Cast asphalt concrete: material features, manufacturing technology and application. The method of preparing a cast asphalt concrete mixture What is the name of the top layer of asphalt

GOST R 54401-2011

Group G18

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

Automobile roads common use

ASPHALT CONCRETE ROAD CAST HOT

Technical requirements

Automobile roads of general use. Hot road mastic asphalt. technical requirements

OKS 93.080.20
OKP 57 1841

Introduction date 2012-05-01

Foreword

Goals and principles of standardization in Russian Federation established by the Federal Law of December 27, 2002 N 184-FZ "On Technical Regulation", and the rules for the application of national standards of the Russian Federation - GOST R 1.0-2004 "Standardization in the Russian Federation. Basic provisions"

About the standard

1 DESIGNED BY AUTONOMOUS non-profit organization"Research Institute of the Transport and Construction Complex" (ANO "NII TSK") and Open Joint Stock Company "Asphalt Concrete Plant N 1", St. Petersburg (JSC "ABZ-1", St. Petersburg)

2 INTRODUCED technical committee according to standardization TC 418 "Road facilities"

3 APPROVED AND PUT INTO EFFECT by Order of the Federal Agency for Technical Regulation and Metrology dated September 14, 2011 N 297-st

4 This standard developed taking into account the main regulatory provisions of the European regional standard EN 13108-6:2006 * "Bitumen mixtures. Specifications on the material. Part 6: Mastic Asphalt" (EN 13108-6:2006 "Bituminous mixtures - Material specifications - Part 6: Mastic Asphalt", NEQ)
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* Access to international and foreign documents mentioned hereinafter in the text can be obtained by clicking on the link. - Database manufacturer's note.

5 INTRODUCED FOR THE FIRST TIME


Information about changes to this standard is published in the annually published information index "National Standards", and the text of changes and amendments - in the monthly published information indexes "National Standards". In case of revision (replacement) or cancellation of this standard, a corresponding notice will be published in the monthly published information index "National Standards". Relevant information, notification and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet

1 area of ​​use

1 area of ​​use

This standard applies to hot cast road asphalt concrete and hot cast road asphalt concrete mixtures (hereinafter referred to as cast mixes) used for pavement on public roads, bridge structures, tunnels, as well as for patching, and establishes technical requirements to them.

2 Normative references

This standard uses normative references to the following standards:

GOST R 52056-2003 Polymer-bitumen road binders based on styrene-butadiene-styrene block copolymers. Specifications

GOST R 52128-2003 Bituminous road emulsions. Specifications

GOST R 52129-2003 Mineral powder for asphalt concrete and organo-mineral mixtures. Specifications

GOST R 54400-2011 Public automobile roads. Asphalt road cast hot. Test Methods

GOST 12.1.004-91 Occupational safety standards system. Fire safety. General requirements

GOST 12.1.005-88 System of labor safety standards. General sanitary and hygienic requirements for the air of the working area

GOST 12.1.007-76 Occupational safety standards system. Harmful substances. Classification and General requirements to safety

GOST 12.3.002-75 Occupational safety standards system. Manufacturing processes. General safety requirements

GOST 17.2.3.02-78 Nature protection. Atmosphere. Rules for establishing allowable emissions harmful substances industrial enterprises

GOST 8267-93 Crushed stone and gravel from dense rocks for construction work. Specifications

GOST 8269.0-97 Crushed stone and gravel from dense rocks and waste industrial production for construction work. Methods of physical and mechanical tests

GOST 8735-88 Sand for construction work. Test Methods

GOST 8736-93 Sand for construction work. Specifications

GOST 22245-90 Viscous oil road bitumen. Specifications

GOST 30108-94 Construction materials and products. Determination of specific effective activity natural radionuclides

GOST 31015-2002 Asphalt concrete mixes and crushed stone-mastic asphalt concrete. Specifications

Note - When using this standard, it is advisable to check the validity of reference standards in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or according to the annually published information index "National Standards", which was published as of January 1 of the current year , and according to the corresponding monthly published information signs published in current year. If the reference standard is replaced (modified), then when using this standard, you should be guided by the replacing (modified) standard. If the referenced standard is canceled without replacement, the provision in which the reference to it is given applies to the extent that this reference is not affected.

3 Terms and definitions

In this standard, the following terms are used with their respective definitions.

3.1 asphalt road cast hot: Asphalt-concrete road cast hot mix frozen in the process of cooling and formed in the coating

3.2 asphalt granulate: Material resulting from milling an existing asphalt pavement (recycled asphalt)

3.3 leveling layer: A layer of varying thickness that is applied to an existing layer or surface to create desired profile surface for the next structural layer of uniform thickness

3.4 astringent (astringent): Organic compound (viscous road bitumen, modified bitumen) designed to connect the grains of the mineral part of the cast mixture

3.5 dephlegmator: Special additives based on natural waxes and synthetic paraffins with a melting point from 70 °C to 140 °C, used to modify petroleum binders in order to reduce their viscosity

3.6 additive: An ingredient that can be added to a mixture in specified amounts to affect the properties or color of the mixture

3.7 road surface: Structure consisting of one or more layers, perceiving the loads from the transport and ensuring its unhindered movement

3.8 given composition of the mixture (composition of the mixture): The optimally selected composition asphalt mix, indicating the curve of particle size distribution of the mineral part of the mixture and the percentage of components

