, insufficiently effective and worsen conditions for moving transport. A mechanical milling process for the upper cover, in which the removal of the upper layer and replacement of it with new material is often used at this time. This is an expensive process requiring applications of large amounts of fresh asphalt.

A sealant compound containing a natural binder, bitumen for example, is known and often used in construction and in industry in order to make, for example, a watertight roof. The same problems occur with this material as described above for asphalt- concrete. Similar methods are used to repair the material as in the asphalt-concrete application. Sealant compounds made on the base of synthetic polymers which are more expensive are used instead of the cheap, but short-lived bitumen sealant compound.

DISCLOSURE OF THE INVENTION

The author of this proposed application has discovered the following: the influence of microorganisms is one of the basic reasons for the asphalt mechanical destruction on a road, especially in warm climates. There exist different microorganisms, which are able to successfully live in an asphalt covering, consume bitumen and destroy it. Regarding the protocol of asphalt research samples,

made in a biotechnological laboratory under the instruction of the author, it has been concluded: "On the basis of preliminary examination results it is possible to affirm that microorganisms are capable of taking part in the process of degeneration of bitumen and of asphalt."

The efficiency of the proposed method was tested by experiment. Destruction of the bitumen was found in samples, which were placed during some months during environmental action on a road. Signs of destruction of bitumen were not found in the same samples, which were placed in the same conditions, for the same period, when an additive of a proposed agent was used.

To endure the lifecycle of a road coating comprising a mixture including bitumen, a stabilizing agent with disinfectant (antiseptic) action is proposed to be added into the mixture. The mixture may be asphalt-concrete, for example, and this asphalt-concrete will be used for covering a road.

An additional hopper with weigh feeder can be established in an existing technological line of an asphalt plant. The additive agent can then be filled in a granulated or powder form into this hopper. A weigh feeder evenly submits it into a kiln-mixer (rotary inclined furnace) existing in the plant, where it is mixed with sand, crushed stones and other fillers (components) and is dehydrated by heating with existing technology.

The additive agent must be heat-resistant since during this process a very high temperature is used (about 1000 ⁰ C), and under the influence of heat the additive may be destroyed and lose its' antiseptic properties.

The additive mixes with the fillers of asphalt-concrete. Some amount of the additive adheres to the granule surfaces of the filler. The small particles of the additive, which did not adhere to the filler, rise with streams of hot air and get lost. Therefore, it is reasonable to use an additive with effective adhesion to surfaces of the asphalt- concrete components. It is better to use any suitable substance in order to improve the adhesive properties of the material and/or the additive.

After this process is completed, fillers wrap around and are mixed in with the melted bitumen in a blender using any existing technology. Thus, all fillers and additives are enveloped by the binding of the bitumen and cling together in clots.

The prepared hot product (mixture) is then transported by trucks to a place of work on the road, spread out in road and rolled down. The clots of the mixture stick together during the process, and generate almost a monolithic layer. This mixed material also contains the disinfectant (antiseptic) additive.

Bacterium, mould and other microorganisms from the environment settle down into the asphalt layer (asphalt-concrete). Some kinds of microorganisms can consume the bitumen binding and destroy it. The fillers (sand, macadam, etc.) loose mechanical

connection with each other, and the asphalt-concrete disintegrates into mechanically disparate and separate components. By contrast, the said added component oppresses the microorganisms; and the disinfectant (antiseptic) additive defends the material. Hence, durability of the road asphalt-covering is increased.

Vital activity of microorganisms is actuated in the presence of water. Water simultaneously dissolves the disinfecting additive from bitumen, which has been destroyed by the microorganism, and places it in the location of the microorganism colonies. It kills the colony. Therefore, it is reasonable to use the additive as a soluble in water. The disinfecting additive is closed by bitumen in undisturbed places and so does not enter the surrounding area.

Copper sulfate (Cu SO ₄ ) is the most acceptable disinfectant additive material because it is cheap, very highly heat resistant and simple to use. The minimal effective weight of concentration of copper sulfate can be about 0.0001% to suppress microorganisms. Despite this fact, a great part of this disinfectant agent is hidden in the material and does not participate in the suppression of microorganisms in the event of a defect, in a crack filled by water, for example. Therefore, the concentration of the agent should be much more, until 2% protected material weight.

