RU2601327C1 - Method of asphalt-mastic asphalt concrete stabilizing additive producing (versions) - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to road construction, in particular, to stabilizing additives used in macadam-mastic asphalt mix (MMAM) production. In production of additive mixing binder - bitumen emulsion aqueous solution with petrolatum and natural fibrous structure-forming agent, chrysotile fiber, granulated in following proportions, wt%: chrysotile fibre - 70-90, binder - 10-30. At that, binder contains, wt%: bitumen - 20-30, petrolatum - 20-30, water - 40-60. According to second version, binder used is mixture of bitumen with petrolatum at temperature of 120-140 °C at ratio of components, wt%: bitumen - 40-60, petrolatum - 40-60. According to third version binder used is mixture of paraffin with petrolatum at temperature of 120-140 °C at ratio of components, wt%: paraffin - 40-60, petrolatum - 40-60.

EFFECT: technical result when using additive consists in improvement of asphalt mix physical and mechanical properties.

18 cl, 1 dwg

Description

The invention relates to the field of road construction, in particular to stabilizing additives and methods for their preparation, used in the production of crushed stone-mastic asphalt mixes (ЩМАС).

The main purpose of the use of stabilizing additives is to increase the thickness of bitumen films, ensuring the presence of free (bulk) bitumen, and the uniformity of crushed stone-mastic asphalt mixtures.

The stabilizing effect of additives is manifested in the form of their ability to homogenize hot asphalt mixtures, that is, to prevent the segregation and delamination (runoff) of a bitumen binder at high technological temperatures. The type and properties of the additives used are of great importance to ensure the required binder content and improve the quality of the mixture.

The stabilizing additive, which is a component of SCHMAS, eliminates the drainage of excess binder from SCHMAS during the manufacture, transportation and laying during the manufacture of the upper layers of coatings for roads, airfields, areas, etc., has a stabilizing effect on SCHMAS, thereby achieving its resistance to delamination .

The prior art stabilizing additives for the production of crushed stone and mastic asphalt and methods for their preparation.

There is a method of producing a stabilizing additive for SCMAS from a substance with a fibrous structure - free cellulose fiber, including its cutting and fluffing (Smirnov V.E. “Crushed-mastic asphalt concrete for three years in Russia, results”, railway Roads, M., CJSC Publishing House Dorogi, No. 1, p. 13).

The disadvantage of this method is that the obtained stabilizing additive from fibrous cellulose has a tape structure and, due to high internal friction, has a low flowability, as a result of which the stabilizing additive hangs up in dosing containers and clumps in the mixer during the manufacture of SCMAS, which leads to its heterogeneity and, as a consequence, to a decrease in quality.

Known granular stabilizer for crushed stone mastic asphalt containing granules of chrysotile fibers of different lengths with a certain mass ratio. % (length from 0.4 mm to 8.00 mm), including paraffin-containing material and / or bituminous material. The fibers are mixed with water and pressed into pellets in a press.

Upon receipt of granules with paraffin-containing material and / or bituminous material, chrysotile fibers are thoroughly mixed with it and fed into an extruder (patent RU No. 39884, IPC С04В 26/26, С04В 30/02, publ. 20.08.2004).

The disadvantage of this stabilizer is the excessive strength of the granules obtained in the press and, as a result, they are not destroyed during the manufacture of a mixture of SchMAS and do not bind free bitumen (binder). Excess strength is the result of hydration of chrysotile fiber with water (similar to cement with water). Also, the excessive strength of the granules prevents the uniform impregnation of chrysotile fibers with a binder, which negatively affects their adhesion to the components of SchMAS and, therefore, indicates the impossibility of achieving the claimed technical result.

