MODELS AND METHODS IN MODERN SCIENCE
International scientific-online conference
16
THE USE OF BITUMEN-EMULSION COMPOSITES IN ROAD
CONSTRUCTION OF THE REPUBLIC OF KARAKALPAKSTAN.
Abdikadirov Polat Urazimbetovich
senior lecturer.
Allanazarov Sharibay Bekanovich
senior lecturer.
Republic of Uzbekistan, Republic of Karakalpakstan.
Karakalpak State University, Nukus.
https://doi.org/10.5281/zenodo.13284599
Summary:
The article presents. Device for treating road surfaces, using
thin-layer coatings, preparing stable bitumen emulsions.
Key words:
protective road surfaces, bitumen emulsions containing Ca O
in mineral lime powder.
To ensure the safety of vehicles on high-category roads, it is necessary to
have high protective layers of road surfaces. The top layers of the road surface
ensure the smoothness and roughness required, and protect the road surface
from the penetration of water into the road surface.
Stops destruction and extends the service life of old coatings that have shown
signs of wear in the form of cracks, peeling, chipping, and others. When installed
on crushed stone and gravel surfaces, it provides dust removal and significantly
more comfortable driving conditions for vehicles.
Surface finishing is a method of creating a rough coating surface and installing
wear layers and protective layers by pouring a thin layer of organic binder onto
the base, spreading high-grade crushed stone and compacting it. The main work
includes pouring bitumen, distributing and compacting crushed stone. The
process of final formation of surface treatment lasts about 10 days
Surface treatment performs the following functions:
-Restores and improves the adhesion qualities of the road surface;
-Forms a wear layer and a protective layer against water penetration into road
clothing;
- Stops destruction and extends the service life of old coatings that show signs of
wear in the form of cracks, peeling, chipping, and others;
The production of high-quality bitumen emulsions is difficult without the use of
surfactants that have the necessary emulsifying properties. Many chemicals are
used to emulsify bitumen emulsions, but in economic and technological terms
only some of them are widely used. The action of the emulsifier is to create a
good structural shell of crushed bitumen droplets that do not burst when they
MODELS AND METHODS IN MODERN SCIENCE
International scientific-online conference
17
meet. Bitumen’s, being non-polar substances, do not dissolve in polar liquid-
water.
Therefore, they can be mixed with water only to form a colloidal disperse system
- emulsions. The formation and stability of the emulsion is achieved by
introducing special emulsifiers into it. Surfactants or finely dispersed solid
powders due to surfactants used as an emulsifier, bitumen road emulsions are
divided into anionic (EBA) and cationic (EBC).
What is an emulsifier in simple words?
Emulsifiers are chemical compounds or mixtures that allow the formation of an
emulsion that is stable over time. The role of the emulsifier is to create stable
micelles that form at the water-oil interface.
Emulsification is the process of mixing at least two difficult-to-mix liquids. The
most difficult task of emulsification is the crushing of the dispersed phase into
small droplets.
Surfactant molecules consist of polar and non-polar parts, which are directed at
the bitumen-water interface. The molecules are non-polar part facing the
bitumen, and the polar part is facing water. In this position, the surfactants
reduce the surface tension at their interface. Bitumen (phase) and water
(medium). Due to the separation of the polar group of the surfactant, the phase
particles acquire an electrical charge (positive with a cationic emulsifier,
negative with an anionic emulsifier). Single charged particles of the phase repel,
which prevents them from sticking together and makes the emulsion more
stable. Mineral emulsifiers adhere to bitumen particles and form protective
shells at the interface between them and water that prevent connection.
To prepare road emulsions, finely ground mineral substances are used, as well
as water-soluble organic emulsifiers.
Emulsions with cationic active emulsifiers are called acidic with anionic
emulsifiers alkaline. The content of mineral emulsifiers in the emulsion usually
does not exceed 5-20% and depends on the dispersion, and the content of
water-soluble emulsifiers in the emulsion is 3%. Resin organic acids, alkaline
naphthenic salts, cotton tar, and second fat tar are used as anionic emulsifiers.
