RU2796216C1 - Complex modifier of asphalt concrete mixture and method for its production - Google Patents

Abstract

FIELD: asphalt coatings.

SUBSTANCE: group of inventions relates to a complex modifier of an asphalt concrete mixture and a method for its production. The technical result consists in improving the properties of the asphalt concrete mixture: fatigue life, frost resistance, water resistance, resistance to rutting, strength, durability, plasticity at low temperatures. The complex modifier contains, wt %: surface-devulcanized elastomeric granulate 91, olefins in the form of polyethylene and its derivatives, in particular, polyethylene wax 5, phenolic resin and/or rosin 2, sorbents based on textiles and/or cellulose 2. The method for producing a complex modifier for an asphalt concrete mixture includes obtaining a surface-devulcanized elastomeric granulate by mixing an elastomeric crumb 0.8 mm in size with a softener and a mineral filler, heating the resulting mixture above 120°C while providing pressure and shear load for the time necessary to start the devulcanization process and finally mixing the surface-devulcanized elastomeric granulate with olefins in the form of polyethylene and its derivatives, phenolic resin and/or rosin and textile and/or cellulose based sorbents in a certain proportion.

EFFECT: improving the properties of the asphalt concrete mixture.

5 cl, 4 tbl

Description

The invention relates to road building materials and can be used in the construction of pavements for roads, bridges, airfields in all climatic zones, as well as waterproofing and roofing materials. The invention relates to improving the quality indicators of the asphalt concrete mixture by introducing a modifier into it as a structuring additive.

Asphalt modifiers are widely known on the market.

So known is the patent of the Russian Federation No. 2472730 dated January 20, 2013, which discloses a granular asphalt concrete mix modifier containing vulcanized rubber and a composition of modifying components. At the same time, the modifier has the form of granules with a linear size of 3 to 15 mm and consists of a binder, an elastic polymer filler, a cross-linking and structuring agent, a mineral structural strengthening filler and a surfactant-adhesive with the number of components in the granules, wt.%:

binder 20-40,

elastic polymer filler 40-60,

crosslinking and structuring agent 1-4,

mineral structural strengthening filler 5-20,

surfactant - adhesive 2.0-4.5.

The disadvantages of this modifier are insufficiently high performance characteristics of the resulting asphalt mixture.

The closest analogue of the proposed technical solution is RF patent No. 2401817 dated October 20, 2010, which discloses an asphalt concrete mix modifier. This modifier contains vulcanized rubber and a composite of modifying components, consisting of needle-shaped calcium metasilicate, epoxy resin, nitrosamine compound, phenolic resin and/or rosin, which are in the ratio by weight, %:

acicular calcium metasilicate 24,

epoxy resin 2,

nitrosamine compound 1,

phenolic resin and/or rosin 4,

vulcanized rubber (rubber crumb) 69.

The disadvantages of this modifier is the lack of durability, due to the sufficient rapid formation of ruts.

The technical result of the claimed invention is the simultaneous improvement of the properties of the asphalt concrete mixture according to the following indicators:

- fatigue life,

- frost resistance,

- water resistance,

- resistance to rutting,

- strength,

- durability,

- plasticity at negative temperatures.

At the same time, the use of this complex asphalt concrete modifier (CMA) does not require additional equipment for standard asphalt concrete plants, and occurs without changing the standard technology for the production of asphalt mixtures. An additional technical result is the duration of storage, ease of transportation, ease and manufacturability of the use of a complex asphalt concrete modifier (CMA) in the manufacture of asphalt mixtures, which positively affects the final cost of the asphalt concrete mixture and, ultimately, the road surface.

The main area of application of the complex modifier of the asphalt concrete mixture (KMA):

- Rubber-dispersion-reinforced asphalt mixes (hereinafter RDA ABS),

- Rubber-dispersion-reinforced asphalt concrete (hereinafter RDA AB),

- Rubber-dispersed-reinforced (RDA) crushed-stone-mastic asphalt concrete (hereinafter referred to as RMA), while stabilizing additives are not required,

- Cast asphalt concrete,

- Vibrated asphalt concrete,

- Thin-layer protective coatings.

The technical result is achieved by the fact that the complex modifier of the asphalt concrete mixture contains: surface-devulcanized elastomeric granulate, olefins in the form of polyethylene and its derivatives, phenolic resin and/or rosin and sorbents based on textiles and/or cellulose. In this case, the components are among themselves in the following ratio by weight,%:

surface-devulcanized elastomeric granulate - 91,

olefins in the form of polyethylene and its derivatives, in particular polyethylene wax - 5,

phenolic resin and / or rosin - 2,

sorbents based on textiles and/or cellulose - 2.

