Current repair of asphalt concrete pavement. On the issue of asphalt pavement repair

The current repair of the asphalt concrete road surface is designed to restore the damaged sections of the roadway. Work begins with a survey of the condition of the road and the identification of damaged sections. This is followed by spot or complete dismantling of the old pavement.

Dismantling is carried out using manual pneumatic and power tools (jackhammers, cutters), or specialized machines (excavators and seam cutters). The destroyed part of the coating is removed and the base is prepared for laying a layer of a new coating, cleaning it as much as possible from crumbs and dust.

patching

Distinguish between overhaul and patching of asphalt concrete pavements. The purpose of patching is to eliminate damage to the road surface that is small in area and thickness.

Repair work must be carried out in compliance with the requirements of laying technology, taking into account temperature and humidity. So, patching with cold and hot asphalt and asphalt concrete can be carried out under various weather conditions. Basically, asphalt is restored using the technology of patching asphalt roads by the method of reverse impregnation, in which, first, bitumen heated to 170 degrees is fed into the pit, then the pit is covered with crushed stone and tamping is performed. In case of severe damage, equipment for patching by the jet-injection method will eliminate defects with high quality.

TO damage pavement includes:

• potholes;
• cracks;
• chipped.

Crack repair

Sealing of cracks refers to the current repair of the road and is an important part of it. The elimination of cracks can significantly extend the life of the pavement and prevent its further destruction. The technology of work involves three stages:

1. crack cutting - a special cutting tool cuts out the collapsed edges of the crack (without water supply), the crack is slightly expanded and deepened;
2. blowing and drying - the resulting cut in the roadway is blown and dried to remove dust and moisture;
3. sealing - the cut is filled with hot mastic using special melting pots and a supply system.

As it hardens, the mixture adheres to the walls of the incision and forms a durable surface.

Asphalt paving

Forming the surface of the road from asphalt chips is a practical and inexpensive way. The crumb itself is obtained in the process of recycling old asphalt pavements, so it has good characteristics and at the same time is affordable. Asphalt crumb is used on unloaded roads (for example, in garage or country cooperatives) as a better alternative to a dirt road.

Laying is carried out by analogy with backfilling with gravel: the base is leveled, asphalt crumb is brought in and crumbles in an even layer. Then it is rammed with a roller, or rolled already in the process of operation by the wheels of machines.

Capital repairs of roads

The overhaul of a highway is a rather difficult and costly business. In the case of asphalt concrete pavements, this may include:

1. complete dismantling of the old coating;
2. replacement of worn out and destroyed elements of the drainage system;
3. strengthening works and restoration of the base of the roadway;
4. installation of a new continuous road surface.

Unlike routine repairs, major repairs to a well-done road are rarely needed. Of all the options for the current repair of roads, only the price of patching the road surface with poured asphalt is close to the cost of major repairs.

Installation of boards and curbs

Laying roads and sidewalks often requires the installation of curbs - boards and curbs. They serve as roadway dividers, separate platforms and lawns. Installation is carried out in several stages:

1. marking and breakdown of the site;
2. land management works - the device of troughs;
3. dumping the base from crushed stone according to the level;

Asphalt pothole repair is a type of current repair of asphalt concrete pavement. This method is associated with the reconstruction of sections of the roadway by replacing the pavement in these same sections.
This type of repair of asphalt concrete pavements, such as patching, allows you to eliminate various damage to the roadbed with an area of ​​​​up to 25 m², for example, potholes, single cracks, peeling of the site, waves on the road, asphalt subsidence and many others.
The technology of patching the pavement consists in rolling asphalt mixtures and involves following the following steps:

• determination of the boundaries on which the repair will be carried out;
• cutting out the coating in the required place of repair;
• complete removal of the coating material;
• application of asphalt mix;
• compaction of the coating and its alignment.

When choosing the boundaries of the patching of asphalt pavements, it should be taken into account that the destruction on the base of the pavement under the defect of the canvas covers much larger frames than the actual destroyed zone. In general, the geometric dimensions of the "patch" should be in accordance with the zone of the destroyed state. Not less than 15 centimeters, the contour of the "patch" should overlap the destruction zone, and preferably even 20-30 centimeters.
Often the width of the "patch" is equated to the width of the lane (with extensive cracks, wide potholes, breaks, as well as other damage that takes up most of the lane), with smaller damage, this zone may be smaller than the zone of the lane, but more than 100 mm.

Places for repair make any contour, but without sharp corners, most often they are rectangular in shape, which is more convenient for repairs. In order to cut the coating at the repair site, it is necessary to use a jackhammer or joint cutter. If you use a jackhammer when processing the outer boundaries of the “patch”, practice shows that later these very boundaries are chipped. This has a very bad effect on the service life of the repaired coating.

If a seam cutter is used, then a jackhammer is used to break the coating and remove it from the "patch". The coating material is removed manually. Asphalt mixture is laid in ready-made patches. The compaction of such a mixture is carried out by a vibrocompactor.

Capital repairs of roads

Capital repair of roads is a whole range of works to fully restore and improve the performance of the road surface, subgrade, structures on the road, replacing old worn-out structures or parts with stronger and more durable ones. If necessary, the geometric parameters of the road are increased, here it is necessary to take into account the intensity of traffic on the road and the axle loads of vehicles within the limits that correspond to certain categories established for repair cases. The width of the subgrade does not change throughout the entire route. Today, the roads are very loaded, and, no matter how they are treated, repairs are needed in a timely manner.

Our climate in its own way affects the condition of the road surface. Cracks that appear on the pavement are not at all an indicator of poor road construction work. To a large extent, the climate influences - snowy winters with thaws. That is, the destruction of roads is quite natural and inevitable.

The main objective of the road overhaul is to restore the transport and operational potential of the road to the level at which it will comply with the measures of safe traffic on it.
The criterion that it is already necessary to resort to a major overhaul of the road is the transport and operational condition of the poured asphalt, in which the strength parameter has dropped to the limit value.
Major repairs of the road, as in the case of construction, must be carried out on all sections of this road, all structures and elements along the entire length of the asphalted area.
Capital repairs, as well as road construction, are carried out in full accordance with specially developed and approved design estimates.

Asphalting roads and other communications has always been very important in our lives. But sooner or later you can observe such a phenomenon as the wear of the roadway. Cracks, chips, potholes, and even pits may appear in the road surface, that is, in some places of various sections of the road, asphalt repair is required.

The technology for the production of pavement repair was developed and mastered a long time ago, but even today you can encounter cases of unfair repair work. However, this no longer applies to the technology itself, it simply becomes necessary to require the heads of repair teams to comply with all established standards.

Yes, the destruction of asphalt is a fairly common phenomenon even in highly developed countries, and not only here.

This happens despite the characteristics of strength, water resistance, frost resistance and similar parameters.

There comes a time when you still need to resort to asphalt repair. Asphalt - the material, in principle, is not very durable, moreover, it is affected by many different factors, which will be discussed below.

Asphalt features

Asphalt is also called asphalt concrete.. In principle, asphalt concrete is similar to concrete - it also consists of sand, crushed stone and binders. But unlike concrete, where the binder component is cement, in asphalt this component is bitumen created by processing petroleum products.

