Grain composition of asphalt. See what Asphalt Concrete is in other dictionaries

Asphalt concrete

Asphalt concrete sample from the core of the Boguchanskaya Dam

Asphalt concrete   - common building material. It is used for the device of road and airfield coatings, operated flat roofs, in hydraulic engineering construction. It turns out as a result of hardening of the compacted asphalt mixture. Asphalt concrete is produced in an asphalt concrete plant.

Asphalt mix

The asphalt mixture consists of optimally selected:

• mineral materials: crushed stone (or gravel), sand (natural or crushed) with fine mineral powder (or without it);
• organic binding material: bitumen (previously tar was also used, but was banned for use within the city, and later completely excluded from production).

The components of the asphalt mixture are mixed in a heated state.

Typically, asphalt concrete is used for the construction of coatings. highways   and airfields or for flooring in industrial buildings.

Main types

According to GOST 9128-2009, asphalt mixes and asphalt concrete are divided into crushed stone (composition: crushed stone, sand, mineral powder, bitumen), gravel (gravel, sand or sand and gravel material, mineral powder and bitumen) by the type of mineral component (stone material) and sandy (sand, mineral powder, bitumen).

According to the viscosity of bitumen, which is part of the composition and the permissible temperature when laying in the coating, the mixtures are divided into:

• hot   (binder - viscous and liquid petroleum road bitumen), stacked with a temperature of at least 120 ° C;
• cold   (binder - liquid oil road bitumen), are stacked with a temperature of at least 5 ° C.

GOST 9128-84, depending on the viscosity of bitumen, divided asphalt mixtures into: hot, cold and warm (using both viscous and liquid bitumen and laid at a temperature of at least 70 ° C). GOST 9128-97, which replaced GOST 9128-84 (entered into force on January 1, 1999), does not define warm asphalt mixtures. Unlike cast asphalt, hot and cold mixes require compaction when laying in the coating.

According to the maximum grain size of the mineral component, hot asphalt mixtures are divided into:

• coarse-grained   (grain size up to 40 mm);
• fine-grained (grain size up to 20 mm);
• sandy   (grain size up to 5 mm).

Cold mixtures are divided into fine-grained   and sandy.

Asphalt concrete from hot mixtures according to the value of residual porosity (expressed as a percentage of the volume of pores in the coating after compaction) are divided into the following types:

• high density   (residual porosity from 1.0 to 2.5%);
• dense   (residual porosity of St. 2.5 to 5.0%);
• porous   (residual porosity of St. 5.0 to 10.0%);
• highly porous   (residual porosity of St. 10.0 to 18.0%).

Coatings from cold mixtures should have a residual porosity of 6.0 to 10.0%.

Hot mixes, crushed stone and gravel, and dense asphalt concrete according to the content of crushed stone (gravel) in them are divided into types:

• A   (gravel [gravel] content of St. 50 to 60%);
• B   (gravel [gravel] content of St. 40 to 50%);
• IN   (crushed stone [gravel] content of St. 30 to 40%).

Cold crushed stone and gravel mixtures and the corresponding asphalt concrete according to the content of crushed stone (gravel) are divided into types Bh   and Bx.

Mixtures of sand, hot and cold, and the corresponding asphalt concrete by type of sand are divided into the following types:

• G   and Gh   - prepared on sand from crushing screenings or on their mixtures with natural sand with a content of the latter of not more than 30% by weight;
• D   and Dh   - prepared on natural sands or mixtures of natural sands with screenings of crushing when the content of the latter is less than 70% by weight.

Depending on the materials used and physical and mechanical properties, asphalt mixtures and asphalt concrete are divided into the following grades:

• hot high-density - MI;
• dense types:
  • A - MI, MII;
  • B, D - MI, MII, MIII;
  • B, D - MII, MIII;
• porous and highly porous - MI, MII;
• cold types:
  • Bx, Bx - MI, MII;
  • Gh - MI, MII;
  • Dx - MII

Selection of the composition of the asphalt mix

The history of designing the composition of hot asphalt mixes dates back to the turn of the 19th and 20th centuries, when various selection methods were developed independently in several countries. Each methodology necessarily included a set of specific compaction measures hot mixassessment of the porosity of asphalt concrete and testing of asphalt concrete to determine its operational characteristics. With all the variety of selection methods, the fundamental principle is the design of the mixture, which ensures compliance with the quality requirements for asphalt concrete adopted at the beginning of the 20th century, the main purpose of which is optimal performance pavement   and its high service life.

