RU2713035C1 - Fiber-containing composite mixture for pavements - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: fiber-containing composite mixture for pavements, characterized by that it contains the following components at their ratio, %: crushed stone 20–60; mineral powder 4–12; water 3–12; organic binder 4–12; reinforcing material consisting of basalt fiber with density of 54–240 tex with cutting length of 12–18 mm and polyacrylonitrile fiber with density of 0.17–0.77 tex with cutting length of 6–18 mm 0.07–0.6; sand – balance, wherein the organic binder is a composite of two types of petroleum bitumens, in % of the total amount of the binder in the mixture: one of the viscous bitumen grades: BND 200/300, BND 130/200, BND 90/130, BND 60/90, BND 40/60 85–95, together with one of grades of liquid slowly bituminous bitumen: MG 40/70, MG 70/130 5–15, and basalt fiber and polyacrylonitrile fiber in following ratio of components of total amount of introduced reinforcing material in mixture, %: polyacrylonitrile fiber 60–95; basalt fiber 5–40.

EFFECT: fiber-containing composite mixture for pavements is proposed.

1 cl, 1 tbl

Description

 The invention relates to the field of road-building materials and can be used in the road-building industry to create modern asphalt pavements.

 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 water, laid at a temperature not lower than + 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 adverse seasonal months depending on the region of use. Cold mixtures have the advantage that they do not require special heating when laying asphalt, which reduces energy consumption in road construction. They can be stored in warehouses for a long period and transported over long distances without the risk of loss of quality or changes in consumer properties.

Important constituent parts of any asphalt mix are: the composition of the group of fillers, which usually contains crushed stone, sand, mineral powder (invention patents RU No. 2240333, RU No. 2232841, RU No. 2447035, RU No. 2535325, RU No. 2310621, CN No. 1908069, RU No. 2262491, copyright certificate SU No. 1778100) and the composition of the binder group.

Among the groups of binders in the compositions of materials for the manufacture of asphalt concrete coatings are known binders, represented by one type of bitumen, for example, a binder from the above-mentioned patent (RU No. 2232841) and others.

Among the groups of binders in the compositions of materials for the manufacture of asphalt concrete coatings, composite binders are of interest, which include liquid or viscous bitumen with various modifying additives:

RU patent No. 2535325 - with oil sludge;

RU patent No. 2601327 - with petrolatum;

SU patent No. 729158 - with an emulsifier in the form of a mixture of sodium salts and sodium hydroxide;

RU patent No. 2183600 - with cationic reagent "BIEM", hydrochloric acid, calcium chloride, RTEP rubber thermoplastic elastomer, fuse (phosphatide concentrate);

RU patent No. 2240333 - with amine type cationic emulsifier, polymer adhesive additive, hydrochloric acid;

RU patent No. 2243949 - with a BIEM cationic emulsifier, KADEM-VT surface-active additive, calcium chloride, hydrochloric acid, neonol (ethoxylated phenol alcohol).

Such additives are introduced into bitumen to adjust not only its properties, but also the future pavement, namely, expanding the temperature range of the pavement performance, reducing brittleness, and increasing cracking or rutting resistance.

The disadvantages of the above mixtures is the increasing number of components with the complex properties of some of them and, as a result, the added cost of the mixture.

The role of such a component for the proposed solution as water is not indifferent in the asphalt mix, since it affects the quality of wetting of the components and determines the nature of further structure formation processes in asphalt concrete. Therefore, the analogues used above are water-containing bitumen-mineral mixtures for road surfaces.

Of particular interest are water-containing asphalt concrete mixtures for coatings with fibrous fillers, which make it possible to obtain reinforced asphalt concrete with resistance to the formation of plastic deformations, as a result of which the durability of the road surfaces is increased. As reinforcing fibers, various types of natural, polymer or synthetic mineral fibers can be used, for example basalt fiber (patents RU No. 2530812, copyright certificate SU No. 1778100, RU No. 2447035, RU No. 2345966), polyacrylonitrile fiber (CN patents No. 101081725, CN No. 1908969, DE No. 3930599), wood fiber (RU patent No. 2262491) cellulose fiber (RU patent No. 2222559, RU No. 2500635), asbestos fiber (RU patent No. 2351561), polyamide fiber (RU patent No. 2272795) and others.

