RU2814397C1 - Asphalt concrete - Google Patents

Abstract

FIELD: construction; chemistry.

SUBSTANCE: invention relates to road construction materials, in particular to compositions of mixtures for making asphalt concrete, and can be used in construction of roads, bridges and airfields. Asphalt concrete contains components in the following ratio, wt.%: crushed stone of 11.2–16 mm fraction — 28–35 and 4–8 mm fraction — 28–35; sand from crushing screenings — 28–36; mineral powder — 3–7; bitumen — 5.3–5.8 (over 100 wt.% of mineral part); low-pressure polyethylene — 3–20 (over 100 wt.% of bitumen); motor oil 0.1–5% of the weight of low-pressure polyethylene.

EFFECT: wider range of road construction materials used for production of asphalt concrete with corresponding operational characteristics and physical and mechanical properties.

1 cl, 1 tbl

Description

The invention relates to road construction materials, in particular to hot fine-grained asphalt concrete mixtures, and can be used in the construction of highways, bridges, and airfields.

An asphalt concrete mixture is known, including a filler consisting of crushed stone (53-65%), sand from crushing screenings (18-28%) and activated mineral powder (17-23%), polymer-bitumen binder (PBB) (4.4- 5.7% over the mass of mineral components) and a stabilizing additive - asbestos mineral fibers (2-7%) (see Review information "Construction of road and airfield pavements from crushed stone-mastic asphalt concrete mixtures." - M.: Publishing House "Informavtodor", 2003. - p.2, 31-33, 39.

The disadvantage of the known asphalt concrete mixture is the unsatisfactory durability of the coating due to the fact that the PMB, which is part of the asphalt concrete mixture, has low resistance to delamination, as a result of which the adhesion of the PMB to the filler surface is unsatisfactory.

A hot asphalt concrete mixture is also known (RF patent 2196751), containing, wt.%: crushed stone fraction 5-20 mm - 32.6-40.8; sand - screening of fraction crushing up to 5 mm - 13.0-16.0; milled asphalt concrete fraction up to 15 mm - 26.0-28.0; oil solution of synthetic high molecular weight polybutadiene rubber - 0.2-0.4; asphalt binder - 20.0-23.0.

This mixture, in addition to the complexity of the preparation technology in production conditions, is characterized by the use of an expensive polymer component and an increased amount of asphalt binder, which compensates for the reduction in the cost of the mixture due to the use of milled asphalt concrete. However, the authors do not take into account the change in the particle size distribution of milled asphalt concrete after heating in an asphalt mixing plant, and due to the heterogeneity of its properties and type in industrial applications, difficulties will inevitably arise in maintaining a constant particle size distribution of asphalt concrete.

As a prototype, an asphalt concrete mixture containing crushed stone (30 - 60%), sand (10 - 30%), mineral powder (3 - 18%) and bitumen (4.0 - 9.0% over the mass of mineral components) was adopted, rationally selected in accordance with the requirements of the standard (GOST 9128-2013 “Mixtures of asphalt concrete, polymer-asphalt concrete, asphalt concrete, polymer-asphalt concrete for highways and airfields” MGS, Moscow, Standartinform, 2014).

The features of the prototype, which coincide with the essential features of the claimed invention, are crushed stone, sand from crushing screenings, mineral powder and bitumen.

The disadvantage of the prototype is the use of only natural raw materials, the cost of which increases every year, which generally increases the cost of road construction.

The problem to be solved by the claimed invention is the expansion of road building materials used for the production of asphalt concrete with performance characteristics and physical and mechanical properties corresponding to the standard for asphalt concrete, through the use of waste low-density polyethylene and motor oil.

