RU2509787C2 - Bitumen-rubber composition for road surface binder and method for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to road construction materials, particularly production of bitumen-rubber compositions for road surface binder based on bitumen, and can be used in building, repairing and overhaul repair of road asphalt coatings, as well as in building and repairing bridge floors and overhead crossings. The composition contains bitumen, rubber crumbs made from spent tyres with particle size of up to 1 mm and petroleum oil with viscosity of 0.005-1.6 Pa·s at 60°C. Components are in the following ratio, wt %: rubber crumbs - 8-20, petroleum oil - 2-12, bitumen - the balance. The invention also relates to a method of producing said composition.

EFFECT: product has high adhesion to road surface, high resistance to cracking at low temperatures, improved adhesion at subzero temperatures, high elasticity in heavy traffic conditions.

14 cl, 3 tbl, 24 ex

Description

Technical field

The invention relates to the field of road-building materials, in particular the production of bitumen-rubber compositions (DBK) of a binder for bitumen-based pavement, and can be used for construction, repair and overhaul of asphalt concrete pavements, as well as for the device and repair of roadway layers parts of bridges and overpasses.

State of the art

The use of bitumen in the construction of roads with the addition of rubber particles (from used tires) has been known since the 1960s and 70s. Nowadays, in most cases, such bitumen contains rubber particles poorly dissolved in it, which does not give optimal results (insufficient elasticity of the asphalt coating, poor adhesion of the mixture to the stone filler). The low quality of rubberized bitumen is justified by the poor solubility of rubber particles in it.

Rubber crumb is usually a recyclable rubber that is crushed to a ground state or to microparticles by mechanical cutting or crushing. In order to regenerate the crushed old rubber material, various methods are used, and the most widely used alkaline treatment, in which crushed rubber is subjected to treatment with an aqueous solution of sodium hydroxide at elevated temperatures. Other regeneration processes include treating crushed rubber in refining oils using various combinations of high temperature and excessive shearing forces to produce liquefied materials that can be used to make new tires or as petroleum fuels.

In addition, it has been suggested that crumb of old rubber may be introduced into bituminous materials for road surfaces. Typically, crumb rubber is introduced into asphalt using one of two methods, namely, the wet method or the dry method.

In the wet method, crumb rubber is mixed into asphalt cement by periodic mixing, in which individual portions of crumb rubber and asphalt are mixed to produce the product, by continuous mixing with continuous production of the product, or by mixing at the outlet.

The elastomeric modifier (rubber) swells in a hot organic binder, in particular bitumen, gradually forming an inhomogeneous mass with it. The processes of swelling and destruction of elastomer particles proceed slowly and, for their intensification, either special destructive components are introduced, or they are affected by technological methods: they increase the temperature of the process, carry out multi-stage heating with a gradual increase in temperature, and purge with hot air. All these factors complicate the process of preparing asphalt concrete mix, while a uniform distribution of the elastomeric modifier is not always achieved, which negatively affects the properties of asphalt concrete.

Another problem is the rapid sedimentation (sedimentation) of rubber particles in the finished bitumen, which is also eliminated due to the increased solubility of the rubber. As a result, rubber settling is reduced, and transportation and handling of bitumen become easier.

Some manufacturers add to the bitumen chemical components for the devulcanization of rubber in order to better dissolve it. In our invention, there is no need to use any chemicals.

An example of a wet process is described in US Pat. No. 4,992,492, published February 12, 1991. Using this method, a mixture of asphalt or sulfur-treated asphalt (81-86%), crumb rubber (8-10%), filling oil (4-6%) and high molecular weight (> 100000) olefin-unsaturated synthetic rubber (2-3 %), which are mixed at a temperature of 175-180 ° C for approximately two hours. However, such compositions are not stable and cannot withstand temperatures up to -33 ° C.

A well-known bitumen-rubber composition comprising bitumen and a dispersed phase, which is a rubber crumb, the surface of which by means of radical polymerization is “stitched” to unsaturated components contained in bitumen. As a result, a heterogeneous reinforcing spatial structure is formed in bitumen from the components of the composition (patent RU 2167898, published May 27, 2001).

