RU2713039C1 - Composition of fiber-containing asphalt concrete mixture for coatings - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the field of road-building mixtures and can be used to create modern asphalt concrete materials for road construction. Composition of fiber-containing asphalt-concrete mixture includes the following components: crushed stone 20–60 %, mineral powder 4–12 %, polyacrylonitrile fiber with density of 0.17–0.77 tex and cutting length of 6–18 mm 0.07–0.6 %, organic binder 4–12 %, sand – balance. Organic binding agent is composite of two types of oil viscous bitumen, in % of total amount of binder in mixture: bitumen of one of grades: BND 90/130, BND 60/90, BND 40/60 – 85–95 % together with bitumen of one of the following grades: BND 200/300, BND 130/200 – 5–15 %.

EFFECT: obtaining a mixture with high shear resistance, water resistance, crack resistance and ultimate strength to produce a strong asphalt concrete coating.

1 cl, 2 tbl

Description

 The invention relates to the field of road-building mixtures and can be used to create modern asphalt materials for the construction of roads.

 Asphalt mixtures, depending on the viscosity of the bitumen used and the temperature when laying the pavement on the road, are divided into hot and cold. Of interest for this patented solution are cold mixtures prepared using oil road bitumen and stacked with a temperature of at least + 5 ° C, since they are much cheaper than other mixtures and are used in a wide range of climatic and geographical latitudes almost all year round, with the exception of 2- 3 months of the coldest season, depending on the region of use of asphalt mixtures.

 Important constituent parts of any asphalt mix are: the composition of the group of fillers, which usually contains crushed stone, sand, mineral powder (RU No. 2560364, RU No. 2351561, RU No. 2310621, RU No. 2182136, RU No. 2351703, USSR copyright certificate No. 707945 ), as well as the composition of the binder group. Moreover, both fillers and astringent analogues described below are included in the mixture hot.

 Among the groups of binders in the compositions for the manufacture of asphalt concrete coatings are known binders, represented by one type of bitumen: see GOSTs, as well as a number of inventions from the above patent documents (RU No. 2310621, RU No. 2182136, RU No. 2351703, USSR copyright certificate No. 707945) and etc.

 Known composite binders in asphalt mixtures, which include liquid or viscous bitumen with various modifying additives - motor oil (patents: RU No. 2623748, RU No. 2625353), oil sludge (patent RU No. 2535325), a stabilized binder containing, along with epoxy resin polyethylene polyamine, divinylsterol thermoplastic and tall oil (patent RU No. 2647740). Such additives are introduced into bitumen to adjust not only its properties, but also the future pavement, namely, to expand the temperature range of the asphalt concrete working capacity, reduce brittleness, increase crack resistance or prevent rutting.

 The disadvantages of the above mixtures is not just the increasing number of components, but also the need to use special equipment to connect them, taking into account the complex properties of some of them. As a result, an increase in labor costs entails the addition of the cost of the produced mixture.

Of particular interest are compositions for asphalt concrete pavement with fibrous fillers, which make it possible to obtain reinforced asphalt concrete with increased resistance to deformation.

 It is known to use in the composition of a mixture for asphalt concrete coating (patent CN 101081725) a fibrous filler, which is a polyacrylonitrile fiber (PAN fiber) 1.5-2.5 decitex 6 mm long, added in an amount of 0.2-0.3% by weight of the mixture based on limestone ore and slag.

 Also known is the composition of the mixture for asphalt concrete paving (patent for invention CN 1908069), including a mineral filler based on limestone and bitumen. The composition additionally contains 0.1-0.5% of a hollow or porous polymer fiber with a particularly complex cross-sectional shape. The polymer fiber is a polyester fiber, a PAN fiber, or compositions of these fibers.

 However, the formation of a complex cross-sectional shape of the fiber additionally increases the cost of the process of obtaining asphalt mix without a noticeable improvement in the properties of the coating.

 Also known is the composition of fiber additives in the asphalt mix (patent CN 101798196) containing a group of fibers: 15-35% polyester fibers, 35-55% wood fiber, 15-35% PAN fiber and 15-35% nylon fiber. The total content of the reinforcing additive is 0.3-0.6% by weight of the mixture.

 However, the mixture of fibers used in the above patent document contains fibers from materials that sharply limit the temperature of the process for producing the asphalt concrete mixture, since their melting or decomposition temperature is much lower than the preparation temperature of most asphalt concrete, usually about 160 ° C. Thus, the use of mixed fiber supplements becomes impossible or ineffective.