3.9 acidic rocks: Igneous rocks containing more than 65% silicon oxide (SiO

3.10 kocher (mobile kocher): Special mobile thermos boiler for cast mixture transportation, equipped with heating, mixing system (with or without independent drive) and devices to ensure cast mixture temperature control

3.11 hot flush method: Technological process creating a rough surface of the top layer pavement by applying a grain mineral mixture (fractionated sand or crushed stone) or blackened crushed stone to a cast mixture that has not cooled down after laying

3.12 modified bitumen: Binder made on the basis of viscous road bitumen by introducing polymers (with or without plasticizers) or other substances in order to impart certain properties to bitumen

3.13 bridge building: Road engineering structure (bridge, overpass, viaduct, flyover, aqueduct, etc.), consisting of one or more span structures and supports, laying a transport or pedestrian path over obstacles in the form of watercourses, reservoirs, canals, mountain gorges, city streets , railways and roads, pipelines and communications for various purposes

3.14 main rocks: Igneous rocks containing 44% to 52% silicon oxide (SiO

3.15 coating surface: The top layer of the road surface that comes into contact with traffic

3.16 polymer-bitumen binder (PBV): Polymer modified viscous road bitumen

3.17 full pass mineral material: The amount of material whose grain size smaller size openings of a given sieve (amount of material passing through a given sieve when sieved)

3.18 total balance of mineral material: The amount of material whose grain size over size openings of a given sieve (the amount of material that did not pass when sifting through a given sieve)

3.19 row (laying strip): Pavement element laid in one working shift or working day

3.20 segregation (stratification): Local change in the granulometric composition of the mineral materials of the cast mixture and the content of the binder in the initially homogeneous mixture, due to individual movements of particles of coarse and fine fractions of the mineral part, during the storage of the mixture or its transportation

3.21 layer (structural layer): A building element of a road surface, consisting of a material of one composition. The layer can be laid in one or more rows

3.22 asphalt road cast hot mix: Castable mixture, with minimum residual porosity, consisting of a grain mineral part (crushed stone, sand and mineral powder) and viscous petroleum bitumen (with or without polymeric or other additives) as a binder, which is laid by injection molding technology, without compaction , at a mixture temperature of at least 190 °C

3.23 medium rocks: Igneous rocks containing 52% to 65% silicon oxide (SiO

3.24 stationary kocher: A special stationary storage hopper for homogenization and storage of the cast mixture after the end of its production process, equipped with heating, a mixing system, a loading device and temperature control devices for the cast mixture

3.25 workability: Qualitative characteristic cast mixture, determined by the forces that ensure its homogenization during mixing, its suitability for transportation and laying. Includes such properties of the cast mixture as flowability, suitability for laying by injection technology, spreading rate over the surface

3.26 blackened gravel: Graded crushed stone treated with bitumen, in an unbound state and intended to create a surface rough layer.

4 Classification

4.1 Cast mixes and asphalt concretes based on them, depending on the largest grain size of the mineral part, the content of crushed stone in them and the purpose, are divided into three types (see table 1).


Table 1

5 Technical requirements

5.1 Cast mixtures must be prepared in accordance with the requirements of this standard according to the technological regulations approved in the prescribed manner by the manufacturer.

5.2 Grain compositions of the mineral part of mixtures of cast and asphalt concrete based on them, when using round sieves, must correspond to the values ​​indicated in table 2.


table 2

Grain compositions of the mineral part of mixtures of cast and asphalt concretes based on them, using square sieves, are given in Appendix B.

Graphs of permitted granulometric compositions of the mineral part of the cast mixture are given in Appendix B.

5.4 Indicators of the physical and mechanical properties of mixtures of cast and asphalt concrete based on them, the temperature of production, storage and laying should correspond to those indicated in Table 3.


Table 3

The physical and mechanical properties of mixtures of cast and asphalt concrete based on them are determined in accordance with GOST R 54400.

5.5 Maximum temperature, indicated in table 3, is valid for any place in the mixing mechanism and containers for storage and transportation.

5.6 The values ​​of the index of the depth of indentation of the stamp, depending on the purpose and place of application of mixtures of cast and asphalt concrete based on them, are shown in Table 4.


Table 4

The index of the indentation depth of the stamp at a temperature of 40 °C during the first 30 minutes of the test and (if necessary) the increase in the index of the indentation depth of the stamp during the next 30 minutes of the test is determined in accordance with GOST R*.

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* The text of the document corresponds to the original. - Database manufacturer's note.

5.7 Cast mixtures must be homogeneous. The homogeneity of cast mixtures is assessed in accordance with GOST R 54400 by the coefficient of variation of the values ​​of the index of the indentation depth of the die at a temperature of 40 °C during the first 30 minutes of the test. The coefficient of variation for mixtures of cast types I and II shall not exceed 0.20. This indicator for a mixture of cast type III is not standardized. The index of homogeneity of the cast mixture is determined at intervals not less than monthly. The index of uniformity of the cast mixture is recommended to be determined for each manufactured composition.

5.8 Material requirements

5.8.1 For the preparation of cast mixtures, crushed stone is used, obtained by crushing dense rocks. Crushed stone from dense rocks, which is part of cast mixtures, must comply with the requirements of GOST 8267.