There are two approaches to the design of compositions of asphalt mixtures. The first is the selection of a mixture with continuous granulometry of stone material (the so-called Macadam, in honor of D.L. Mac-Adam, who developed the technology for the construction of roads with gravel). This option guarantees high mechanical properties of the coating due to wedging in small fractions of crushed stone of larger fractions. A coating made of a mixture with continuous granulometry of the mineral part has a high roughness and shear resistance. The properties of the mixture do not change as a result of deviations in the dosage of mineral powder and bitumen; it is easily distributed, formed and compacted during the coating process. For mixtures of this type, strong stone materials with more than half grain surface are required. The shape of the grain composition curve (sieving curve) of a mixture of mineral materials approaches a cubic parabola. An important condition is the use of bitumen resistant to aging (changes in group and phase composition) and having good adhesion to the surface of stone materials, since open porosity is typical for these coatings.

In the second method of selecting the mixture - on the principle of dense concrete - it is allowed to use stone materials with a rounded grain shape and intermittent granulometry (in the absence of any fraction of mineral materials). In the process of compaction of these mixtures, asphalt concrete with closed porosity is formed, the coating acquires higher water resistance and frost resistance. However, such mixtures are more prone to uneven distribution in the volume of grains of the mineral component and bitumen. Deviations in the dosage of mineral powder and bitumen have a great influence on their physical and mechanical properties. For coatings from mixtures selected on the principle of dense concrete, a low roughness is characteristic.

The selection begins with determining the properties of the constituents of the mixture and verifying their compliance with the standards established technical documents. Then the optimal ratio between the components is found, which guarantees a mixture with certain properties. The final step is to evaluate the obtained selection options from a technical and economic point of view and to issue trial lots for asphalt plant.

see also

Notes

Literature

• GOST 9128-2009 Mixes asphalt concrete road, airfield and asphalt concrete. Technical conditions Interstate Standard (as national standard Russian Federation   put into effect by order of the Federal Agency for technical regulation   and metrology of April 22, 2010 N 62-st)

See what "Asphalt Concrete" is in other dictionaries:

Asphalt Concrete ... Spelling Dictionary

Asphalt concrete   - compacted asphalt mix.

.

A rationally selected mixture of mineral materials [crushed stone (gravel) and sand with or without mineral powder] with bitumen, taken in certain proportions and mixed in a heated state.

The laying temperature of the a / b mixture is at least 120 ° C.

Fine-grained a / b mixture with the number of grains up to 20 mm.

High-density a / b from the hot mixture has a residue. porosity of st. 2.5 to 5.0%;

A / b: Type A (depending on the gravel content of St. 50 to 60%).

Asphalt mix: Brand I.

Asphalt concrete mix type D, grade II, dense asphalt concrete in accordance with GOST 9128-2009

It is used for the installation of upper layers of coatings during new construction and overhaul of roads of category III, pedestrian zones and sidewalks. Characteristics of the mixture:

sandy asphalt mix on natural sand, with the size of mineral grains up to 5 mm;

temperature of the asphalt mixture during shipment from 145 to 155 ° C.

The physical and mechanical properties of asphalt concrete meet the requirements of GOST 9128-2009.

Asphalt concrete mix type B, grade II dense asphalt concrete in accordance with GOST 9128-2009

It is used for the installation of upper layers of coatings for new construction and major repairs of roads of category III, streets, driveways, sites, pedestrian zones. Characteristics of asphalt mix and asphalt concrete:

fine-grained asphalt mix, with a grain size of up to 20 mm;

dense asphalt concrete with residual porosity of st. 2.5 - 5.0%;

temperature of the mixture during shipment from 145 to 155 ° C.