The disadvantage of this composition is that it requires the use of expensive initiators (peroxide compounds) and co-initiators (nitrons) of radical polymerization. In addition, the formation of a spatial grid inside the composite implies its destruction upon secondary heating upon receipt of the final asphalt material, which should adversely affect its operational properties.

Known bitumen composition, which is dissolved in bitumen devulcanized rubber, which is achieved by heating a mixture of rubber crumb, bitumen and organic base additives (aromatic or heteroaromatic amines, phosphines) in a sealed reactor (patent RU 2164927, published 04/10/2001). The method allows to obtain a homogeneous system with a low temperature of brittleness, however, the particle sizes of the rubber crumb to be dissolved are not indicated, which involves the use of very finely ground (therefore, expensive) rubber crumb. In addition, the use of a sealed reactor implies operation with excess pressure and the discontinuity of the process for producing a bitumen-rubber composite.

A known composition and method of its preparation according to patent RU 2327719, published on June 27, 2008, containing bitumen, crumb rubber from crushed spent rubber of automobile tires and a naphthalene fraction of coal tar. The components are mixed in an unpressurized container at a temperature of 200-220 ° C for 30-60 minutes, and then the mixture is hot pressed through a screw device through dies with a diameter of 1 mm.

The physicomechanical characteristics of the composition obtained by the known method are very high, but a significant drawback is the use of coal tar fractions with a boiling point of more than 200 ° C as a plasticizer during its preparation. This product is extremely harmful to the health of personnel, as it contains toxic substances, especially benzopyrenes.

In addition, the use of rubber crumb with a size of 5-10 mm and a sufficiently short mixing time of 30-60 minutes does not ensure the complete solubility of the rubber crumb in bitumen, which also negatively affects the properties of the mixture during storage and the operational characteristics of the final product, as well as the use of additional a screw device for forcing the hot mixture through the nozzles complicates the cooking process.

A rubber-bitumen composition and a method for its preparation are known, including bitumen, rubber crumb, vegetable oil as a plasticizer and maleic anhydride (patent RU 2448134, published on 04/20/2012). The disadvantage of the composition is the use of maleic anhydride as an additional plasticizer to create a polymer complex with rubber crumb, providing an increase in the softening temperature and elasticity of the composition after it hardens, as well as an increase in the adhesive ability of the composition with various materials (fillers, concrete).

Maleic anhydride is a very toxic substance that irritates the mucous membranes of the eyes and upper respiratory tract.

The closest in technical essence is patent RU 2162475, published on January 27, 2001, from which a composition and a method for producing it, comprising bitumen and rubber dissociated to the absence of distinguishable particles, are obtained by thermal and mechanical action of a mixture of bitumen, hydrocarbon oil, liquid rubber and rubber crumbs. The disadvantages of this composition and its production method is the long and complex process of multiple downloads and heating with vigorous stirring, the use of expensive reagents - aromatic oils with the trade names "SUNTEH" and "HYDROENE", low molecular weight liquid rubber (polybutadiene or polyisoprene with a molecular weight of 300- 60,000). In addition, rubber crumb with a sufficiently wide range in size is used, which also affects the uniformity of its dissolution; it is not indicated what operational properties a bitumen-rubber composite has.

Disclosure of invention

The objective of the invention is to expand the range of bitumen-rubber compositions with improved performance while simplifying the technology of preparation of the composition, reducing the duration of the cooking process.

The technical result is an increase in frost resistance, an increase in the melting temperature, stability (reduction of sedimentation) during storage, increased elasticity and improved adhesion to the road surface.

The present invention is one of the effective approaches for the disposal of amortized rubber products and waste products.

The specified technical result is achieved in a bitumen-rubber binder composition for road surface, including bitumen, crumb rubber from crushed waste automobile tires with a particle size of up to 1 mm and petroleum oil with a viscosity of 0.005-1.6 Pa · s at 60 ° C, the following the ratio of components in wt.%:

rubber crumb 8-20 petroleum oil 2-12 bitumen rest.

Preferably, petroleum mineral oil with a density of 0.85-1.04 g / cm ³ at 15 ° C and a flash point of more than 225 ° C is used in the bitumen-rubber binder composition.