The closest analogue of the claimed invention is the composition of the asphalt-concrete water-free mixture (patent RU 2465231), which contains crushed stone, fine aggregate, mineral powder, as well as a bituminous binder and reinforcing fibrous filler, in the following ratio of components, wt.%: Crushed stone - 30- 70, fine aggregate - 10-65, mineral powder - 5-40, bitumen binder - 3-15 (in excess of 100% of the mineral material), PAN-fiber - 0.1-0.15 (in excess of 100% of the mass of the mineral material ) and carbon fiber - 0.01-0.15 (in excess of 100% by weight of the mineral mater ala). As a carbon fiber, the mixture contains finely chopped carbon fibers with a length of 3 to 40 mm and with an average diameter of 20-22 microns of continuous carbon fiber.

However, weak adhesive interaction, as it turned out, at the interface between fiber and bitumen due to the lack of chemical bonds between the binder and the filler, does not always lead to the expected increase in the strength characteristics of the asphalt mix.

The objective of the invention is to obtain a cold mixture with increased shear resistance, water resistance, fracture toughness and tensile strength to create a durable asphalt concrete coating taking into account natural and climatic factors and the effects of static and dynamic traffic loads.

The essence of the claimed invention is characterized in that the composition of the fiber-containing asphalt mix for coatings includes hot - heated to a temperature of 140-180 ° C, crushed stone, sand, mineral powder, astringent with a temperature of 110-160 ° C and polyacrylonitrile fiber,%:

crushed stone 20-60 mineral powder 4-12 organic binder 4-12 density polyacrylonitrile fiber 0.17-0.77 tex and cut length 6-18 mm 0.07-0.6 sand rest,

while organic binder is a compound of two types of bitumen

viscous oil, in% of the total amount of binder in the mixture:

one of the brands: BND 90/130, BND 60/90, BND 40/60 together with 85-95 bitumen of one of the brands: BND 200/300, BND 130/200 5-15

The technical result of the claimed invention.

The use of a hot binder in the form of a pair of viscous oil road bitumen: one of the grades: BND 90/130, BND 60/90, BND 40/60 with one of the grades BND 200/300, BND 130/200, and in combination with reinforcing material - PAN fiber with a density of 0.17-0.77 tex and a cut length of 6-18 mm is a distinctive feature of the proposed composition of the mixture. The combination of any of the pairs of bitumen compiled by the Applicant presented above with PAN fiber at the same time, and the named type of its density and cutting, is not known. The set of all components of the inventive asphalt mixes, including those heated to 140-180 ° C of crushed stone, sand and mineral powder, among the sets of components of the mixtures described in the literature and used in industry, in the claimed concentration ranges were also not previously described and were not used.

It is these differences of the claimed mixture that provide a solution to the problem posed in the invention. This is the technical result of the proposed solution.

The subsequent presentation of the material of the invention is shown using tables 1.1; 1.2; 1.3; 2, demonstrating the physical and mechanical properties of fiber-containing asphalt concrete with and without PAN fiber, namely, table 1.1 shows the compressive strength at 50 ° C in MPa, table 1.2 shows the shear resistance by the coefficient of internal friction in MPa, table 1.3 - shear resistance to adhesion at shear at a temperature of 50 ° C in MPa, table 2 - comparison of the above indicators for different compositions of the mixture due to the changing composition of the binder and fiber.

Studies conducted by the Applicant to select the optimum amounts of bitumen included in the binder and compared with existing binder compositions have shown the advantages of the inventive binder in asphalt concrete mix. Any of the selected bitumen pairs with different bitumen penetrations paired empirically selected by the Applicant, grades: BND 90/130, BND 60/90, BND 40/60 with one of the grades BND 200/300, BND 130/200, as it turned out, is optimal solves the problem of wetting and the formation of a bitumen film on the surface of mineral elements and PAN fibers in the volume of fiber-containing asphalt mix. As a result, the problem of the formation of lumps in the mixture is eliminated, which was a stable marriage when using not optimally selected fiber lengths of fibers and ordinary fibers unprepared by special treatment, for example, without fluffing the fibers.