Asphalt is a very durable material, but, however, over time, various kinds of cracks, pits, and potholes appear in it.

Asphalt wear occurs due to a number of factors, and not only because of the relatively high pressure of vehicles on the road surface:

• Weather and climatic conditions, of which frost is the most destructive;
• In addition, ultraviolet, which eventually destroys bitumen, and even oil from cars adversely affects the road surface.

In general, these phenomena need to be fought. eliminates problems with the road surface, although a set of preventive measures must be applied.

Asphalt pavements are resurfaced every few years, and the various pothole cracks are treated with a special water-resistant sealant.

These sealants are essential in order to deal with various chemical attacks. And if the asphalt is already starting to crumble, then it is necessary to change the coating in this place entirely. If the cracks are more than 20 mm, then a special repair compound with the addition of sand can be used to seal them, this is necessary to create a more rigid content. Allow all components to dry after application.

Both cracks and pits and potholes have different sizes, therefore, to eliminate them, it is necessary to use a variety of technologies.

If various types of sealants can be used in small cracks, then the so-called “cold asphalt” is used to eliminate holes and potholes with a diameter larger than ordinary damage. This material has its own article numbers and data, which indicate rather high properties of cold asphalt. is made directly from the container by pouring the material onto the repaired surface and in full compliance with the technological process.

Also, factors such as improper asphalt paving technology affect the wear of the road surface.

The nuances of laying asphalt

In our country, unfortunately, this is not uncommon. The quality is greatly affected by the fact that asphalt paving takes place in a humid environment, although any builder should be aware that the ingress of moisture into the consistency of the material is not only undesirable, but also harmful. This is especially unfavorable when the moisture that has got inside the canvas freezes and destroys the internal integrity of the road surface, significantly worsening its characteristics.

And of course, when working in wet conditions, it is very difficult to achieve adhesion of the base and the asphalt itself.

Phenomena such as subsidence of soil under the roadway are very common, leading to its deformation in some areas. Often, the loads on the roadway exceed the maximum allowable according to the calculations of the properties of the material used.

A gust under the groundwater bed has a very bad effect on the quality of the road surface. In such cases, asphalt repair is carried out more thoroughly, often with a complete replacement of not only the asphalt pavement, but the entire foundation of the road. Such repairs turn into major repairs, when it is necessary to use a large amount of equipment and building materials.

When to overhaul asphalt

So, major repairs are carried out when very serious solutions to the problems of the roadway are necessary. This repair includes two types of repair:

• First- this is when the topmost layer is removed - asphalt and lining. The damaged area is again covered with sand, filled with various solutions, and then everything is again laid with bitumen. A completely new asphalt surface is being laid on top;
• Second type of overhaul - this is when asphalt repair, in principle, does not make sense in case of large damage, and it remains only to prepare the laying of a new roadway, taking into account the need to comply with all required norms and rules.

But often it is not required, especially in cases where its construction was carried out in full compliance with all necessary standards. If the canvas is damaged, only current repairs are required, which only affect the condition of the asphalt. Asphalt maintenance is usually performed when it is necessary to correct minor flaws, patch up some small details, cover up cracks or eliminate relatively small potholes and holes.

13.4. Pothole repair of asphalt concrete and bituminous materials. The main methods of patching and technological operations

The task of patching is to restore the continuity, evenness, strength, adhesion and water resistance of the coating and ensure the standard service life of the repaired areas. When patching, various methods, materials, machines and equipment are used. The choice of one or another method depends on the size, depth and number of potholes and other defects in the coating, the type of coating and the materials of its layers, available resources, weather conditions, requirements for the duration of repair work, etc.

The traditional method involves trimming the edges of the pothole to give it a rectangular shape, cleaning it from asphalt concrete scrap and dirt, priming the bottom and edges of the pothole, filling it with repair material and compacting. To give the pothole a rectangular shape, small cold milling machines, circular saws, and punchers are used.

As a repair material, asphalt concrete mixtures that require compaction are mainly used, and from the means of mechanization, small-sized rollers and vibrorammers are used.

When working in conditions of increased moisture, potholes are dried before priming with compressed air (hot or cold), as well as using infrared burners. If the coating is repaired with small cards (up to 25 m 2), the entire area is heated; when repairing large maps - along the perimeter of the site.

After preparation, the pothole is filled with repair material, taking into account the margin for compaction. With a pothole depth of up to 5 cm, the mixture is laid in one layer, more than 5 cm - in two layers. Compaction is carried out from the edges to the middle of the repaired areas. When filling potholes deeper than 5 cm, a coarse-grained mixture is placed in the bottom layer and compacted. This method allows you to get a high quality repair, but requires a significant number of operations. It is used in the repair of all types of coatings made of asphalt concrete and bitumen-mineral materials.

Small potholes up to 1.5-2 cm deep on an area of ​​1-2 m 2 or more are repaired by the method of surface treatment using crushed stone of fine fractions.

The repair method with heating the damaged pavement and reusing its material is based on the use of special equipment for heating the pavement - an asphalt heater. The method makes it possible to obtain a high quality of repair, saves material, simplifies the technology of work, but has significant limitations due to weather conditions (wind and air temperature). It is applied at repair of all types of coverings from asphalt concrete and bituminous mixes.

The method of repair by filling potholes, pits and subsidence without cutting or heating the old pavement consists in filling these deformations and destructions with cold polymer-asphalt concrete mix, cold asphalt concrete, wet organo-mineral mix, etc. The method is simple to perform, allows you to work in cold weather with a wet and wet coating, but does not provide high quality and durability of the repaired coating. It is used when repairing pavements on roads with low traffic volumes or as a temporary, emergency measure on roads with high traffic volumes.

According to the type of repair material used, there are two groups of patching methods: cold and hot.

cold ways are based on the use of cold bituminous mineral mixtures, wet organic mineral mixtures (VOMS) or cold asphalt concrete as a repair material. They are mainly used for the repair of black gravel and cold asphalt concrete pavements on low-grade roads, as well as, if necessary, urgent or temporary patching of potholes at an earlier date on high-grade roads.

Work on patching by this method begins in the spring, as a rule, at an air temperature of at least + 10 ° C. If necessary, cold mixtures can be used for patching and at lower temperatures (from +5°C to -5°C). In this case, before laying, cold black crushed stone or cold asphalt concrete mixture is heated to a temperature of 50-70 ° C, with the help of burners, the bottom and walls of potholes are heated until bitumen appears on their surface. In the absence of burners, the surface of the bottom and walls is coated with bitumen with a viscosity of 130/200 or 200/300, heated to a temperature of 140-150°C. After that, the repair material is laid and compacted.

The formation of the coating at the place of repair in a cold way occurs under the traffic for 20-40 days and depends on the properties of liquid bitumen or bitumen emulsion, type of mineral powder, weather conditions, traffic intensity and composition.

Cold asphalt concrete layers for patching are prepared using liquid medium thickening or slow thickening bitumen with a viscosity of 70/130, using the same technology as hot asphalt concrete mixtures, at a bitumen heating temperature of 80-90 ° C and a mixture temperature at the outlet of the mixer 90-120 °C. Mixtures can be stored in stacks up to 2 m high. In summer, they can be kept in open areas, in autumn and winter - in closed warehouses or under a canopy.

