RU2713015C1 - Composition of fibrous composite material for making asphalt concrete coating - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to road construction mixtures and can be used in making road concrete asphalt materials. Composition of fiber-containing composite material,%: crushed stone 20–60, mineral powder 4–12, reinforcing material 0.07–0.6, organic binder 4–12, sand – the rest, where the organic binder is a composite of two types of oil road viscous bitumen, in% of the total amount of the binder in the mixture: bitumen of one of the following 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, and reinforcing material is a set of basalt fiber with density of 54–240 tex with a cutting length of 12–18 mm in amount of 5–40 % of total amount of reinforcing material and polyacrylonitrile fiber with density of 0.17–0.77 tex with a cutting length of 6–18 mm in amount of 60–95 % of total amount of reinforcing material.

EFFECT: higher resistance to transport loads and to influence of climatic factors.

1 cl, 1 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.

 Important constituent parts of any asphalt mixture 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, copyright certificate SU No. 261236 ), as well as the composition of the binder group.

 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 the proposed 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 the mixtures.

Among the groups of binders in the compositions for the production of asphalt concrete coatings are known binders, represented by one type of hot 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. 261236 and etc.

Compound hot binders are known in asphalt mixtures, which include liquid or viscous bitumens with various modifying additives - engine oil (patents: RU No. 2623748, RU No. 2625353), oil sludge (RU patent 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, expanding the temperature range of the performance of asphalt concrete pavement, reducing brittleness, and increasing crack resistance parameters.

The disadvantages of the above mixtures are not just the increasing number of components in each of them, 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 all of the compositions described below for fiber-reinforced asphalt concrete paving, which make it possible to obtain reinforced asphalt concrete with increased resistance to deformation and obtaining without inclusion in the composition of water, using heating aggregates and the use of hot bitumen.

The known composition of the asphalt mixture (patent RU No. 2156227) containing mineral powder with coarse basalt fibers, stone materials and bitumen. The length of basalt fibers is 2-40 mm, diameter is 150-200 microns in the amount of 0.8-1.1% by weight of mineral materials.

The disadvantage of the mixture composition presented above is the lack of, as it turned out, a uniform distribution of long basalt fibers in the asphalt mix (with a length of cut with dimensions in the upper part of the range of ≈ 20 mm and higher in the last patent cited above), which leads to the formation of tangled threads, clods in mixtures and deterioration of the properties of the resulting asphalt coating.

Also known is the composition of the asphalt mixture (patent RU No. 2345967) containing crushed stone, bitumen 4.5 ÷ 7% by weight of crushed stone, solar oil 20 ÷ 25% by weight of bitumen, fatty organic acid 8 ÷ 16% by weight of bitumen, polyethylene polyamine 5 ÷ 12% by weight of bitumen, nanomodified basalt microfiber 1 ÷ 3% by weight of bitumen, cellulosic microfiber 3 ÷ 5% by weight of bitumen.

Also known is the composition of the mixture for asphalt concrete paving (patent for invention CN 1908069), including limestone-based mineral filler, bitumen and a hollow or porous polymer fiber with a particularly complex cross-sectional shape in an amount of 0.1-0.5% of the total mixture. 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% fiber based on polyester, 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 a composition for asphalt mix (patent RU 2465231), which contains crushed stone, fine aggregate, mineral powder, as well as bituminous binder and reinforcing fiber filler in the following ratio of components, wt.%: Crushed stone - 30-70, small aggregate - 10-65, mineral powder - 5-40, bitumen binder - 3-15 (in excess of 100% of the mineral material), 0.1-0.15 wt.% PAN fiber and 0.01-0.15 wt. .% carbon fiber (in excess of 100% by weight of the mineral material). 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.

A disadvantage of the closest analogue is the weak adhesive interaction at the interface between the fiber and bitumen due to the lack of chemical bonds between the binder and the filler, which leads to some decrease in the strength characteristics of the asphalt mix.

The objective of the invention is to obtain the composition of a cold mixture for the preparation of asphalt concrete coatings with variable properties depending on seasonality and other operating conditions, giving asphalt concrete increased resistance to traffic loads and to the influence of climatic factors.

The essence of the claimed invention is characterized in that the composition of the fiber-containing composite material for the manufacture of asphalt concrete coating includes hot, heated to a temperature of 140-180 ° C, crushed stone, sand, mineral powder, an organic binder with a temperature of 110-160 ° C and reinforcing material,%:

crushed stone 20-60 mineral powder 4-12 organic binder 4-12 reinforcing material in a pair of basalt fiber with a density of 54-240 tex with a cutting length of 12-18 mm together with polyacrylonitrile fiber density 0.17-0.77 tex with a cut length of 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,

and basalt fiber paired with polyacrylonitrile fiber in the following ratio of the total amount of reinforcing material in the mixture,%:

polyacrylonitrile fiber 60-95 basalt fiber 5-40

The technical result of the claimed invention

The use of a hot binder in the form of a pair of viscous oil road bitumen, each composed of one brand: BND 90/130, BND 60/90, BND 40/60 in conjunction with one of the brands: BND 200/300, BND 130/200 with different penetration, moreover, in combination with a composite reinforcing material consisting of basalt fiber with a density of 54-240 tex with a cut length of 12-18 mm together with a PAN fiber with a density of 0.17-0.77 tex and a cut length of 6-18 mm feature of the proposed composition of the mixture. A combination of any of the pairs of bitumen compiled by the Applicant presented above with a pair of basalt and PAN fiber of the above types of density and cutting at the same time in one mixture is not known. The set of all components of the claimed anhydrous asphalt mix among those described in the literature and used in industry in the claimed concentration ranges has also not been previously described and has not been used.