For the preparation of cast mixtures, crushed stone of fractions from 5 to 10 mm is used; over 10 to 15 mm; over 10 to 20 mm; over 15 to 20 mm, as well as mixtures of these fractions. There should be no foreign contaminants in the crushed stone.

The physical and mechanical properties of crushed stone must comply with the requirements specified in Table 5.


Table 5

5.8.2 For the preparation of cast mixtures, sand from crushing screenings, natural sand, and their mixture are used. Sand must comply with the requirements of GOST 8736. In the production of cast mixtures for the upper layers of road and bridge structures, sand from crushing screenings or its mixture with natural sand containing no more than 50% natural sand should be used. Grain composition natural sand in size should correspond to sand not lower than the fine group.

The physical and mechanical properties of the sand must comply with the requirements specified in Table 6.


Table 6

5.8.3 For the preparation of cast mixtures, non-activated and activated mineral powder is used that meets the requirements of GOST R 52129.

The permissible content of powder from sedimentary (carbonate) rocks from the total mass of mineral powder must be at least 60%.

It is allowed to use technical dust from the removal of basic and medium rocks from the dust collection system of mixing plants in an amount of up to 40% of the total mass of the mineral powder. The use of dust from acid rocks is allowed, provided that it is contained in the total mass of the mineral powder in an amount of not more than 20%. The values ​​of the indicators of fly-away dust must comply with the requirements of GOST R 52129 for MP-2 grade powder.

5.8.4 For the preparation of cast mixtures, viscous oil road bitumen grades BND 40/60, BND 60/90 according to GOST 22245, as well as modified and other bituminous binders with improved properties, are used as a binder according to regulatory and technical documentation agreed and approved by the customer in in accordance with the established procedure, subject to ensuring the quality indicators of cast asphalt concrete from these mixtures at a level not lower than those established by this standard.

5.8.5 When using cast asphalt concrete on bridge structures, in the upper and lower layers of road surfaces with high traffic intensity and design axle loads, polymer-modified bitumen should be used. In these cases, preference should be given to polymer-bitumen binders based on block copolymers such as styrene-butadiene-styrene grades PBB 40 and PBB 60 according to GOST R 52056.

5.8.6 When designing compositions of cast mixtures, the type of binder should be assigned taking into account climatic features area of ​​construction, destination and place of application of the structural layer, the required (designed) deformation properties of mixtures of cast and asphalt concrete based on them. The suitability of the binder to achieve the required functional characteristics mixtures of cast and asphalt concrete based on them are confirmed in the process of mandatory and optional tests specified in GOST R 54400.

5.8.7 In the production of cast mixtures, it is permissible to use binders modified by introducing dephlegmators into their composition, which make it possible to reduce the temperatures of production, storage and laying of cast mixtures by 10 °C to 30 °C without compromising their workability. The introduction of reflux condensers is carried out in bitumen (polymer-bitumen binder) or in a cast mixture during its production at an asphalt mixing plant.

5.8.8 The specified composition of the cast mixture must be ensured during its production at the asphalt mixing plant. It is forbidden to change the composition of the cast mixture after the completion of its production process by introducing a binder, petroleum products, plasticizers, resins, mineral materials and other substances into the mobile coher in order to change the viscosity of the cast mixture and physical and mechanical characteristics cast asphalt concrete.

5.8.9 It is allowed to use recycled asphalt concrete (granulated asphalt) as a filler in a cast mixture. At the same time, its content should not exceed 10% of the mass fraction of the composition of the cast mixture for the device of the lower or upper layers of the road surface and patching and 20% of the mass fraction of the composition of the mixture of cast for the device of the leveling layer. At the request of the consumer, the permissible percentage of asphalt granulate content in the cast mixture can be reduced. The maximum grain size of the crushed stone contained in the asphalt granulate must not exceed maximum size crushed stone grains in a cast mixture. When designing the compositions of cast mixtures with the use of asphalt granulate, the mass fraction of the content and properties of the binder in the composition of this aggregate should be taken into account.

6 Safety and environmental requirements

6.1 When preparing and laying cast mixtures, the general safety requirements in accordance with GOST 12.3.002 and the requirements fire safety according to GOST 12.1.004.

6.2 Materials for the preparation of cast mixtures (crushed stone, sand, mineral powder and bitumen) must correspond to a hazard class not higher than IV in accordance with GOST 12.1.007, referring to the nature of harmfulness and the degree of impact on the human body as low-hazard substances.

6.3 The norms of maximum permissible emissions of pollutants into the atmosphere during the production of works should not exceed the values ​​established by GOST 17.2.3.02.

6.4 Air in working area when preparing and laying cast mixtures, it must meet the requirements of GOST 12.1.005.

6.5 Specific effective activity of natural radionuclides in mixtures of cast and cast asphalt concrete should not exceed the values ​​established by GOST 30108.

7 Acceptance rules

7.1 Acceptance of cast mixtures is carried out in batches.

7.2 A batch is considered to be any amount of a cast mixture of the same type and composition, produced at the enterprise at the same mixing plant during one shift, using raw materials from one delivery.

7.3 To assess the compliance of cast mixtures with the requirements of this standard, acceptance and operational quality control is carried out.