Known asphalt mixture (patent RU No. 2345967) containing crushed stone, bitumen 4.5 ÷ 7% by weight of crushed stone, hydrochloric 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 a fiber additive in an 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 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.

Also known is a 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.

The closest analogue of the claimed invention is asphalt concrete mixture (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, 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 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.

However, weak adhesive interaction, as it turned out, at the interface between fiber and bitumen due to the lack of chemical bonds of the binder with the filler, leads to some decrease in the strength characteristics of the asphalt mix.

The objective of the invention is to obtain a cold water-containing mixture to create an asphalt concrete pavement with variable properties depending on seasonality and other operating conditions, which make the asphalt concrete resistant to the influence of climatic factors.

The essence of the claimed invention is characterized in that the fiber-containing composite mixture for road surfaces includes the following components in their ratio,%:

crushed stone 20-60 mineral powder 4-12 water 3-12 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 with a density of 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 oil

bitumen road, in% of the total amount of binder in the mixture:

one of the brands of viscous bitumen: BND 200/300, BND 130/200,
BND 90/130, BND 60/90, BND 40/60 together with 85-95 one of the brands of liquid slow-thickening bitumen:
MG 40/70, MG 70/130 5-15,

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

polyacrylonitrile fiber 60-95 basalt fiber 5-40

The technical result.

Distinctive features of the proposed mixture with this composition is the use of a binder in the form of a pair of oil road bitumen: one of the grades of viscous bitumen: BND 200/300, BND 130/200, BND 90/130, BND 60/90, BND 40/60 with one of grades of liquid slowly thickening bitumen: MG 40/70, MG 70/130, in combination with the use of water and reinforcing material, represented by basalt fiber with a density of 54-240 tex and a cut length of 12-18 mm and PAN fiber with a density of 0.17- 0.77 tex with a cut length of 6-18 mm. The combination of any of the bitumen pairs identified and compiled by the Applicant presented above with water and a pair of basalt and PAN fibers of the aforementioned types of density and cutting simultaneously in one mixture is not known. The set of components of the inventive water-containing asphalt mixture, among those described in the literature and used in industry, in the claimed concentration ranges has not been previously described and has not been used.

It is these differences of the claimed mixture that provide a solution to the problem posed in the invention. In addition, increased economic efficiency.

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 on the selection of optimal quantities of bitumen included in the binder and in comparison with existing binder compositions have shown the advantages of the inventive binder in the patented water-containing asphalt mixture. Any of the obtained pairs of bitumen empirically selected by the Applicant, grades of viscous road bitumen: BND 200/300, BND 130/200, BND 90/130, BND 60/90, BND 40/60 with one of the grades of liquid slowly thickening bitumen: MG 40 / 70, MG 70/130, as it turned out, optimally solve the problem of wetting and the formation of a bitumen film on the surface 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 in the claimed invention is made from technical and chemical considerations along the way of finding 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, ⁰ С F, N Note PAN thread fifty 0.4 - 1.5 The thread is covered with bitumen. 25 27 - 33 The thread is covered with bitumen. 0 125 - 141 The thread has broken Basalt thread fifty 0.5 - 1.1 The thread is covered with bitumen. 25 18 - 23 The thread is covered with bitumen. 0 265 - 332 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 - 55%

 mineral powder - 4%

 water - 5%

 viscous bitumen BND 60/90 - 6%

 liquid bitumen MG 40/70 - 1%

 sand - 28.4%

 basalt fiber - 0.18%

 PAN fiber - 0.42%

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)

Fiber-containing composite mixture for road surfaces, characterized in that it includes the following components in their ratio,%: crushed stone 20-60 mineral powder 4-12 water 3-12 organic binder 4-12 reinforcing material consisting basalt fiber density 54-240 tex with a cut length of 12-18 mm and polyacrylonitrile fiber density 0.17-0.77 tex with a length cuts 6-18 mm 0.07-0.6 sand rest, while organic binder is a compound of two types of road oil bitumen, in% of the total amount of binder in the mixture: one of the brands of viscous bitumen: BND 200/300, BND 130/200, BND 90/130, BND 60/90, BND 40/60 85-95 in conjunction with one of grades of liquid slow-thickening bitumen: MG 40/70, MG 70/130 5-15, and basalt fiber and polyacrylonitrile fiber in the following ratio of components of the total amount of reinforcing material introduced in the mixture,%: polyacrylonitrile fiber 60-95 basalt fiber 5-40