Is it possible to lay asphalt in puddles, mud or just on snow? infographics

Editorial response

Many have observed the process of laying asphalt in winter or late autumn more than once. But hardly anyone tried to penetrate into technical features this process. It turns out that it is possible to repair roads at this time of the year, but under certain circumstances.

According to the current Soviet SNIPs, asphalt cannot be laid at temperatures below +15, but now new materials and technologies have appeared that allow you to perform work even at sub-zero temperatures. But not below -10 ºС.

What needs to be done to lay asphalt in winter?

To repair the road in winter, it is necessary to prepare the area: remove snow, ice and treat the place with special reagents.

Rain and snow reduce the temperature of the mixture, therefore, in wet weather, it is not recommended to lay thick layers of asphalt. In case of light precipitation, it is possible to lay the pavement only along the entire width of the road, and not in parts in different days. In a downpour and a snowstorm, laying the canvas is impossible.

How is asphalt laid?

Asphalt laying consists of the following steps: the cleared area for the new route is covered with rubble. Then pour the emulsion, which should ensure the fixation of the asphalt. Another layer of bitumen and dry gravel is applied on top, the surface is leveled with a roller.

Why do holes and cracks appear on the road?

When laying asphalt, road services often save money. First of all, on an emulsion, the task of which is to hold the rubble. As a result, the asphalt is laid on a dry surface, so it quickly begins to disperse, forming cracks.

The second thing they are trying to save on is crushed stone. Instead, they can put a chipped brick under the asphalt, which is incomparable in strength with gravel. As a result, the asphalt fails, forming holes. According to the regulations, for an “easy” road, one layer of medium fraction (20-40 mm) is enough. If this is a highway, then it is recommended to lay crushed stone in several layers: the first layer is from a large fraction (40-70 mm), followed by a medium one, the last one is from a fine one (5-20 mm). The main thing is to roll each layer with a roller.

Road builders also save on the surface itself - asphalt. It, like bitumen emulsion, is made from oil. But not every grade of this raw material is suitable for quality styling roads. As a rule, builders do not check the quality of oil, hence the fragility of the coating. The thickness of the asphalt depends on the intended use of the road. The minimum thickness is 4-5 cm (for yard areas, etc.). At high intensity traffic asphalt is again laid in layers, using different grain sizes. Coarse-grained asphalt concrete is placed in the first layer, fine-grained concrete is placed on top. For greater reliability, a third surface layer is placed. Before applying each next layer, the previous one is poured with bitumen.

Well, the main reason for bad roads is negligence. Cracks often appear due to water that penetrates under the pavement and freezes during cold weather, thereby expanding holes in the roadway. Builders can ignore the technical requirements and put asphalt on the snow. In these actions lies not only negligence, but also the possibility of obtaining another order. You put it in a puddle - in a couple of months everything will be redone, so a new order is ready, and everything can be attributed to the harsh climate.

When should cold and hot asphalt be used?

There is a cold and hot way asphalt laying.

Cold laying is most often used in road repairs. The main thing in this process is to compact the coating well. The advantage of using cold asphalt is its all-weather application.

Work on the repair of the road can not be stopped even in winter.

There are several types of cold asphalt:

Summer cold asphalt. Temperature environment when laying from +15 to +30 °С.

Interseasonal cold asphalt. Ambient temperature during laying from -5 to +15 °С.

But this method is not suitable for the construction of a new road or the overhaul of an old one. In this case, resort to hot styling. Asphalt must be installed hot. However, in autumn and in early spring it is difficult to achieve high-quality repair of roads using hot laying.

Instead, poured asphalt technology is used. Molded asphalt is a mixture of sand, gravel and crushed limestone with bitumen. Cast asphalt does not have to be rolled with rollers, its consistency is such that it lays down in a dense cast layer without the need for additional compaction. Molded asphalt is water resistant, so it can be laid even when it rains. The temperature of the poured asphalt during laying can vary between 200-250 degrees. The technology allows laying asphalt at -10 °C. The maximum thickness of the poured asphalt should not exceed 25-30 mm. Cast asphalt, like other types of asphalt, can be used not only in road construction, but also in such types of work as roofing, bridge covering, and interior decoration.

