Bitumen market in Russia. Production of petroleum bitumen. Chemical nature of the process. Properties, types of bitumen.

Quality road bitumen and, accordingly, the operational durability of road asphalt concrete pavement largely depend on the quality of raw materials for the production of bitumen. Can be used different kinds organic raw materials (see table).

AT road construction application is predominant oil bitumen obtained by processing heavy residual fractions of oil.

The existing trends in oil refining and, in particular, the ever deeper processing of petroleum feedstock pose the problem of taking into account the characteristics of the chemical composition and structure of the petroleum feedstock used for the production of road bitumen, and, accordingly, the composition, structure and physical and mechanical properties of the resulting road bitumen.

Bitumens are a complex mixture of high-molecular hydrocarbons of petroleum origin, including naphthenic (C n H 2 n), aromatic (C n H 2 n -6) and methane (C n H 2 n +2) series, as well as their derivatives, containing oxygen, sulfur, nitrogen and complex metal compounds. The main part of bitumen molecules includes 25–150 C atoms.

The composition of bitumens is characterized by elemental and group chemical composition.

Elemental composition of bitumen(% by mass): carbon - 80–85; hydrogen - 8–12.5; oxygen - 0.2–4; sulfur - 0.5–10; nitrogen - 0.2–0.4. The content of some metals in asphalt concentrates of oil (such as Arlan) is (% by weight): V - 0.22; Ni; –0.115; Fe - 0.110; Ca - 0.054, etc. The average molecular weight of bitumens does not exceed 700–800 k.u.

Given the wide variety of individual chemical compounds that make up bitumen, data on their group chemical composition are usually used to determine their chemical composition.

Group chemical composition of bitumen provides for the division of all various individual chemical compounds included in bitumen into three main groups: asphaltenes, resins and oils (maltenes).

According to their suitability for the production of bitumen, oils are divided into three groups:

Highly resinous low-paraffin, resinous low-paraffin, highly resinous paraffin. The composition of such oils corresponds to the condition A + C - 2.5P ≥ 8, where A is the content of asphaltenes, C is the content of resins, P is the content of paraffins.
Resinous paraffinic, low-resinous, low-paraffinic, whose composition meets the condition A + C - 2.5P, is in the range from 0 to 8 with A + C more than 6.
Oils of three types unsuitable for the production of bitumen: resinous highly paraffinic, low resinous paraffinic and low resinous highly paraffinic, the composition of which meets the condition A + C - 2.5P, is in the range from 0 to 8 when A + C is less than 6, and also if A + C - 2.5P less than 0.

For the production of road bitumen, the best raw materials are heavy, resinous, low-paraffin oils.

The requirements for raw materials for the production of viscous road bitumen were formulated in the Specifications TU 38 101583 approved by the Ministry of Highways of the RSFSR in 1988. In addition to the specified TU Giprodornia, it was proposed to additionally introduce requirements for such important indicators as the homogeneity of oil feedstock and the absence of foaming components in it.

The presence of deasphalting asphalts and cracking residues in its composition has a negative impact on the quality of petroleum feedstock.

The main goal of forming the qualitative characteristics of raw materials is aimed at the formation of nanostructured bitumen from it. As is known, the oxidation reactions of heavy oil residues occur with the formation of mycelial nanoaggregates of asphaltenes, which develop into cluster nanoaggregate structures. From how the process of interaction of nanoclusters with each other will go, from asphaltene cluster sizes and the rate of the process of formation of a mesh frame of clusters of asphaltene nanoaggregates and depend on the properties of the resulting bituminous binders.

The decisive factors in the choice of technology are the temperature, time and rate of the oxidation reaction. .

Professor F. G. Unger pointed out that “the size and structure of each colloidal particle depend on the balance of the energies of the kinetic movement of molecules and the potential of their pair interaction. Conditions technological process the formation, existence and destruction of supramolecular structures (associative combinations, micelles, complex structural units, macromolecules) of petroleum dispersed systems of tar-asphaltene substances predetermine the structure and physicochemical properties of bitumens.

Bitumen systems are thermodynamically mobile systems in which hemolytic transitions (diamagnetic molecules to paramagnetic and vice versa) are continuously carried out, and it is paramagnetic molecules and hemolytic processes that cause the reorganization of the supramolecular structures of oil dispersed systems, i.e., determine the behavior of the system as a whole and the conditions for the formation of the structure at change in the external conditions of the technological process.

Analysis of numerous data from various instrumental research methods and their comparison indicate that heavy carbon molecules or individual carbon atoms are combined into large structures such as associates, polymers or crystal lattices due to spin excitation and spin polarization through the influence of a solvent and temperature.

This made it possible to draw a conclusion about the possibility of the existence of an equilibrium dynamics of the colloidal state of such complex objects as bitumen, and to formulate requirements for the parameters of the technological impact on oil dispersed systems in order to obtain bituminous binders with desired properties.

The main production methods for viscous road bitumen are as follows:

Concentration of oil residual fractions by distillation in vacuum in the presence of water vapor (obtaining residual bitumen).
Air oxidation of oil residues (fuel oil, tars, etc.), which makes it possible to obtain oxidized bitumen.
Mixing (compounding) of liquid oil residues with viscous residual or oxidized bitumen, solid natural bitumen (asphaltites, gilsonites).

In order to obtain bituminous binders of the required quality, various additives can be introduced into their composition, which make it possible to obtain modified, complex and composite bituminous binders.

Numerous solutions are known for introducing various

modifying components, including adhesive additives,

polymers, crumb rubber, natural bitumen, sulfur, as well as structuring and stabilizing components.

Modified bituminous binders are obtained by introducing special additives (modifiers) into bitumen that improve certain properties of bitumen. These include bitumens (or other organic binders) containing up to 10% (by weight) modifier additives.

As modified bitumen widely known are various polymer-bitumen, rubber-bitumen binders, bitumens modified with additives of surfactants, natural bitumens, as well as petrochemical products, coke-chemical and wood-chemical industries .

Complex organic binders (CBOs) are binders consisting of two or more components in which the content of the main component (petroleum bitumen) is less than 90% by weight. Natural bitumen, heavy oils, coal and shale bitumen, products of petrochemical, coke-chemical and wood-chemical industries can be used as components of the KOV. Among the KOV are tar-bitumen and bitumen-tar binders, sulfur-bitumen, binders obtained using heavy oils and natural bitumens, residues from the regeneration of used lubricating oils, as well as composite binders.

Composite binders include KOV containing more than three components, including various modifying additives, plasticizers, structuring and stabilizing additives (for example, fine powders and fibrous fillers).

The most well-known component of complex organic binders among natural bituminous materials is Trinidadian lake asphalt, as well as natural refractory bitumens such as asphaltites or gilsonites.