7.4 Acceptance control of the cast mixture is carried out for each batch. During acceptance tests, water saturation, the depth of indentation of the stamp and the composition of the cast mixture are determined. Indicators of the porosity of the mineral core and residual porosity and the indicator of the specific effective activity of natural radionuclides are determined when selecting the compositions of the cast mixture, as well as when changing the composition and properties of the starting materials.

7.5 During the operational quality control of cast mixtures in production, the temperature of the cast mixture in each shipped vehicle is determined, which must not be lower than 190 °C.

7.6 For each batch of the shipped cast mixture, the consumer is issued a quality document containing the following product information:

- name of the manufacturer and his address;

- number and date of issue of the document;

- name and address of the consumer;

- order number (batch) and quantity (mass) of cast mixture;

- type of cast mixture (composition number according to the manufacturer's nomenclature);

- temperature of the mixture cast during shipment;

- the brand of binder used and the designation of the standard according to which it was produced;

- the designation of this standard;

- information about the introduced additives and asphalt granulate.

At the request of the consumer, the manufacturer is obliged to provide the consumer with full information on the released batch of products, including the data of acceptance tests and tests carried out during the selection of the composition, according to the following indicators:

- water saturation;

- depth of indentation of the stamp (including an increase in the index after 30 minutes);

- porosity of the mineral part;

- residual porosity;

- homogeneity of the cast mixture (according to the results of tests of the previous period);

- specific effective activity of natural radionuclides;

- granulometric composition of the mineral part.

7.7 The consumer has the right to conduct control check compliance of the supplied cast mixture with the requirements of this standard, observing the methods of sampling, sample preparation and testing specified in GOST R 54400.

8 Test methods

8.1 The porosity of the mineral core, residual porosity, water saturation, the depth of indentation of the stamp, the composition of the cast mixture, the tensile strength during splitting of cast asphalt concrete are determined according to GOST R 54400.

If square sieves are used in the selection of grain compositions, a set of sieves must be used in accordance with Appendix B to determine the grain composition of the cast mixture.

8.2 Preparation of samples from mixtures of cast and asphalt concrete based on them for testing is carried out in accordance with GOST R 54400.

8.3 The temperature of the cast mixture is determined by a thermometer with a measurement limit of 300 °C and an error of ±1 °C.

8.4 The specific effective activity of natural radionuclides is taken according to its maximum value in the mineral materials used. This data is indicated in the quality document by the supplier enterprise.

In the absence of data on the content of natural radionuclides, the manufacturer of the cast mixture carries out input control materials in accordance with GOST 30108.

9 Transport and storage

9.1 Prepared cast mixtures must be transported to the place of laying in cochers. It is not allowed to transport the cast mixture in dump trucks or other vehicles in the absence of installed and functioning systems for its mixing and maintaining the temperature.

9.2 The maximum temperature of the cast mixture during storage must comply with the values ​​specified in Table 3 or the requirements of technological regulations for this type of work.

9.3 Mandatory conditions for the transportation of cast mixtures to the place of laying:

- forced mixing;

- exclusion of segregation (stratification) of the cast mixture;

- protection from cooling, precipitation.

9.4 In the case of long-term transportation or storage of the cast mixture in stationary cochers at asphalt mixing plants, its temperature should be reduced for the period of the expected storage time. When storing a mixture of cast from 5 to 12 hours, their temperature should be lowered to 200 ° C (when using polymer-bitumen binders) or up to 215 ° C (when using viscous oil bitumen). After the end of the storage period, immediately before the production of laying work, the temperature of the cast mixture is increased to the permissible values ​​\u200b\u200bspecified in Table 3 or in the technological regulations for this type of work.

9.5 The time elapsed from the production of a cast mix at an asphalt mixing plant to its complete unloading from a mobile coher when laying in a pavement should not exceed 12 hours.

9.6 cast mix must be disposed of as construction waste under the following conditions:

- exceeding the maximum allowable shelf life of the cast mixture;

- unsatisfactory workability of the mixture, loss of the ability to be a pourable mixture and the ability to spread over the base, friability (incoherence), the presence of brown smoke emanating from the cast mixture.

9.7 Instrumentation that monitors the temperature of the cast mixture at the asphalt mixing plant and in the Kocher (stationary and mobile) must be calibrated (verified) at least once every three months.

10 Instructions for use

10.1 The device of coatings from a cast mixture is carried out in accordance with technological regulations approved in the prescribed manner.

10.2 The cast mixture must be placed in the coating only in a liquid or viscous-fluid state that does not require compaction.

10.3 Laying cast mixtures should be carried out at a temperature of the ambient air and the underlying structural layer of at least 5 °C. It is allowed to use cast mixtures at an ambient temperature of up to minus 10 °C for the performance of works to remove an emergency situation on the carriageway of roads with asphalt concrete pavements. In these cases, measures should be taken to ensure sufficient quality of adhesion of cast asphalt concrete with the underlying structural layer.

10.4 Cast mixtures for paving, sidewalks and patching should be unloaded directly onto the surface of the underlying structural layer or waterproofing layer. The surface of the underlying layer must be dry, clean, dust-free and must meet the requirements for asphalt concrete and monolithic cement concrete bases and coatings.

When laying the mixture cast on concrete base or asphalt pavement prepared by cold milling should be produced pre-processing such surfaces with a bituminous emulsion according to GOST R 52128 with a flow rate of 0.2-0.4 l / m in order to ensure proper adhesion of the layers. Accumulation of the emulsion in low areas of the base surface is not allowed. It is obligatory to require complete disintegration of the emulsion and evaporation of the moisture formed in this case before laying the cast mixture. The use of bitumen instead of bitumen emulsion for surface treatment is not allowed.