Roads are measured to serve three years

Since 2011, new rules have come into force, according to which road repairs should be carried out not once every seven years, as it was before, but once every three years. According to officials, due to climatic conditions, the road in Russia serves no more than three years.

In the same year, the capital's communal services began to keep the history of roads. The documents indicate when a particular kilometer of the highway was repaired. If a marriage is found, the contractors who carried out the work must correct the errors at their own expense.

Comparative cost of roads in Russia and abroad

Some road works in Russia cost many times more than the cost of roads abroad. The first in this list is the land that needs to be redeemed from the owners. In Russia, it is usually included in the cost of the project, but not in Europe. At the same time, the cost of land acquisition in Russia is 6-7% of the project cost, in the Moscow region - 30%, and in Moscow - up to 70%. Many people buy up the land adjacent to the future highway in advance and then sell it to the state at exorbitant prices.

The next most expensive is the cost of design. In Russia, there are virtually no standard projects roads, so every new road has to be redesigned. Then the project is sent for state expertise, which is almost impossible to pass the first time. The re-examination costs up to 70% of the initial one - and this is without taking into account the cost of finalizing the project.

And the third is the delivery of materials. High-quality sand and gravel often have to be transported for tens or even hundreds of kilometers. A simple example: during the construction of some tunnels in the Olympic Sochi, finishing produced in Krasnoyarsk was used. With delivery for five thousand kilometers.

As a result, it is not surprising that the construction of the Adler - Krasnaya Polyana road cost 285 billion rubles - 1.9 times more expensive than foreign analogues. In Europe, the cost of laying one kilometer of a tunnel in a mountain range is about $70 million.

The only reason why a road in Russia can be cheaper than a European one is thinner pavement, designed for a shorter service life. In Germany, the thickness of the top layer of asphalt should be 22 cm. In Russia - 8 cm. All this affects the service life. In addition, if the quality of the asphalt used can be checked, then the amount of sand and gravel cannot. Therefore, road builders use this: if you want, put less material, if you want, indicate in the documents the delivery range of the necessary sand is 200 km, and bring the usual one from the nearest quarry.

Russians can only dream of good roads or build them under contracts life cycle so that the contractor himself maintains the constructed road and pays fines in case of poor laying.

According to the official regulatory documents (SNiPam), which regulate asphalt laying standards, it is possible to carry out asphalting of roads only at a temperature of +5 С°. How to carry out urgent road repairs in the winter? New technologies come to the rescue of road services.

Asphalt is more expensive in cold weather

In the cold Russian climate temperature regime asphalt laying is broken every now and then, which leads to a significant deterioration in the quality of the created road surface and an increase in the cost of seasonal and major repairs. In an effort to complete the work on time, contractors carry out road construction at sub-zero temperatures and high humidity. After the mixture hardens, moisture that has entered the smallest pores and cracks of the new coating quickly turns into ice under the influence of low temperatures. The volume of frozen water increases by about 8-9%, due to which, during periods of severe cold, one can observe bursting water pipes and various liquid containers. The same expansion effect causes ice-filled cracks in the asphalt concrete to increase in size and erode the pavement from the inside.

An additional problem is also the adhesion between the individual layers of pavement laid at low temperatures or in the rain. According to experts, even constant heating and drying of the soil base with the help of special devices does not allow 100% to get rid of moisture that prevents high-quality adhesion of pavement layers. In accordance with modern standards, the only type of asphalt paving that can be carried out under almost any weather conditions (excluding severe frosts) is patching with the use of special mixtures.

"Cold technologies": does the quality match the price?