Known stabilizing additive for gravel and mastic asphalt concrete (patent RU 2348662, IPC C08L 1/02, 08L 23/12, C04B 16/02, C04B 16/06), including cellulose fibers, the granules of which contain oxidized atactic polypropylene in the following ratio mass. %:

Cellulose fiber 70-95 Oxidized Atactic Polypropylene 5-30

The disadvantage of this additive is the impossibility of its use at a temperature of mixing, laying and sealing SchMAS 150-170 ° C. This is due to the fact that when heated to 150-170 ° C, the cellulose fibers that are part of the granules undergo thermal degradation, as a result, the quality of the stabilizing additive does not fully meet the requirements of the SchMAS production technology (thermal degradation of cellulose begins at 150 ° C and leads to to the release of low molecular weight compounds of H ₂ , CH ₄ , CO, alcohols, carbonic to-you, carbonyl derivatives, etc., the fibers disintegrate into powder and the additive ceases its stabilizing effect on SchMAS). In addition, cellulose fiber granules have insufficient chemical resistance, low mechanical strength of the fibers and are prone to enzymatic hydrolysis (decay), which negatively affects the longevity of the roadway and the physicomechanical characteristics of crushed stone mastic asphalt concrete.

The closest in technical essence and the achieved result is a method of producing a stabilizing additive for crushed stone-mastic asphalt concrete mixture, including granulation, in which fibrous magnesium silicate is used as a substance with a fibrous structure, which is mixed with water to a moisture content of 60-80% before granulation, the obtained granules are structured on an oscillating inclined plane with subsequent drying to a moisture content of not more than 2% (patent RU 2274617, IPC С04В 26/26, publ. 04/20/2005).

A significant drawback of this technical solution is the increased strength of the obtained granules, as a result of which they are not destroyed during the preparation of crushed stone-mastic asphalt concrete mix and a significant part of the fibers does not come into contact with bitumen, therefore, the main function is not performed to prevent the runoff of excess bitumen during preparation, transportation and laying of crushed stone and mastic asphalt concrete mix.

In addition, this method is energy-intensive due to the need for the drying process of the granules after their structuring.

The technical problem to which the proposed variants of the invention are directed, and the technical result achieved, are to develop methods for obtaining stabilizing additives with:

- increased resistance to delamination of the asphalt mix during transportation, loading, unloading;

- increased heat resistance of the fibers;

- higher efficiency of laying and compaction of crushed stone-mastic asphalt concrete mixture, as well as reduced cost.

The proposed technical solutions are designed to obtain a granular stabilizer from natural fiber of chrysotile grade 5 (TU 5721-010-0281476-2001 of OJSC Uralasbest).

The use of natural chrysotile fibers as a structural agent is due to their tubular structure and the ability to divide into many finest fibers with a high specific surface, which ensures the binding of excess bitumen in crushed stone-mastic asphalt concrete mixture.

In addition, chrysotile fiber in granules withstands heating up to 700 ° C and can be introduced into mixers for asphalt concrete mixtures at any preparation temperatures for SCMAS.

1 option. To achieve the claimed technical result of a method for producing a stabilizing additive for crushed stone and mastic asphalt concrete, including the use of an organic binder, fibrous structure former, their mixing and granulation, chrysotile fiber is used as a structure former, and an aqueous solution of a bitumen emulsion with a paraffin-containing component as a binder is used which is used as petrolatum in the following ratio, mass. %:

Chrysotile fiber 70-90 Astringent 10-30,

in the following ratio of the components of the binder, mass. %:

Bitumen 20-30 Petrolatum 20-30 Water 40-60%.

Wherein:

- the length of chrysotile fibers is 0.1-10.00 mm;

- mixing is carried out until a uniform distribution of the binder in the mixture;

- before supplying the finished mass to the pellet mill, the latter is constantly mixed;

- additionally finished granules are placed on a vibrating screen with subsequent separation of fractions less than 2 mm;

- fractions less than 2 mm in size are returned to granulation;

- the moisture content of the granules is less than 3%.

The use of an aqueous solution of bitumen emulsion can significantly improve the mixing conditions and increase the uniformity of the mass, which ultimately ensures the quality of the final product. In addition, the operation of a mixture of bitumen with petrolatum is excluded, since bitumen and petrolatum are mixed at the stage of preparation of the emulsion. The use of an aqueous solution of bitumen emulsion can reduce the cost of heating the binder and mixer, since the mixture of chrysotile fiber and bitumen emulsion is carried out at a temperature of 15-25 ° C.

The presence of bitumen in the additive reduces the mixing time of chrysotile and binder fibers, increases the adhesion between chrysotile fibers and components of SchMAS, which significantly improves the quality of the builder, and ultimately, ChMAS.