MIXES ASPHALT CONCRETE AND ASPHALT CONCRETE

1. Definitions Asphalt mix   - a rationally selected mixture of mineral materials (crushed stone (gravel) and sand with or without mineral powder) with bitumen, taken in certain proportions and mixed in a heated state. Asphalt concrete   - compacted asphalt mixture. Asphalt is often called the word asphalt. 2. History   Initially, in the 19th century, city streets were paved with stones (cobblestone pavement). Beginning in the middle of the 19th century, in France, Switzerland and the USA and in a number of other countries, paving is started from bitumen-mineral mixtures. In 1876, for the first time in the United States, cast asphalt prepared using oil bitumen. For the first time, asphalt concrete pavement was used to cover the sidewalks of the Royal Bridge in Paris in the 30s of the XIX century. In the early 1930s, sidewalks on the Moran bridge across the Rhone River in Lyon were covered with asphalt in France in the Department of En. The booming road network required new types of pavements that could be built as quickly as subgrade. So, in 1892, in the USA, the first road construction was made of concrete with a width of 3 m by industrial method, and 12 years later using a tarmac with the free flow of hot bitumen 29 km of the road. Asphalt turned out to be the most suitable material for paving. Firstly, it becomes more even, which means less noisy and has the necessary roughness. Secondly, on laid asphalt concrete, you can immediately open the movement and not wait until it hardens, unlike cement concrete, which gains the necessary strength only on the 28th day. Thirdly, the coating of asphalt concrete is easily repaired, washed, cleaned, any marking is well supported on it. In the summer of 1839, sidewalks were covered in St. Petersburg over 45.5 linear fathoms 5 feet wide (97.08 * 1.52 m) and part of the bridge 8.5 feet long and 6.5 feet wide (2.59 * 1 , 98 m) at the dam of the Tuchkov bridge. The first in Russia to establish the production of asphalt was engineer I.F. Buttats. The cost of 1 square. m of coverage cost 14 rubles. For the first time, Russian asphalt was mined at the Syzran plant in 1873 (on the right bank of the Volga 20 km higher than Syzran). In 1876, the Moscow City Duma allocated 50 thousand rubles to conduct an experiment on the construction of asphalt concrete pavement. Several sections of new material were built on Tverskaya Street. 3. Main parameters and types   Asphalt mixtures (hereinafter referred to as mixtures) and asphalt concrete are divided into crushed stone, gravel and sand depending on the type of mineral component. Mixtures, depending on the viscosity of the bitumen used and the temperature during installation, are divided into:

hot, prepared using viscous and liquid petroleum road bitumen and stacked with a temperature of at least 120 ° C;

coldprepared using liquid petroleum road bitumen   and stacked with a temperature of at least 5 ° C.

Hot mixes and asphalt concrete, depending on the largest size of mineral grains, are divided into:

coarse-grained with a grain size of up to 40 mm;

fine-grained - up to 20 mm;

sand - up to 5 mm .;

Cold mixtures are divided into fine-grained and sandy. Asphalt concrete from hot mixtures, depending on the value of residual porosity, is divided into types:

high density residual porosity from 1.0 to 2.5%;

dense - from 2.5 to 5.0%;

porous - from 5.0 to 10.0%;

highly porous - from 10.0 to 18.0%.

Asphalt concrete from cold mixtures should have a residual porosity of more than 6.0 to 10.0%. Crushed stone and gravel hot mixes and dense asphalt concrete, depending on the content of crushed stone (gravel) in them, are divided into types:

"A"    - with crushed stone content from 50 to 60%;

"B"    - from 40 to 50%;

"IN"    - from 30 to 40%.

Crushed stone and gravel cold mixtures and the corresponding asphalt concrete, depending on the content of crushed stone (gravel) in them, are divided into types Bx and Bx. Hot and cold sand mixtures and the corresponding asphalt concrete, depending on the type of sand, are divided into types:

"G and Gh"    - on sands from crushing screenings, as well as on their mixtures with natural sand when the content of the latter is not more than 30% by weight;

"D and Dh"    - on natural sands or mixtures of natural sands with screenings of crushing when the content of the latter is less than 70% by weight.

Mixtures and asphalt concrete, depending on the indicators of physical and mechanical properties and the materials used, are divided into grades indicated in the table:

The brand of the mixture and asphalt concrete determines the indicators of physical and mechanical properties, water saturation, grain compositions and porosity of the mineral part. Characteristics of grades of mixtures and asphalt concrete in accordance with GOST 9128-97. "Mixtures of asphalt concrete road, airfield and asphalt concrete" (230kB) 4. Material Requirements   Crushed stone from dense rocks and gravel, crushed stone from slag, which are part of the mixtures, by grain composition, strength, content of dust and clay particles, clay content in lumps must meet the requirements   The content of lamellar (flaky) grains in the gravel and gravel should be no more than the mass:

15% - for mixtures of type A and high-density;

25% - for mixtures of types B, Bx;

35% - for mixtures of types B, Bx.