The use of cold mix asphalt today is one of the most modern technologies emergency patching during the cold season. Unlike traditional hot asphalt, cold asphalt contains elastic bitumen, the viscosity of which increases with decreasing ambient temperature. The formula of the brands on the market is constantly being improved, including special composite additives that improve the adhesion of the mixture to the substrate and guarantee increased ease of installation and durability. Under pressure during rolling and further operation of the road, cold asphalt finally polymerizes and acquires significant hardness.

Consider the advantages and disadvantages of cold mixes in comparison with conventional hot asphalt.

pros

• Ready-made cold mixes can be stored without loss of their properties for up to 1 year, which allows you to always have ready-made material for urgent work;
• The minimum temperature for cold asphalt paving is from -20°C to -25°C according to various suppliers;
• A cold repaired track can be opened to traffic immediately after paving. Under the weight of the transport, the cold mixture is finally compacted and becomes more durable;
• Laying cold asphalt does not require expensive special equipment and special vehicles for transporting the material.

Minuses

• "Cold laying" can only be used for small potholes and pits;
• "Patch" from cold mix easily gives in to shift and quickly collapses on sites of braking - crossroads, pedestrian crossings, etc.;
• Fresh asphalt areas adjacent to unused areas of the road (strips at the edge of the curb, around hatches and other technical objects) are not sufficiently compacted by the wheels of cars and are destroyed faster;
• The price of cold mixes is many times higher than the price of ordinary hot asphalt (the cost of 1 ton of imported cold asphalt is about 60 thousand rubles, 1 ton of standard asphalt is about 2.5 thousand rubles).

Hot casting: an expensive alternative

Molded asphalt differs from the standard one in the presence of high-viscosity hard bitumen and mineral inclusions (sand, fine gravel). Work with hot mixes is carried out at temperatures from +200 ° C, due to which patching of highways can be carried out at high humidity and low temperatures. The cost of the material is somewhat lower than the price of cold mixes, however, poured asphalt requires additional costs for the rental of special equipment. Due to excessive ductility during the hot summer season, hot casting is considered a temporary emergency repair method.

Compared with conventional hot asphalt, cast asphalt has the following advantages and disadvantages:

pros

• Once poured, the hot mix compacts itself during the curing process, eliminating the need for an asphalt roller;
• Molded asphalt has exceptional adhesive properties and forms a strong bond with the base even at low temperatures and high humidity;
• The ability to carry out urgent repairs at sub-zero temperatures and during precipitation.

Minuses

• Transportation of a hot mix requires expensive road equipment (boilers and cohlers), which makes it possible to maintain a consistently high temperature of the material and constantly mix it;
• Repairing roads with poured asphalt requires a lot of energy (the required laying temperature is about +200 C°);
• In the warm season, “patches” can heat up in the sun up to +60 ° C and squeeze through under the wheels of cars.

Summing up, it can be noted that today the most modern and universal method of patching under any weather conditions is the use of cold asphalt mixtures. According to some experts, in the coming years further improvement formulas of cold asphalt will effectively carry out emergency road repairs even at ultra-low temperatures. But the high-quality construction of roads in the cold season is still a matter of the future - on this moment there are no materials and technologies on the market that allow, at high humidity and sub-zero temperatures, to create a durable asphalt pavement that meets all required standards.

With small sizes of potholes, the distribution and leveling of the mixture is carried out, as a rule, manually with shovels and trowels or using boxes without a bottom (Fig. 9), and on large repaired maps (area of ​​more than 20–25 m2), it is advisable to use a small sidewalk paver.

After filling the pothole (card) with a hot mixture, it is compacted with special vibrating plates or small-sized vibrating rollers in compliance with all technological rules and requirements (see Section 3). The surface of the repaired area after compaction should be at the level of the main coating, i.e. it should not have any depressions, or protrusions, or the appearance of a “clumsy blotch”.