Preferably, rubber crumb up to 0.6 mm in size is used in the bitumen-rubber composition.

An additional block copolymer of polystyrene-polybutadiene-polystyrene in an amount of up to 0.2-5.0 wt.% Can be added to the bitumen-rubber binder composition.

Ethylene vinyl acetate in an amount of up to 0.2-5.0 wt.% Can be added to the bitumen-rubber binder composition.

Polybutadiene in an amount of up to 0.2-5.0 wt.% Can be added to the bitumen-rubber binder composition.

The specified technical result is achieved in a method for producing a bitumen-rubber binder for paving, including heating bitumen to a temperature of 185-220 ° C, introducing petroleum oil with a viscosity at 60 ° C of 0.005-1.6 Pa · s in an amount of 2-10 mass. % and crumb rubber from used car tires with a particle size of up to 1 mm in an amount of 8-20 wt.%, with constant stirring for 2-5 hours at a constant temperature of 185-220 ° C.

Preferably, in the method for producing a bitumen-rubber binder, petroleum oil with a density of 0.85-1.04 g / cm ³ at 15 ° C and an ignition temperature of more than 225 ° C is used.

Preferably, in the method for producing a bitumen-rubber binder, rubber crumb up to 0.6 mm in size is used.

Preferably, ethylene vinyl acetate or block polystyrene-polybutadiene-polystyrene block copolymer in an amount of up to 0.2-5.0 wt.% Is additionally added to the binder at a temperature of 185-220 ° C.

Ethylene vinyl acetate or polystyrene-polybutadiene-polystyrene block copolymer is introduced 2-5 hours after the addition of rubber crumb either during mixing or at the beginning of mixing.

To prepare the composition using road bitumen brand BND 60/90 or 90/130 in accordance with GOST 22245-90.

Petroleum oil obtained at oil refineries is used as hydrocarbon oil, which increases the solubility of rubber particles in bitumen and increases frost resistance.

Characteristics of petroleum (mineral) oil, which is used in a bitumen-rubber binder, are presented in table 1.

Various types of oils can be used as petroleum oils, for example oils of the following grades: Oltech 518 (density 0.87 g / cm ³ at 15 ° C, viscosity at 60 ° C - 0.02 Pa · s, flash point above 250 ° C), or, for example, Grade AP / E Core 2500 (density = 0.90 g / cm ³ at 15 ° C, viscosity at 60 ° C - 0.15 Pa · s, flash point above 294 ° C), or Bituflux 250, ExxonMobil brand oil (viscosity at 60 ° C 1.54 Pa · s, density at 15 ° C 1.03 g / cm ³ , flash point above 292 ° C).

Rubber crumb up to 1 mm in size, preferably 0.6 mm, can be prepared by grinding shock-absorbed automobile tires, both without cord and with synthetic cord.

The lower limit is 20% of the rubber crumb content due to a noticeable change in the properties of the final product compared to the original bitumen.

The best option for implementing the method

Bitumen (grade BND 90/130 or 60/90) is heated in a tank at 185 ° C-220 ° C. With constant stirring, 2-12% of petroleum oil is added to bitumen, for example, Oltech 518 (1), AP / E Core 2500 (2), Bituflux 250 (3). You can use other brands that satisfy the properties listed in table 1.

Further, crumb rubber (maximum particle size 1 mm) is added to this mixture in a volume of 8-20%. The resulting mixture is mixed with a mixer for 2-5 hours. At each stage of production, a constant temperature of 185-220 ° C should be maintained.

The composition of bitumen-rubber compositions (DBK), temperature and time regime for the preparation of compositions of various compositions are given in table 2.

The test results of samples of bitumen-rubber compositions of various compositions are shown in table 3.

The test results obtained according to the invention of rubber-bitumen compositions show that they are characterized by a wider plasticity interval compared with similar compositions.

Petroleum oil with the properties indicated in table 1 provides an increased degree of solubility of the rubber, lowers the temperature of brittleness. Thus, the final product has increased adhesion to the road surface and increased resistance to cracking at low temperatures. The binder of the invention has improved adhesion at a temperature of minus 33 ° C.