The problem was solved due to the fact that the known asphalt concrete containing crushed stone, sand from crushing screenings, mineral powder and bitumen, according to the invention, additionally contains low-density polyethylene as a binder and structure-regulating material, crushed to a particle size from 0.5 to 45 mm (reinforcement of asphalt concrete is ensured), contaminated with motor oils, and it contains crushed stone of fractions 11.2-16 mm and 4 - 8 mm with the following ratio of ingredients, wt. %: crushed stone fraction 11.2-16 mm (28-35%) and fractions from 4 to 8 mm (28-35%); crushed sand (crushing screenings) fraction 0-4mm (28-36%); mineral powder (3-7%); bitumen 5.3-5.8% (over 100 wt.% of the mineral part), low-density polyethylene 3 - 20 (over 100 wt.% bitumen), motor oil 0.1 - 5% by weight of low-density polyethylene.

Distinctive features of the proposed invention from that claimed in the prototype are: the use of low-density polyethylene contaminated with motor oils, crushed to a particle size of 0.5 to 45 mm, as a binder and structure-regulating material; use of crushed stone of fractions 11.2-16 mm and 4 - 8 mm; other quantitative ratio of ingredients used, wt. %: crushed stone fraction 11.2-16 mm - 28-35 and fractions from 4 to 8 mm - 28-35; sand from crushing screenings - 28-36; mineral powder - 3-7; bitumen - 5.3-5.8 (over 100 wt.% of the mineral part); low-density polyethylene - 3 - 20 (over 100 wt.% bitumen); motor oil from 0.1 to 5% by weight of low-density polyethylene.

The use of crushed low-density polyethylene in the asphalt concrete mixture to a particle size of 0.5 to 45 mm in an amount of 3-20 in excess of 100 wt.% bitumen contaminated with motor oil residues (from 0.1 to 5% by weight of low-density polyethylene) ensures creation, in the structure of asphalt concrete, of a frame made of polyethylene particles, which makes it possible to more effectively distribute external forces from vehicle wheels to the underlying layers of road pavement.

Containing motor oil in an amount of more than 5% by weight of polyethylene is impractical, because this leads to liquefaction of bitumen and a change in its physical and mechanical properties.

Distinctive features, in combination with known ones, make it possible to reduce the cost of asphalt concrete, while ensuring compliance of asphalt concrete with the requirements of regulatory documents for operational characteristics and physical and mechanical properties. In addition, this will reduce the anthropogenic load on the environment, and the arsenal of road construction materials will also be expanded.

To prepare asphalt concrete, the following component composition is used:

1. Crushed stone, fraction 11.2-16 mm and 4 to 8 mm in accordance with GOST 32703-14 “Public automobile roads. Crushed stone and gravel from rocks. Technical requirements"

2. Sand from crushing screenings, fraction from 0 to 4 mm in accordance with GOST 32730-2014 “Public roads. Crushed sand. Technical requirements".

4. Low-density polyethylene 3 - 20%, individual particle size no more than 45 mm.

5. Motor oil (content from 0.1 to 5% by weight of low-density polyethylene).

6. Bitumen BND 70/100 (over 100% of the mineral part), in accordance with GOST 22245-90 “Petroleum road bitumens. Technical conditions".

7. Mineral powder GOST 32761-2014.

The use of polyethylene waste in the composition of asphalt concrete does not change the technological scheme of its production. The technological process for producing an asphalt concrete mixture with the addition of polyethylene waste is as follows:

Pre-crushed low-density polyethylene (consumer waste contaminated with motor oil) to a particle size of 0.5 to 45 mm is introduced into bitumen heated to a temperature of 165-175°C. After mixing and bringing the temperature of the mixture of bitumen and low-density polyethylene to the required temperature, depending on the type of asphalt concrete being produced, it is mixed with the mineral part of the asphalt concrete mixture. The technology allows the use of standard equipment used in mass-produced asphalt concrete plants.