The choice of reinforcing PAN fiber was carried out along the way to find the optimum density and size of the fibers, which do not form lumps of tangled threads, but are evenly distributed over the layers of the asphalt concrete mixture. According to the results of studies of composite asphalt mixes made using PAN fiber, it can be concluded that with an increase in the length of PAN fiber cutting exceeding the sizes recommended by the Applicant above, the quality of the mixture deteriorated. For example, with a cut length approaching 19 mm, lumps were already noticed in the mixture, which caused a deterioration in the quality of the mixture. With a reduction in the length of the cut from 6 mm or less, no improvement in properties was manifested. Optimal for ensuring the quality of the mixture was PAN fiber with a density of 0.17 - 0.77 tex with a cut length of 6-18 mm. As a result, complete harmony and compatibility of PAN fiber with other components of the mixture, in particular with hot bitumen, and its more uniform and uniform distribution between the hot (up to 140-180 ° C) mineral components of the mixture were achieved, followed by an increase in tensile strength and shear stability ( tables 1.1, 1.2, 1.3).

 Table 1.1

 Table 1.2

 Table 1.3

 During the tests of the claimed technical result in the example described below, an asphalt concrete mixture was prepared in which the following materials were used:

- crushed granite of the Potapovsky quarry of the Rostov region and limestone crushed stone of the Zhigulevsky quarry of the Samara region, fractions from 5 mm to 10 mm, st. 10 mm to 15 mm, st. 15 mm to 20 mm, corresponding to the requirements of GOST 9128-2013, GOST 31015-2002;

- limestone mineral powder of the Ozinsky plant of the Saratov region, corresponding to the requirements of GOST R 52129-2003;

- river sand produced by OJSC “Saratov River Transport Enterprise”, which meets the requirements of GOST 8735-88, GOST 8736 - 2014, GOST 9128;

- bitumen of the Saratov refinery related to viscous oil road bitumen grades BND 90/130, BND 60/90, BND 40/60, BND 200/300, BND 130/200, meeting the requirements of GOST;

- PAN fiber with a density of 0.17-0.77 tex and a cut length of 6-18 mm.

  The composition of the asphalt mixture of the components in the example included:

crushed stone - 48.5%;

sand - 40.7%;

mineral powder - 5.1%;

 viscous bitumen 60/90 BND - 4.95%

viscous bitumen BND 130/200 - 0.55%;

PAN fiber - 0.2%.

Table 2 shows the comparative characteristics of the mixture with the above composition and reference:

- without the addition of fiber;

- with the addition of PAN fiber and just one type of bitumen grade BND 60/90;

- with the addition of PAN fiber with an optimal cutting length of 12 mm and a density of 0.56 tex and a binder, consisting of a pair of bitumen grades BND 60/90 and BND 130/200 of different penetration.

table 2

 From table 2 it is seen that the crack resistance index of asphalt concrete increases by an average of 32%, shear adhesion at shear at a temperature of 50 ° C increases by 77%, shear resistance by internal friction coefficient increases by 16%, water resistance coefficient increases by 5%, tensile strength compression increases by about 94.5% compared with fiber-containing asphalt mixtures using only one of the known types of bitumen.

 For the processing of fiber, we used the FSBEI HE Saratov State Technical University named after VOLGODORTRANS developed at the Volga Educational and Research Center Gagarina Yu.A. ” a prototype installation for the production of composite fiber-containing asphalt mixes, which allows you to prepare fibrous materials (basalt, polyacrylonitrile and other types of fiber) to introduce them into the composition of asphalt mixes with the aim of reinforcing, increasing the physico-mechanical properties and durability of road surfaces. The installation includes a device for fluffing (splitting) of fiber and a device for blowing it into the mixer of an asphalt concrete plant.

Claims (5)

The composition of the fiber-containing asphalt mix for coatings, characterized in that it includes hot gravel heated to a temperature of 140-180 ° C, sand, mineral powder, a binder with a temperature of 110-160 ° C and polyacrylonitrile fiber,%: crushed stone       20-60 mineral powder         4-12 organic binder          4-12 density polyacrylonitrile fiber 0.17-0.77 tex and cut length 6-18 mm     0.07-0.6 sand rest, while organic binder is a compound of two types of bitumen viscous oil, in% of the total amount of binder in the mixture: one of the brands: BND 90/130, BND 60/90, BND 40/60                         85-95 together with bitumen of one of the brands: BND 200/300, BND 130/200 5-15