Gravel-sand mixtures according to the grain composition must meet the requirements of GOST 23735, and gravel and sand, which are part of these mixtures, - GOST 8267-93. "Crushed stone and gravel from dense rocks for construction work." (179kB)   and GOST 8736-93. "Sand for construction work." (106kB) respectively. Crushed stone and gravel fractions from 5 to 10 mm, from 10 to 20 (15) mm, from 20 (15) to 40 mm, and also mixtures of these fractions are used to prepare mixtures and asphalt concrete. Mineral powder, which is part of mixtures and asphalt concrete, must meet the requirements of GOST 16557. It is allowed to use industrial waste (ground basic metallurgical slag, ash, ash and slag) as porous and highly porous asphalt concrete, as well as for dense asphalt concrete of grades II and III. mixtures, dust-entrainment of cement plants, etc.). Viscous petroleum bitumens in accordance with GOST 22245 and liquid in accordance with GOST 11955, as well as polymer-bitumen binders and modified bitumen   according to the technical documentation agreed in the prescribed manner.

Asphalt, price   on which depends on many of its characteristics - this is a viscous non-crystalline material, in its bulk consisting of hydrocarbons. In terms of chemical composition, asphalt is at least 80% carbon and about 15% hydrogen, the remaining 5% include

oxygen, sulfur, nitrogen and a number of different metals.

Most in natural asphalt (up to 75%) contains bitumen, which is an artificial, residual product of oil refining, which differs in a solid or viscous consistency.

The composition of petroleum bitumen includes several groups of substances that have different solubilities: asphaltenes, asphaltene acids, neutral resins, petroleum oils, carbenes and carbides (substances that cannot be dissolved using organic compounds).

Asphaltenes provide such characteristics as hardness and high softening temperature of bitumen, resins give them elasticity and cementing properties, oils - frost resistance.

Asphalt is a complex material: it is considered colloidal and is a dispersion of a material having a high molecular weight in a liquid with a lower molecular weight.

Asphalt is a very flexible material, it adheres well to other surfaces, is wear-resistant and waterproof, and is also extremely resistant to the effects of a large amount of salts, acids and alkalis. With all its remarkable properties, it tends to collapse if used improperly. Before as buy asphalt, carefully study the properties of the mixtures offered to you. The effect of water, the influence of temperature extremes and ultraviolet radiation lead to a slow splitting of asphalt into carbon dioxide and water.

Asphalt has excellent thermoplastic properties: for example, hard asphalts are plastics that can be easily molded and processed in the mold in hot or cold state under high pressure.

At ambient temperature, asphalt is a liquid with very high viscosity characteristics, unsuitable for processing. In this case, asphalt can be converted to give it a composition suitable for processing. You can do this using the following methods:

Heating: asphalt is heated for use on large and medium areas (road surfaces, roofing of large buildings, etc.);

Mixing with petrochemical solvents (dilution) is the most expensive operation in which solvents are used to reduce the viscosity of asphalt;

Emulsification in water to create an emulsion is the cheapest process that does the least harm to the environment.

Buy asphalt concrete   It is worth only carefully studying the documentation from the manufacturer of the material.

Properties of asphalt emulsions

Asphalt emulsions are dispersions of very finely ground bitumen in an aqueous medium. Such emulsions are characterized by low viscosity - they are used at ambient temperature, that is, this material is ideal for the construction industry and is used very widely. There are two classes of asphalt emulsions: chemical (emulsions with an alkaline emulsifier) \u200b\u200band clay.

Asphalt emulsions are most often used in the construction of road surfaces for freeways, the installation of roofing, as well as adhesive and sealing compounds in the construction industry.

One of the main advantages of adhesives and sealants on a bitumen basis is their low cost. Bitumen is several times cheaper than synthetic polymers and rubbers, so the benefit of its use both as an independent material and in mixtures with other polymers does not raise any doubts.

Using emulsions, gluing, coating, impregnation of surfaces, the creation of moisture-proof coatings, and surface insulation are carried out. Use bitumen emulsions and as adhesives when laying the roof,

the creation of building shells, insulation of buildings, as well as other operations that require the rapid evaporation of water from joints.