The increased solubility of rubber provides an improved distribution of its particles throughout the composition, which lengthens the shelf life of the product and facilitates the work with it. It also provides improved traction with stone aggregate and road surface.

Under certain climatic conditions, an increased schedule, or mandatory technical conditions for the operation of the pavement, polymers such as ethylene vinyl acetate, block copolymer polystyrene-polybutadiene-polystyrene, or polybutadiene in an amount of up to 0.2-5.0 wt.% Can be added to the mixture. Polymers in the form of granules or powder can be added at the beginning of the mixing process together with rubber crumb or at the time of dissolution of the rubber crumb.

It is most preferable to add the polymer after the rubber particles have dissolved (i.e. after 2-5 hours), but can also be added while mixing bitumen with rubber. The dissolution of the polymer occurs at a temperature of 185-200 ° C for 0.5-2 hours

The main advantages of the final product.

1. Rubber particles dissolve better in bitumen.

2. Only hydrocarbon binder oil is added to bitumen to achieve better dissolution of the rubber.

3. It has a greater degree of penetration at low temperatures compared to conventional bitumen.

4. The road surface with such bitumen does not melt at high temperatures (the softening temperature on the ring and the ball is increased).

5. Significantly reduced brittleness temperature.

6. A lower percentage of sedimentation of rubber in the mixture during storage and road works.

7. The viscosity of the final product is reduced, which facilitates its mixing with hot asphalt.

8. High resistance to cracking and ruts from heavy equipment.

9. Increased grip with stone filler.

10. Increased elasticity in conditions of heavy traffic.

The first 6 hours the binder should be stored at a temperature above 200 ° C. During transportation, the product should be mixed for 20 minutes for every 4 hours of transportation.

If necessary, long-term storage of the product should be stored at a temperature of 185-205 ° C for 7 days with constant stirring.

The optimal ratio of the amount of oil and the size of the crumb rubber determines the effect of accelerating the process of dissolution of rubber in bitumen and excellent performance characteristics of the final product.

The indicated limits of the temperature regime of heating the composition are optimal, because below 185 ° C, the dissolution of rubber occurs very slowly, and above 225 ° C it is not practical to increase the temperature, because processes of destruction of rubber macromolecules are underway.

Table 1 Viscosity at 60 ° С, Pa · s Density at 15 ° С, g / cm ³ Flash point 0.005-1.6 0.85-1.04 above 225 ° C