The purpose of choosing high-quality raw materials for the production of road bitumen and an effective technology for their production is to ensure their compliance with the requirements of the current GOST 22245-90 for viscous petroleum road bitumen, as well as the requirements for ensuring stable adhesion to the stone materials used and the value of the plasticity interval corresponding to the climatic conditions of the area of application.

LITERATURE

Rudenskaya I. M., Rudensky A. V. Organic binders for road construction. M.: Infra-M, 2010. S. 267.

2. Unger FG, Andreeva LN Fundamental aspects of oil chemistry. The nature of resins and asphaltenes. Novosibirsk: Nauka, 1995. P. 192.

A. V. Rudensky, Dr. Sc. sciences, professor

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Introduction

Oil bitumens are large-tonnage products and are widely used in construction, industry, and agriculture. The leading area of use is the construction and repair of roads, residential buildings, industrial enterprises, airfields.

Oil bitumens are widely used and remain indispensable in road, industrial and civil construction. The importance of bitumen in the production of road surfaces is paramount: in Russia they make up about 80% in the structure of total production (roofing and construction bitumen account for 10% each), and in France, for example, 92%. Such coatings are stronger, safer and significantly cheaper than concrete. The widespread use of petroleum bitumen is primarily due to high technological, operational and economic indicators, as well as the fact that, by introducing various additives and additives, it is possible to obtain high-quality bituminous materials for various purposes.

The production of oil bitumen is carried out in different ways: by blowing tars with air, distillation of fuel oil with a deep selection of distillers, deasphalting of tars with propane. Compounding of products of various processes is also widely used. The main production process in our country is oxidation - blowing tar with air in order to obtain high-quality road, construction and special bitumen. Compared to known methods for the production of bitumen, in particular, obtaining by oxidizing technology, has the following advantages:

reduced production costs;

the technology is low-waste and easy to implement;

all equipment used is mass-produced;

allows to produce bitumen of various grades and areas of use (road, roofing, construction);

compared to similar grades of oxidized road bitumen, compounded samples have 15-40% higher extensibility and 10-15% better adhesion to mineral materials;

durability roadbed, obtained on the basis of compounded bitumen, is 20-30% higher than when using similar grades of oxidized bitumen;

the resulting bitumens are quite easily modified with various polymers and emulsified.

With tightening requirements for condition Russian roads, the growth of traffic density, a high degree of wear and unsatisfactory technical condition, the requirements for the quality of petroleum bitumen are significantly increased in order to obtain durable materials based on them with a set of necessary structural-mechanical and adhesive properties in accordance with consumer requirements. Asphalt concrete pavement should provide maximum resistance to fatigue failure, be resistant to daily and seasonal temperature cycles. One of the promising areas to solve this problem is the use of high quality bitumen.

The Ministry of Transport, the Ministry of Finance and the Ministry of Economic Development have submitted an amended sub-program "Roads", which is part of the federal target program "Modernization of the transport system of the Russian Federation up to 2010" approved by the Government. In this regard, the need for high-quality bitumen for road construction and the successful fulfillment of the tasks of the federal target program is sharply increasing.

Consumption of bitumen in all countries of the world is continuously increasing. The leading place is occupied by the United States, where consumption is almost twice as much as in European countries. This is due to the branching of the US road network and the heavy traffic load. In our country, the share of bitumen consumption in industrial and civil construction and other areas National economy the largest. The share of road pavements using bitumen is 93-95% of all improved pavements, and only 3-5% falls on pavements using cement concrete.

Such a significant increase in the production and consumption of bitumen, as well as an increase in the requirements for their quality, urgently requires a deeper and more comprehensive study of the composition and properties of bitumen, the influence of technological regime parameters, kinetics and hydrodynamics of processes and the nature of raw materials on these indicators.

The problem of increasing the operational reliability of road bitumen in coatings in our country is becoming increasingly acute. In the federal network alone, at least one third of the existing roads and at least 15% of the operated bridges and overpasses need serious reconstruction and modernization.

In order to rationally use material and financial resources, it is necessary to conduct constant quality control at all stages, starting with the quality of the materials used, the results of the selection of compounded bitumen compositions, technological modes of the preparation process and ending with the quality check of the resulting product in accordance with regulatory documents.

1. Theoretical foundations of the process

1.1 Mechanism and kinetics of the process of oil bitumen oxidation

The term "bitumen" means liquid, semi-solid or solid compounds of carbon and hydrogen with a small amount of oxygen-, sulfur-, nitrogen-containing substances and metals and a significant content of asphaltene-resinous substances that are readily soluble in carbon disulfide, chloroform and other organic solvents.

There are three main methods for the production of petroleum bitumen.

1) Concentration of oil residues by distilling them in a vacuum in the presence of water vapor or an inert gas (when processing heavy asphalt-tar oils, residual bitumens are obtained by atmospheric distillation).

2) Air oxygen oxidation of various oil residues (fuel oil, tars, semi-tars, deasphalting asphalts, extracts of selective oil refining, cracking residues or their mixtures at a temperature of 180-300 C.

3) Compounding (mixing) of various oil residues with distillates and with oxidized or residual bitumen, etc.

There are combinations of the above methods. Commodity bitumen is obtained as a direct product of a particular process or by compounding products of different processes.

The main process for the production of bitumen in our country is oxidation - blowing tars with air. Oxidized bitumen is obtained in devices of periodic and continuous action, and the proportion of bitumen obtained in devices of continuous action, more economical and easy to maintain, is constantly increasing.

Oxidized bitumen can be of various consistency at room temperature - semi-liquid, relatively solid and intermediate. They are more resistant to temperature fluctuations and weather changes than, respectively, the residual bitumen obtained from the steam distillation of oil residues.

Air oxidation is used in the production of bitumen, when the feedstock contains little resinous-asphaltene substances and their content can be increased by blowing. If in the bitumens obtained during distillation and extraction, the asphalt-resinous components of the raw material practically do not change, then the oxidation with air oxygen under certain conditions leads to significant changes in both the qualitative and quantitative composition of the feedstock.

Modern technology consists in the oxidation of oil residues with air oxygen without a catalyst at a temperature of 230-300 0C with a supply of 0.014 - 0.0233 m2 / s of air per 1 ton of bitumen for up to 12 hours. Air can be supplied to the reactor under pressure or sucked in due to vacuum in system up to 500 mm Hg. The distillation and losses depend on the content of volatile substances in the raw material, the depth of oxidation and are in the range of 0.5-10% of the mass. from raw materials. Water vapor and carbon dioxide are removed from the system. The exothermic oxidation reaction raises the temperature in the reaction zone.