Emulsion treatment of the underlying layer of cast asphalt concrete not produced when the lower and upper layers of the pavement are made of poured asphalt concrete.

The emulsion treatment of the underlying layer of cast asphalt concrete is allowed not to be carried out when the upper layer is made of crushed stone-mastic asphalt concrete mixture according to GOST 31015 with a time interval between the layers of no more than 10 days, and also in the absence of traffic in this period along the underlying layer.

10.5 The value of the maximum allowable longitudinal and transverse slopes road construction, when using a cast mixture, ranges from 4% to 6%, depending on the characteristics of the given composition of the cast mixture and its viscosity.

10.6 Cast mixtures of all types may be laid as mechanized way using a special device for leveling the cast mixture (finisher), and manually. The required workability of cast mixes is achieved by the manufacturer by adjusting the specified composition and selection of bituminous binder, introducing reflux condensers during the production of cast mixes, provided that cast asphalt concrete retains the strength characteristics specified in 5.4. The workability can be regulated by changing the temperature regime of the cast mixture during its laying, taking into account the fulfillment of the requirements for the minimum and maximum allowable temperatures cast mixtures. A mixture intended for mechanized laying may have an increased viscosity and a slower spreading rate on the surface when unloading.

10.7 The final stage of the paving with the top layer of poured asphalt concrete is the device of a rough surface, carried out by the "hot" method of embedding in accordance with the technological regulations approved in the prescribed manner.

10.8 The physical and mechanical properties of the crushed stone used for the device of the rough surface of the top layer of the coating of asphalt concrete poured by the method of embedding "hot" must comply with the requirements given in Appendix A.

Appendix A (recommended). Physical and mechanical characteristics of crushed stone used for the device of the rough surface of the upper layers of the pavement of road cast hot asphalt concrete by the "hot" method of embedding

For the device of the rough surface of the upper layers of the pavement of hot cast asphalt concrete by the method of embedding "hot", fractionated crushed stone of igneous rocks of fractions from 5 to 10 mm, more than 10 to 15 mm and a mixture of fractions from 5 to 20 mm according to GOST 8267 with a consumption of 10 -15 kg/m.

When arranging the lower layers of coatings from cast mixtures, in order to additionally ensure adhesion to the upper layers of coatings from all types of compacted asphalt concrete, crushed stone of igneous rocks of fractions from 5 to 10 mm is distributed "hot" with a flow rate of 2-4 kg / m. It is allowed not to sprinkle the lower layer with crushed stone when installing two-layer pavements of cast asphalt concrete, provided that there is no movement along the lower pavement layer.

To ensure proper adhesion of crushed stone surface treatment with cast asphalt concrete, it is recommended to use crushed stone treated with bitumen (blackened crushed stone). The content of bitumen should be selected so as to exclude its runoff, sticking of crushed stone or uneven coating of the surface of crushed stone with bitumen.

The physical and mechanical properties of the crushed stone used for the device of the rough surface of the upper layers of the poured asphalt concrete pavement by the embedding method must comply with the requirements presented in Table A.1.


Table A.1

The recommended temperature range of the cast mixture at the beginning of the process of distribution of grain mineral materials over its surface is from 140 °C to 180 °C and must be specified in the process of work.

For the device of a rough surface of footpaths, sidewalks and bicycle paths, natural fractionated sand is used with a consumption of 2-3 kg / m.

The recommended grain composition of natural sand is determined by the total residues on the control sieves shown in Table A.2.


Table A.2

It is acceptable to use crushed graded sand with a grain size of 2.5 to 5.0 mm and a consumption of 4-8 kg/m.

Appendix B (recommended). Complete passages of mineral material using square sieves

B.1 Complete passages of mineral material when using square sieves in percent by weight are given in Table B.1.


Table B.1

Annex B (recommended). Requirements for the granulometric composition of the mineral part of all types of mixtures

The permitted values ​​of the composition of the mineral part for all types of mixture are in the zone between the two broken lines shown in the graphs of Figures B.1-B.6.

Figure B.1 - Grain composition of mixture type I (round sieves)

Figure B.2 - Grain composition of mixture type I (square sieves)

Figure B.3 - Grain composition of type II mixture (round sieves)

Figure B.4 - Grain composition of type II mixture (square sieves)

Figure B.5 - Grain composition of type III mixture (round sieves)

Figure B.6 - Grain composition of type III mix (square sieves)

After hot mixes, the second most common patching material is cast asphalt concrete. In composition, it differs from them in a larger proportion of bitumen and the use of fine mineral aggregate. In fact, it is an analogue of natural asphalt.

The advantage of repair using cast asphalt concrete mixtures is the greater strength and frost resistance of the patched areas, as well as the possibility of performing work in winter. Let's talk in detail and step by step about the technology of using cast asphalt concrete in patching roads with cutting maps.

