The device of crushed stone pavement (base) of highways by the method of impregnation with bitumen. What is black gravel? Bitumen pouring of crushed stone base

Impregnation is a technological process for the construction or restoration of an improved lightweight type pavement by successive layer-by-layer scattering and compaction of stone materials (crushed stone, gravel of various sizes) with the base layer being cleaved and impregnated with organic binders. Depending on the thickness of the structural layer, impregnation is carried out to a depth of 4-10 cm. Impregnation to a depth of 4-7 cm is often called semi-impregnation.

Coatings according to the method of impregnation are mainly made of crushed stone of igneous rocks of a grade of at least 800 or sedimentary and metamorphic grades of at least 600. For bases, crushed stone of a grade of at least 600 is used. breeds for construction works. Specifications".

For impregnation, crushed stone is used, divided into fractions, for example, 40-70, 20-40, 10-20 (or 15-20), 5-10 (or 3-10) mm in size. If the impregnation depth is less than 8 cm, the first fraction (40-70 mm) is not used. The last, smallest fraction, intended for the protective layer, is not used in the construction of foundations.

The volume of crushed stone of the main (first) fraction with a size of 40-70 mm or 20-40 mm should be determined taking into account a coefficient of 0.9 to the design thickness of the structural layer and an increase in this volume by 1.25 times for compaction. The volume of each subsequent crushed stone fraction is taken equal to 0.9-1.2 m 3 per 100 m 2 of the base or coating.

Viscous organic binders with needle penetration depth from 90 to 200×0.1 mm or bituminous emulsions of EBK-2, EBK-3 and EBA-2 classes are used as binders for impregnation.

The binders used for impregnation must withstand the film water resistance tests according to amendment No. 2 to GOST 12801-98. If necessary, to improve the adhesion of bitumen to the surface of crushed stone, appropriate surfactants are introduced into the bitumen.

The consumption of viscous binder and emulsion in terms of bitumen is assumed to be 1.0-1.1 l/m 2 per centimeter of layer thickness. When using an emulsion, the concentration of bitumen in it is 50-55% when limestone crushed stone is used and 55-60% when granite crushed stone is used.

Coatings and bases according to the method of impregnation suit mainly in warm time year in the absence of rain and the air temperature in spring and summer is not less than 5°C, in autumn it is not lower than 10°C. The sequence of work during the installation of crushed stone coatings and bases according to the method of impregnation (semi-impregnation) is given in Table. 1 and 2.

Table 1

The sequence of work in the construction of coatings and bases with a thickness of 8-10 cm

table 2

The sequence of work in the construction of coatings and bases with a thickness of 5-7 cm

The crushed stone is distributed by a mechanical distributor, the binder is poured by asphalt distributors. In exceptional cases, a motor grader can be used to distribute the main fraction of crushed stone.

The length of the simultaneously processed area (the length of the grip) is assigned such that within one day the entire cycle of work is completed, or at least the first wedging fraction of crushed stone is distributed and compacted.

The main fraction of crushed stone is evenly distributed over the entire width of the carriageway, observing the required evenness and transverse profile. AT individual cases, for example, if it is impossible to provide a bypass for a section under construction, it is allowed to cover alternately on halves of the carriageway.

The distributed crushed stone is first compacted with light rollers (5-6 tons) in 2-3 passes along one track, starting from the edge of the carriageway. Then compaction is continued with heavy rollers (10-12 tons). Crushed stone of low strength (grade 600) is compacted only with light rollers weighing up to 6 tons in order to avoid crushing. When compacting, make sure that crushed stone does not crush.

The number of passes of the roller along one track is set by a trial compaction. During compaction, the surface density and cross profile are constantly monitored using a cross rail and templates. All irregularities must be eliminated in the very initial stage of compaction. Crushed stone, as a rule, is compacted without watering. When the air temperature is above 20 ° C, it is advisable to water crushed stone of low strength at a rate of 8-10 liters of water per 1 m 2 of surface. After compaction of the main fraction, a binder is poured, while the emulsion can be poured over wet rubble, and bitumen - only after it has dried.

The temperature of the binder with a needle penetration depth of 130 to 200×0.1 mm should be 110-130°C; a binder with a needle penetration depth of 90 to 130×0.1 mm should be heated to 130-150°C. Emulsions, as a rule, are used without heating, however, at air temperatures below 10°C, they should be used in a warm form (with a temperature of 40-50°C).

The binder can be poured over the entire width of the carriageway or one half of it, which must be poured evenly, without gaps.

Before the spilled hot binder cools down, the next fraction of crushed stone is scattered with a mechanical distributor to fill the pores between the crushed stones of the main fraction, without forming an independent layer. Mechanical distributors move over crushed stone.