Repair work can be carried out at a lower air temperature, and repair material must be prepared in advance. The cost of work on this technology is lower than with the hot method. The main drawback is the relatively short service life of the repaired pavement on roads with the movement of heavy trucks and buses.

hot ways are based on the use of hot asphalt concrete mixtures as a repair material: fine-grained, coarse-grained and sandy mixtures, poured asphalt concrete, etc. The composition and properties of the asphalt concrete mixture used for repair should be similar to that of which the coating is made. The mixture is prepared according to the usual technology for the preparation of hot asphalt concrete. Hot methods are used in the repair of roads with asphalt concrete pavement. Works can be carried out at an air temperature of at least +10°C with a thawed base and a dry coating. When using a heater of the repaired coating, it is allowed to carry out repairs at an air temperature of at least +5°C. Hot patching methods provide higher quality and longer service life of the repaired pavement.

As a rule, all patching work is carried out in early spring, as soon as weather conditions and pavement conditions allow. In summer and autumn, potholes and pits are sealed immediately after they appear. Technology and organization of work in various ways have their own characteristics. However, for all methods of patching there are common technological operations that are performed in a certain sequence. All these operations can be divided into preparatory, main and final.

Preparatory work includes:

installation of fencing of work sites, road signs and lighting, if work is performed at night;

marking of places of repair (maps);

cutting, breaking or milling of damaged areas of the coating and cleaning of the removed material;

cleaning potholes from material residues, dust and dirt;

drying the bottom and walls of the pothole, if the repair is carried out in a hot way with a wet coating;

processing (priming) of the bottom and walls of the pothole with bitumen emulsion or bitumen.

The marking of repair sites (repair maps) is carried out using a stretched cord or chalk using a rail. The repair site is outlined with straight lines parallel and perpendicular to the axis of the road, giving the contour the correct shape and capturing the intact coating to a width of 3-5 cm. Several potholes located at a distance of up to 0.5 m from one another are combined into a common map.

Cutting, breaking or milling of the coating within the marked map is carried out for the thickness of the destroyed layer of the coating, but not less than 4 cm throughout the repair area. In this case, if the depth of the pothole has affected the lower layer of the coating, the thickness of the lower layer with the destroyed structure is loosened and removed.

It is very important to remove and remove the entire destroyed and weakened layer of asphalt concrete, capturing a strip of at least 3-5 cm wide from a strong, undestroyed asphalt concrete along the entire marked contour. These edge bands of the pothole cannot be left unremoved, since the solidity of the asphalt concrete is weakened here due to the formation of microcracks, loosening and chipping of individual gravel from the walls of the pothole (Fig. 13.10, a). Water collects in the pothole, which, under the dynamic influence of the wheels of cars, penetrates into the interlayer space and weakens the adhesion of the upper layer of asphalt concrete to the lower one. Therefore, if the weakened edges of the pothole are left, then after laying the repair material, after some time, the weakened edges may collapse, the newly laid material will lose its connection with the strong old material and the development of the pothole will begin.

Rice. 13.10. Cutting a pothole before laying the repair material: a - cutting weak spots; b- cutting the edges of the pothole after milling; 1 - weakened wall of the pothole; 2 - exfoliated part of the coating; 3 - destroyed part of the bottom of the pothole; 4 - chopped off or beveled wall of the pothole

The walls of the edges of the pothole after cutting should be vertical along the entire contour. The cutting and breaking of the coating can be carried out using a pneumatic jackhammer or scrap, a concrete breaker, a seam cutter and a ripper, or using a road milling machine.

When using a road milling machine to cut a pothole, rounded front and back walls of the pothole are formed, which must be cut with a circular saw or a jackhammer. Otherwise, the upper part of the laid layer of repair material at the interface with the old material will be very thin and will quickly collapse (Fig. 13.10, b).

The loosened material of the old pavement is manually removed from the pothole, and when using a road milling machine, the removed material (granulate) is fed into a dump truck by a loading conveyor and taken out. The cleaning of the map is carried out with the help of shovels, compressed air, and with a large area of ​​the map - with the help of sweepers. Drying of the bottom and walls of the card is carried out as necessary by blowing with hot or cold air.

Treatment with a binder (priming) of the bottom and walls of potholes is carried out in the case of laying hot asphalt mixes as a repair material. This is necessary in order to ensure better adaptation of the old asphalt concrete material to the new one.

The bottom and walls of the cleaned card are treated with liquid medium-thickening bitumen with a viscosity of 40/70, heated to a temperature of 60-70°C with a flow rate of 0.5 l/m 2 or a bituminous emulsion with a flow rate of 0.8 l/m 2 . In the absence of means of mechanization, bitumen is heated in mobile bitumen boilers and distributed over the base using a watering can.

Filling the pothole with repair material can only be done after all the preparatory work has been completed. The laying technology and the sequence of operations depend on the method and volume of work performed, as well as on the type of repair material. With small volumes of work and the absence of mechanization, the laying of repair material can be done manually.

The temperature of the hot mix asphalt delivered to the place of laying should be close to the temperature of preparation, but not lower than 110-120°C. It is most expedient to lay the mixture at such a temperature when it is easily processed, and during the laying process, waves and deformations are not formed during the passage of the rink. Depending on the type of mixture and its composition, such a temperature is considered: for a multi-gravel mixture - 140-160 ° C; for medium crushed stone mixture - 120-140 ° C; for low gravel mixture - 100-130°C.

Laying the mixture in the card is carried out in one layer at a cutting depth of up to 50 mm and in two layers at a depth of more than 50 mm. In this case, a coarse-grained mixture with a crushed stone size of up to 40 mm can be laid in the lower layer, and only a fine-grained mixture with a fraction size of up to 20 mm can be placed in the upper layer.

The thickness of the laying layer in a loose body should be greater than the thickness of the layer in a dense body, taking into account the safety factor for compaction, which is taken: for hot asphalt mixes 1.25-1.30; for cold asphalt mixes 1.5-1.6; for wet organo-mineral mixtures 1.7-1.8, for crushed stone and gravel materials treated with a binder, 1.3-1.4.

When laying the repair material in a mechanized way, the mixture is fed from the thermos hopper through a rotary tray or a large-diameter flexible hose directly into the pothole and is evenly leveled over the entire area. The laying of asphalt concrete mixtures when embedding maps with an area of ​​10-20 m 2 can be carried out by an asphalt paver. In this case, the mixture is laid over the entire width of the map in one pass in order to avoid an additional longitudinal seam for conjugating the laying strips. The compaction of the asphalt concrete mixture laid in the bottom layer of the coating is carried out by pneumatic rammers, electric rammers or manual vibratory rollers in the direction from the edges to the middle.

The asphalt concrete mixture laid in the top layer, as well as the mixture laid in one layer with a pothole depth of up to 50 mm, is compacted with a self-propelled vibratory roller (first two passes along the track without vibration, and then two passes along the track with vibration) or light-type static smooth-roller rollers weighing 6-8 tons up to 6 passes along one track, and then heavy rollers with smooth rollers weighing 10-18 tons up to 15-18 passes along one track.

The compaction coefficient should be at least 0.98 for sandy and low-gravel asphalt concrete mixtures and 0.99 for medium- and high-gravel mixtures.