Emulsion viscosity is the main criterion for its use. As a rule, when creating a coating or sealing the surface, it is necessary to give the emulsion a higher viscosity in order to obtain a film of the required thickness. The asphalt emulsion, which is used when bonding the layers of the shell, must have sufficient fluidity so that the layer is as uniform as possible. Therefore, to obtain the desired properties, it may be necessary to dilute the emulsion with water.

The road is considered one of the most profitable coatings. It is practical, inexpensive and generally provides the necessary characteristics for operation. Of course, it is not without its drawbacks, but they, as a rule, are manifested in cases of non-compliance with the styling technology. On the other hand, a well-constructed asphalt concrete coating provides a sufficiently high bearing capacity and elasticity. At the same time, there are different approaches to the creation of such roads and sites, the differences in which are determined by the composition of the mixture and laying technologies.

The composition of the asphalt mix

The traditional technology of the device of asphalt provides for the presence in the main composition of mineral fillers and a binder component. The first group of materials includes sand and gravel. In this case, crushed stone can be replaced by gravel, and sand is used in whole or crushed form.

Also, depending on the requirements for the coating and the conditions of its operation, a finely dispersed Organic component can be used to bind the main composition, usually bitumen. The characteristics that the asphalt concrete coating receives as a result are determined by the approach to the formation of the base mixture. The differences in the methods of manufacturing the solution are due to the parameters of the components used. For example, gravel or crushed stone can be selected with a fraction of 10 to 40 mm. So bitumen can have different viscosity and density indicators. These and other factors ultimately determine the characteristics of the coating.

Instructions for the delivery of mixtures to the facility

First of all, the type, quantity and carrying capacity of vehicles that will deliver will be determined. This choice depends on the size of the work, the volume of the mixture and the pace of future styling. The transportation process includes several stages, including weighing, loading the material, transportation and unloading directly to the collection point. For servicing crushed stone, cold and hot mixtures, a dump truck with a clean body is used, which is covered by a protective awning or waterproof canopies. Cast mixture, from which the asphalt concrete coating is formed, is transported in the so-called coaches. These are cars with thermos-mixers that provide mixing and heating of the composition during transportation. As for the transportation time, in the case of hot and mastic mixtures, it depends on the characteristics of the mixture, and for cold solutions there are no restrictions on the duration of transportation.

Preparatory work

The main event in the process of preparing for the final laying of the mixture is the test coating device. The length of such a strip is not less than 200 m, and the width is taken in accordance with the parameters of the passage of the paver. Based on the results of the test laying, the technologists determine the most suitable mixture recipe, and also, if necessary, make adjustments to the method of laying it and the sealing technology.

Trial asphalt concrete pavement is checked for such characteristics as temperature, compaction quality, base condition, etc. Special control technologies are used for this. In particular, non-destructive express methods and sampling, which are subsequently investigated in the laboratory. Based on the findings, the technologists make recommendations for the manufacturer. If necessary, the composition of the mixture is adjusted under the specific operating conditions of the coating.

Mix Distribution Technique

Before the distribution of the finished mass, the paver plate is installed on the edge of the previously laid timber, the height of which will correspond to the thickness of the layer being arranged. To prevent spreading of the mixture, a sliding type of formwork is used - it must be moved behind the paver. If there is no such device, then before starting the distribution in the longitudinal direction, it is necessary to fix metal strips with a length of about 20 m. Moreover, the thickness of this fence should be no less than the height of the formed coating. By the way, the thickness of asphalt concrete coatings on average varies from 5 to 10 cm. As the laying and compaction of the mass are completed, the metal bars are removed. As for the width, most often the distribution of the mixture is performed with the coverage of the entire roadway.

If defects are detected after the distribution of the substrate on the surface, they must be processed manually. The use of tammers is practiced, which allows precise correction of loose seams, tubercles and other flaws. Typically, defects are formed in the areas where the strips adjoin the stop elements - the same metal bars. Separate gravel is also covered with gravel. Data layers asphalt concrete pavement   form evenly in bulk immediately after distribution of the mixture. Further, the granular material is recessed into the base of the coating with a light roller.

Compaction technology

The compaction process should go parallel to the operation of the asphalt distributor, which distributes the mixture. Tamping is performed continuously by the link of the rollers. Also, smooth-roll, pneumowheel and combined special equipment can be used in the work. The force and load of compaction of cold and hot asphalt in the structural layers are calculated according to several indicators. In particular, technologists take into account density characteristics and mass temperature.