The process of raw material oxidation to bitumen is a heterogeneous reaction between gas (air, air + oxygen, air + carbon dioxide, air + water vapor, etc.) and liquid (oil residue) phases. In this case, reactions of four types take place: leading to a decrease in molecular weight with the formation of distillate, water and carbon dioxide; slightly changing the molecular weight with the formation of water; leading to an increase in molecular weight with the formation of water, carbon dioxide and asphaltenes; concentration (distillate distillation and asphaltene concentration).

The oxygen in the air reacts with the hydrogen contained in the raw material, forming water vapor. The increasing loss of hydrogen is accompanied by compaction processes with the formation of high-molecular products of a high degree of aromaticity - asphaltenes. As a result, the consistency of bitumen changes. The main part of oxygen in the air goes to the formation of water, 10-20% of the mass. on the formation of carbon dioxide, a small part - on the formation of organic substances containing oxygen.

Petroleum hydrocarbons are oxidized simultaneously in two directions:

Hydrocarbons acids > hydroxy acids > asphaltene acids

resins > asphaltenes > carbenes > carboids

The transformation scheme during the oxidation of raw materials into bitumen is as follows:

At the beginning of the oxidation process:

The interaction of the resulting radicals with a new hydrocarbon molecule leads to the production of stable products:

RRH + RH > RRHRH - disproportionation.

Due to the relatively low concentration of hydrocarbon radicals, their recombination is unlikely, and the interaction of radicals with oxygen proceeds to a lesser extent than with the molecules of the original substance:

ROO+RH>ROOH+R

RH + OH > R + H2O

Chain continuation:

RH + HOO > R + H2O2

RH + OH > R + H2O

The kinetics and mathematical description of the reactions of oxidation of raw materials into bitumen is of great technical importance for the calculation and optimization of the process. However, research in this area is insufficient. The main difficulties of the mathematical description of the process are related to the following: during the oxidation, the gas-liquid contact surface changes, distillation processes take place, the static pressure decreases and the temperature rises; as a result of the absorption of oxygen from the gas phase, a continuous decrease in its concentration occurs; the partial pressure of oxygen decreases due to a decrease in its concentration and a decrease in static pressure; the liquid phase is saturated with chemically indifferent nitrogen; the diffusion coefficient of a gas into a liquid during oxidation changes with a change in the viscosity of the reaction products.

The concept of the reaction rate of the process of oxidation of raw materials into bitumen is considered differently. The most convenient is the determination of the softening point, usually carried out to control the quality of the finished product.

In the literature, the reaction equation is given in the following form:

where tР - bitumen softening temperature, 0F, 0С = 5/9 (0F - 32);

Duration of oxidation, h;

K is the reaction rate constant;

Q - air supply rate, m3 (sect).

The total reaction rate constant K0 is determined by the formula:

where tР - bitumen softening temperature over time, 0С;

tР0 - softening temperature of the feedstock, 0С.

Taking the increased softening temperature tР as the criterion for the completion of the reaction and considering the concentration of the reactant to be inversely proportional to the softening temperature, that is, С = a / tР (where a is the proportionality coefficient), we can represent the differential equation

After differentiation and transformation, we get:

This first-order reaction equation can be used for practical purposes, since under industrial conditions, the oxidation process is usually carried out at a temperature not higher than 270 0C.

Bitumen chemically binds the less oxygen, the higher the oxidation temperature of the raw material. The main amount of oxygen supplied for oxidation is carried away with the exhaust gases, the oxidation process is dehydrogenation in nature. With the deepening of oxidation, a relative increase in the content of compounds with short alkyl chains (CH2)n, where n 4, is observed in bitumen, due to the elimination of alkyl groups of cyclic compounds with long alkyl chains; a relative increase in the proportion of benzene rings in the cycles is also observed, which confirms the dehydrogenation nature of the reactions.

The amount of chemically bound oxygen in oxidized bitumen increases with an increase in the content of aromatic hydrocarbons in the raw material - oil residue. The main amount of oxygen bound in oxidized bitumen is in the form of ester groups. The content of chemically bound oxygen in bitumen increases with the lightening of the raw material - tar, since with a decrease in its molecular weight and with an increase in penetration, more ester bridges.

By changing the penetration and extensibility of bitumen in the process of its oxidation, three phases can be distinguished. In the first phase, there is a strong decrease in penetration and an increase in extensibility, in the second phase, a decrease in extensibility and penetration, and in the third, stabilization of these values.

1.2 Influence of raw material properties on the quality of oxidized and compounded bitumen

The raw material for vacuum distillation is usually fuel oil or tar, for deasphalting and oxidation - tar. Commodity bitumen is obtained as a direct product of a particular process or by compounding products of different processes or the same process.

Vacuum distillation feedstock is a complex mixture of organic and heteroorganic series. The usual raw material of vacuum distillation is the residue of atmospheric distillation of oil - fuel oil.

The main purpose of the tar deasphalting process with paraffins is to obtain deasphalted oil, which is a raw material for the production of oils and catalytic cracking and hydrocracking units. The residue of deasphalting in some cases meets the requirements of the standard for bitumen, and more often it is used as a raw material component of bitumen production.

Oxidation of refinery residues with air is the main process for the production of bitumen. Upon receipt of oxidized bitumen, blowing out the residues of oil refining with air is accompanied by its thickening.

Oxidized bitumen can be obtained from oils containing 5% wt. and more resinous-asphaltene substances. It is desirable that the oil contains more than 25% of the mass. .

The properties of oxidized bitumen are influenced by the nature of the raw material. By appropriate selection of raw materials, it is possible to obtain oxidized bitumens of various properties. With a decrease in the oil content in the original tar, the extensibility, brittleness temperature and flash point of bitumens increase, their heat resistance and plasticity range decrease, air consumption and the duration of oxidation decrease.

Bitumens from asphalt deasphalting contain less paraffin-naphthenic compounds and more resins and asphaltenes, which causes their lower penetration, plasticity interval and greater extensibility, brittleness temperature and cohesion compared to bitumens of the same softening point obtained by oxidation of tar from the same oil.

The action of paraffin compounds depends on the dispersed structure of bitumen, and their content is up to 3% wt. allowed in the raw material. Increasing the content of paraffin compounds in raw materials reduces the extensibility of bitumen, increases air consumption and the duration of oxidation.

Paraffin-naphthenic compounds in raw materials are thinners and a plasticizer that improves the properties of bitumen, their presence up to 10-12% is desirable.

The presence of sulfur and sulfur compounds in raw materials improves the properties of oxidized bitumen.

Monocyclic aromatic compounds behave similarly to paraffin-naphthenic hydrocarbons: they improve the plasticity and brittleness temperature of oxidized bitumens. The similar behavior of paraffin-naphthenic and monocyclic aromatic compounds, which is expressed in inhibition of the oxidation process, is explained by the similarity of the structure of their molecules. The best raw materials for the production of oxidized bitumen are the residues of highly resinous oils of an aromatic base.