Traffic on the repaired area of ​​​​the coating is opened immediately after the completion of all work and the cooling of the laid mixture to a temperature not exceeding 30 ° C. In hot weather, the cooling time of the mixture can be shortened by pouring water at a rate of approximately 2 l/m 2 .

Quite often the question arises about the repair of pavements with the help of poured asphalt, which has been known since 1914. Molded asphalt is a hot mixture of pasty consistency in which essential component is a mastic consisting of highly viscous hard bitumen‚ a large number mineral powder and sand (sometimes fine gravel). Molded asphalt can contain up to 13% bitumen and up to 30–35% mineral powder, which makes it much more expensive than traditional asphalt mixes. In addition, the temperature of its preparation and placement must be sufficiently high (220–250°C).

The need for special vehicles (coherers with agitators and heating) and special pavers (for pavement construction) that cannot work on paving other mixtures also lead to a noticeable increase in the costs of using poured asphalt. All this hinders the use in Russia of quite attractive cast asphalt for patching and pavement construction.

Jet-injection cold technology for filling potholes on road surfaces using bitumen emulsion is now one of the most advanced and progressive, despite the fact that in some European countries and in America it has been successfully used for a long time.

Its essence lies in the fact that all the necessary operations (Fig. 10) are performed by the working body of one machine (installation) of a self-propelled or trailed type (Fig. 11).

The preparation of a pothole for repair actually comes down to its thorough cleaning of dust, debris and moisture by blowing with a high-speed air jet and to treating the surface of the pothole with a bitumen emulsion. The operation of cutting, breaking or milling asphalt around a pothole may not be performed in this technology.

The very filling of the pothole is carried out by filling it with fine gravel, pre-treated with bituminous emulsion in the mixing chamber of the machine. Due to the involvement and supply of crushed stone with an air jet, its laying in a pothole occurs with high speed‚ which ensures its good packaging (seal)‚ practically eliminating the need for additional use vibrating plates and vibrating rollers.

For patching according to the jet-injection cold technology, it is recommended to use pure fine crushed stone of a fraction of 5–10 (15) mm and a rapidly disintegrating cationic (for acidic rocks, for example, granite) or anionic (for basic rocks, for example, limestone) bitumen emulsion 60 - percentage concentration.

Beforehand, the laboratory should check the adhesion of bitumen to crushed stone and the time of disintegration of the emulsion, which should not exceed 25–30 minutes. If necessary, make adjustments to the composition of the emulsion and adhesive additives.

The consumption of the emulsion of the specified concentration for priming potholes and processing crushed stone in the mixing chamber of the machine can approximately be 3-5% by weight of crushed stone (for bitumen consumption - no more than 2-3%).

The main elements of the machine or installation for the jet-injection method of filling potholes are shown in fig. 12.

All these elements and assemblies can be permanently mounted on a light trailer or base truck. In some cases, it is possible to combine them on a separate frame in the form of a hinged or rearranged module for a suitable transport.

Such units and machines provide for the exit of the repairman-machinist from the cab of the vehicle to perform patching at the rear of the car or trailer. In the future, some improvements were made to this technology and the scheme of work, which reduced the cost of the repair itself.

In particular, a flexible hose that feeds materials into a pothole was installed in front of the car and mounted on a light hydraulic manipulator boom, which is able to lengthen, fold and turn horizontally, serving a certain sector of coverage. The control panel for all operations is located in the cab of the truck, and the driver of the repairman no longer needs to leave his workplace. He fills the pothole directly from the cab within 20-30 seconds (Fig. 13).

The jet-injection method for patching potholes can be used for almost all year round. Little experience in Russia (Roshchinskoye DRSU Leningrad region‚ Moscow region, Saratov region and elsewhere) and more extensive practice of its application‚ for example in the USA‚ England and Sweden‚ show that in fact strong and durable termination potholes can be provided even at air temperatures up to -10 ... -15 ° С.