The asphalt concrete pavement is made of a dense hot mixture with a compaction coefficient of 0.99. Cold mixtures assume a load with a coefficient of 0.96. The transverse mates of the laid lines are arranged perpendicular to the road axis in one lane without leaving ledges. To fulfill this condition, the end of the previously arranged strip is trimmed with a special tool with

Repair Instructions for Asphalt Concrete Pavements

Before performing repair operations directly, a coating inspection is performed. To do this, the surface is cleaned using road brushes, after which geodetic tools are used to check the evenness of the coating. Depending on the nature of the defects identified, appropriate repair measures are applied. To further ensure the evenness of the layers with the help of a rail, the stump is marked. A bar with a level is applied to the overlap. The place under the bar where the decrease in thickness is noted is considered as the line of the future transverse trimming. Also, repair of asphalt concrete pavement may include layer building operations. Typically, such measures are applied to the device coating, framing the wells. For this, special inserts and reinforced concrete segments can be used.

Safety instructions

Even before the start of work, the target area should be fenced with the use of appropriate road signs. People working on the site should be in overalls established by the regulations. At night, the site should also be provided with lighting and signal lights. Separate safety measures are provided for solution handling processes. So, when unloading the carrier with a mixture, it is forbidden for people to be between the car and the material bunker. During laying and compaction, the asphalt concrete pavement of roads should be free from foreign objects and workers. After the completion of activities, all inventory, equipment and supplies should be removed from the cover and delivered to appropriate storage locations.

Coating quality control

Quality control arranged coating   made using special tools. In particular, calibrated automated measuring instruments are used, as well as special equipment, which makes it possible to derive a complex conclusion based on the data obtained. Among the most common characteristics, on the basis of which the “work” of asphalt concrete pavements is evaluated, compliance with design parameters in terms of thickness and width, evenness of layers, slopes, temperature and quality of joints between the strips are noted.

Conclusion

Work on the installation of asphalt is a complex of technical measures. At the same time, the initial design calculations are of considerable importance from the point of view of the formation of high-quality pavement. Even with good laying and sealing, the coating will not be able to perform its functions if the wrong mixture has been selected. Although the basic technology of asphalt concrete coatings involves the use of a standard set of components to obtain a mortar for laying, their parameters may vary. Therefore, laying test mixtures is practiced, which subsequently gives an idea of \u200b\u200bthe most favorable coating characteristics for a particular site. And already in the future, responsibility for the quality of the road goes directly to the working team, which distributes and compacts the asphalt concrete mass.

  - suitable building material for roads. Its technical characteristics make it possible to ensure smoothness and the required surface roughness with the help of a leveling paver. Another advantage of the asphalt mix is \u200b\u200bthe ability to use roadbed immediately after installation. In turn, cement concrete acquires the necessary structure only after twenty-eight days. In addition, warm asphalt mixtures are distributed with a uniform leveling layer. Such surfaces are easy to repair, wash, and paint lasts a long time.

Asphalt concrete is a building material, which includes bitumen, building sand, gravel, sometimes a special powder with minerals. The ingredients of the sand mixtures are mixed in the required proportions at a certain temperature. Asphalt mixture is made in accordance with state standard.

Application

Dense porous building materials are used when laying layers of the roadway, runways, sites and other surfaces. For this, specialists use asphalt concrete road, airfield and asphalt concrete mixtures.

Kinds

Solutions are classified according to several parameters. The classification depends on the characteristics of the components contained in the asphalt mixes. There are four types of solutions. The classification of asphalt mixtures is as follows:

1. By the presence of a mineral component. Solutions are classified depending on what type of component is used in the manufacture. There are different types of components included in. For example, type A is characterized by a fifty percent content of crushed stone in solution.
2. By the size of mineral grains, the compositions are of three types: sand (grains for a sand mixture must be less than five millimeters), coarse (grains less than forty millimeters) and fine-grained asphalt mix (grains less than twenty millimeters).
3. Depending on the building material used, the mixture is sandy, gravel and gravel.
4. Temperature also affects specifications   solutions. The classification is carried out according to the temperature that was recorded at the time when the mixture was laid. There are two varieties: hot asphalt mixes and warm asphalt mixes. In particular, during distribution, the cold asphalt mixture should have a temperature of about 5 ° C, hot - not lower than 120 ° C.