The presence of a paraffin-containing component - petrolatum reduces the pellet clumping and increases their flowability, ultimately significantly improves the conditions for unloading, loading, dosing of the stabilizing additive in the manufacture of SchMAS.

Mass ratio. % of the components are selected on the basis of pilot tests conducted by Uralasbest OJSC and enterprises using crushed stone-mastic asphalt concrete mixtures.

According to the results of a practical test, it was found that the content of chrysotile fiber over 90% worsens the granulation process in the press granulator because the mass loses its plasticity and the output of the granules stops, and the content of chrysotile fiber less than 70% entails an increase in the cost of the stabilizing additive, since the binder has the highest cost among the constituent components.

A decrease in the content of the binder (bitumen emulsion) of less than 10% worsens the granulation conditions in the press granulator, since the mass loses its plasticity and the output of the granules stops, and an increase in the content of more than 30% leads to a decrease in the mechanical strength of the granules and problems during transportation and loading, because . the latter stick together.

When bitumen is included in the binder composition over 30%, the performance of the press granulator is significantly reduced, and when bitumen is turned on less than 20%, the impregnation of chrysotile fibers and, as a consequence, the adhesion of the fibers to the SchMAS components are significantly reduced.

When the petrolatum is included in the binder for more than 30%, the adhesion of chrysotile fibers with the SchMAC components deteriorates, and when the petrolatum is turned on less than 20%, the performance of the press granulator is significantly reduced.

The water content in the binder composition of more than 60% will lead to waterlogging of the granules, which will lead to additional drying of the stabilizing additive, and if the water content is less than 40%, it will increase the cost of the stabilizing additive, since water is replaced by more expensive components (bitumen, petrolatum).

The use of a press granulator to obtain granules of a structuring agent, in comparison with the prototype, allows to exclude the stage of drying of granules, because excess moisture evaporates during the granulation process by heating the mass in a press granulator, which eliminates the cost of moisture evaporation. In addition, the uniformity of the granules is improved, their uniform length and diameter are ensured, which improves the accuracy of dosing and distribution of granules in the mixture of SchMAS. The same diameter is provided by the profiled hole of the matrix of the press granulator, and the same length of the granules is provided by the presence of a knife for cutting finished granules from the surface of the matrix.

In the presence of granules with sizes less than 2 mm, the bulk density of the stabilizing additive will change and, as a result, the dosing accuracy in the manufacture of SchMAS will decrease.

When the moisture content of the granules is more than 3%, the adhesion of chrysotile fibers to the SchMAS components deteriorates, in addition, the bulk density of the stabilizing additive increases and, as a result, the dosing accuracy decreases during the manufacture of SchMAS.

The essence of the method is illustrated by the drawing, which shows the proposed scheme for the production of stabilizing additives for crushed stone-mastic asphalt concrete.

The implementation of the proposed method is illustrated in the drawing, which shows the installation diagram for receiving a stabilizing additive (for all three variants of the method).

The installation comprises a mixer 1. Tedder 2, a press granulator 3, a vibrating screen 4, a screw conveyor 5, an elevator 6.

Carry out the proposed method (option 1) as follows.

Chrysotile fiber, an aqueous emulsion of bitumen and petrolatum are loaded into the mixer 1. Then they carry out the mixing of chrysotile fiber with an aqueous solution of bitumen emulsion and petrolatum until the binder is evenly distributed in the fiber. The resulting homogeneous mass is fed using a screw conveyor 5 and an elevator 6 to the agitator 2, where continuous mixing takes place. After that, the finished mass is fed into the press granulator 3. In the press granulator 3 of a homogeneous composition, the mixture of binder and structurant passes through the profiled holes of the matrix, is cut with a knife, which ensures the same length and thickness of the finished granules. This causes the evaporation of excess moisture due to mass friction in the pellet mill. After that, the granules are transferred to a conveyor belt (not shown), with which they are transferred to a vibrating screen, where they are classified, i.e. fractions of 2 mm or more are fed to the packaging, and the rest are returned to the granulator 3.