As a rule, potholes are repaired in this way at the initial stage of pitting destruction of coatings, i.e., mainly small size(diameter no more than 40–60 cm)‚ although there are no fundamental and serious objections and obstacles to the repair of potholes and larger maps.

Research and experimental work for several recent years(mainly in the USA) have shown that the cleanliness and dryness of the pothole play a more important role than even the temperature of the material and the outside air for the quality of patching. Therefore, jet-injection technology in Lately underwent further qualitative improvement, the essence of which was to replace the cleaning and drying of the pothole by blowing with a high-speed air jet for vacuum cleaning (Fig. 14).

high performance Vacuum pump sucks debris, dust and moisture out of potholes. The surface is drier and cleaner than with conventional sweeping or blowing with compressed air.

Priming with bitumen emulsion and filling the pothole with crushed stone treated with emulsion in vacuum-jet-injection technology are similar to the same operations in jet-injection technology.

The developers of the method and equipment, based on experience in its use in 25 US states, guarantee a 3-year service life of the repaired sites.

Russian road builders have already begun a broader practical use jet-injection repair method using the BCM-24 equipment kit, manufactured by JSC "Betsema" (Moscow region), trailed to a dump truck (Fig. 15).

It is appropriate to note that in some Russian places the method of patching with mixtures has not lost its relevance and attractiveness so far.

Cold asphalt mixes include all types or compositions according to GOST 9128-97 (except for type A), prepared on liquid or liquefied bitumen grades SG 70/130 (medium thickening) or MG 70/130 (slow thickening). As a rule, preference is given to medium-thickening bitumen, since with it a layer of material in the coating is formed faster than on slow-thickening bitumen.

Such mixtures are prepared in the same mixing units as hot ones. However, the temperature for preparing cold mixes is 40–50% lower. After the agitator, the mixture goes through the obligatory stage of cooling to the outside temperature, then it is stored and only after that it can be laid in the coating layer in a cold state. It is allowed to store it in a warehouse in a stack and use it as needed within 3-5 months. It lends itself well to loading cars and transporting conventional vehicles for any distance.

The most important and special technological problem for a cold mix is ​​to ensure its non-caking, i.e., maintaining looseness without sticking mineral grains into lumps. Without this, it is impossible to prepare the mixture for future use and further effective use.

Usually, the caking of the mixture before storage is reduced by cooling it in air with repeated shoveling with the blade of a bulldozer, loader or motor grader, and sometimes with watering. Cooled and hardened on mineral grains, thin layers and films of bitumen lose their stickiness, and the mixture in stock piles does not cake. In order to restore stickiness to bitumen and form the structure of the mixture after laying in the coating, it must be warmed up for some time by the heat of air and the sun to evaporate light bitumen fractions with simultaneous good compaction by rollers and transport within 2–3 weeks. Therefore, such patching of asphalt concrete pavements is preferable in spring or summer, and only on roads of categories III–IV (traffic intensity is not more than 3000–1000 vehicles/day).

The technology and all repair operations in this case are similar to patching coatings with hot mixes. In cold technology, there is only a strict restriction on the laying and compaction time, which is imposed in hot technology due to the possibility rapid cooling mixture and reduce its compaction.

In some foreign countries(Sweden, Finland, Norway, etc.) asphalt concrete mixtures based on low-viscosity and liquid bitumens, as well as on a special oil binder (the mixture in this case is called oil gravel) are used for the construction of coatings from the so-called "soft asphalt concrete", the use of which is limited to roads with traffic intensity up to 1000–1500 vehicles/day Moreover, when using low-viscosity or liquid bitumen, a mixture for soft asphalt concrete is prepared and laid in a coating using conventional hot technology.

If an oil binder or a bitumen emulsion based on low-viscosity and liquid bitumens is used as a binder, the material for such mixtures can be cold or warm (heated with steam up to 40 ° C). Thus, in particular, in Finland, cold storage mixes are obtained for the specified type of asphalt concrete. Their high-quality preparation is carried out in special mobile (mobile) installations MX-30S of the Finnish company Kalottikon, in which there is no drying drum, but there is a special container for the emulsion and a turbine unit for steam production.