Compaction of hot asphalt mixes is started at the highest possible temperature at which deformations are not formed during the rolling process. Compaction should provide not only the required density, but also the evenness of the repair layer, as well as the location on the same level of the repaired coating with the old one. For better mating of the new coating with the old one and the formation of a single monolithic layer when laying hot mixes, the joint along the entire contour of the cutting is heated using a line of burners or an electric heater. The joints of potholes that protrude above the surface of the coating are eliminated by milling or grinding machines. The final work is the cleaning of the remaining repair waste with their loading into dump trucks and the removal of fences and road signs, the restoration of marking lines in the patching area.

The quality of the repair and the service life of the repaired coating depend primarily on compliance with the quality requirements for the performance of all technological operations (Fig. 13.11).

Rice. 13.11. The sequence of basic patching operations: a - correct; b- wrong; 1 - pothole before repair; 2 - cutting or cutting, cleaning and processing with a binder (priming); 3 - filling with repair material; 4 - seal; 5 - view of the repaired pothole

The most important requirements are:

repairs must be carried out at an air temperature not lower than that allowed for this repair material on a dry and clean surface;

when cutting down the old coating, weakened material should be removed from all areas of the pothole where there are cracks, breaks and spalling; the repair card must be cleaned and dried;

the shape of the repair map must be correct, the walls are sheer, and the bottom is even; the entire surface of the pothole must be treated with a binder;

repair material must be laid at the optimum temperature for this type of mixture; the layer thickness should be greater than the depth of the pothole, taking into account the margin for the compaction factor;

the repair material must be carefully leveled and compacted flush with the surface of the coating;

the formation of a layer of new material on the old coating at the edge of the map is not allowed to avoid shocks when a car runs over and the rapid destruction of the repaired area.

The result of a properly executed repair is the height of the laid layer after compaction, exactly equal to the depth of the pothole without unevenness; correct geometric shapes and invisible seams, optimal compaction of the laid material and its good connection with the material of the old pavement, long service life of the repaired pavement. The result of an incorrectly performed repair may be unevenness of the compacted material, when its surface is higher or lower than the surface of the pavement, arbitrary map shapes in plan, insufficient compaction and poor connection of the repair material with the material of the old pavement, the presence of protrusions and sags on the edges of the map, etc. Under the influence of transport and climatic factors, the areas of such repair are quickly destroyed.

Pothole repair of black crushed stone or gravel coatings. When repairing such pavements, simpler materials and repair methods can be used to reduce the cost of maintaining roads with black gravel and black gravel pavements. Most often, these methods are based on the use of cold bituminous mineral mixtures or materials treated with bitumen emulsion as a repair material. One of these materials is a mixture of organic binder (liquid bitumen or emulsion) with wet mineral material (crushed stone, sand or gravel-sand mixture), laid in a cold state. Cement or lime is used as an activator when using liquid bitumen or tar.

So, for example, to repair potholes up to 5 cm deep, a repair mixture is used in the composition: crushed stone 5-20 mm - 25%; sand - 68%; mineral powder - 5%; cement (lime) - 2%; liquid bitumen - in excess of 5% mass; water - about 4%.

The mixture is prepared in forced action mixers in the following sequence:

mineral materials are loaded into the mixer at natural humidity (crushed stone, sand, mineral powder, activator), mixed;

add the calculated amount of water and mix;

enter the organic binder, heated to a temperature of 60°C, and finally mix.

The amount of water introduced is adjusted depending on the intrinsic moisture content of the mineral materials.

During the preparation of the mixture, mineral materials are not heated or dried, which greatly simplifies the preparation technology and reduces the cost of the material. The mixture can be prepared ahead of time.

Before laying the mixture, the bottom and walls of the pothole are not primed with bitumen or emulsion, but moistened or washed with water. The laid mixture is compacted and movement is opened. The final formation of the layer occurs under the traffic.

Patching with the use of wet bituminous mineral mixtures can be carried out at a positive temperature not higher than +30°C and at a negative temperature not lower than -10°C in dry and damp weather.

Pothole repair of black gravel coatings by impregnation. As a repair material, crushed stone is used, pre-treated in a mixer with hot viscous bitumen in an amount of 1.5-2% by weight of crushed stone.

After marking the contour of the pothole, its edges are cut off, old coatings are scraped off and loosened material is removed, the bottom and walls of the pothole are treated with hot bitumen at a flow rate of 0.6 l / m 2. Then, black crushed stone with a fraction of 15-30 mm is laid and compacted with a manual rammer or vibratory roller; bitumen is poured with a flow rate of 4 l / m 2; lay the second layer of black crushed stone with fractions of 10-20 mm and compact it; crushed stone is treated with bitumen at a rate of 2 l/m 2 ; scatter stone screenings of fractions of 0-10 mm and compact with a pneumatic vibrating roller. Using the same technology, it is possible to carry out repairs by impregnation and using crushed stone not treated with bitumen. This increases the bitumen consumption: at the first spill - 5 l/m 2 , at the second - 3 l/m 2 . The distributed bitumen impregnates the layers of crushed stone to the full depth, as a result of which a single monolithic layer is formed. This is the essence of the impregnation method. For impregnation apply viscous bitumen 130/200 and 200/300 at a temperature of 140-160°C.

A simplified method of patching with impregnation of crushed stone with bitumen emulsion or liquid bitumen is widely used in France for patching small potholes on roads with low and medium traffic. Such potholes are called "chicken nest".

The repair technology consists of the following operations:

first, potholes or pits are manually covered with large-sized crushed stone - 10-14 or 14-25 mm;

then, as it is filled, small crushed stone of fractions of 4-6 or 6-10 mm is scattered until the road profile is completely restored;

binder is poured: bitumen emulsion or bitumen in a ratio of 1:10, i.e. one part binder per ten parts crushed stone by weight;

compaction is carried out manually using a vibrating plate.

The binder penetrates the crushed stone layer to the base, as a result of which a monolithic layer is formed. The final formation occurs under the action of moving cars.

In addition to direct impregnation for patching, the reverse impregnation method is used. In this case, bitumen with a viscosity of 90/130 or 130/200, heated to a temperature of 180-200°C, is poured onto the bottom of the prepared card. The thickness of the bitumen layer should be equal to 1/5 of the depth of the pothole. Immediately after the spill of hot bitumen, mineral material is poured: crushed stone of fractions 5-15; 10-15; 15-20 mm, ordinary crushed stone or gravel-sand mixture with a particle size of up to 20 mm. The mineral material is leveled and compacted with a rammer.

When the mineral material, which has natural moisture, interacts with hot bitumen, foaming occurs and the material is impregnated with bitumen from the bottom up. If the foam has not risen to the surface of the material, the binder is poured again at the rate of 0.5 l / m 2, covered with a thin layer of crushed stone and compacted.

With a pothole depth of up to 6 cm, all its fillings are performed in one layer. At a greater depth, filling is carried out in layers 5-6 cm thick. Patching works can be performed in this way even at negative air temperatures. However, the service life of the repaired sections in this case is reduced to 1-2 years.

Pothole repair using crushed stone treated with bituminous emulsion has a number of advantages: there is no need to heat the binder to prepare the mixture; can be laid at a positive ambient temperature, i.e. from the beginning of spring to the end of autumn; rapid disintegration of the cationic emulsion, which contributes to the formation of a repair layer; no edge trimming, material removal or priming.