1.3 Modification of road bitumen with additives

By modifying bitumen with various additives, their performance properties are improved, including a decrease in the brittleness temperature, an extension of the temperature range, an increase in deformation stability and durability (durability, according to certain data, doubles), adhesion, and resistance to aging.

To improve the quality of asphalt concrete pavements in the upper layers highways Order No. 9 of the FDD of January 31, 1995 and Order No. 23 of the FADS of April 3, 1997 recommended the use of modified bitumens with a higher level of physical and chemical properties.

The regulation of bitumen properties can be carried out in accordance with the basic provisions of physical and chemical mechanics by directed regulation of their spatial dispersion of the structure by changing the particles of the dispersed phase.

Ideas about bitumens characterized by a dispersed structure three types depending on the size of complex structural units (CSU) in them, suggests that the introduction of the optimal amount of surfactant additives, plasticizers, polymers, and other fillers can lead to the formation of new dispersed particles of two modifications. Firstly, these additives can be distributed in the dispersion medium of the binder and, at certain concentrations, different depending on the size of the CCE, create a new independent spatial dispersed structure. In this case, if the additive is a plasticizer in relation to the given system, at low concentrations, being distributed in the free dispersed phase, it can lead to interstructural plasticization, i.e. increase the mobility of the spatial disperse structure, practically without reducing its strength, and at high concentrations lead to a decrease in strength.

Secondly, these additives at certain concentrations can form, due to the formation of CCE, spatial structures conjugated with the existing particles of the dispersed phase. In this case, the properties of bitumen will be determined by this new spatial conjugated structure.

There are additives (for example, sulfur) that can have such a composition and properties that at low concentrations they can have a structuring effect, and at high concentrations they can have a plasticizing effect, and vice versa: at low concentrations, the effect will be plasticizing. In the first case, this should be due to the fact that at a content above a certain one, the additive will not be able to be distributed in the dispersion medium. In the second case, at a certain content, it will be enough to form an independent or conjugated with the particles of the dispersed phase of the given system spatial structure.

Surfactant additives, in addition to affecting the spatial dispersed structure of bitumen, have an exceptionally large effect on the surface tension of bitumen, changing the nature of the bond.

First of all, surfactant additives make it possible to improve the conditions for wetting the surface of bitumen mineral materials, forming an absorption layer facing the polar groups to the surface of the mineral material and the hydrocarbon part to the bulk of the bitumen. This possibility reduces the temperature and time for obtaining a homogeneous mixture, and also significantly reduces the intensity of bitumen aging processes.

Secondly, due to the use of surfactants, a monomolecular chemisorption layer can form at the interface between the mineral material and bitumen, which contributes to the formation of a strong bond between them.

The following additives are distinguished according to the mechanisms of surfactant influence on the structure and properties of road bitumen:

Destructuring, reduce the degree of association in the system, which is expressed in a change in the nature and strength of the interaction between the bitumen components due to the adsorption of surfactants on the surface of the bitumen structure-forming components. A similar effect can be exerted by surfactants of the class of high molecular weight amines and diamines. In this case, not only the viscoelastic and strength properties of the systems change, but the transition temperature from one rheological state to another direction of lower temperatures also shifts;

Structuring, the mechanism of their action is expressed in the formation of a spatial dispersed structure conjugated with asphaltene complexes of bitumen. This is how surfactants of the class of iron or calcium salts of high-molecular carboxylic acids behave. At the same time, the structuring effect manifests itself with a certain concentration and only in the presence of a spatial coagulation structure in bitumen;

Plasticizing. They reduce the viscosity of the bitumen dispersion medium, i.e. eliminate the diffusion factor, and, consequently, reduce the strength of the coagulation framework. Such an effect is exerted by surfactants of the class of high molecular weight carboxylic acids.

Classification of additives-modifiers according to features:

increase in adhesive strength;

increase in heat, water, frost resistance;

increasing the strength of the product;

increased weather resistance;

ensuring the durability of the coating;

improving the ductility and stability of the product.

The disperse structure of bitumens can be controlled by introducing low molecular weight hydrocarbons. At the same time, depending on their concentration in bitumen, they can plasticize or liquefy it. At low concentrations of low molecular weight hydrocarbons - 4% vol. (concentration threshold) there is a slight change in the yield strength and the highest plastic viscosity of bitumen, and then their sharp decrease. At concentrations less than the "threshold", partial plasticization of the dispersion medium occurs in the interframe layers, leading to an increase in the elasticity of the system while maintaining a sufficiently strong coagulation framework in bitumens. When the concentration of hydrocarbons is more than the "threshold" liquefaction of the system is observed, leading to the destruction of the coagulation framework and the conversion of bitumen into a dilute suspension of asphaltenes.

It is very effective to use polymer additives to control the spatial dispersed structure of binders. All polymers used as bitumen additives belong to the class of organic or organoelement compounds and can be assigned to one of four groups.

rubbery polymers. Elastomers - natural rubber (NR) and devulcanized rubber crumb, synthetic rubbers, mainly styrene-butadiene rubbers, silicone rubbers, polyisobutylene, atactic copolymer of propylene and ethylene, as well as waste products from the production of synthetic rubbers and nylon fiber, polydiene. Rubber-like polymers, as a rule, do not have the ability for specific interactions, therefore, a larger amount of them will be required to form a network.

Thermoplastics, molecular and chlorinated polypropylene, polyvinyl acetate, fluorine-containing carbon-chain thermoplastics. Thermoplastic polymers are effective only when they are contained in bitumen in an amount of 10–20 wt %, and the viscosity of such PBBs in the temperature range of its combination with mineral material is so high that it makes it untechnological,

Thermosetting plastics - epoxy resin; epoxy resin modified with aliphatic resin, aromatic-based epoxy resin, as well as polyepoxy compounds with the addition of a polybasic carboxylic acid derivative; furyl, furfural-formaldehyde resins, phenol-formaldehyde resin. Thermosetting plastics are effective in bitumen only in the presence of a hardener, and the chemically irreversible bonds that form in this case can disrupt the technological modes of preparation asphalt mixes and devices of them for road surfaces.

Thermoplastic polymers, thermoplastic elastomers, divinyl-styrene block copolymers. Thermoelastomers retain high: strength and ability to highly elastic deformations in the temperature range from + 80 to - 80 0C due to the work of the spatial structural network formed due to physical bonds between macromolecules. The temperature of destruction of thermoplastic elastomers is 230-250 0C.

Some requirements for polymers:

polymer macromolecules must have a tendency to association and the ability to immobilize the largest possible volume of the dispersion medium;

the polymer should be quickly and well distributed in the dispersion medium of bitumen without degradation;

the polymer must form in bitumen such a structural network that retains strength at temperatures above 60 0C and elasticity at low temperatures;

should be available and cheap;

the structural network" of the polymer should be formed in bitumen after the end of the rolling of the bitumen-mineral mixture or be reversibly destroyed when exposed to real stresses.