Equally effective for patching are cold asphalt mixes prepared on very popular and widely used emulsions based on viscous bitumen. Such mixtures are called emulsion-mineral, and they can be both porous and dense.

Depending on the category of the road and the strength of the material in the coating, the required type or grade of emulsion is selected according to the viscosity of the bitumen used, the necessary mineral materials and cold mixtures are prepared that can be stored and stored.

In "cold" mixing plants, an emulsion of a given type, concentration and temperature is mixed with an unheated aggregate. Mixing plants themselves can be of almost any design and purpose, including very simple ones with low capital investments. When using high grade emulsions and mineral aggregates in combination with more efficient and sophisticated mixing and dosing equipment, emulsion-mineral mixes can provide pavement properties and quality close to those of hot mix asphalt pavements.

Terms (up to 2–3 months) and conditions of storage in a warehouse (open area‚ indoors‚ airtight containers or sealed polyethylene bags) of such cold mixes depend on the type of emulsion, bitumen viscosity, emulsion disintegration time and are set individually in each specific case.

If necessary, urgently repair potholes that are dangerous for traffic, you can use any simple and available methods‚ materials and means capable of providing temporary (at least 2-3 months) trouble-free operation of the road.

Emergency repairs are carried out at any time of the year - in late autumn (wet and cold)‚ winter (cold) and early spring (cold and wet), which, of course, cannot but affect the quality of repair work.

Such poorly repaired places with the onset of warm and dry weather are subject to re-repair, but in compliance with all the requirements and rules for the implementation of high-quality pothole repair. This is economically quite feasible and acceptable, given the not quite massive nature and insignificant volumes of accident-defective places on the coating.

During emergency repairs, as a rule, such methods of temporary sealing are used that do not require special preparation of potholes, with the exception of their possible cleaning from dirt, moisture, snow and ice.

The main thing in such a repair is to fix the material used in the pothole so that it has an acceptable connection with the bottom and walls of the pothole and that the particles of such material have sufficiently strong contacts between themselves due to mechanical expansion and bitumen, cement, polymer or other adhesive layers.

For emergency repairs, it is recommended to use limestone, dolomite or other not very strong crushed stone materials (fractions of 5–20 mm) pre-treated (“cold” black crushed stone) or processed directly in the pothole with liquid bitumen with surfactant or bitumen emulsion.

As a rule, liquid bitumen should have a viscosity index of at least 130–200 s, and the bitumen emulsion should be rapidly disintegrating, 50–60% concentration when heated. Crushed stone for these purposes is sometimes treated with lime or cement (1.5–2% by weight).

Some of the repair materials with appropriate technologies of use can be used even when negative temperatures air (up to -10...-15°C), although other materials and technologies are effective only at +5°C and above.

Recently, in foreign countries, emergency sealing of potholes and other defective places with special repair mixtures with a shelf life of 1–2 years in finished form in sealed plastic containers (buckets, barrels, boxes)‚ in sealed plastic bags(25-50 kg each) and even in stacks in the open air. Such mixtures include Repasfalt, Bormix and Stralasfalt from Germany, Vespro and Silvax from the USA, Kolmak from England, Excel from Canada and a number of others.

For the most part, the binder for these cold materials is liquid bitumen modified with polymers with special additives or an emulsion based on it, which makes such repair mixtures quite expensive - about 200 USD / t, while the binder price is about 1000 USD / t. However, their attractive technological advantages (cold technology, long shelf life, performance of work on a wet surface and even in frost), together with a high strength of sealing defective places, make it possible and even expedient to use them in small and single emergency patching.

Sometimes, given the temporary nature and not too high quality emergency repair, they deliberately go to simplify and reduce the cost of both the repair material itself, and the technology of its preparation and application.