After distribution, the crushed stone is compacted with rollers in 5-7 passes along one track using one wedging fraction and in 3-4 passes with two wedging fractions. Crushed stone of strong rocks is compacted with heavy rollers, and low-strength rocks are first light and then heavy.

Having sealed the wedging fraction, a closing mat is arranged on the coating. To do this, the binder is poured and, before it cools, crushed stone 5 (3) -10 or 5 (3) -15 mm in size is distributed and compacted with 3-4 passes of a skating rink weighing 6-8 tons. In the process of compacting the last fraction of crushed stone, it continues to be scattered with hard brooms, filling in the remaining pores. The surface of the coating after the distribution and compaction of the last fraction of crushed stone must be dense.

When using bituminous emulsions as a binder, arrange protective layer on the coating of the last smallest fraction of crushed stone, as well as arrange a coating layer on the prepared base after 3-5 days to ensure the evaporation of water from the underlying layers.

While distributing and compacting proppant and closing fractions, they continue to control the evenness and transverse profile of the surface, while eliminating deviations from established requirements. Evenness is estimated by the size of the gaps under the three-meter rail. The gaps under the rail should be no more than 10 mm.

During binder pouring, the asphalt distributor must move at a constant speed. When pouring the binder alternately on one and the other half of the carriageway, it is necessary to ensure the correct pairing of both halves. To do this, a strip of spilled binder at the inner edge 10-15 cm wide is not covered with crushed stone. When pouring the binder, crushed stone is scattered on the second half, capturing the remaining uncovered strip on the first half.

To avoid the appearance of unevenness due to excess binder, the transverse joints of adjacent sections should not overlap when pouring the binder. To do this, the end of the finished mating section for 2-3 m is covered with paper, roofing paper. The asphalt distributor must reach the set speed before approaching the closed end finished plot. During the passage of the asphalt distributor through a closed place, the nozzles of the distribution pipe are opened. The binder consumption is regulated in advance.

During the construction of coatings and bases, the impregnation method controls the quality of crushed stone and binders, their consumption rates, the temperature of binders, and the quality of compaction. The degree of compaction of the layers arranged by the impregnation method is checked by a test run of a skating rink weighing 10-13 tons; in this case, there should be no movement of crushed stone or the formation of waves in front of the roller of the rink.

After completion of work on the installation of coatings by the method of impregnation (semi-impregnation), within 20-25 days, it is necessary to regulate the movement, ensuring uniform formation and compaction of the coating over the entire width; if necessary, compact the coating with rollers to create flat surface; sweep with a broom rubble scattered by passing cars; sprinkle with fine gravel areas where there is an excess of binder.

During the formation of the coating, peeling of the coating, local loosening, delayed formation, potholes may occur; such defects must be corrected. Small potholes that appeared during the formation of the coating are cleaned of dust and dirt, watered with bitumen or emulsion (0.8-1.2 l / m 2), sprinkled with fine gravel in the amount necessary to fill the potholes, and compacted.

bituminous emulsion. Processing, impregnation, primer. Price 11 rubles. m2. (EBA-2). Reinforcement of pavement layers. Modern eco-friendly material for road works.

EBA-2 is an indispensable, modern and environmentally friendly material for road construction and patching. The most common application of bituminous emulsion is foundation waterproofing, asphalt treatment, processing. Bituminous road emulsion is a low-viscosity liquid Brown. Everyone knows that the pavement gains its final strength as the mixture cools. As an alternative solution, the bitumen is diluted with petroleum solvents (kerosene) until it becomes liquid, and the final strength of the material is only achieved when the solvent evaporates. In this case, bitumen emulsion provides an alternative approach in which the bitumen is liquefied by dispersion in water.
Bituminous emulsions can be used with wet and cold stone materials, and due to this, the final “hardening” process takes place. road material when the emulsion breaks down - returns to the continuous bituminous phase - the water disappears. In other words, bituminous emulsion used as a binder that provides comfortable conditions for the treatment of road surfaces. It is used for different types coatings: asphalt, crushed stone and concrete. Bitumen emulsion is divided into two types: anionic (EBA) and cationic (EBK). The main difference between the above types of emulsions lies in the interaction with the processed materials.

The most popular use of bitumen, in which crushed stone is impregnated with a binder, is the installation of asphalt pavement. Another application of this technology is the foundation waterproofing device.

There are two main types of bitumen: natural and artificially created oil.

If necessary additional protection foundation, you can use materials such as bitumen and crushed stone. Consistency (a product of oil refining) is different, liquid and solid. Other nuances of its application and required flow on the impregnation of crushed stone, we will consider further.