The technical result is confirmed by tests for compliance with the requirements of GOST 9128-2013 “Asphalt concrete mixtures, polymer-asphalt concrete, asphalt concrete, polymer-asphalt concrete for highways and airfields. Technical conditions”, for which asphalt concrete mixtures were used with the following ratio of components, wt. %:

Mixture 1,%: crushed stone fraction 11.2-16 mm (28%) and fraction 4 to 8 mm (32%); crushed sand (crushing screenings) fraction 0-4mm (36%); mineral powder (4%); bitumen BND 70/100 (5.3% over 100 wt.% mineral part), low-density polyethylene (3% over 100 wt.% bitumen), motor oil (0.1% by weight of low-density polyethylene).

Mixture 2,%: crushed stone fraction 11.2-16 mm (35%) and fraction 4 to 8 mm (30%); crushed sand (crushing screenings) fraction 0-4mm (32%); mineral powder (3%); bitumen BND 70/100 (5.5% over 100 wt.% mineral part), low-density polyethylene (10% over 100 wt.% bitumen), motor oil (3% by weight of low-density polyethylene).

Mixture 3,%: crushed stone fraction 11.2-16 mm (35%) and fraction 4 to 8 mm (28%); crushed sand (crushing screenings) fraction 0-4mm (31%); mineral powder (6%); bitumen BND 70/100 (5.8% over 100 wt.% mineral part), low-density polyethylene (15% over 100 wt.% bitumen), motor oil (5% by weight of low-density polyethylene).

Mixture 4,%: crushed stone fraction 11.2-16 mm (30%) and fraction 4 to 8 mm (35%); crushed sand (crushing screenings) fraction 0-4mm (28%); mineral powder (7%); bitumen BND 70/100 (5.8% over 100 wt.% mineral part), low-density polyethylene (20% over 100 wt.% bitumen), motor oil (2% by weight of low-density polyethylene).

The physical and mechanical properties of the resulting asphalt concrete are presented in the table:

INDICATORS GOST 9128-2013 Mix 1 Mix 2 Mix 3 Mix 4 Porosity of the mineral part by volume, % 14.0 - 19.0 15.5 17.5 18.3 18.8 Residual porosity by volume, % 2.5 - 5.0 2.1 2.7 2.9 2.8 Water saturation, by volume, % 1.5 - 4.0 1.5 2.1 2.3 2.3 Ultimate compressive strength, MPa - at a temperature of 20 °C, > 2.5 3.98 4.48 4.55 4.40 - at a temperature of 50°C, > 1.0 1.97 2.26 2.36 2.33 - at a temperature of 0°C, < 11.0 10.53 9.46 9.25 8.80 Water resistance coefficient, Not less than 0.90 1.00 1.00 0.98 0.95 Water resistance coefficient for long-term water saturation, Not less than 0.85 0.96 0.93 0.93 0.91 Shear resistance according to:
- coefficient of internal friction, Not less than 0.87 0.96 0.93 0.91 0.89 - shear adhesion at a temperature of 50°C, MPa, Not less than 0.25 0.41 0.60 0.65 0.55 Crack resistance, when split at 0°C, MPa 2.5-6.0 3.55 3.33 3.10 2.90 Average density, g/cm3 - 2.57 2.50 2.44 2.38

Thus, a hot fine-grained asphalt concrete mixture was created with the addition of crushed HDPE containers containing motor oil residues, which has the required strength characteristics, which made it possible to expand the range of materials used in the road construction industry, reduce the cost of asphalt concrete, and also reduce the anthropogenic load on the environment .

Claims (1)

Asphalt concrete containing crushed stone, sand from crushing screenings, mineral powder and bitumen, characterized in that it additionally contains low-density polyethylene, crushed to a particle size of 0.5 to 45 mm, contaminated with motor oils, and it contains crushed stone of fractions 11.2-16 mm and 4-8 mm with the following ratio of ingredients, wt.%: crushed stone fraction 11.2-16 mm - 28-35, crushed stone fraction 4-8 mm - 28-35, sand from crushing screenings - 28-36, mineral powder - 3-7, bitumen - 5.3-5.8 over 100 wt.% of the mineral part, low-density polyethylene - 3-20 over 100 wt.% bitumen, motor oil - 0.1-5% by weight of low-density polyethylene .