Thus, of the existing polymers, thermoplastic elastomers satisfy the requirements - these are new class polymers, which combines both the high strength inherent in plastics and the elasticity inherent in elastomers.

The patent literature provides various types of modifiers and methods for their preparation. Compounding them with bitumen in various ratios allows you to achieve the required quality indicators.

In patent No. 2267506, the invention relates to the field of obtaining sealing compositions based on petroleum road bitumen and polymer used for waterproofing in road construction. The bituminous composition contains, wt. %: oil road bitumen 62.0-59.2; styrene butadiene-styrene thermoplastic elastomer 1.5-2.0; organic solvent 13.5-18.0; solid residue of car tire pyrolysis 12.0-10.0; crumb rubber 10.0-12.0; adhesive additive BP-KSP 1.0-0.8.

In patent No. 94029817, an active additive to bitumen is considered, which provides it with high technical performance and, as a result, sufficient durability of the road surface. It is obtained by reacting the VAT distillation residue of acids obtained after saponification of animal and vegetable fats with triethanolamine and sulfur.

In patent No. 2158742, the invention relates to the building materials industry, to the production of a modifier for polymer-bitumen binders used in road and civil engineering to cover roads, airfields, sports grounds, and roofs. The modifier is obtained in the form of a solid, non-sticky mass, convenient for transportation and direct introduction into heated bitumen at the site of road construction. EFFECT: modifier provides low (up to - 27-29 0С) brittleness temperatures and high (up to + 53-55 0С) softening temperatures of polymer-bitumen binders (PBB) based on it, which guarantees reliable performance of PMB under conditions of significant temperature differences. The modifier consists of the following components: bitumen 50-80 wt. %, pre-destructed in bitumen crumb rubber, which is a waste rubber production 10-25 wt. %, polydiene rubber SKI-3 1-5 wt. %, polyethylene (LDPE) or a ternary copolymer of ethylene with propylene and dienes - SKEPT-40 1-10 wt. %.

In patent No. 2185401, the development of a cation-active adhesive additive to bitumen, which is a product of the interaction of acidic and basic components, is considered. As an acid component, either hardwood pyrolysis resin, or flotation tar, or a residual product of the distillation of fatty acids, or a distillation residue from the production of synthetic fatty acids, is used, and either a distillation residue from the production of monoethanolamine, or a distillation residue from morpholine rectification is used as the main component.

In patent No. 94028231, the use is considered: the invention relates to building materials and improves the adhesion of bitumen to acidic rocks. The essence of the invention: the active substance "Penazolin 17-20" according to TU 38-40753-75 - a stabilizer of non-aqueous foams in the production of foam plastics is used as an adhesive additive to bitumen.

Patent No. 2130954 describes an adhesive additive for polyfunctional bitumens, including imidazolines of various structures, characterized in that imidazolines of various structures are represented by amido-, bis- and aminoethylimidazolines and additionally the additive contains amido-piperazines, wt. %: 1) Amidoimidazolines - 40-50, n = 1.2; 2) Bisimidazolines - 10-20; 3) Aminoethylimidazolines - 15-25, m = 1.2; 4) Amidopiperazines - 5-25, x = 0.1, where R is the C15-55 hydrocarbon radical of saturated and unsaturated acids or mixtures thereof. EFFECT: obtaining "Amidan" surfactant for bitumen, which maximizes the adhesion of bitumen to acid rocks at minimum consumption, has high thermal stability and good antioxidant effect in bitumen.

2. Research part

2.1 Purpose of research

The purpose of the research is to determine the dependence of tsize and P25 of road bitumen on the tar content in the compounding process for a bitumen production plant.

2.2 Objects of study

The objects of study are:

road bitumen with a softening temperature according to KiSh 47 0С; penetration at 25 0С - 60 0.1 mm; penetration at 0 0C - 35 0.1 mm;

building bitumen with a softening temperature according to KiSh 99 0С; penetration at 25 0C - 4 0.1 mm; penetration at 0 0C - 2 0.1 mm;

tar (West Siberian oil) with a softening point of 20 0С according to KIS, penetration at 25 0С - 220 0.1 mm; at 0 0С - 2 0.1 mm;

bitumen oxidized from K-1 of the bitumen production unit shop No. 14 of OAO Salavatnefteorgsintez with a softening temperature according to KiSh 72 0С; penetration at 25 0C - 34 0.1 mm;

tar is the target product of AVT-4 workshop No. 14 of JSC Salavatnefteorgsintez with the following characteristics: softening point according to KiSh 27 0C, flash point in an open crucible - 316 0C, conditional viscosity - 42s, density - 991 kg / m3, water - absence.

2.3 Research methods

Compounding is the mixing of two grades of bitumen in different proportions, with a total volume of 300 g. Compounding was carried out at a temperature of 140 0C for 30 minutes until the softening temperature of the resulting compounds was 43 and 47 0C.

Road and construction bitumen was placed in a metal container, placed on a tile, a stirrer was installed and stirred for 30 minutes, then the stirrer was turned off, a sample was taken to determine the softening point by the R&S method.

Bitumen compounding with additive.

A mixture of bitumen was taken into a metal container and, depending on the ratio, an additive - tar, a stirrer was placed there and stirred for 30 minutes, turning off the stirrer, a sample was taken to determine the softening point by the K&S method. The resulting bitumen samples were analyzed for some quality indicators. The research results are presented in tables.

Methods for analyzing bitumen quality indicators:

The softening temperature (oil residues) is the temperature at which bitumen (oil residues) changes from a relatively solid state to a liquid when heated.

The essence lies in the fact that a layer of bitumen 5 mm thick, located in the ring under the load of a standard ball, was heated until the ball passed the bitumen layer and touched the control disk of the apparatus located at a certain distance under the ring. The temperature at which the ball touched the surface was recorded as the softening temperature of the bitumen. The procedure for the analysis is carried out in accordance with GOST 11506-78.

Penetration - this indicator characterizes the depth of penetration of a standard-shaped body into semi-liquid and semi-solid products under a certain regime, which determines the ability of this body to penetrate into the product, and the product - to resist this penetration. Penetration indirectly characterizes the degree of bitumen hardness.

Essence - measurement of the depth of penetration of the penetrometer needle into the test sample under certain conditions: temperature 25 0C, load 1N, duration of the load 5 s (P25) and temperature 0 0C, load 2N, duration of the load 60 s (P0). The procedure for the analysis is carried out in accordance with GOST 11501-78.