table 2 The composition of the bitumen-rubber compositions, wt.% DBK preparation temperature, ° С Mixing time, h one Bitumen 60/90 - 84; rubber crumb (0.8 mm) - 11; Petroleum Oil (2) - 5 185-220 four 2 Bitumen 60/90 - 82; rubber crumb (0.4 mm) - 13; Petroleum Oil (2) - 5 185-220 four 3 Bitumen 60/90 - 79; rubber crumb (0.8 mm) - 16; Petroleum Oil (1) - 5 185-220 four four Bitumen 60/90 - 75; rubber crumb (0.6 mm) - 20; Petroleum Oil (1) - 5 185-220 four 5 Bitumen 60/90 - 81; rubber crumb (0.8 mm) - 11; Petroleum Oil (2) - 8 185-220 four 6 Bitumen 60/90 - 77; rubber crumb (0.8 mm) - 13; Petroleum Oil (1) - 10 185-220 four 7 Bitumen 60/90 - 74; rubber crumb (1 mm) - 16; Petroleum Oil (2) - 10 185-220 four 8 Bitumen 60/90 - 70; rubber crumb (0.8 mm) - 20; Petroleum Oil (3) - 10 185-220 four 9 Bitumen 60/90 - 84; rubber crumb - 11; Petroleum Oil (2) - 5 185-220 four 10 Bitumen 60/90 - 79.5; rubber crumb (0.8 mm) - 11; Petroleum oil (1) - 8; POLYSTYRENE-POLYBUTADIENE-POLYSTYRENE - 1.5 185-220 5 eleven Bitumen 60/90 - 77; rubber crumb (0.8 mm) - 11; Petroleum oil (2) - 8; POLYSTYRENE-POLYBUTADIENE-POLYSTYRENE - 3 185-220 5 12 Bitumen 60/90 - 90; rubber crumb - 0, Petroleum oil (2) - 6; POLYSTYRENE-POLYBUTADIENE-POLYSTYRENE - 4 190-203 1,5 13 Bitumen 60/90 - 79; rubber crumb (0.5 mm) - 11; petroleum oil (3) - 8; POLYSTYRENE-POLYBUTADIENE-POLYSTYRENE-2, the polymer was added simultaneously with rubber crumb 185-220 four fourteen Bitumen 60/90 - 80; rubber crumb (1.0 mm) - 11; petroleum oil (2) - 8; POLYSTYRENE-POLYBUTADIENE-POLYSTYRENE - 1, the polymer was added simultaneously with rubber crumb 185-220 four fifteen Bitumen 90/130 - 84; rubber crumb (0.8 mm) - 11; petroleum oil (1) - 5 185-220 four 16 Bitumen 90/130 - 82; rubber crumb (0.6 mm) - 13; petroleum oil (1) - 5 185-220 four 17 Bitumen 90/130 - 79; rubber crumb (0.8 mm) - 16; petroleum oil (2) - 5 185-220 four eighteen Bitumen 90/130 - 75; rubber crumb (0.6 mm) - 20; petroleum oil (2) - 5 185-220 four 19 Bitumen 90/130 - 81; rubber crumb (0.6 mm) - 11; petroleum oil (2) - 8 185-220 four twenty Bitumen 90/130 - 80; rubber crumb - 11; petroleum oil (2) - 8; POLYSTYRENE-POLYBUTADIENE-POLYSTYRENE - 1, the polymer was added simultaneously with rubber crumb 185-220 four 21 Bitumen 60/90 - 81; rubber crumb (0.8 mm) - 11; petroleum oil (1) - 8 185-220 four 22 Bitumen 60/90 - 81; rubber crumb (0.6 mm) - 11; petroleum oil (3) - 8 185-220 four 23 Bitumen 60/90 - 80; rubber crumb (0.8 mm) - 11; petroleum oil (3) - 8; POLYSTYRENE-POLYBUTADIENE-POLYSTYRENE - 1, the polymer was added simultaneously with rubber crumb 185-220 four 24 Bitumen 60/90 - 80; rubber crumb - 11; petroleum oil (1) - 8; POLYSTYRENE-POLYBUTADIENE-POLYSTYRENE - 1, the polymer was added simultaneously with rubber crumb 185-220 four

Used in table 2 labeling of petroleum oils:

Petroleum oil (I): viscosity at 60 ° C = 0.02 Pa · s, density at 15 ° C = 0.87 g / cm ³ , flash point> 250 ° C

Petroleum oil (2): viscosity at 60 ° С = 0.15 Pa · s, density at 15 ° С = 0.90 g / cm ³ , flash point 294 ° С

Petroleum oil (3): viscosity at 60 ° C = 1.54 Pa · s, density at 15 ° C = 1.03 g / cm ³ , flash point> 292 ° C.

Table 3 Sample No. Softening point, ° С Viscosity at 180 ° C Recovery at 25 ° C,% The degree of adhesion at -33 ° C, (/ 10 **) The degree of resistance to cracking at -33 ° C (/ 10 ##) Description of product thin film at -33 ° C after 24 hours storage one 57.9 0.52 thirty 6 9 Semi gloss 2 60.6 0.54 thirty 8 5 Semi gloss 3 69.6 1.20 34 four 5 Glossy four 72.6 2.55 34 3 3 Semi gloss 5 57.8 0.47 34 9 10 Soft 6 56.3 0.31 33 9 6 Soft 7 62.5 1.12 35 four four Semi gloss 8 69.5 2.05 39 3 four Glossy 9 54.6 0.2 thirty 9 7 Soft 10 68.3 0.72 45 9 8 Soft eleven 77.3 0.88 72 8 6 Glossy 12 80 0.25 80 2 one Glossy, fragile 13 78.4 0.87 68 9 6 Semi gloss fourteen 66.4 0.66 47 10 9 Soft fifteen 56.8 0.44 32 8 9 Soft 16 59.8 0.51 32 8 5 Semi gloss 17 69.2 1.17 34 5 5 Semi gloss eighteen 72.2 2.51 34 2 2 Semi gloss 19 55.7 0.42 35 9 9 Soft twenty 65.2 0.60 49 10 9 Soft 21 56.1 0.44 31 8 8 Soft 22 58.2 0.56 32 8 8 Soft 23 67.3 0.75 44 8 7 Soft 24 66.1 0.62 48 8 8 Soft Bitumen 60/90 48.1 0.05 5 one one Glossy, fragile ** 10/10 - the best grip, 0/10 - no grip ## 10/10 - no cracks at -33 ° C, 0/10 - complete cleavage at loads at -33 ° C