Cutting cards for patching with poured asphalt does not differ from the same stage of work when using any other material and is carried out with the same tools and equipment. The requirements for cut cards are practically the same - the verticality of the edges, the complete removal of damaged asphalt, the absence of sharp corners. But there are two nuances:

• The area of ​​cards is limited to 2-3 square meters. This is due to the fact that poured asphalt has a smoother surface and lengthens the braking distance. It is especially dangerous if the car, when braking, hits the wheels of one axle on long sections with different coefficients of friction, it is automatically skidded. It is also undesirable to use cast asphalt concrete on bends. However, there is a way to get around this limitation - before the final solidification of the composition, cover the map with small gravel.
• Molded asphalt can reliably adhere to damp surfaces. Therefore, if it is not possible, it is not necessary to dry the card to the end. But water still needs to be removed completely, since steam bubbles violate the structure of the hardened repair composition.

Requirements for a sliced ​​card: area up to 2-3 square meters, vertical edges, no sharp corners.

It should be noted that if the mixture is not brought from the factory, but is heated on site in a recycler, then it is advisable to cut and clean the cards during its heating. Thus, by correctly distributing workers so that they can prepare the right number of cards, which is filled with one load of the recycler, downtime can be completely avoided.

Paving of poured asphalt concrete

Unlike the use of other patching materials, the bottom and sides of the cards do not need to be primed before poured asphalt is applied. Its installation is extremely simple. Having received cast asphalt, which is transported in a thermos-bunker, we control the temperature, it should be at least 190-220 degrees. Machines for transporting this mixture are usually equipped with special trays from which you can unload the required amount of poured asphalt directly into the cut card. Then the composition is leveled with shovels and trowels and remains until the final hardening. Traffic on the repaired section of the road can be opened in an hour, and earlier in winter.

At the same time, it should be taken into account that overheated cast asphalt has increased plasticity and its surface tends to become strictly horizontal. The roadbed has a slight transverse slope. So that water does not accumulate in the repaired place, the temperature of the material to be laid must strictly correspond to its passport, and the trowels must be given the same level with the rest of the road surface.

The process of laying poured asphalt is simple: unload poured asphalt into a map, level it with trowels or shovels.

Preparation of poured asphalt concrete in a recycler

But most often, especially in winter, the mixture is not brought from the asphalt plant, but is prepared at the place of work in recyclers. These are devices that provide heating and mixing of the mixture. Most often they have a wheel drive and a towing device for towing.

The preparation of the mixture in this unit can be divided into several stages.

• The prepared asphalt concrete is loaded by turning the drum so that the loading hatch is at the top. It is recommended to introduce an additional small amount of pure bitumen into the composition.
• Then the hatch is closed and the nozzle is lit. The drum must constantly turn, making several revolutions in one direction or the other. During the operation of the recycler, the temperature of the mixture must be carefully monitored.
• When poured asphalt is heated to required value, the burner is switched off.
• The recycler is adjusted to the prepared cards, the drum is turned upside down. By opening the damper, the required amount of material is unloaded, then the laying of the mixture begins.

All laying processes are carried out in exactly the same way as when delivering the finished mixture from the factory. When moving the recycler from card to card, continue to mix the heated mixture by rotating the drum. If the temperature drops, the burner is switched on again for a short time.

AT winter period cast asphalt concrete is prepared at the work site in a recycler.

As with any other method of filling potholes, only complete and correct compliance with all technological requirements for repairs using poured asphalt concrete can achieve high quality.

It is a complex structured composite substance widely used for construction purposes. The main difference between poured asphalt and asphalt concrete is its laying procedure.

Making a mixture

The composition of cast asphalt includes the same components as for asphalt concrete, however, the proportions for mixing are different. The main components of the cast mixture are crushed stone, sand, and bitumen. However, the ingredients themselves are slightly different in composition. Sand is used of natural origin or from screening of rocks, and mineral powder is made from highly active

The amount of bitumen and powder is much higher than that of asphalt concrete, which makes the cast version more ductile and ductile. Most manufacturers use asphalt chips in the manufacture of a cast mixture, which undoubtedly reduces the cost of creating a pavement, but negatively affects its properties.

Characteristics

The main advantage of this type of coating is complete waterproofing due to the solid, not porous structure, which increases durability and expands the scope. If the technological requirements are met during the manufacture, the service life of cast asphalt reaches half a century, which is much longer than the service life of asphalt concrete.

The use of such mixtures makes it possible to make the road surface smoother and reduce the thickness without losing its sealing properties. This type of asphalt concrete has increased corrosion and wear-resistant characteristics, is resistant to temporal changes and fatigue damage, and is also able to withstand huge strains of a deformation nature. Molded asphalt is more resistant to damage by caterpillar vehicles or studded tires, withstands sudden temperature changes and prolonged thermal exposure. It does not require the use of a sealing mixture, and the repair of the coating can be carried out during low temperatures.

disadvantages

However, this coverage has negative qualities, which include the high cost of manufacturing due to the use of an increased number of expensive components, as well as the need to apply professional equipment for laying and replacing asphalt (specialized thermo-mixers and heaters). In addition, due to the high content of bitumen, the binding properties of the road surface suffer, which necessitates additional work on pressing black crushed stone onto the installed asphalt layer.

Molded Asphalt Technology

The technique itself is not innovative. The production of poured asphalt is carried out at asphalt concrete plants in special bitumen-mixing structures, similar to huge concrete mixers, using a technology similar to the production of conventional asphalt concrete. Ready mix has a high temperature (from 200 C), which is maintained until the material is used for its intended purpose. When transporting cast asphalt, it is necessary to constantly mix the mixture and maintain a high temperature, for which special machines have been created - “kochers”, which are thermo-mixers.