Adhesion (quantification of adhesion) is the ability of liquid or viscous bitumen to adhere to the surface of sand or marble. Adhesion is explained by the formation of a double electric field on the interface between bitumen film and solid mineral (stone) material. Adhesion depends on the polarity of bitumen components (asphaltenes and maltenes). The adhesion of bitumen to stone materials is also characterized by surface tension at their interface and represents the work expended on separating bitumen from stone material.

The essence lies in the ability of bitumen to be retained on the surface of marble or sand when exposed to boiling water for 30 minutes. At the end of the test, the samples were placed in cold water for 3-5 minutes, then laid out on the filter. The air-dried sample was weighed. Bitumen adhesion index is determined by the formula

where m1 is the mass of the bituminous mineral mixture after boiling, g;

mbs - sample of mineral material, g;

0.6 - bitumen weight (constant for this method), g,

Road bitumen must have high adhesive power over a wide temperature range in order to firmly hold mineral materials in the road surface under the influence of vehicle wheels. The procedure for the analysis is carried out in accordance with GOST 11508-74.

The brittle point is the temperature at which a material breaks under a short-term applied load. The brittleness temperature characterizes the behavior of bitumen in the road surface: the lower it is, the higher the quality of the road bitumen. The brittleness temperature was determined according to the Fraas plot.

One of the quality indicators of bitumen is the range of plasticity, equal to the difference in softening and brittleness temperatures (TP - THR) in 0C. Its value and relationship with the IP penetration index is expressed by the equation

From the softening point and the penetration index, you can find the brittleness temperature.

Penetration index - characterizes the degree of bitumen colloidality or the deviation of its state from purely viscous. The penetration index (PI) is determined by the formula

where PI - penetration index;

P - penetration at 25 0C, 0.1 mm;

tР - softening temperature, 0С.

The change in mass after heating (Dm) characterizes the stability of bitumen over time at elevated temperatures and shows the presence of light oil fractions in it. The test was regulated by GOST 18180-72 and consisted in the fact that bitumen (not less than 4 mm thick) was kept at a temperature of 163 0C for 5 hours, and then the weight loss was determined by the formula

where mb is the mass of bitumen before testing, g;

mbs is the mass of bitumen after the test, g.

Bitumen softening temperature change after heating (D tr) - this is the difference between the bitumen softening temperature determined after the bitumen mass loss test (trc) and the bitumen softening temperature before testing (tr)

Д tр = tрс - tр (2.5)

2.4 Research results

In order to study the effect of the quality of the initial bitumen on the process of obtaining road bitumen grades BND 60/90 and BND 90/130 by compounding with tar, bitumen samples with different softening temperatures were prepared by mixing building and road bitumen.

The research results are presented in tables 2.1-2.3 and in figures 2.1-2.6.

Table 2.1 - Results of the study of compounding road and construction bitumen

construction, %	road, %	Penetration, 0.1 mm

Figure 2.1 - Graph of the dependence of the softening temperature on the content of construction and road bitumen

Figure 2.2 - Graph of the dependence of penetration at 25 0С on the content of construction and road bitumen

Figure 2.3 - Graph of the dependence of penetration at 0 0С on the content of construction and road bitumen

Dependence graphs tsize, P25, P0 showed a linear dependence of these indicators on the content of road and construction bitumen during compounding. Initial samples of compounded bitumens do not correspond to GOST indicators. However, after compounding in different proportions, they have the properties necessary for use as a starting binder for compounding with tar and obtaining road building material.

The obtained bitumens were compounded with the use of tar to tsize = 47 0С (BND 60/90) and tsize = 43 0С (BND 90/130). Physicochemical and operational properties of the resulting bitumen are presented in Table 2.2. Based on the results of the properties studies, the dependences of tdimension, P25 and bitumen adhesion on the tar content in them were constructed (Figures 2.4, 2.5, 2.6).

Table 2.2 - The results of the study of compounding bitumen with tar (bold type indicates the interval of the optimal compounding mode)

		Penetration, 0.1 mm				Weight loss, Dm, %

Table 2.3 - Results of the study of compounding bitumen with tar with

Point on the chart	% tar	Penetration, 0.1 mm

Figure 2.4 - Graph of the dependence of the softening temperature on the tar content when compounding the initial bitumen with tar

Figure 2.5 - Graph of the dependence of penetration at 25 0C on the tar content when compounding the initial bitumen with tar

Analysis of tables 2.2 and 2.3, figures 2.4 and 2.5 shows the possibility of obtaining road bitumen grades BND 60/90 and BND 90/130 in bitumen:tar ratios in samples No. 4, respectively, with the best rheological, adhesive properties and more stable during aging.

Figure 2.6 - Graph of the dependence of adhesion on the tar content when compounding the initial bitumen with tar

The study of the initial tar for adhesion with mineral material showed that the sample does not have a high index, adhesion is 18% (sample No. 3), therefore, the resulting bitumen grades do not have sufficiently high adhesive properties, basically correspond to sample No. 2.

As a result of the research, the dependences of the change in the softening temperature, the penetration of the compound on the content of tars in oxidized bitumen were analyzed. On the basis of the experimental data, correlation lines were constructed for the softening temperature using the KiSh method and penetration at 25 and 0 0С from the tar content, and the regression equations were determined, which are presented in the figures above. The resulting equations of their regression, which are linear in nature, which allow, based on the initial softening temperature (y) or penetration (y1) of bitumen, to determine the content of tar (x) to obtain bitumen with the required softening temperature and penetration. In all obtained regression equations, the coefficient of determination R2 > 0.95, that is, they can be considered reliable.

For bitumen brand BND 60/90

softening point y = 1.066 x + 33.774, whence

% wt. (3.1)

penetration at 25 0С y1 = -1.325 x + 76.832, whence

% wt. (3.2)

For bitumen brand BND 90/130

softening temperature y \u003d 1.483 x + 7.583, from where

% wt. (3.3)

penetration at 25 0С y1 = -1.836 x + 109.290, whence

% wt. (3.4)

For the reliability of the obtained regression equations, the bitumen oxidized with K-1 and the tar of the bitumen production unit were analyzed. The results are presented in Figures 2.4 and 2.5.

Thus, when producing road bitumen by compounding with tar, the quality of the initial bitumen is of great importance. In order to obtain bitumen grade BND 60/90 with best performance quality, it is necessary to use the original bitumen with tdim = 64.9 0C, P25 = 37.30.1 mm, with a content of 30% tar in it. To obtain bitumen grade BND 90/130, the best bitumen is with tsize = 64.9 0C, P25 = 37.30.1 mm, with a content of 40% tar in it.

bitumen tar compounding oxidized

List of sources used

1. Gun R.B. Oil bitumen. - M.: Chemistry, 1973.

2. Gureev A.A., Gokhman I.M., Gilyazetdinov L.P. Technology of organic binders: Method, manual. - M.: MING im. I.M. Gubkina, 1990.