To perform work, a repair vehicle is used, which includes: a base vehicle with a heat-insulated emulsion tank with a capacity of 1000 to 1500 liters; distribution device for emulsion (compressor, hose, nozzle); bunkers of crushed stone of fractions from 2-4 to 14-20. The cationic emulsion used must be fast disintegrating, contain 65% bitumen and be kept warm at temperatures between 30°C and 60°C. The surface to be treated must be clean and dry.

The technology for repairing deep pits over 50 mm of the "chicken's nest" type (French terminology) consists of the following operations: laying a layer of crushed stone of fraction 14-20; distribution of binder on a layer of crushed stone 14-20; laying the 2nd layer of crushed stone 10-14; spraying binder on a layer of crushed stone 10-14; laying the 3rd layer of crushed stone 6-10; spraying binder on a layer of crushed stone 6-10; laying the 4th layer of crushed stone 4-6; spraying binder on a layer of crushed stone 4-6; laying the 5th layer of crushed stone 2-4 and compaction.

It is important to ensure the correct dosing of the binder when spraying the emulsion over crushed stone. Crushed stone should only be covered with a binder film, but not drowned in it. The total consumption of the binder should not exceed the ratio binder: crushed stone = 1:10 by weight. The number of layers and the size of crushed stone fractions depends on the depth of the pothole. When repairing small potholes up to 10-15 mm deep, the repair is carried out in the following order: laying a layer of crushed stone 4-6; spraying binder on crushed stone 4-6; crushed stone distribution 2-4 and compaction.

These methods are applicable in the repair of black gravel and black gravel pavements on roads with low traffic volumes. The disadvantages of using such methods are that the presence of a layer of variable thickness can cause destruction of the edges of the patch, and the appearance of the patch repeats the outlines of the pothole.

Pothole repair of asphalt concrete pavements using an asphalt heater. The technology of work is greatly simplified in the case of patching with preliminary heating of the asphalt concrete pavement over the entire area of ​​the map. For these purposes, a special self-propelled machine can be used - an asphalt heater, which allows you to heat the asphalt concrete pavement up to 100-200 ° C. The same machine is used for drying repaired areas in wet weather.

The heating mode consists of two periods: heating the coating surface to a temperature of 180°C and further more gradual heating of the coating over the entire width to a temperature of about 80°C in the lower part of the heated layer at a constant temperature on the coating surface. The heating mode is regulated by changing the gas flow rate and the height of the burners above the coating from 10 to 20 cm.

After heating, the asphalt concrete pavement is loosened with a rake to the entire depth of the pothole, a new hot asphalt concrete mixture is added to it from the thermos hopper, mixed with the old mixture, distributed over the entire width of the map with a layer 1.2-1.3 times greater than the depth, taking into account the compaction coefficient and compact from the edges to the middle of the repaired area with a manual vibratory roller or a self-propelled roller. The junctions of the old and new coatings are heated using a line of burners that are part of the asphalt heater. The line of burners is a mobile metal frame with infrared burners mounted on it, which are supplied with gas from cylinders through a flexible hose. During the repair work, the temperature of the coating should be in the range of 130-150°C, and by the end of the compaction work - not lower than 100-140°C.

The use of an asphalt heater greatly simplifies the technology of patching and improves the quality of work.

The use of gas-fired asphalt heaters requires special attention and compliance with safety regulations. It is not allowed to operate gas burners at a wind speed of more than 6-8 m / s, when a gust of wind can extinguish the flame on part of the burners, and the gas from them will flow, concentrate in large quantities and may explode.

Asphalt heaters operating on liquid fuel or with electrical sources of infrared radiation are much safer.

Repair of asphalt concrete pavements with the use of special machines for patching or road repairers. The most effective and high-quality type of patching is the repair performed using special machines, which are called road repairers. Road repairers are used as a means of complex mechanization of road repair work, since they are used not only for patching road surfaces, but also for sealing cracks and filling joints.

The technological scheme of patching with the use of a road repairer includes the usual operations. If the repairer is equipped with a heater, the repair technology is greatly facilitated.

Simplified methods of patching (injection methods). In recent years, simplified methods of patching using special machines such as Savalco (Sweden), Rasko, Dyura Petcher, Blow Petcher, etc. have become more widespread. In Russia, similar machines are produced in the form of special trailed equipment. - sealer brand BCM-24 and UDN-1. Repair of potholes by injection is performed using a cationic emulsion. Cleaning the pothole for repair is carried out with a jet of compressed air or by suction; primer - heated to 60-75 ° C emulsion; filling - with blackened crushed stone in the process of injection. With this repair method, edge trimming can be omitted.

As a repair material, crushed stone of a fraction of 5-8 (10) mm and an emulsion of the EBK-2 type are used. A concentrated emulsion (60-70%) is used on bitumen BND 90/130 or 60/90 with an approximate consumption of 10-11% by weight of crushed stone. The surface of the repaired area is sprinkled with white gravel with a layer of one gravel. The traffic opens in 10-15 minutes. Works are carried out at an air temperature of at least +5 ° C, both on dry and wet surfaces.

Patch repair by injection is performed in the following order (Fig. 13.12):

Rice. 13.12. Pothole repairs according to a simplified technology: 1 - cleaning potholes by blowing with compressed air; 2 - priming with bituminous emulsion; 3 - filling with crushed stone treated with emulsion; 4 - applying a thin layer of raw gravel

the first stage - the place of the pit or patch is cleaned with a jet of air under pressure to remove pieces of asphalt concrete, water and debris;

the second stage - priming with a bitumen emulsion of the bottom, walls of the pothole and the surface of the asphalt concrete pavement adjacent to it. The emulsion flow is controlled by a control valve on the main nozzle. The emulsion enters the air stream from the spray ring. The temperature of the emulsion should be about 50°C;

the third stage is filling the pothole with repair material. Crushed stone is introduced into the air stream by means of a screw conveyor, then it enters the main mouthpiece, where it is covered with an emulsion from a spray ring, and from it the treated material is ejected at high speed into a pothole, distributed in thin layers. Compaction occurs due to the forces resulting from the high speeds of the ejected material. The suspended flexible hose is controlled remotely by the operator;

the fourth stage is the application of a protective layer of dry, untreated crushed stone to the patch area. In this case, the valve on the main nozzle that controls the flow of the emulsion is turned off.

It should be noted that the exclusion of pre-cutting the edges of the pothole leads to the fact that in the marginal zone of the pothole there remains old asphalt concrete with a disturbed structure, which, as a rule, has reduced adhesion to the underlying layer. The service life of such a patch will be less than with traditional technology. In addition, patches have irregular shapes, which impairs the appearance of the coating.

Pothole repairs using cast asphalt mixes. A distinctive feature of cast asphalt mixes is that they are laid in a fluid state, as a result of which they easily fill potholes and do not require compaction. Fine-grained or sandy cast asphalt can be used for repairs at low air temperatures (down to -10°C). Most often, a sandy cast asphalt concrete mixture is used for repair work, consisting of natural or artificial quartz sand in an amount of 85% by weight, mineral powder - 15% and bitumen - 10-12%. For the preparation of cast asphalt, viscous refractory bitumen with a penetration of 40/60 is used. The mixture is prepared in mixing plants with forced action mixers at a mixing temperature of 220-240°C. Transportation of the mixture to the place of laying is carried out in special mobile boilers of the Kocher type or in thermos bunkers.