It is the listed identified differences of the claimed mixture that provide a solution to the task of the invention.

The subsequent presentation of the material of the invention was performed using table 1, which presents the test results of the asphalt concrete material of the composite "bitumen-fiber", carried out at temperatures of 0 ° C, 25 ° C and 50 ° C.

Studies conducted by the Applicant to select the optimal amounts of bitumen included in the binder and compared with existing binder compositions have shown the advantages of the inventive binder in anhydrous asphalt mix. Any of the obtained pairs of bitumen 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 with different penetration optimally solve the problem of wetting and formation of bitumen film on surfaces of mineral elements and fibers in the volume of fiber-containing asphalt mix. The problem of the formation of lumps in the mixture is also eliminated, which was a persistent defect when using ordinary fibromaterials unprepared by special treatment, for example, without fluffing the fibers.

The choice of composite reinforcing material in the claimed invention is made from technical and chemical considerations along the way to find the optimal types of fiber - basalt and PAN fiber. Basalt fiber is resistant to chemical components, namely alkali and resistant to low temperatures. Chopped basalt fiber withstands temperature extremes from -260 ° C to 600 ° C and does not absorb water. And the properties of PAN fibers are characterized by a high modulus of elasticity, high adhesion, resistance to alkali and high heat resistance. Together they complement the indispensable properties of each other, which are best manifested in one in some seasonal periods, and in the second - in others.

One of the key roles in ensuring the strength of fiber-reinforced asphalt concrete is played by the adhesive strength of the fiber-bitumen joint in the composite material model. In the course of the Applicant's study of the value of the fracture strength of asphalt concrete samples, the amount of necessary force was determined to pull the fiber out of the cured matrix at a constant embedment depth. The test results of the composite "bitumen - fiber", conducted at temperatures of 0 ° C, 25 ° C and 50 ° C are presented in table 1.

Table 1 - Dependence of the force F on the test temperature

Fiber Temperature ° C F, N Note PAN thread fifty 0.5 - 1 The thread is covered with bitumen. 25 25 - 35 The thread is covered with bitumen. 0 130 - 145 The thread has broken Basalt thread fifty 0.5 - 1 The thread is covered with bitumen. 25 18 - 25 The thread is covered with bitumen. 0 270 - 330 The thread has broken

Based on the analysis of the data obtained, we can conclude that the interaction at the “bitumen-fiber” interface in the selected temperature range has different mechanisms, which is associated with a change in the viscosity of bitumen and its surface energy. At a temperature of + 50 ° С, PAN fiber and basalt fiber, as reinforcing elements, behave identically. Therefore, hardening of asphalt concrete substantially depends on the quality of bitumen - softening temperature - the higher the softening temperature of bitumen, the more effective is fiber reinforcement. At a test temperature of + 25 ° C, the cohesion and adhesion forces of bitumen with fibers begin to compete, while the forces of drawing fibers from the matrix increase, which indicates the possibility of real hardening of asphalt concrete with fibers. It turns out that in this role, PAN fibers are preferable to basalt fibers, since they are better wetted by bitumen and, accordingly, form a better adhesive contact. At zero temperature and below, cohesion of bitumen and interfacial interaction between bitumen and fiber significantly increase. In this case, the decisive role is played by the strength of the fibers. As can be seen from table 1, in this temperature range, reinforcement with basalt fibers is preferable, since their strength characteristics are much higher than that of PAN fibers.

During the tests of the claimed technical result, the composition of the asphalt 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” that 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 22245-90;

- basalt fiber manufactured by Izhbazalt LLC with a density of 54-240 tex and a cut length of 12-18 mm, having an average chemical composition (% by weight): SiO ₂ (47.5-55.0); TiO ₂ (1.36-2.0); Al ₂ O ₃ (14.0-20.0); Fe ₂ O ₃ + FeO (5.38-13.5); MnO (0.25-0.5); MgO (3.0-8.5); CaO (7-11.0); Na2O (2.7-7.5); K ₂ O (2.5-7.5); P ₂ O ₅ (not more than 0.5); SO ₃ (not more than 0.5); other breeds (no more than 5).

- 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 included:

crushed stone - 45.3%;

sand - 45%;

mineral powder - 4.5%;

 viscous bitumen BND 60/90 - 4.32%;

viscous bitumen BND 130/200 - 0.48%;

PAN fiber - 0.28%;

basalt fiber - 0.12%.

 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 (6)

The composition of the fiber-containing composite material for the manufacture of asphalt concrete pavement, characterized in that it includes crushed stone, sand, mineral powder heated to a temperature of 140-180 ° C, an organic binder with a temperature of 110-160 ° C and reinforcing material,%: crushed stone 20-60 mineral powder 4-12 organic binder 4-12 reinforcing material consisting of: basalt fiber with a density of 54-240 tex with a cut length of 12-18 mm and polyacrylonitrile fiber density 0.17-0.77 tex with a cut length of 6-18 mm 0.07-0.6 sand rest, while an organic binder is a compound of two types of viscous oil road bitumen, 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, and basalt fiber and polyacrylonitrile fiber in the following ratio of the total amount of reinforcing material in the mixture,%: polyacrylonitrile fiber 60-95 basalt fiber 5-40