3. Tanatarov M.A. Technological calculations of oil refining installations. - M.: Chemistry, 1987.

4. Evdokimova N.G., Zhirnov B.S., Ishkildin A.F. Technology for obtaining oil oxidized bitumen. Teaching aid for preparation for course and diploma design. - Ufa: UGNTU, 2002.

5. Gurevich I.L. Oil and gas processing technology. - M.: Chemistry, 1972.

6. Evdokimova N.G., Prozorova O.B., Kortyanovich K.V. Methods for studying the properties of bitumen and oil residues. - Ufa: UGNTU, 2004.

7. Khaimova T.G., Mkhitarova D.A., Starovoitova N.R. Petroleum bitumens and composites based on them in world practice and in Russia. - M.: TSNIITENEFTEKHIM, 2005.

8. http://www.kaoil.ru/ru/index.php?m=oilguide.

9. http://www.stroibk.ru/s/1034.html.

10. Rospatent - Federal Institute Industrial Property http://www.fips.ru/.

11. Sardanashvili A.G., Lvova A.I. Examples and tasks for oil and gas processing technology. - M.: Chemistry, 1980.

12. Basic design of the bitumen production unit technology, - Ufa: Institute of Oil Refining of the Republic of Belarus, 2005.

13. Technological regulations bitumen production plants.

14. Khaimova T.G., Mkhitarova D.A., Starovoitova N.R. Petroleum bitumens and composites based on them in world practice and in Russia. M.: TsNIITENEFTEKHIM, 2005.

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Composition of bitumen

If we consider the elemental composition, then bitumen contains up to 14% hydrogen and at least 70% carbon. The rest is impurities in the form of sulfur, oxygen and other elements. That is, bitumen can be characterized as a hydrocarbon with impurities. But the properties of bitumens do not depend on the elemental composition, but in what compounds carbon and hydrogen are combined. These groups of compounds are:

- oils that ensure the fluidity of bitumen;
- pitches thanks to which bitumen is elastic;
- asphaltenes characterized by viscosity.

So oils in bitumen are 45-60%. These liquid and light compounds, therefore, occupy the predominant share in the composition of bitumen. The depth of bitumen penetration into other media depends on their quantity.

Resins in bitumen are somewhat less - 15-30%. These compounds are viscous, their density is higher than oils. They can be either semi-liquid, viscous, or solid or semi-solid (depending on the softening point).

Bitumen production technology

Bitumens are natural and artificial (petroleum). Naturally, the technologies for their production will differ. natural bitumenwere formed sometime due to the movement of oil in the earth's crust and the filling of voids with it. Artificial ones are obtained from oil in several ways.

As a matter of fact, it is not necessary to produce natural bitumens, they have been produced by mother nature for millions of years. They just need to be extracted from bituminous rocks. They are obtained in two ways: either by extraction (dissolution in organic solvents), or by digestion in boilers with water.

Petroleum bitumen is obtained in three ways:

- concentration of oil residues. After separating light fractions (gasoline, gas oil, etc.) from oil, tar remains. Distilling it in a vacuum, they get more oils and motor fuel, and the remaining tar and asphalt - together this is already residual bitumen;
- Oxidation of oil residues is carried out with oxygen from the air (by blowing) at temperatures up to 300°C. Due to oxidation, the content of asphalt-resinous substances increases, which increases the yield of bitumen;
- compounding, or mixing of residual and oxidized bitumen.

Bitumen quality control

The main indicators of quality are penetration, softening point, ductility and brittleness temperature. It is these qualities that determine their consistency and heat resistance.

Penetration shows the depth of penetration of a standard body (needle) into the bitumen. This value strongly depends on the bitumen temperature. Penetration is measured in abstract units, each of which means the immersion of the needle on 0.1 mm.

The softening point is the temperature at which bitumen changes from a solid to a liquid state. The indicator is closely related to penetration: when heated, the bitumen passes into a colloidal state, and so the penetration index shows how its former solid state deviated from the viscous one.

Ductility is the distance of stretching into a bitumen thread before it breaks. This characteristic is maximum for road bitumen - at a temperature of 25 ° C, the extensibility reaches 40 cm.

The brittleness temperature is an indicator at which bitumen begins to break down from the applied load. For road bitumen, this value is -2 - -30°C.

As you can see, there are not enough concrete, interconnected digital indicators. The fact is that some indicators are determined for the initial bitumen, and some - for the bitumen of the heating field. In addition, the desired characteristics will be different, and because different properties and characteristics are needed in different areas applications.

More about bitumen:

Methods for obtaining petroleum bitumen

There are several ways in which bitumen is produced:

By concentrating oil residues by their vacuum distillation under the influence of water vapor or an inert gas;
With the oxidation of oil residues by oxygen at high temperature;
By mixing oil residues with residual products and distillate;
A combination of several of the above methods.

The best raw materials for manufacturing are the remnants of heavy oil processing - asphalts, cracking residues, tars, etc. The best bitumens are obtained with a low content of paraffins (paraffins prevent adhesion to minerals) and a high content of resinous asphaltene components. At the same time, for production, oil must be well desalted.

Where are residual products used?

In the West, bitumen produced from residues is widely used. France, for example, has 85 percent of them. Such materials are characterized by increased strength, density, ability to resist tearing, and resistance to temperature changes. Not all types of oil go into their production, but only those that have less paraffins.

The great need of the national economy for bitumen dictates the need to produce them from heavy, highly resinous oil. By deasphalting tar, precipitated bitumen is obtained, for which special installations are used in the USA and other countries. At the same time, paraffin oils that are unsuitable for the main bitumen production are more often used for production.

In Russia, as well as throughout the entire territory of the former Soviet Union, there is not a single deasphalting unit that would work directly on the production of these products. The installations that are available are aimed at the release of residual oil. At the same time, the quality of asphalt is not regulated and is not subject to real control.

At the same time, the use of heavy grades of oil abroad does not always provide high-quality distillation and quality. Therefore, the oxidation process increases the viscosity and temperature sensitivity. And the development of oxidation for industrial production seems to be a good help when using the recycling of oil residues in the development of secondary refining processes.

Pressure oxidation

Oxidation is more active with increasing pressure in the oxidation zone. At the same time, raw materials with a low amount of oils give bitumens with high extensibility, and intervals of plasticity, as well as penetration. With an increase in air consumption, the intensity of the process also increases and the heat resistance of the final bitumen product increases. Residual fractions are usually oxidized in the cube - this method is used abroad, in old plants and in the production of low-tonnage types of bitumen.