Option 2. To achieve the claimed technical result in a method for producing a stabilizing additive for crushed stone-mastic asphalt concrete, including the use of an organic binder, fibrous structure former, their mixing and granulation, according to the invention, chrysotile fiber is used as a structure former, and a mixture of bitumen with petrolatum at temperature is used 120-140 ° C, in the following ratio, mass. %:

Chrysotile fiber 70-90 Astringent 10-30,

in the following ratio of the components of the binder, mass. %:

Bitumen 40-60 Petrolatum 40-60.

Wherein:

- the length of chrysotile fibers is 0.1-10.00 mm;

- mixing is carried out until a uniform distribution of the binder in the mixture;

- before supplying the finished mass to the pellet mill, the latter is constantly mixed;

- additionally finished granules are placed on a vibrating screen with subsequent separation of fractions less than 2 mm .;

- fractions less than 2 mm in size are returned to granulation;

- the moisture content of the granules is less than 3%.

The use of a binder at a temperature of 120-140 ° C is due to the fact that at a given temperature the binder has the lowest viscosity and mixes easily with fiber.

The presence of a paraffin-containing component - petrolatum reduces the pellet lumpiness and increases their flowability, ultimately, the operation of the metering devices of the SchMAS plant and the conditions for unloading additives from containers to the consumer improve.

Mass ratio. % of the components are selected on the basis of pilot tests conducted by Uralasbest OJSC and enterprises using crushed stone-mastic asphalt concrete mixtures.

According to the results of a practical test, it was found that the content of chrysotile fiber over 90% worsens the granulation process in the press granulator, since the mass loses its plasticity and the output of the granules stops, and the content of chrysotile fiber less than 70% entails an increase in the cost of stabilizing additives, since the binder has the most high cost among components.

A decrease in the composition of the binder “bitumen + petrolatum” less than 10% worsens the granulation conditions in the press granulator, as the mass loses its plasticity and the output of the granules stops, and an increase in the composition of more than 30% leads to a decrease in the mechanical strength of the granules during transportation and loading, because the latter stick together.

When the content of bitumen in the binder is over 60%, the performance of the press granulator is significantly reduced.

When the content of bitumen in the binder is less than 40%, the impregnation of chrysotile fibers and, as a consequence, the adhesion of the fibers to the components of ASMAC are significantly impaired.

When petrolatum is included in the composition of the binder for more than 60%, the adhesion of chrysotile fibers to the components of SchMAC deteriorates.

When petrolatum is included in the binder composition of less than 40%, the performance of the press granulator is significantly reduced.

The use of a press granulator to obtain granules of the structure-forming agent, in comparison with the prototype, allows to improve the uniformity of the granules, to ensure their uniform length and diameter, which improves the accuracy of dosing and distribution of granules in the mixture of SchMAS. The same diameter is provided by the profiled hole of the matrix of the press granulator, and the same length of the granules is provided by the presence of a knife for cutting finished granules from the surface of the matrix.

In the presence of granules with sizes less than 2 mm, the volumetric weight of the stabilizing additive will change and, as a result, a decrease in the dosage accuracy in the manufacture of SchMAS. When the moisture content of the granules is more than 3%, the adhesion of chrysotile fibers to the SchMAS components deteriorates, in addition, the bulk density of the stabilizing additive increases and, as a result, the dosing accuracy in the manufacture of SchMAS decreases.

The essence of the method is illustrated by the drawing, which shows the proposed scheme for the production of stabilizing additives for crushed stone-mastic asphalt concrete.

Carry out the proposed method as follows.

Chrysotile fiber, a mixture of bitumen and petrolatum at a temperature of 120-140 ° C are loaded into the mixer 1. Then, chrysotile fiber is mixed with bitumen and petrolatum until the binder is evenly distributed in the fiber. The obtained homogeneous mass with the help of a screw conveyor 5 and elevator 6 is fed into the agitator 2, where continuous mixing is carried out, after which the finished homogeneous max is fed into the press granulator 3. In the granulator press 3 of a homogeneous composition, the mixture of binder and structure former passes through the profiled holes of the matrix, it is cut with a knife, which ensures the same length and thickness of the finished granules. Then the granules are transferred to a conveyor belt (not shown), with which they are transferred to a vibrating screen 4, where they are classified, i.e. fractions of 2 mm or more are fed to the packaging, and the rest are returned to the granulator 3.