Grades of solutions

There are two brands on the building materials market. The first brand involves the use of crushed stone 1000-1200. For the second brand - apply gravel 800-1000. Before using this or that mixture, it is necessary to determine its brand. Hot formulations that are stacked at a specific temperature are labeled (i):

• brand solution;
• high density; i;
• dense;
• A; i, ii;
• B, C; i, ii, iii;
• G, D. ii, iii;
• porous i, ii.

Organomineral compounds

In addition to the above classifications, there are organomineral solutions. They are made by mixing bitumen and limestone. The use of dense compositions is to repair asphalt concrete pavement.

Mixture Requirements

In accordance with the state standard, the content of lamellar grains in gravel and gravel should not exceed the following values:

• fifteen percent - for high-density compositions and solutions "A";
• twenty-five percent - for materials B and Bh;
• thirty-five percent for solutions B and Bx.

Features

Building materials must be produced at the enterprise in compliance with the rules. Shipment must be carried out to the dump truck. Crushed stone and mastic mortar is used for compaction of the surface leveling layer of highways, laying of runways, sidewalks, squares, etc. The properties of the building material can enhance adhesion to the roadbed layer, which increases the safety of vehicles.

As the practice of using asphalt concrete in the past has shown, some time after the start of operation of the pavement, irregularities quickly appeared on the upper layer, and later potholes. This was due to the fact that during loading, transportation and laying work, the solution was subjected to delamination (or segregation).

The segregation of asphalt concrete pavement is a process that leads to improper distribution of grains, air bubbles and bitumen in the building material. Segregation provokes imbalances in the components contained in the mixture. The segregation process shortens the life of the coating. In other words, segregation causes the opposite effect of mixing the components. Segregation makes the solution heterogeneous.

Acceptance rules

To create a supply of mortar, transport and paver, using cranes. The material handler is a special equipment designed for the smooth operation of a special paver. Cranes are used when accepting asphalt concrete from vehicles and moving it to the paver.

In addition, there are a number of nuances that must be considered when accepting a prepared solution from a reloader. In particular, acceptance from the loader should be done in batches. By batch is meant one-piece building material produced on a machine during one shift at the enterprise.

As for hot trains, their number should be no more than six hundred tons, and cold - no more than two hundred tons. The amount of solution is determined by its weight. To do this, use truck or rail scales. If it is necessary to load material onto a ship, then after completion of the acceptance of the cargo, the draft of the vessel is measured.

To check the conformity of the goods to the specified characteristics, there are a number of tests that will confirm the conformity of the goods to the requirements. After the inspection, the buyer receives a document confirming the conformity of the material. In this case, for each consignment it is necessary to write a separate document.

Consumption and density of building material

The quality and compaction of the road surface depends on the properties specified in state standard. In accordance with the regulations, for weight and density of 1m3 asphalt concrete composition   sand that is added to its composition. Thus, the mass is:

• quartz sand - 2200 kilograms per cubic meter;
• slag sand - 2350 kilograms per cubic meter.

Slag sand is used to compact the mixture. Specific gravity   concrete, which contains crushed stone of a large fraction, is more than other types of building materials. Obtaining an exact figure is extremely difficult, but the average weight is approximately 2100 kilograms per m3. The indicators are taken into account when calculating the required amount of building material for specific work. In addition, such data are sometimes taken into account when disassembling roads, this will determine the carrying capacity of special equipment and the number of cars. When carrying out construction work on a private territory (concreting a site, etc.), it is necessary to first calculate the composition consumption. Thus, you will determine the cost and quantity of building material in advance. The flow rate of the solution can be calculated as follows:

1. First of all, you should determine the area of \u200b\u200bthe territory that will be paved. For example, there is a site of 50 m2. In this case, the thickness of the asphalt concrete is one centimeter.
2. To cover 1 m2 of the road will require twenty-five kilograms of the composition. Therefore, for a site of 50 m2, 25 * 50 \u003d 1250 kilograms of material will be required.
3. Since there are about 2250 kilograms of asphalt concrete in one m3, it will take 1250: 2250 \u003d 0.55 m3 of concrete to cover such a site.

Conclusion

Asphalt concrete is widely used in the construction of roads, sites and runways. When carrying out work, it is important to follow the established rules and take into account the weight of asphalt concrete, which depends on the ingredients that make up its composition.

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