Polyethylene wax is used as olefins in the form of polyethylene and its derivatives.

Also proposed is a method for producing a complex modifier for an asphalt concrete mixture, which includes obtaining a surface-devulcanized elastomeric granulate and final mixing of the surface-devulcanized elastomeric granulate with olefins in the form of polyethylene and its derivatives, phenolic resin and/or rosin, and sorbents based on textiles and/or cellulose. In this case, the preparation of a surface-devulcanized elastomeric granulate is carried out:

- mixing of 0.8 mm elastomer crumb with softener and mineral filler,

- heating the resulting mixture above 120°C with pressure and shear load for the time necessary to start the devulcanization process, and the final mixing of the surface-devulcanized elastomeric granulate with olefins in the form of polyethylene and its derivatives, phenolic resin and/or rosin and sorbents on based on textiles and/or cellulose is carried out at the following ratio by weight, %:

surface-devulcanized elastomeric granulate - 91,

olefins in the form of polyethylene and its derivatives, in particular polyethylene wax - 5,

phenolic resin and / or rosin - 2,

sorbents based on textiles and/or cellulose - 2.

Bitumens or tars are used as softeners.

The essence of the claimed invention lies in the fact that the surface-devulcanized elastomer granulate (devulcanizate) acts as the main cross-linking agent (modifier), as well as a structuring additive that increases the elasticity of the asphalt concrete mixture, in contrast to analogs (prototypes) using vulcanized non-polar rubber in the form of an elastomeric crumb from used tires, which performs only the function of a structuring additive. The dual function of the surface-devulcanized elastomer granulate (devulcanizate) is provided by the incomplete regeneration process of the vulcanized elastomer chips, and is an advantage over other asphalt mix modifiers. An additional advantage of the surface-devulcanized elastomeric granulate (devulcanizate) as part of a complex asphalt mix modifier (CMA) is the reduction in the proportion of additional cross-linking agents based on virgin materials (rubbers, olefins and other polymers) used in the production of asphalt mix. Modification of bitumen binder (road bitumen), building bitumen, waterproofing mastics and materials is achieved by a composite of modifying ingredients (components) included in the complex modifier:

- Olefins (polyethylene and its derivatives, in particular polyethylene wax) - an additional cross-linking agent, modifier,

- Phenolic resin and / or rosin - adhesive,

- Sorbents based on textiles and / or cellulose - stabilizer.

The composition and mass fraction of modifying components are determined experimentally (empirically), based on existing knowledge about asphalt concrete, bituminous binders, building bitumens, knowledge about the chemical and physical interaction of various bitumens with mineral components, polymers and rubbers, including secondary ones, obtained by the method of devulcanization (regeneration) from the vulcanized rubber of used tires.

The optimization of the composition of the components of the complex asphalt concrete modifier (CMA) was carried out on the basis of the selection of asphalt concrete compositions and the analysis of the properties of these asphalt concretes in terms of strength, durability, resistance to positive and negative temperatures, resistance to rutting, water resistance, crack resistance, manufacturability of asphalt concrete laying, etc.

To obtain a complex modifier for an asphalt concrete mix (CMA), it is necessary to first obtain a surface-devulcanized elastomeric granulate (devulcanizate), including from crumb rubber obtained from waste tires. The thermomechanical method of obtaining regenerate was taken as the basic technology. When receiving the regenerate, various chemicals are used: softeners, activators, modifiers, emulsifiers, etc. In our case, only softeners are used. Oil refining products - bitumen, tars - are used as softeners. Modifiers, activators and other chemicals are not used to slow down the regeneration process. A distinctive feature of the technological process, in our case, will be operation at the boundary technological parameters (heating temperature, shear force, pressure and regeneration time), which, on the one hand, ensure the start of the regeneration process of the elastomer crumb, and, on the other hand, do not allow this process to go through the entire volume of the elastomeric crumb. For the same purpose, 0.8 mm elastomer chips (22 US mesh) are used, and in the traditional production of regenerate, as a rule, chips less than 0.8 mm (less than 22 US mesh) are used. To do this, the elastomer crumb is mixed when heated above 120 ° C with pressure and shear load for the time necessary to start the devulcanization (regeneration) process, after which the remaining components of the complex modifier of the asphalt concrete mix (CMA) are added and mixed with a decrease in temperature below 120 ° C, the devulcanization process stops.

The claimed complex asphalt mix modifier (CMA) can be produced in the form of powder, granules. For manufacturers of asphalt mix, waterproofing and roofing materials, the complex asphalt concrete modifier (KMA) is supplied in a package agreed with the customer.