Active cation emulsifiers include finely ground powders of lime, cement,
limestone, carbonate, coal, etc. Depending on the content and properties of
emulsifiers, the amount of bitumen, two types of emulsions can be obtained:
direct, when drops of bitumen are dispersed in water, and reverse, when water
is dispersed in bitumen. In the road industry, direct emulsions are mainly used.
When emulsions interact with mineral material due to the adsorption of the
MODELS AND METHODS IN MODERN SCIENCE
International scientific-online conference
18
emulsifier, absorption and evaporation of water, the balance of the system is
destroyed and its disintegration occurs. The decomposition of road bitumen
emulsion composites depends on the type of emulsifier and the ambient
temperature. The rate and degradation characteristics of bitumen emulsion
composites can be controlled by introducing the desired additives. The stability
of emulsions with anionic emulsifiers is PH=7...11, active cation 3..7. With
increasing pH, the stability of cation-active emulsions decreases, and that of
anion-active emulsions increases. Determination of PH is carried out by
introducing salt and acid or alkali into the emulsion of materials. By treating
mineral materials with cement and lime, it improves the adhesion of the binder
to stone materials.
Preparation of emulsion composite bitumen uses viscous bitumen grades from
BND 200/300 to BND 40/60, depending on the climatic conditions of the
construction site and the type of road pavement. An emulsifier is added to
bitumen or water. The finished components of the emulsion composite are
stored in special containers, from which they are supplied to the emulsion
installation. In an emulsion installation, with the help of rotating blades, bitumen
is crushed (dispersed) in an aqueous environment. The emulsifier is adsorbed
on the surface of bitumen particles and gives stability to the resulting emulsion.
During the production of emulsions, aqueous solutions of the emulsifier (when
the emulsifier is introduced into bitumen) are heated to a temperature of 70 ...
90 * C. When preparing mineral emulsifiers, paddle mixers are used. First, water
is introduced into the installation at a temperature of about 90* C, then the
required amount of finely ground emulsifiers is added. All these materials are
mixed well until a homogeneous creamy mass is obtained at a temperature of
about 70-80* C, after which hot bitumen is gradually introduced into the
solution. The entire mixture is mixed well in a mixer until a homogeneous
mixture is obtained, easily diluted with water.
In regulating the structural properties of bitumen emulsions, the main role
belongs to mineral powder. Combining with bitumen, the filler forms a double
system “Mineral powder bitumen”. For many years it was assumed that the
purpose of mineral powder in bitumen emulsions was limited to filling voids,
that is, ensuring the required density. While studying the literature on the
purpose of mineral powder in asphalt concrete, many researchers gave great
importance to the role of mineral powder in asphalt concrete. The finely crushed
material is not just a void filler - it acts as a complement to the bitumen binder.
The introduction of mineral powder improves the quality of emulsions with fine
MODELS AND METHODS IN MODERN SCIENCE
International scientific-online conference
19
crushing of all mineral material. As a result, the multiplication of the number of
points of contact between particles increases the strength of the asphalt
concrete road surface.
Bitumen emulsions are liquid bitumen dispersed (crushed) in water with the
addition of an emulsifier in the form of surfactants. The main parameters are the
work ability of substances. The main parameters of the work-ability of wear
layers are the stability of the structure, due to the adhesion of bitumen to the
mineral filler, bending strength, resistance of the structure to changes in
moisture and temperature (periodic freezing and thawing) conditions, fatigue
failure, and others. It is known that the destruction of road pavements when
water penetrates into the structure of the material occurs due to a change in the
pore space, that is, its increase, resulting in a breakdown of the bonds between
binders (bitumen) and mineral materials due to the stresses that arise when
water penetrates the pores. Water under the influence of pore pressure has an
explosive effect on the pores, destroying the material. The use of bitumen
emulsion wearing layers should reduce the penetration of moisture into
pavements.
