RU2603310C1 - Road pavement - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction and can be used in pavement of automobile roads. Pavement includes a base - underlayer, layer of compacted sand, compacted crushed stone and a layer of hot coarse porous asphalt concrete, on which there is a coating of macadam-mastic asphalt concrete. Coating material used is macadam-mastic asphalt concrete with addition of fine grinding screenings of expanded clay with thickness of 40 mm.

EFFECT: reduced thickness of layers of road pavement, high strength, shear resistance, crack resistance and reduced flow of macadam-mastic mixture.

1 cl, 2 tbl, 1 dwg

Description

The invention relates to the field of construction and can be used in the device of coatings for pavements of roads, parking lots, airfields, bridge crossings, sidewalks.

A known construction of pavement, including: a base made of crushed stone and highly porous asphalt concrete, and a two-layer asphalt concrete pavement with a thickness of the lower layer of 50 mm and an upper layer of 40 mm (Road asphalt concrete / LB Gezentsvey, N.V. Gorelyshev, AM Boguslavsky, I.V. Korolev under the editorship of L.B.Gezentsvei. - 2nd ed., Revised and additional - M: Transport, 1985. - S. 292).

The disadvantage of this design is the significant thickness of the coating layers.

The standard construction of pavement using crushed stone-mastic asphalt concrete (ASHMA) is known, including a coating of a layer of ASHMA (50-60 mm), a base of porous asphalt concrete, compacted crushed stone, sand and the underlying layer (GOST 31015-2002. - M .: 2002 . - 22 p.). The disadvantages of the coating material are low shear resistance and crack resistance, a significant thickness of the coating layer, increased runoff of bitumen from the SchMA mixture.

As a prototype, a pavement construction was adopted, consisting of a coating — a 50 mm thick layer of ACA, a base — porous coarse-grained asphalt concrete (70 mm), a layer of compacted crushed stone (300 mm), fine sand (360 mm), and the underlying layer. In the coating, alkali-alkali metal oxide of the following composition is used, wt. %: road petroleum bitumen - 6.0; crushed stone of the fraction 5.0-20.0 mm - 77; sand from screenings of crushing crushed stone 0.16-5.0 - 11.6; limestone mineral powder - 10.8 stabilizing additive - 0.4; a mixture of crystalline salts - 0.6 (Vejukov E.V., Salikhov M.G. Technologies for the production and use of anti-icing gravel-mastic asphalt concrete for pavement of timber roads. // Basic research. - 2012. - No. 11. - P. 917- 921). The disadvantages of this design are the insufficiently high strength, increased cost in comparison with standard SchMA.

The technical result of the invention is to reduce the thickness of the structural layers of pavement, increase strength, shear resistance, fracture toughness, reduce the stackability of the SchMA mixture and the cost of the road surface.

The specified technical result is achieved by the fact that, as the structural layer of the coating, gravel-mastic asphalt concrete mixture modified by highly dispersed screenings of expanded clay crushing, which includes, by weight, is used. %:

- aggregate: crushed stone fractions of 5.0-20.0 mm - 61.0-61.5;

- sand from screenings of crushing crushed stone 0.16-5.0 mm - 15.0-15.5;

- filler: limestone mineral powder - 14.5-16.0;

- fine screenings of crushed claydite crushing - 1.9-2.4;

- road oil bitumen - 6.1.

The design of the pavement is shown in FIG. 1. Pavement consists of an asphalt concrete pavement, base and underlay. The coating consists of a layer of the proposed SchMA (1) - 40 mm; the base includes a layer of hot coarse-grained porous asphalt concrete (2) - 70 mm, a layer of compacted crushed stone (3) - 300 mm, compacted sand (4) - 360 mm; underlying layer (5).

New is that finely dispersed claydite crushing screenings are used as a stabilizing additive in the SMA layer, which can significantly reduce bitumen runoff from the mixture, increase strength characteristics, shear resistance, crack resistance of the road surface and reduce the coating thickness. The use of finely dispersed screenings of expanded clay crushing in the mixture allows to reduce the cost of alkali metal oxide and, therefore, the entire structure as a whole.

Example. The compositions of macadam mastic asphalt concrete mixtures (SCMAS) were prepared (Table 1). SCHMAS was prepared as follows: bitumen and mineral aggregate were heated to a temperature of 170 ± 2 ° C, then mineral powder and a stabilizing additive (highly dispersed screenings of expanded clay crushing) were added; then all the components were mixed in a laboratory mixer until a homogeneous mass was obtained. The alkaline-alkali metal mixture was compacted at a pressure of 40 MPa for 3 minutes in cylindrical metal forms (the dimensions of the sample cylinders were 71.4 × 71.4 mm). The determination of physical and mechanical properties and shear stability was carried out according to GOST 12801-98. The test results of alkaline microorganisms are presented in table. 2.

According to the table. 1 and 2, the content of bitumen is taken in the range of 6.0-6.3 wt. % When the content of bitumen in the mixture is more than 6.1 wt. %, for example, 6.2-6.3 wt. % (compositions 3, 4) strength indicators, shear resistance are reduced (table. 2). When the content of bitumen in the mixture is less than 6.1 wt. %, for example, 6.0 wt. % (composition 1), strength indicators are reduced.

The content of screenings crushed expanded clay was accepted as optimal, within 2.4 wt. % With an increase in the content of screenings for crushing expanded clay, bitumen intensity increases, as well as the rigidity of the mixture. With a decrease in the content of screenings for crushing expanded clay in the compositions of alkali, for example, 1.9 wt. % (composition 5), the stackability of bitumen in the mixture increases.

From a comparison of the quality of the proposed compositions (compositions 2.5-9) with the prototype (composition 10) (Table 2), increased strength, heat resistance, fracture toughness, and shear resistance of the proposed MMA were revealed. The binder runoff rate (composition 9) is quite high and is not inferior to the prototype.

The process of laying and compacting pavement does not differ from the device of coatings from traditional crushed stone-mastic asphalt concrete.

Claims (1)

Road clothing, including the base - the underlying layer, a layer of compacted sand, compacted crushed stone and a layer of hot coarse-grained porous asphalt concrete, on which a coating of crushed stone-mastic asphalt concrete is placed, characterized in that crushed stone-mastic asphalt concrete with the addition of finely divided screenings is used as the coating material expanded clay with a thickness of 40 mm in the following ratio of components, wt.%:
crushed stone fractions of 5.0-20.0 mm 61.0-61.5 sand from crushing screenings 0.16-5.0 mm 15.0-15.5 limestone mineral powder 14.5-16.0 fine screenings of expanded clay crushing 1.9-2.4 road oil bitumen 6.1

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