The delivered mixture at a temperature of 200-220°C is poured into the prepared pothole and easily leveled with wooden trowels. The easy-moving mixture fills all the irregularities, due to the high temperature it heats up the bottom and walls of the pothole, as a result of which a strong connection of the repair material from the side of the coating is achieved.

Since a fine-grained or sandy cast mixture creates a surface with increased slipperiness, measures must be taken to improve its grip. For this purpose, immediately after the mixture is distributed, black crushed stone 3-5 or 5-8 is scattered over it with a consumption of 5-8 kg / m 2 so that the crushed stone is evenly distributed in a layer of one crushed stone. After the mixture has cooled down to 80-100°C, crushed stone is rolled with a manual roller weighing 30-50 kg. When the mixture has cooled to ambient temperature, the excess gravel that has not sunk into the mixture is swept away and movement is opened.

Laying of cast asphalt mixes during patching can be done manually or with a special asphalt paver with a heating system. The advantage of this technology lies in the fact that the operations of priming the repair card and compacting the mixture are excluded, as well as the high strength of the repair layer and the reliability of the joints of the interface of new and old materials. The disadvantages are the need to use special mixers, heated mobile rollers and mixers or thermos bunkers, viscous refractory bitumen, as well as increased safety and labor protection requirements when working with a mixture that has a very high temperature.

In addition, poured asphalt during operation has a significantly greater strength and lower deformability compared to conventional asphalt concrete. Therefore, in the case when poured asphalt is repairing a coating of conventional asphalt concrete, after a few years this coating begins to collapse around the patch of poured asphalt, which is explained by the difference in the physical and mechanical properties of the old and new material. Molded asphalt is most often used for patching city roads and streets.

One of the ways to simplify the work technology and increase the construction season is the use of cold asphalt concrete mixtures based on polymer bitumen binder (PBV) as a repair material. These mixtures are prepared using a complex binder, which consists of bitumen with a viscosity of 60/90 in an amount of about 80% by weight of the binder, a polymer modifying additive in an amount of 5-6% and a solvent, for example diesel fuel, in an amount of 15% by weight of the binder. The binder is prepared by mixing the components at a temperature of 100-110°C.

Asphalt-concrete mix on PMB is prepared in mixers with forced mixing at a temperature of 50-60°C. The mixture consists of fine crushed stone fractions 3-10 in the amount of 85% by weight of the mineral material, screenings 0-3 in the amount of 15% and a binder in the amount of 3-4% of the total mass of the mineral material. The mixture is then stored in an open stack, where it can be stored for up to 2 years, or loaded into bags or barrels, in which it can be stored for several years, retaining its technological properties, including mobility, plasticity, lack of caking and high adhesive characteristics.

The repair technology using this mixture is extremely simple: the mixture from the body of a car or from the bunker of a road repairer is manually or using a hose fed into a pothole and leveled, after which traffic is opened, under the influence of which the road layer is formed. The whole process of repairing a pothole takes 2-4 minutes, since operations for marking the map, cutting and cleaning the pothole, as well as compacting with rollers or vibratory rollers are excluded. The adhesive properties of the mixture are also preserved when it is laid in potholes filled with water. Repair work can be carried out at negative air temperatures, the limit of which needs to be clarified. All this makes this method of patching very attractive for practical purposes.

However, it also has a number of significant drawbacks. First of all, there is a possibility of rapid destruction of the repaired pothole due to the fact that its weakened edges are not removed. When performing work in wet weather or in the presence of water in a pothole, part of the moisture can get into microcracks and pores of the old coating and freeze when the coating temperature drops below 0. In this case, the process of destruction of the zone of conjugation of new and old materials can be initiated. The second disadvantage of this method of repair is the preservation of the irregular external shape of the pothole after repair, which worsens the aesthetic perception of the road.

The presence of a large number of patching methods makes it possible to choose the optimal one based on specific conditions, taking into account the condition of the road, the number and size of coating defects, the availability of materials and equipment, the timing of repairs and other circumstances.

In any case, it is necessary to strive to eliminate pitting at an early stage of its development. After patching, in many cases it is advisable to arrange a surface treatment or lay a protective layer, which will give a uniform appearance to the coating and prevent its destruction.

Experience in the operation of asphalt concrete pavements on city streets and roads shows that their service life before overhaul is approximately 8-10 years. All sorts of cracks, shifts and ruts appear on asphalt concrete pavements during operation (especially at public transport stops), breaks and subsidence (near well hatches, tram rails, in places of former pavement openings, etc.). Under the influence of the wheels of transport, the process of wear (abrasion) of the surface layer of the asphalt concrete pavement manifests itself, and over time, the road pavement loses the necessary bearing capacity.
In accordance with the classification, the repair of pavement and coatings is divided into three types: current, medium and capital. Current repairs include work on the urgent correction of minor damage in order to prevent further damage to the coating. Medium repair of execution in order to restore the bearing capacity of the pavement and improve the transport and operational performance of the road. During the overhaul, work is carried out on the complete or partial replacement of the structural layers of the asphalt concrete pavement.
Types of deformations of asphalt concrete pavements, their causes and methods of elimination are given in Table. 86.
The scope of work on the current repair of asphalt concrete pavements includes sealing cracks, repairing subsidence and potholes, restoring pavement after tearing, eliminating wave formation, sags, ruts, and shifts.

Cracks in asphalt concrete pavements usually occur during periods of a sharp decrease in temperature (during severe and fast-setting frosts). Depending on the width, the cracks are divided into small ones - up to 0.5 cm, medium ones - up to 2 cm and large ones - up to 3 cm. Cracks, growing, lead to the destruction of the road surface. Therefore, their termination should be considered an important preventive measure. The following materials are recommended for filling and sealing cracks: liquefied or liquid bitumen grades SG-70/130, SG-130/200, MG-70/130, MG-130/200, followed by surface treatment of the seam with black screenings of a fraction of 3-7 mm; rubber-bitumen binder (RBV), consisting of bitumen, rubber crumb, softener; mastics, consisting of rubber-bitumen binder and solid fillers.
Bituminous binders and mastics are prepared in special stationary installations.
It is advisable to fill small cracks (0.5 cm) with rubber-bitumen binder or liquefied bitumen, followed by powdering with mineral material; cracks with a width of more than 0.5 cm, as a rule, are filled with rubber-bitumen binder or mastics. Liquid and liquefied bitumen is obtained by adding kerosene to viscous bitumen heated to 80-100 ° C before use.
The material for sealing cracks should have elasticity, heat resistance, good adhesion (adhesion) with asphalt concrete and stone materials, high fluidity, when pouring, it should easily pour out of the working body of the pourer and completely fill the crack. Elasticity is achieved by introducing synthetic rubber or rubber crumb into the mastic, and heat resistance is achieved by introducing solid fillers: mineral powder, asbestos crumb or the combined use of viscous road and construction bitumen. The most common of the synthetic materials for the preparation of mastics is the elastic material polyisobutylene, which has good adhesive properties and high resistance to chemicals.
In urban road construction, various compositions of mastics are used to seal cracks in asphalt concrete pavements. In table. 87 shows the compositions of mastics, selected for their use in II, III and IV climatic zones.