Application

Molded asphalt concrete is used for the construction of highways and highways, road and bridge pavements and pedestrian sidewalks. In addition, due to its viscous properties, it is used for waterproofing or flooring in rooms. Molded asphalt gained wide popularity due to its comfortable use in the repair of road pits in the cold season at sub-zero temperatures. After all, this coating easily withstands up to minus 10 degrees and conveniently fills the space of the pit.

Molded asphalt is also used for pavement coatings. This allows you to save all the positive qualities of the track and give it an aesthetic shape and structure. Grass does not grow through such a sidewalk, cracks do not appear. This coating is able to withstand both high weight loads and temperature differences. However, the use of a cast mix in the production of paving slabs not only retains all the useful properties of asphalt, but also creates new ones. Such a sidewalk has increased heat resistance and environmental friendliness, because the heating temperature of the tile is higher, which prevents the coating from releasing into environment carcinogenic substances.

Molded asphalt can be easily removed and dismantled, and it is also quite easy to re-install. This saves money on repairs. The use of high-quality cast asphalt concrete for the production paving slabs guarantees a long service life of the coating, which, unlike the asphalt itself, can reach 100 years. Cast compound pavement is the best option for use in private areas, because it is distinguished by a high level of quality and environmental friendliness. Due to the wide range of useful properties and the absence of disadvantages, cast asphalt concrete is ideally suited for the production of paving surfacing.

Molded asphalt concrete is very popular in Europe. In Russia, this type of asphalt is less common due to the high cost of equipment and the asphalt mix itself. However, poured asphalt is the highest quality product for the construction of new roads, parking lots and bridges.

Molded asphalt differs from conventional asphalt concrete in its paving technology. The composition of both mixtures is approximately the same, that is, the asphalt components are the same (crushed stone, mineral powder, sand and bitumen), but their proportions are different. Thus, cast asphalt concrete contains an increased amount of bitumen (from 8 to 10% of the total mass) and mineral powder (from 20 to 30%), which makes it viscous and somewhat liquid.

The laying technology involves pouring the required area with an asphalt concrete mixture. Asphalt is leveled manually or using a special installation. Compaction with a roller of such material is not required.

Photo source: House53.ru

Features of cast asphalt concrete

It is used for the construction of tracks, bridge pavement, bicycle and pavement paths. Each type of road has its own size of crushed stone fractions (from 5 to 20 mm). Also, due to the properties of the mixture, it is often used for covering floors in residential and other premises, as well as for waterproofing.

The advantages of such an asphalt pavement cannot be underestimated. Unlike conventional asphalt, cast asphalt concrete is water resistant. Due to the fact that the asphalt concrete mixture is not porous, water does not get inside the asphalt concrete and does not destroy it from the inside. It is also harmless and more environmentally friendly. Such asphalt is not sensitive to high temperatures.

The undoubted positive qualities of the material include its durability. Yes, at correct use and the preparation of an asphalt concrete mixture without violating the technology, the road will last 20 or even 30 years. It is not sensitive to salt and chemicals. Cast asphalt mix is ​​often used for bridge pavement because of its ability to dampen vibrations.

Convenience styling plays big role in the choice of asphalt pavement. Cast asphalt is laid at street temperatures down to -10 o, and this is due only to the comfort of the road builders themselves, and not to the properties of the mixture.

Photo source: house53.ru

Laying is carried out at an asphalt concrete temperature of 190-250 o. This high temperature contributes to the fluidity of the asphalt. Its consistency resembles mastic, so the asphalt itself is evenly distributed over the surface, without requiring the work of a roller for compaction. To improve coating performance, some companies add polymer-modified mineral powder to the mix. This helps to increase or decrease the binding properties of the bitumen.

The coating is characterized by good grip, that is, the wheel does not slip on the surface even during rain. In Russia, the coefficient of adhesion is increased by immersing crushed stone (5-10 mm) into a still hot, not hardened asphalt mixture. This paving technology protects the road from damage caused by studded truck wheels.

This material is suitable for laying on uneven surfaces or surfaces with complex geometric shapes. Also, the mixture is easily painted in the required colors, the gamut of which is very wide.

Photo source: neruds.ru

Mastic asphalt paving technology

Transportation of this type of mixture occurs with the help of a special device - a kocher. This is a kind of tank or reservoir capable of maintaining the desired state of the mixture and its constant mixing. The mixture is then spread evenly in the required place with the help of a road paver. The road is able to take the load after 12 hours.

Although the technology of manufacturing and laying asphalt concrete reduces the number of workers involved, the use of a large number bitumen and mineral powder leads to an increase in the cost of the mixture. In addition, the use of special equipment during laying significantly increases the cost of poured asphalt. Therefore, while in Russia its use is not very common.

Cast asphalt got its name only because it is laid on the prepared roadbed without compaction. It is produced according to injection technology, which uses bitumen as a binder, sand and gravel, mineral powder and active additives of surface action. The ingredients that make up the cast asphalt are loaded in certain proportions into special equipment that works like a mixer. Inside the components are mixed at a temperature of +220C. After that, cast asphalt concrete is simply fed through a special material pipeline to the place of laying.