Types and features

Table of physical and mechanical properties of bitumen.

Before highlighting the question of what consumption is necessary for the impregnation of crushed stone, let's find out what bitumen is. This product is a substance of solid or resinous consistency.

It consists of various complex mixtures of hydrocarbons and its derivatives. Most often, this is a combination of a hydrocarbon with sulfur, nitrogen and oxygen. It is impossible to identify all its components.

• This name in Latin means "mountain resin".

Bitumens are characterized by an amorphous structure; they do not have a certain degree of melting.

• Resistance to acid, alkaline, saline solutions of an aqueous nature has been proven more than once. But organic solvents, such as gasoline, turpentine, acetone and others, perform their function quite well when exposed to bitumen;
• Another property is such an indicator as hydrophobicity. In other words, they are not exposed to water, do not let it through, as they have a dense structure and zero porosity.

Scheme for the preparation of bitumen emulsions.

It is in connection with these qualities that they remain impervious to water and resistant to low temperatures. Due to these properties, bitumen is a fairly popular material in construction (roofing, waterproofing) and paving (for crushed stone). Using this impregnation, you will provide reliable waterproofing foundation.

There are two main types depending on their origin:

• natural character;
• artificially created oil.

Natural bitumen is found in fossil fuels. Their extraction is carried out most often by a quarry method (or mine), a further process of extracting bitumen from rock carried out using an organic solvent or by boiling.

An artificial analogue (technical) is produced from the remains of oil refining products, the coal industry and shale, which have similar compositions to bitumen of natural origin.

The purpose is divided for construction, roofing and road purposes.

Characteristics

Characteristic table

All types have a special marking, which has the following decoding:

• For example, BNK - oil roofing. The first number in the marking indicates the temperature regime at which bitumen softens, the second - penetration. This is the depth to which bitumen penetrates with a special needle, when temperature regime at 25 degrees and a degree of load of 100 g (indicated in tenths of a millimeter);
• Such a type as construction is a combustible substance, in which the flash point is from 220 to 240 degrees, and the autoignition temperature is 368 degrees. Such bitumen is produced in the process of oxidation of oil distillation products (as well as its mixtures);
• The use of construction bitumen (BN50/50; BN70/30, BN90/10) is especially in demand in construction waterproofing works;
• Bitumen for roofing has a flash point of at least 240 degrees, and a self-ignition temperature of 300 degrees. Produced by the same method as the construction. Its application, in accordance with the name, is various roofing materials: glassine, ruberoid and others.

There is also such a view as a modified one. It differs from the usual improved, due to the addition of specialized additives (polymers), qualities.

Now let's look at such an indicator as consumption.

Table for assessing the adhesion of crushed stone and bitumen.

Bitumen consumption will also depend on the purpose for which bitumen is used. For example, when waterproofing with bitumen, it needs to be heated to a liquid consistency. The recommended application layer is from 1.5 to 2.5 millimeters, while the consumption will be from 1 to 1.5 kg per square meter.

• When making a road surface using bitumen, its bottling (BND90/130) is carried out at a heating temperature of about 150 degrees, using an asphalt distributor over the entire width of the existing coating.

The surface of the layer is pre-cleaned from dirt and dust. The consumption of the substance corresponds to the following ratio, from 1 to 1.1 l/sq.m. per cm of impregnating layer thickness; consumption, from 1.5 to 2 l / sq.m for the coating device.

• To reduce consumption, use asphalt concrete pavements containing activated powder. In this case, bitumen consumption is reduced by about 25%.

In addition to saving the bitumen component, there is a significant decrease in such quality as plasticity, and this circumstance directly contributes to an increase in the degree of stability of the resulting coating to deformation changes in the form of shear.

Scheme of the device of asphalt concrete pavements.

Any asphalt coating is made using a hot bituminous mixture, crushed stone (gravel), sand and mineral powder. The technological order of operations includes the following steps:

• applying a primer mixture, the layer of which is 1 mm on the concrete surface;
• laying an asphalt concrete mixture (it can be rigid or cast) and its subsequent compaction.

Asphalt concrete pavement requires a hard mix and subsequent compaction with a mechanical roller. Seal manually poured asphalt concrete is allowed only when the amount of work to be done is not very large or hard-to-reach places for a mechanical roller are subject to compaction.

clutch table road bitumen with gravel surface.

Asphalt concrete, or rather its cast mixtures, are laid during the coating with strips no more than two meters wide, limited by slats that act as beacons when performing asphalt work, which will allow not to exceed the material consumption.