The selection of the composition of mastics is to obtain such a mixture of binder and fillers, which would have a given softening temperature and a sufficiently high fluidity at operating temperature. The softening temperature of mastics for the II road-climatic zone should be within 60 ° C, and III and IV - from 60 to 75 ° C.
Cracks are sealed in dry weather at an air temperature of at least +5 ° C. It is best to seal cracks in the first half of the road repair season, when the cracks are most open. Before sealing, they must be thoroughly cleaned of dust and dirt and dried. The dirt that has accumulated in medium and large cracks is first loosened with metal hooks, and then they are cleaned of dust with flat metal brushes. For final cleaning of dust and dirt, cracks are blown out of the hose with a jet of compressed air. After cleaning and drying, they are poured with waterproofing materials.
For cutting and cleaning cracks during the current repair of asphalt concrete pavements, a DE-10 machine is used. The machine is a manually operated three-wheeled trolley, on which a compressor, a fuel tank and a thermal tool are installed, which is the working body of the machine in the form of a jet burner. Fuel from the tank is supplied under the pressure of air entering the tank and to the tool. When cutting the edges of cracks to a depth of 40 mm, the productivity of the machine is 100-110 m/h, when cleaning cracks of the same depth, the productivity reaches 600 m/h.
Cracks wider than 3 cm can be patched with cold and hot asphalt mix. When sealing with a cold mixture, cracks are filled with liquefied bitumen and stone screenings in such a way that after compacting them, 8-10 mm remain to the surface of the coating. A layer of cold asphalt concrete is laid on top of the screenings, which is compacted with motor rollers weighing 1.5-3 tons. When sealing with a hot mixture, cracks are lubricated with liquefied bitumen, and then filled with hot asphalt concrete mixture, which is compacted with motor rollers weighing 5-6 tons.
If there is a continuous fine network of cracks on the asphalt concrete pavement, caused by the destruction of the pavement due to the mismatch of the asphalt concrete properties with the required or weak base, the cracks are not sealed, and the damaged pavement is removed completely and restored after the base is repaired.
Repair of individual subsidences and potholes in the asphalt concrete pavement must be carried out with asphalt concrete mixtures of approximately the same compositions from which the pavement is built. Materials should be imported in the amount necessary for the repair of this section of the road. Unused materials and waste must be removed in a timely manner.
The trimming of the repaired area should be carried out along a straight contour. Destroyed places located at a distance of up to 0.5 m from each other are repaired with a common map. The outline of the cutting is outlined along the rail. If only the top layer of the coating with a thickness of not more than 1.5 cm is damaged, then the repair is carried out without cutting out the lower layer. If the coating is damaged to a greater depth, the coating is cut down to the base. Before laying the asphalt concrete mixture, the area to be repaired is thoroughly cleaned and treated (lubricated) along the edges and base with hot or liquefied bitumen. Lubrication provides the necessary adhesion of the newly laid coating to the old base.
The temperature of the laid mixture should be from 140 to 160 ° C. The mixture should be homogeneous, without lumps, it should be compacted with motor rollers. After compaction, the junction of the old and newly laid asphalt concrete is treated with hot irons or heat radiation burners to ensure a sufficiently tight interface.
When repairing small damages in cold asphalt concrete pavements with a depth of potholes of more than 4 cm, they are repaired in two layers. A hot fine-grained or medium-grained mixture is laid in the bottom layer, taking into account that, when it is compacted, at least 2 cm is left for laying the top layer from the cold mixture.
During the current repair of asphalt concrete pavements, along with cutting out the destroyed layer, the method of removing deformed asphalt concrete with the help of asphalt heaters has become widespread. It is expedient to use asphalt heaters when correcting shifts, waves, influxes, ruts at public transport stops. Asphalt heater DE-2 (D-717), shown in fig. 119, mounted on the chassis of a UAZ-451DM vehicle, in the closed body of which the following equipment is located: a gas-cylinder installation, including liquefied gas cylinders, a low-pressure reducer, pipelines and hoses; a block of infrared radiation burners with a lifting mechanism; hydro and electrical equipment. In addition to the described asphalt heater manufactured by the industry, individual road maintenance organizations manufacture for their own needs heaters of thermal radiation mounted on the chassis of cars (RA-10, RA-20, AR-53, etc.).

Along with asphalt heaters, repairers DE-5 (D-731) are used for current repairs, which heat up asphalt concrete pavements using infrared emitters. The remonter is mounted on the chassis of a GAZ-5EA vehicle, in the back of which there is a thermos hopper for asphalt mix, containers for mineral powder and bitumen emulsion, portable units with infrared burners, a mobile infrared heater, a distribution trolley, an electric vibrating roller, an S-349 electric hammer, an electric rammer C-690, hand tools (shovels, trowels, brushes, etc.) and fencing boards and signs.
As a result of the use of machines equipped with infrared radiation sources, more advanced methods of repairing asphalt concrete pavements have been developed, in which the heating of the pavement occurs without bitumen burnout, which makes it possible to use the asphalt concrete treated in this way for the construction of a lower or leveling layer with overlapping with fresh mix. At present, a machine for repairing asphalt concrete pavements using electric quartz emitters has been tested and recommended for production.
After the repair or laying of underground utilities, the destroyed pavement is restored after thorough compaction of the holes and complete stabilization of the subgrade subsidence. If it is not possible to achieve the required density of the base and the subgrade and subsidence is possible, a temporary coating is arranged using coarse-grained black crushed stone mixtures or cold asphalt concrete with periodic, as it settles, correction of the profile with the same materials. After attenuation of precipitation, pavement in the places of openings is arranged from the same materials from which the repaired road was built.
The performance of work on the current repair of sidewalks with asphalt concrete pavement is carried out by the same methods and rules that are used when performing the current repair of the carriageway of streets and roads with asphalt concrete pavement. The main difference is that when repairing sidewalks, special sidewalk machines of small dimensions and lower productivity are used: sidewalk spreaders, sidewalk rollers, crack fillers, etc.
If the asphalt concrete pavement loses the required roughness, a large number of cracks appear, as well as significant wear of the surface layer, a medium repair of the pavement is planned. The roughness of the coating is restored by surface treatment. Surface treatment improves the appearance of a coating that has undergone significant repairs, creates an independent wear layer, eliminates slipperiness and gives the coating a roughness that increases traffic safety.
For surface treatment, crushed stone with a strength of at least 600 kgf / cm2 (60 MPa) of fractions 5-10, 10-15, 15-20 and 20-25 mm is used. Crushed stone is pre-treated in stationary asphalt mixing plants or mobile concrete mixers with bitumen or bitumen emulsion. The consumption of black crushed stone of various fractions and a binder can be taken in accordance with the data in Table. 88.