3 option. To achieve the claimed technical result in a method for producing a stabilizing additive for crushed stone-mastic asphalt concrete, including the use of an organic binder, fibrous structure former, their mixing and granulation, according to the invention, chrysotile fiber is used as a structure former, and paraffin with petrolatum is a binder mixture at a temperature of 120 -140 ° C, in the following ratio, mass. %:

Chrysotile fiber 70-90 Astringent 10-30,

in the following ratio of the components of the binder, mass. %:

Paraffin 40-60 Petrolatum 40-60.

Wherein:

- the length of chrysotile fibers is 0.1-10.00 mm;

- mixing is carried out until a uniform distribution of the binder in the mixture;

- before supplying the finished mass to the pellet mill, the latter is constantly mixed;

- additionally finished granules are placed on a vibrating screen with subsequent separation of fractions less than 2 mm;

- fractions less than 2 mm in size are returned to granulation;

- the moisture content of the granules is less than 3%.

The use of astringent paraffin + petrolatum can significantly improve the mixing conditions and increase the uniformity of the mass, which ultimately ensures the quality of the final product. It also allows to reduce heating costs, since the melting point of paraffin is 50 ° С lower than the melting temperature of bitumen 120-140 ° С.

The presence of paraffin in the additive reduces the mixing time of chrysotile and binder fibers, increases the adhesion between chrysotile fibers and components of the SchMAS, which significantly improves the quality of the builder, and ultimately the SchMAS.

The presence of a paraffin-containing component - petrolatum reduces the pellet lumpiness and increases their flowability, ultimately improves the operation of the metering devices of the SchMAS plant and the consumer’s conditions for unloading additives from containers.

Mass ratio. % of the components are selected on the basis of pilot tests conducted by Uralasbest OJSC and enterprises using crushed stone-mastic asphalt concrete mixtures.

According to the results of a practical check, it was found that the content of chrysotile fiber over 90% worsens the granulation process in the press granulator, since the mass loses its plasticity and the output of the granules stops, and the content of chrysotile fiber less than 70% entails an increase in the cost of stabilizing additives, since the binder has the most high cost among components.

A decrease in the composition of the binder “paraffin + petrolatum” less than 10% worsens the granulation conditions in the press granulator, since the mass loses its plasticity and the output of the granules stops, and an increase in its composition by more than 30% leads to a decrease in the mechanical strength of the granules during transportation and loading, because . the latter stick together.

When the paraffin content in the binder is over 60%, the performance of the press granulator is significantly reduced.

When the paraffin content is less than 40%, the impregnation of chrysotile fibers and, as a consequence, the adhesion of the fibers to the components of ASMAC are significantly impaired.

When petrolatum is included in the composition of the binder for more than 60%, the adhesion of chrysotile fibers to the components of SchMAC deteriorates.

When petrolatum is included in the binder composition of less than 40%, the performance of the press granulator is significantly reduced.

The use of a press granulator to obtain granules of the structure-forming agent, in comparison with the prototype, allows to improve the uniformity of the granules, to ensure their uniform length and diameter, which improves the accuracy of dosing and distribution of granules in the mixture of SchMAS. The same diameter is provided by the profiled hole of the matrix of the press granulator, and the same length of the granules is provided by the presence of a knife for cutting finished granules from the surface of the matrix.

In the presence of granules with sizes less than 2 mm, the bulk density of the stabilizing additive changes and, as a result, the dosing accuracy in the manufacture of SchMAS decreases. When the moisture content of the granules is more than 3%, the adhesion of chrysotile fibers to the SchMAS components deteriorates, in addition, the bulk density of the stabilizing additive increases and, as a result, the dosing accuracy decreases during the manufacture of SchMAS. A moisture content of less than 3% does not affect the properties of the additive.

The essence of the method is illustrated in the drawing.

Carry out the proposed method as follows.