Claims (14)

1. A bituminous-rubber binder composition for a road surface comprising bitumen, crumb rubber from crushed used car tires and hydrocarbon oil, characterized in that rubber crumb with a particle size of up to 1 mm is used, and petroleum oil with a viscosity of 0.005 is used as hydrocarbon oil -1.6 Pa · s at 60 ° C, with the following ratio of components in wt.%:
rubber crumb 8-20 petroleum oil 2-12 bitumen rest. 2. The bitumen-rubber binder composition according to claim 1, characterized in that petroleum oil with a density of 0.85-1.04 g / cm ³ at 15 ° C and a flash point above 225 ° C is used. 3. The bitumen-rubber binder composition according to claim 1, characterized in that it is preferable to use crumb rubber up to 0.6 mm in size. 4. The bitumen-rubber binder composition according to claim 1, characterized in that it further comprises a block copolymer of polystyrene-polybutadiene-polystyrene in an amount of up to 0.2-5.0 wt.%. 5. The bitumen-rubber binder composition according to claim 1, characterized in that it further comprises ethylene vinyl acetate in an amount of up to 0.2-5.0 wt.%. 6. The bitumen-rubber binder composition according to claim 1, characterized in that it further comprises polybutadiene in an amount of up to 0.2-5.0 wt.%. 7. The bitumen-rubber binder composition according to claim 1, characterized in that the bitumen grade BND 90/130 or bitumen grade BND 60/90 is used. 8. A method of obtaining a bitumen-rubber binder for road surface comprising heating bitumen with the subsequent introduction of hydrocarbon oil and rubber crumbs from the crushed waste car tires with constant stirring, characterized in that the bitumen is pre-heated to a temperature of 185 ° C-220 ° C, and sequentially with constant stirring, hydrocarbon oil is introduced into petroleum oil with a viscosity of 0.005-1.6 Pa · s at 60 ° C in an amount of 2-12 wt.%, rubber crumb with a particle size of up to 1 mm in an amount of 8-20 wt.%,stirred for 2-5 hours at a constant temperature of 185 ° C-220 ° C. 9. A method of producing a bitumen-rubber binder according to claim 8, characterized in that hydrocarbon oil with a density of 0.85-1.04 g / cm ³ at 15 ° C and an ignition temperature of more than 225 ° C is used. 10. A method of producing a bitumen-rubber binder according to claim 8, characterized in that it is preferable to use crumb rubber up to 0.6 mm in size. 11. The method of producing a bitumen-rubber binder according to claim 8, characterized in that ethylene vinyl acetate or block polystyrene-polybutadiene-polystyrene is additionally added to the binder at a temperature of 185-220 ° C in an amount of up to 0.2-5.0 wt.%. 12. The method of producing a bitumen-rubber binder according to claim 8, characterized in that the binder further comprises polybutadiene in an amount of up to 0.2-5.0 wt.%. 13. A method of producing a bitumen-rubber binder according to claim 8, characterized in that they use bitumen grade BND 90/130 or bitumen grade BND 60/90. 14. A method of producing a bituminous-rubber binder according to claim 8, characterized in that ethylene vinyl acetate or block polystyrene-polybutadiene-polystyrene block copolymer is introduced 2-5 hours after adding crumb rubber or during mixing or at the beginning of mixing.