The solution to the issue of regulating the structural and mechanical properties
of bitumen emulsions depends on the bitumen and mineral material. An
important role in the processes of structure formation of bitumen emulsions
belongs to the mineral powder included in the composition of the composite
[4,21,37,38]
Combining with “bitumen, mineral powder” it is noted [36-37,57-58] that at a
certain ratio of bitumen-mineral powder, the highest strength of the structured
disperse system is achieved, forming with these materials. As a result, the
resistance of bitumen to impact loads increases, the density of the resulting
mass increases, and the strength under shear and compression stresses
increases, and fragility decreases. Mineral powders make it possible to regulate
deformation and reduce subsidence of road surfaces. When filling bitumen with
mineral powder, the viscosity of the mixture increases and heat resistance
increases. A traditional powder with a large number of positive adsorption
centres’ and high structuring ability is limestone mineral powder [4]. Research
work has found that the best are mineral powders obtained by fine grinding of
limestone and dolomite. Almost everyone comes to this conclusion. Researchers
working in this area [17,49-50,68]. To find the possibility of using such bitumen
powders-mineral mixtures without deteriorating their properties, it is necessary
MODELS AND METHODS IN MODERN SCIENCE
International scientific-online conference
20
to understand the mechanism of interaction between the mineral powder and
the organic binder (bitumen).
An analysis of literature sources on the use of lime in road construction for the
preparation of bitumen emulsions made it possible to establish that lime (fluff,
boiling powder) and cement are considered effective and affordable mineral
powders [30,85]. According to data [4,30], when the fluff lime activator is
introduced into bitumen, not only better wetting and adhesion of the bitumen is
achieved, but also its faster mixing with wet mineral material.
In the process of research, the authors of [142] proved that by adding slaked
lime to bitumen, the adhesion of the mineral powder to the binder can be
improved. Also, the addition of a water molecule to lime molecules can form a
crystallization structure. Based on this, it can be assumed that when asphalt
concrete pavements containing lime in the composition of mineral powder are
saturated with water, physical and chemical processes will occur in the div of
the composite.
Associated with the hydration of lime, leading to the formation of a stable
structure. And further, it will entail an improvement in the quality, durability
and performance properties of asphalt concrete in road pavement.
Bibliography:
1 Volkov M.I., Borsh I.M. Research of mineral powders for asphalt concrete
Proceedings of HADI-1956 issue 18. pp. 12-17.
2. Traxler R.N. Asphalt. Its Composition Properties and Uses-New-York Reinhold
1961-37p.
3 Peterson J.C., Ensley E.K., Barbour F.A. Molecular interaction of asphalt in the
asphalt-aggregate interrace-region/Trans. Res 1974-No.515. -P. 67-68.
4 Zolotarev V.A. Features of wetting the surface of stone materials with bitumen
// Izvestia vuzov. Construction and architecture. -L991. -No. 8. -WITH. 68-70.
5 Lisikhina A.Ts. The use of surfactants and other additives in the construction of
asphalt concrete and similar coatings. -M: Motor transport, 1957-56s.
6 Khudyakova T.S. Influence of mineral material on the adhesive strength of
bitumen-mineral mixtures // Chemistry and technology of fuels and oils. -1990.
-No. 12. -p.28-29.
7. Rybyeva T.G. Study of the influence of the mineralogical composition of
powders on the structural and mechanical properties of bitumen-mineral
materials: Author's abstract. dis... cand. tech. nauk.-M., 1960. - 18 p.
8. Rebinder P.A. Surfactants.- M.: Knowledge, 1961.-46 p.
9. Ambros R.A. On the study of the effect of chemical additives on
MODELS AND METHODS IN MODERN SCIENCE
International scientific-online conference
21
adhesion of bitumen to stone materials // Tr. Tallinn Polytechnic Institute: -
Estonian Publishing House. - 1956. - Series A. -
No. 69.-S. 74-77.