Chrysotile fiber, a mixture of paraffin and petrolatum (shown by arrows) are loaded into the mixer 1, and chrysotile fiber is mixed with a mixture of paraffin and petrolatum until the binder is evenly distributed in the fiber. The resulting homogeneous mass is fed using a screw conveyor 5 and an elevator 6 to the agitator 2, where continuous mixing is carried out, from where the finished mass is fed into the press granulator 3. In the granulator press 3, the mixture of binder and structure former passes through the profiled holes of the matrix, cut off with a knife that allows you to ensure the same length and thickness of the finished granules. Then the granules are transferred to a conveyor belt (not shown), with which they are transferred to a vibrating screen 4, where they are classified, i.e. fractions of 2 mm or more are fed to the packaging, and the rest are returned to the granulator 3.

Claims (18)

1. A method of obtaining a stabilizing additive for crushed stone and mastic asphalt concrete, including the use of an organic binder, fibrous structure former, their mixing and granulation, characterized in that chrysotile fiber is used as a structure former, and an aqueous solution of a bitumen emulsion with a paraffin-containing component is used as a binder, the quality of which is used petrolatum, in the following ratio of components, wt.%:
chrysotile fiber 70-90 astringent 10-30,
in the following ratio of binder components, wt.%:
bitumen 20-30 petrolatum 20-30 water 40-60. 2. A method of obtaining a stabilizing additive according to claim 1, characterized in that the length of the chrysolite fibers is 0.1-10.0 mm 3. The method of obtaining a stabilizing additive according to claim 1, characterized in that the mixture is produced until the binder is evenly distributed in the mixture. 4. The method of obtaining the stabilizing additive according to claim 1, characterized in that before feeding the finished mass into the press granulator, the latter is constantly mixed. 5. The method for producing a stabilizing additive according to claim 1, characterized in that the finished granules are additionally placed on a vibrating screen, fractions smaller than 2 mm are separated and returned to granulation. 6. The method of producing a stabilizing additive according to claim 1, characterized in that the moisture content of the granules is less than 3%. 7. A method of obtaining a stabilizing additive for crushed stone-mastic asphalt concrete, including the use of an organic binder, fibrous structure former, their mixing and granulation, characterized in that chrysotile fiber is used as a structure former, and a mixture of bitumen with petrolatum at a temperature of 120-140 is used as a binder ° C in the following ratio of components, wt.%:
chrysotile fiber 70-90 astringent 10-30,
in the following ratio of binder components, wt.%:
bitumen 40-60 petrolatum 40-60. 8. The method of producing a stabilizing additive according to claim 7, characterized in that the length of the chrysolite fibers is 0.1-10.0 mm 9. The method of producing a stabilizing additive according to claim 7, characterized in that the mixture is produced until the binder is evenly distributed in the mixture. 10. The method of producing a stabilizing additive according to claim 7, characterized in that before feeding the finished mass into the press granulator, the latter is constantly mixed. 11. The method of producing a stabilizing additive according to claim 7, characterized in that the finished granules are additionally placed on a vibrating screen, fractions of less than 2 mm are separated and returned to granulation. 12. The method of producing a stabilizing additive according to claim 7, characterized in that the moisture content of the granules is less than 3%. 13. A method of obtaining a stabilizing additive for crushed stone and mastic asphalt concrete, including the use of an organic binder, fibrous structure former, their mixing and granulation, characterized in that chrysotile fiber is used as a structure former, and a mixture of paraffin with petrolatum at a temperature of 120-140 ° C in the following ratio of components, wt.%:
chrysotile fiber 70-90 astringent 10-30,
in the following ratio of binder components, wt.%:
paraffin 40-60 petrolatum 40-60. 14. The method of obtaining the stabilizing additive according to item 13, wherein the length of the chrysotile fibers is 0.1-10.0 mm 15. The method of producing a stabilizing additive according to item 13, wherein the mixture is produced until the binder is evenly distributed in the mixture. 16. The method of obtaining the stabilizing additive according to item 13, characterized in that before feeding the finished mass into the press granulator, the latter is constantly mixed. 17. The method of producing a stabilizing additive according to claim 13, characterized in that the finished granules are additionally placed on a vibrating screen, fractions of less than 2 mm are separated and returned to granulation. 18. The method of producing a stabilizing additive according to item 13, wherein the moisture content of the granules is less than 3%.

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