The material has a liquid movable structure, so it is easily and evenly distributed over the roadway. When the temperature of the mixture decreases, it turns into a durable coating. In addition, the poured bituminous material has high moisture resistance, water resistance and crack resistance.

Main Features of Molded Asphalt Components

The classification of cast bituminous composites is based on the proportions of bitumen and fillers. Oil road bitumen is used as a binder. But since there are several brands of this material, each of them is chosen taking into account the type of expensive, climatic conditions of their operation.

There is mineral powder among the fillers. This material is considered the main filler component that makes up the structure of asphalt concrete. It is with its help that bitumen is transferred from the bulk state into a film coating. It is the mineral powder that increases the strength of cast asphalt and its viscosity.

A mixture of bitumen and mineral powder is called asphalt binder among specialists. In it, the proportions of each component are: bitumen - 11%, mineral powder - 25%. This is the standard recipe.

Mineral powder is produced from various natural stone materials, as well as from blast-furnace slags, by grinding. Most often it is prepared from lime stone or dolomite.

The mixture obtained by mixing must meet certain characteristics. Special meaning attached to such an indicator as hydrophilicity (easier - the swelling of the composite). The optimal value of the swelling coefficient is 1.25 mm. In this case, the swelling of the solution itself should not exceed 2.5%.

Today, not all manufacturers of cast asphalt concrete use mineral powder from the above-mentioned materials. Many prefer to use local raw materials, thereby reducing the cost of the finished composite mixture. This is not prohibited by GOST on cast asphalt. But when compiling a recipe, it is necessary to take into account the characteristics of the added powders, which can be made from ash, sugar production waste and other waste. Therefore, the recipe for cast asphalt concrete in each case will be different.

Crushed stone and sand

As crushed stone for the production of cast asphalt, either rocks or blast-furnace slags from metallurgical production are used. Both materials are subject to several strict requirements.

1. The shape of the granules should be acute-angled. The content of flat grains should not exceed 15%.
2. The strength of monolithic natural granules should be 100-120 MPa, porous slag 80-100 MPa. With low strength characteristics of blast-furnace slags, they have good adhesion (adhesion) with the binder components of the composite due to their porous rough surface.

As for sand, it is also produced by crushing or grinding from hard rock (strength up to 40 MPa) or blast-furnace slag (80 MPa). In this case, the grain size of the material should be either medium or coarse. But sand should add only one fraction to the mixture of poured asphalt. Thus, homogeneity of the finished composite solution is achieved.

Production technology

The technology for the preparation of cast asphalt concrete is based on mixing components in certain proportions and sequences. At the same time, considering that composite material should fit on roadbed heated to a certain temperature, and the production process itself is not organized at the place of laying the mixture, therefore, special container vehicles are used for transportation.

Here is the production technology:

Since cast type asphalt is a standardized material (using various methods tests), then a certificate of conformity is issued for it.

Laying process

The technology of laying poured asphalt concrete is work carried out in warm and dry weather at temperatures above +5C. In this case, the temperature of the composite itself should be in the range of 185-235 C. The spread of the temperature regime depends on the type of bituminous binder used in the mixture and the technological conditions of the work.

The sequence of application of poured asphalt concrete:

• preparation,
• acceptance of cast composite,
• his styling.

It should be noted that asphalt concrete of this type can also be used for laying on the old roadway, on newly built roads and in the process of patching. The process of receiving a cast composite depends on the means by which it will be laid.

If asphalt pavers are used for this, then the mixture is fed from the cocher directly into the paver bunker. And then it is evenly distributed at a speed of 1-3 m / min over the road surface with a minimum thickness of 25-30 cm. No pressure and tamping. A few hours after laying the road can be exploited.

The distribution of the composite mixture can also be done manually, using shovels and other devices. Usually this method is used for sidewalks. This method has several downsides:

• laying speed is reduced;
• it is difficult to achieve a uniform distribution of material along the plane of the roadway.

As for cast asphalt and patching, the same technology is used here as when laying on the canvas. The mixture is simply poured into the pit, distributed evenly over the volume (with a shovel), after which it is left to cool and harden in the air.

If asphalt concrete is used for bridges, high-load tracks and roads, then special components are added to the composite mixture formulation, which increase the viscosity of the material. That is why the manual method of laying such a composite is impossible. The mechanized technology of a flooring is used.

Attention! In the technology of laying poured asphalt for pavement and roads, there is one point that determines the quality of the final result. This is a vertical junction of two layers, which are formed when work is stopped, for example, during a shift change. Therefore, the workers finishing the work level the end of the laid layer, and apply a wooden beam to it. The second change removes the beam, the end is heated to a temperature of 220-240C and the laying of a new layer begins.

Advantages and disadvantages

As for the advantages of cast asphalt concrete, there are four positions:

• there is no need to carry out sealing operations, due to which the complexity of the work performed and their price are reduced;
• high strength characteristics, low abrasion, increased water resistance and corrosion resistance;
• absorption of material stresses ensures its plasticity;
• high adhesion with underlying layers.

In addition to the advantages, cast asphalt also has four serious disadvantages:

• the price is higher in comparison with traditional asphalt solutions;
• with an increase in the operating temperature, the resistance to plastic deformations decreases;
• the complexity of manual laying;
• 100% vapor tightness, due to which asphalt pavement may swell, especially often if the density of the poured asphalt is high and it is laid on a concrete base.