Use of columns in continuously operating bitumen plants

Recently, bituminous hollow columns have been actively used for production. The presence of several columns makes production more flexible, which is important given the seasonal fluctuations in bitumen. This method makes it possible to stabilize the thermal regime of oxidation by changing the temperature of the raw materials entering the columns and using compressors. An example of a high-quality and effective application of this method is an Austrian company with its Perner technology. This technology is distinguished by the presence of an internal nozzle in the column.

compounding method

It is used when working with a bituminous mixture. It replaces the oxidation method and is used quite actively abroad in the production of construction bitumen. Such bitumen can be obtained in different ways, in order to choose the preferred one, it is necessary to conduct special studies, taking into account the characteristics of the processed raw materials, the conditions of a particular refinery. In short, we can highlight the main thing:

the most promising production of bitumen - on the apparatus of the column type;
work on the study of such oxidation is carried out constantly;
non-oxidized bitumen has a high level of adhesion, extensibility, high resistance to aging against oxidized type bitumen;
In Russia and Belarus, the production of peroxidized bitumen is developed with a further process of compounding with weighted tar.

Petroleum bitumen- liquid, semi-solid or solid petroleum products consisting of asphaltenes, resins and oils: asphaltenes give hardness and high softening point; resins increase cementing properties and elasticity; oils are a thinning medium in which resins dissolve and asphaltenes swell.

Raw material: tar, heavy oil fuel oil, deasphalting asphalts, cracking residues. Than > asphaltenes in relation to resins and< ТВ.парафинов, тем качеств-й ьитумы.

Products: The main apparatus of continuous bitumen plants is either a tubular reactor or an oxidizing column. Oxidation columns are preferable for the production of road bitumen (98% bitumen, 2% - oxidation products, decomposition, hydrocarbons carried away with gas - black solarium, which is sent to the afterburner for disposal), tubular reactors - in the production of construction bitumen.

For the production of petroleum bitumen, three methods are used:

1. By concentrating oil residues by distilling them in a vacuum, residual bitumen is obtained. To obtain residual bitumen, only raw materials with a high content of asphalt-resinous substances, which are present in sufficient quantities in heavy, high-resinous sour oils, can be used. In the processes of vacuum distillation and deasphalting, residual and precipitated bitumens are obtained. The main purpose of these processes is the extraction of distillate fractions for the production of motor fuels - in the case of the first, the preparation of raw materials for production base oils(initial stage) - in the case of the second. At the same time, by-products of these processes - distillation tar and deasphalting asphalt - meet the requirements for raw materials in the production of bitumen or they are used as raw materials in the production of oxidized bitumen.

2. Air oxygen oxidation of various oil residues and their compositions at a temperature of 180 - 300 0C (oxidized bitumen). Oxidation with air can significantly increase the content of asphalt-resinous substances, the most desirable component in the bitumen composition. For the production of oxidized bitumen, it is proposed to classify oils according to the content (%, wt.) in them of asphaltenes (A), resins (C) and solid paraffins (P).

The main production process of bitumen is oxidation - purging of tars with air. Oxidized bitumen is obtained in devices of periodic and continuous action. The latter are more economical and easier to maintain. The principle of obtaining oxidized bitumen is based on compaction reactions at elevated temperatures in the presence of air, leading to an increase in the concentration of asphaltenes, which contribute to an increase in the softening temperature of bitumen, and resins, which improve the adhesive and elastic properties of the commercial product. Apparatus used in the production of bitumen - tubular reactors or oxidation columns. When receiving building bitumen, the first ones are preferable, road - the second ones.

3. By mixing various oxidized and residual bitumens, as well as oil residues and distillates, compounded bitumens are obtained with each other. Residual bitumen - soft fusible products, oxidized - elastic and thermostable. Bitumens obtained by oxidation of cracked residues contain a large amount of carbenes and carboids, which disrupt the uniformity of bitumens and impair their cementing properties. Residual bitumen is produced from fuel oils with a high concentration of asphalt-resin substances by vacuum distillation as a residue of this distillation. Recall that fuel oil is a residue from the atmospheric distillation of oil.

The most widespread production of oxidized bitumen.

The production of petroleum bitumen is one of the thermal processes of oil refining. The main parameters of thermal processes that affect the assortment, material balance and quality of the products obtained are the quality of raw materials, pressure, temperature and duration of thermolysis (thermal process).

bitumen properties depend on the methods of production, the quality of raw materials(the nature of the processed oil), as well as on the parameters of the thermolysis process - temperature , pressure, duration.

Holy bitumen:

penetration- depth of penetration into bitumens of a standard needle under certain conditions.

softening temperature, determined by the ring-to-ball method (R&S).

Extensibility (ductility)- is characterized by the distance to which its sample can be pulled under certain conditions into a thread before breaking.

Brittleness temperature is the temperature at which a bitumen film deposited on a steel plate cracks when this plate is bent (from -2 to -30 °C). The lower this temperature, the higher the quality of the bitumen.

Viscosity bitumen - characterizes their consistency at various application temperatures.

Adhesion (sticking) evaluated by the degree of bitumen coverage of the surface of crushed stone or gravel particles after processing the sample in boiling water. The adhesive ability of bitumen depends on its chemical composition: in the presence of paraffin, it decreases, so its content is limited (no more than 5%).

^ Types of bitumen .

Oil bitumens are solid, viscoplastic or liquid products of oil refining. By chemical composition bitumen - complex mixtures of high molecular weight hydrocarbons and their non-metallic derivatives of nitrogen, oxygen and sulfur, completely soluble in carbon disulfide. To study bitumen, they are divided into the main groups of hydrocarbons (similar in properties) - oils, resins, asphaltenes, asphaltogenic acids and their anhydrides.

Oils are a mixture of cyclic hydrocarbons (mainly of the naphthenic series) of a light yellow color with a density of less than 1 and molecular weight 300...500; the increased content of oils in bitumens gives them mobility, fluidity. The amount of oils in bitumens ranges from 45...60%.

Resins are dark brown viscoplastic substances with a density of about 1 and a molecular weight of up to 1000. Resins have a more complex composition of hydrocarbons than oils. They consist mainly of oxygen heterocyclic compounds of a neutral nature and give bitumen greater ductility and elasticity. Resin content 15.30%.

Asphaltenes and their modifications (carbenes and carboids) are solid, infusible substances with a density somewhat greater than 1 and a molecular weight of 1000 ... 5000 or more. This group of hydrocarbons is an essential component of bitumen. The increased content of asphaltenes in bitumen determines its high viscosity and thermal stability. The total content of asphaltenes in various bitumens is 5...30% or more.

^ Carbenes and carboids are relatively rare in bitumen in small quantities (1 ... 2%) and contribute to the increase in the fragility of bitumen.

Asphatic acids and their anhydrides are brownish resinous substances with a density of more than 1. They belong to the group of polynaphthenic acids and can be not only viscous, but also solid. Asphaltogenic acids are the surface-active part of bitumen and increase its adhesion to the surface of mineral aggregates. Their content in oil bitumen is about 1%.