Asphalt mix is produced by known technological methods at asphalt plants in mixing plants equipped with intermittent or continuous forced mixing mixers. The complex asphalt mix modifier (CMA) is introduced directly into the mixer, during or immediately after the introduction of bitumen into the mixer. The mixing time is determined by the technological regulations for the production of a particular type of asphalt mix for a particular mixing plant. The complex asphalt mix modifier (CMA) does not require preheating or other treatment before use.

The proposed complex asphalt mix modifier (CMA) provides a stable and high-quality asphalt mix, in which the surface-devulcanized elastomeric granulate (devulcanizate) is in physical and chemical relationship with other components of the asphalt mix and provides a qualitative improvement in the performance of the asphalt mix.

We have compared the performance of asphalt concrete mixtures, see Table 1.

The use of a complex asphalt mix modifier (CMA) in the amount of 0.8-1% for crushed stone-mastic asphalt concrete without the use of stabilizing and cellulose additives makes it possible to obtain crushed stone-mastic asphalt concrete (SMA) corresponding to GOST R58406.1-2020, GOST 31015-2002.

The use of a complex asphalt mix modifier (CMA) in the amount of 1% -1.5% for RDA ABS asphalt concretes makes it possible to obtain asphalt concrete corresponding to GOST R58406.1-2020.

In both cases, the performance of asphalt concrete with a complex asphalt concrete mix modifier (CMA) exceeds the performance of control samples, which allows us to make a statement about the applicability of the proposed complex asphalt mix modifier (CMA) to produce asphalt concrete of other grades. Asphalt concretes modified with a complex asphalt concrete modifier (CMA) show higher physical and mechanical characteristics.

An increase in strength at high positive air temperatures, on average, by 24-30%, shows an improvement in shear resistance, while the crack resistance of such asphalt concrete remains within the specified parameters of GOST 31015-2003.

Comparative results of determining the resistance to rutting by rolling a loaded wheel according to PNST 181-2016 of crushed stone-mastic asphalt concrete based on a complex modifier of an asphalt concrete mixture (CMA) and a control composition using a stabilizing additive based on cellulose (see Table 2) show that the use of a complex modifier of asphalt concrete mixture (CMA) in the amount of 0.8-1% in the composition of crushed stone-mastic asphalt concrete significantly increases the resistance to rutting of crushed stone-mastic asphalt concrete.

Fatigue life improvements are shown in Table 3.

The use of a complex asphalt mix modifier (CMA) in an amount of 1% in the composition of crushed stone-mastic asphalt concrete increases the abrasion resistance of studded rubber, which is confirmed by Prall wear resistance tests, see Table 4.

Complex modifier of asphalt concrete mixture and method for its production

Complex modifier of asphalt concrete mixture and method for its production

Complex modifier of asphalt concrete mixture and method for its production

Complex modifier of asphalt concrete mixture and method for its production

Claims (15)

1. A complex modifier of an asphalt concrete mixture containing a surface-devulcanized elastomeric granulate, olefins in the form of polyethylene and its derivatives, phenolic resin and/or rosin and sorbents based on textiles and/or cellulose, which are in the ratio by weight, %: surface-devulcanized elastomeric granulate - 91, olefins in the form of polyethylene and its derivatives, in particular polyethylene wax - 5, phenolic resin and / or rosin - 2, sorbents based on textiles and/or cellulose - 2. 2. Modifier according to claim 1, characterized in that polyethylene wax is used as olefins in the form of polyethylene and its derivatives. 3. The method for producing a complex modifier for an asphalt concrete mixture includes obtaining a surface-devulcanized elastomeric granulate and final mixing of the surface-devulcanized elastomeric granulate with olefins in the form of polyethylene and its derivatives, phenolic resin and/or rosin and sorbents based on textiles and/or cellulose, while obtaining a surface-devulcanized elastomeric granulate is carried out: - mixing of 0.8 mm elastomer crumb with softener and mineral filler, - heating the resulting mixture above 120°C with pressure and shear load for the time necessary to start the devulcanization process, and the final mixing of the surface-devulcanized elastomeric granulate with olefins in the form of polyethylene and its derivatives, phenolic resin and/or rosin and sorbents on based on textiles and/or cellulose is carried out at the following ratio by weight, %: surface-devulcanized elastomeric granulate - 91, olefins in the form of polyethylene and its derivatives, in particular polyethylene wax - 5, phenolic resin and / or rosin - 2, sorbents based on textiles and/or cellulose - 2. 4. The method according to claim 3 of the formula, characterized in that bitumen or tars are used as softeners. 5. The method according to claim 3 of the formula, characterized in that the elastomer crumb is rubber crumb obtained from used tires.