During surface treatment, it is necessary to prepare the coating for pouring, pour the binder and scatter the stone material, compact the material with rollers and take care of the coating until the mat is formed. To prepare the coating for surface treatment, it is necessary to carry out the necessary repairs and repair cracks, as well as eliminate irregularities in the coating. The last operation is especially important, since the existing irregularities cannot be eliminated by surface treatment.
The binder is poured with asphalt distributors and evenly distributed over the coating. In a single-layer treatment, after pouring the binder, blackened crushed stone is immediately scattered. In double processing, stone material of larger fractions is first scattered and compacted, and then bitumen is poured a second time and stone material of smaller fractions is scattered. For better contact of the stone material with the binder, the blackened crushed stone should be compacted with rollers immediately after its scattering, while the spilled bitumen has the highest temperature. Sealing is carried out from the edges to the middle; the number of passes of the rink on one track 4-5. To avoid crushing the crushed stone by the rollers of the roller, it is necessary to use rollers on pneumatic tires.
The outdoor temperature during surface treatment should not be lower than +15-20°C, and the surface of the coating should not be wet to ensure good adhesion of the binder to the stone material. The final mat is formed under the influence of moving traffic, therefore, for some time after the start of movement, surface treatment should be monitored.
Along with surface treatment, the wear layer is restored by building up a new layer of asphalt concrete over the existing pavement. As with surface treatment, a wear layer is applied only after cracks, subsidence, potholes and other deformations of the coating have been repaired. At the same time, in order to improve the safety of automobile traffic, the layer to be built up must have a roughness that ensures reliable adhesion of the car wheels to the road surface. The installation of coatings with an increased coefficient of adhesion should be started at the beginning of the season of road repair work at a stable air temperature of at least 15 ° C. In urban conditions, three methods of coating with an increased coefficient of adhesion are used.
According to the first method, specially selected mixtures with a high content of crushed stone are placed in the top layer of the coating. To obtain a rough surface, it is necessary to have 60% crushed stone in the mixture. When arranging a rough surface, the technology of work remains the same as when arranging conventional asphalt concrete pavements. In this case, the rolling of the layer is carried out immediately with heavy rollers. With insufficient rolling, such a coating becomes short-lived.
According to the second method, hot black crushed stone is scattered on the uncompacted upper layer of the asphalt concrete pavement and rolled down. An asphalt concrete mixture of the usual composition is laid with an asphalt paver and slowly rolled with light rollers, then hot black crushed stone of fractions of 15-20 or 20-25 mm is scattered and leveled and rolled with heavy rollers. Black crushed stone of fraction 15-20 mm is scattered in the amount of 15-20 kg/m2, and fractions of 20-25 mm - 20-25 kg/m2. By the beginning of the placer, the temperature of black crushed stone should be 130-150 ° C, and the temperature before rolling with rollers should not be lower than 100 ° C. The mixture should be fed continuously to the place of laying; every 5-6 cars with a mixture, you need to supply a car with hot black gravel.
According to the third method, a rough surface is created by embedding materials (fractions less than 100 mm) treated with bitumen during the final compaction of the asphalt concrete mixture in the following technological sequence: the top layer of the coating is laid from a fine-grained plastic mixture with a crushed stone content of 30%; pre-compact the mixture with light rollers (2-6 passes along one track); distribute the material treated with bitumen over the surface of the coating in a continuous even layer using a lightweight asphalt paver or manually; compact the material with pneumatic tyred rollers or heavy rollers. The temperature of the spreading material should be 120-140°C, and the coating temperature -80-100°C. The consumption of materials treated with bitumen, fraction 5-10 mm is 10-13 kg/m2, fraction 3-8 mm - 8-12 kg /m2 and fractions 2-5 mm - 8-10 kg/m2. Vehicle traffic on the pavement with embedded bitumen-treated materials can be opened the next day after the completion of work.
During the overhaul of asphalt concrete pavements, the base is prepared for laying asphalt concrete, laying the mixture, compacting asphalt concrete and surface finishing. The preparation of the base consists in building up the wells with reinforced concrete segments to the design mark, cleaning the base from dust and dirt, drying it and lubricating it with a bitumen emulsion. The base is cleaned with mechanical brushes, sweepers. If necessary, the surface of the base is washed with watering machines (PM-130, PM-10) or cleaned with compressed air supplied from the compressor receiver through special nozzles.
Laying asphalt concrete mixture on a wet surface is not allowed, as this does not provide the necessary adhesion of the coating to the base. Wet bases are dried with asphalt heaters or hot sand heated to 200-250 ° C. Before laying asphalt concrete, the base is covered with bitumen emulsion or liquefied bitumen using mechanical sprayers mounted on an asphalt distributor, as well as with a special brush mounted on a watering and washing machine.
The bituminous emulsion is applied in a thin uniform layer 2-3 hours before the asphalt concrete mix is ​​laid. The binder consumption per 1 m2 of coating is 200-300 g. The approximate composition of the emulsion is: bitumen 55-58%, water 41-43%, sulfite-yeast brew up to 4%. The laying of the asphalt concrete mixture can only be started after the bituminous film is completely dry and has a good adhesion to the base.
To obtain the required coating thickness, after pouring the bitumen emulsion, control beacons are installed or marks are made on the top of the coating on the curb stone. The top of the beacon or mark on the curbstone must match the top of the pavement after compaction. All protruding parts of underground structures are lubricated with bitumen. When installing a two-layer coating, the bottom layer is laid on such an area that can be covered in the next shift with the top layer. This achieves a better adhesion of the coating layers and significantly reduces additional cleaning work.
The asphalt concrete mixture is laid at a temperature of at least 130 ° C by various types of asphalt pavers. Asphalt pavers allow you to smoothly change the layer thickness (from 3 to 15 cm) and ensure the laying of the mixture in compliance with the specified transverse profile. To increase the paving strip, the paver kit includes auger, tamper and screed extensions. Extensions 30 cm long can be installed on one or both sides.
The number of lanes of the laid asphalt concrete mix along the width of the carriageway is taken taking into account the length of the tamper bar of the asphalt paver and the need to overlap each lane by an average of 5 cm. longitudinal adhesion of asphalt concrete strips, the length of the strip laid in one pass of the asphalt paver should be taken depending on the air temperature.
In the presence of curbs, the paver moves at a distance of 10 cm from them, and the resulting gap and other places that are inaccessible for mechanical laying (near wells, on sharp turns) are closed manually simultaneously with the paver. The thickness of the laid layer is taken taking into account the compaction coefficient of 1.15-1.20.
Before laying each next strip, it is necessary to warm up the adhesion of the previously laid one. To do this, the edge of the compacted strip is covered with a roller of hot mix to a width of 15-20 cm, which is removed before rolling. It is also possible to heat up adhesions with asphalt heaters or with a burner of an autogas repairer. The asphalt concrete mixture is first compacted with light rollers, and after 4-6 passes along one track - with rollers on pneumatic tires or vibratory ones, 10-13 passes along one track. Compaction should be carried out at a mixture temperature of 100-125 ° C. It should be completed at a temperature not lower than 75 ° C. Rolling of the lower layer at an air temperature below 10 ° C is allowed immediately with heavy rollers.
The upper layer is laid on the lower one only after it has cooled down to 50 ° C at an air temperature of 10 ° C or to 20-30 ° C at an air temperature above 10 ° C. The process of arranging the upper layer is the same as the lower one. To compact the top layer of the coating during mechanical laying of the mixture, 5-7 passes of light and 20-25 passes of heavy rollers are required in one track.