• It is necessary to align mixtures using a rule. You need to move it along the beacons (rails), applying further compaction with a roller equipped with electric heater and weighing 70 kg;
• The end of tamping of cast asphalt concrete is expedient in case of elimination of its mobility under the influence of a roller;
• Each compacted layer, or rather its maximum thickness, cannot be more than 25 mm. Sometimes in hard-to-reach places rollers are used to compact the mixture;
• If there was a break in the work on the asphalt pavement, then the edge of the previously compacted area is heated. The seams must be carefully tamped until they become invisible. Areas with marriage (cracks, shells) are subject to cutting and smearing with a hot mixture.

As for the cases when crushed stone is used for the coating device, then it is necessary to use parts of natural origin that are identical in strength.

Crushed stone, or rather its size, should correspond to a value from 25 to 75 millimeters. The main thing is not to exceed 0.7% of the thickness of the covering layer. On the initial stage crushed stone (its layer) is processed using a wedge with a size of 15 to 25 millimeters, or pebbles no more than 15 mm.

• Crushed stone is laid in layers from 80 to 200 mm. Do not forget that each of its layers must be trimmed, and then rammed with a roller. When performing tamping operations, crushed stone must be treated with water. After the mobility of the crushed stone has completely disappeared, and the traces of the roller have become invisible, compaction can be completed.

As noted above, crushed stone, or rather its layer, is covered with wedges, then with small pebbles, as well as sand no larger than 5 millimeters. After applying the above materials, the surface is moistened with water and rammed with a 12-tonne roller. Please note that if no marks remain after passing through the roller, compaction can be completed.

In a similar way, a coating of crushed stone impregnated in the form of bitumen is performed. Before impregnation, the gravel must be dry. If it is wet, it must be dried. In this case, the material consumption does not change, but this is how it should be according to technology.

Most often, the bitumen grade BN11 is used for impregnation. Impregnation is carried out by pouring hot bitumen in a uniform layer on crushed stone three times (over the entire area).

• Bitumen during the spill should have a temperature of 150 to 170 degrees. After spilling for the first time, it is necessary to immediately carry out the sprinkling with a wedge. After the second and third layers of bitumen, small stones are scattered in compliance with the ratio of 1 cubic meter per 100 square meters of surface. Do not forget about the even distribution of the stone between the pieces of rubble;
• The coating made in this way (with impregnation) has good strength, roughness and easily withstands traffic with an intensity of about 1000 cars per day.

As a disadvantage, one can note the high consumption of the bitumen component and the not always uniform distribution of the binder between the parts of the crushed stone. If you use bitumen in in large numbers, then the appearance of shifts and undulating bulges is possible.

And an insufficient amount affects the quality of cohesion of crushed stone and, as a result, contributes to the rapid destruction of the road surface. Therefore, it is advisable to comply with the consumption recommended by experts.

Standard Requirements

Table of requirements for crushed stone and bitumen.

As already known, for the arrangement of the road surface, such a component as crushed stone is used. It is obtained by crushing rock. Depending on the method of construction and the type of road surface, choose one or the other.

I would like to note that when making a road surface using impregnation, lamellar grains can be contained in crushed stone, not exceeding a value of 35%.

With regard to binders, the following options can be used for paving:

• viscous road oil in accordance with GOST 22245-76;
• liquid road oil bitumen with slow and average speed thickening (GOST 11955-74);
• road coal tar, corresponding to GOST 4641-74;
• other organic binders.

The choice of brand and type is directly dependent on what kind of coating is supposed to be done, the purpose of the layer, the method of performing work and other important factors.

crushed stone impregnation

If you are planning to build a house with basement and ground floor, then you can not do without a waterproofing device. This is very milestone in construction.

If you take care of the device high-quality waterproofing, then in the future avoid problems with high level ground water and inadequate foundation strength.

Therefore, take our advice and take care of the installation of a waterproofing layer at the stage of foundation construction. In any case, this will only increase the life of your building and get rid of dampness in the premises of the house.

About what consumption is most appropriate, it was said above. Next, you can get acquainted with the technological procedure for carrying out waterproofing work.

• Additional protection of the foundation is carried out using bitumen. They carry out the pouring of crushed stone intended for the foundation layer. First, you need to fill the crushed stone into the prepared pit of the future basement;
• Experts recommend using larger gravel. The filling of the remaining empty spaces is carried out by adding smaller parts of rubble;
• A mandatory action when building a foundation is to compact the rubble, as a result, its height should be about 40 millimeters. Now pouring is possible.

The layer is poured with hot bitumen, as a result of which an even more reliable seal is obtained. All voids not filled with small stones must be filled with an astringent.

This spill will provide reliable protection from moisture. After the impregnation of crushed stone is completed, it is necessary to fill it with a concrete mixture.