These processes are also expedited with the use of other additive agents using disinfectant (antiseptic) action. For example, antibiotics, fungicides, salts of heavy metals and other disinfectant substances in content proportional to their disinfectant

action, in relation to specified copper sulfate can be used. The basic requisite properties for the agents are efficacy, affordability, heat resistance, water solubility and long life terms.

If the stabilizing disinfectant agents by grinding it to a dry power is too complicated, it may be more practical to add it to the kiln-mixer in the form of a solution, suspension or emulsion. The same conditions exist in this case to use the stabilizing additive agent in small quantities. A liquid is made with the agent. Then one, several or all fillers are moistened. After this, the component is loaded into the existing kiln- mixer with the help of the weigh feeder. It is necessary to install an additional metering pump in the technological line before a filler hopper, or before the kiln- mixer stage in order to complete the process.

If the additive is not heat resistant to bear temperatures in the asphalt plant's kiln- mixer, then it is expected to utilize it after the kiln-mixer stage. The blender for fillers and bitumen in the existing plant is the optimum equipment for this operation. The temperature of the bitumen is 160 ⁰ C, fillers are entered in after hot drying and also have a high temperature - about 250° C. Therefore, the additive must stand the temperature. The additive is milled as much as possible into a fine powder to make the mixture more homogeneous. Water can bloat bitumen in the process of asphalt- concrete manufacture. Therefore, the additive has to be dehydrated by heating or chemically.

The same additive disinfectant agents can be loaded into a bitumen compound. The finer the powder, the more accessible the additive becomes. Then this powder is uniformly added to the bitumen, which has been warmed until it is in a fluid condition, and this admixture is carefully mixed. It is essential that the material has potent adhesive properties.

Another possible method of introducing the additive into the bitumen is to mix additive solutions with the bitumen. The additive is diluted in a solvent and mixed with bitumen. Afterwards the solvents usually evaporate, but the additive remains in the protected material. Lesser heat resistance is required in such a process, but an ability to dissolve in a substance compatible with a solvent and bitumen is an essential characteristic.

This method can be used for prolongation of the service life of materials £road coatings) which are already in use. Destruction of existing asphalt road coverings begins with the location of cracks and potholes. In these places, fixed settlements of gradually expanding microorganisms begin to destroy all of the covering. In order to preserve the covering, additive disinfectant material is loaded in the places where the beginning of deterioration has become apparent. A powder of the disinfectant additive material is dusted or sprayed, or the location can be moistened with the disinfectant liquid material. If necessary this place is left to dry. After this stage takes place, the defect is sealed with new melted material, for example bitumen, or

alternatively the surface layer where the additive was added is melted down and resolution of the defect is completed. In these ways, minor defects can be resolved.

Specified operations of repair also allow the disbursement of the component in small amounts; to fix the additive material in the necessary place; and to prevent its' release into the environment. The same procedures are applied for repair as the bitumen compound begins to collapse.

The proposed method can be applied in those cases when a factory is not equipped with devices for the loading of the disinfectant additive material in a mix during its' manufacture. In this case, it is necessary to lay this additive between layers of asphalt during its' stacking, for example, and place it on the surface of the first asphalt layer before the stacking of the second layer. Such use of the additive is less effective in the defense of imminent destruction of the asphalt, but it is better to proceed with this method, instead of leaving the asphalt without total protection. It is similarly possible to introduce the additive between layers of bitumen compound, and other materials containing organic components.

There is also proposed a mixture (a composition) including asphalt and/or bitumen for coating surfaces, wherein an additive having a property of suppressing development of microorganisms is added into the mixture. A number of variations of components, proportions and ways of preparing the mixture are described above with reference to the proposed method.

INDUSTRIAL APPLICABILITY

All transport roads asphalt/bitumen covering technology, and other techniques for coating surfaces with asphalt/bitumen mixtures can benefit from the proposed efficient use of the inventive mixture (composition), and the method of introducing the additive into a mixture for road coating, as well as for developing other technologies for the transport roads asphalt covering, roofs/walls covering, and the like.