For example, the road service of Helsinki has taken this path, which for more than 20 years has been annually producing about 3,000 tons of stored cold mix "Korsal" for urgent (urgent) repair of coatings and temporary sealing of trench openings on city streets.

It consists of crushed stone (3–8 mm)‚ sand and bitumen emulsion (7–8%). Cooking repair mix in a cold way in a conventional concrete mixer (capacity 3 m 3) of periodic action and stored on open area. Before use in winter, the mixture is heated in a warm room.

In the presence of a bitumen emulsion and an appropriate machine or installation, it is advisable to use the already considered jet-injection cold method for emergency patching. However, due to the inability to do a thorough cleaning and preparation of the pothole, the life of such an insert will be significantly lower than under normal normal conditions.

In the absence of the required jet-injection technique, filling a pothole is possible by manually stuffing (ramming) it with cold gravel (preferably blackened) and then treating it from the surface with a bitumen emulsion by simple spraying from improvised means. As a result, the pothole will be filled with rubble impregnated with bitumen emulsion.

The method of impregnation of crushed stone in a pothole, but with bitumen, somewhat liquefied and hot, is also practiced by road builders different countries‚ including Russia‚ to eliminate emergency pitting. Its difference from the emulsion impregnation method is that the impregnation itself is carried out before crushed stone is compacted. In this case, the bitumen is heated to a temperature not lower than 170–180°C. Satisfactory results can be obtained even at low air temperatures (down to -5...-10°C).

The peculiar technological methods include the Russian method of reverse impregnation, in which the bitumen heated to a minimum of 170-180 ° C, getting on the moisture remaining on the bottom and walls of the potholes and on the wet rubble, foams with a multiplicity of up to 4-6 and covers the surface of the pothole with a thin layer and rubble particles. The penetration of bitumen between the particles and grains of crushed stone goes from the bottom up, therefore this technological method of repair is called the "reverse impregnation method". Its efficiency is limited by air temperature +5...+10°С. At lower temperatures, bitumen is poorly and difficult to foam.

In the impregnation method, polymeric materials are sometimes used instead of bitumen. In particular, when repairing with polymer concrete, the pothole is filled with crushed stone, which is then impregnated with a fluid composition based on polyurethane, acrylic or other resin, while in the process of tamping, the residual water is squeezed out of the hole up.

Such repairs are possible at air temperatures from -30 to + 50°C. Traffic opens in 30 minutes. In adverse weather conditions (dampness, cold), emergency patching can also be carried out with a wet organo-mineral mixture (VOMS), the composition and technology of preparation and use of which was developed at RosdorNII.

VOMS consists of limestone or dolomite crushed stone with a fraction of 5–20 mm (up to 40%), sand with a particle size modulus of at least 1.0, mineral powder (6–12%), binder (tar, liquid or liquefied viscous bitumen) in the amount of 6 -7% and water. Instead of crushed stone, it is possible to use screenings of crushing, ASG, crushed slag. Such a mixture is prepared in cold form in ABZ mixing plants, equipped with a system for supplying and dosing water to the mixer. After unloading from the mixer, the finished mixture is fed to the warehouse at a temperature of 25–40°C, where it is stored in a pile for several months.

Potholes with a depth of at least 3-4 cm are repaired with such a mixture. The main advantage of VOMS is that it is used already in finished form using cold technology, on dry or wet surfaces and at air temperatures up to -10 ° C. However, it should be borne in mind that in winter and early spring, the formation of a strong FOMS structure in the coating is slow and difficult due to frequent transitions of air temperature through 0°C.

This material acquires the greatest strength after complete drying, but this strength is not so great (1.5–2 times lower than the strength of cold and 2.5–3 times lower than the strength of hot asphalt concrete) to use FOMS even for ordinary patching of road surfaces high categories. Only emergency (temporary) repair of such roads is permissible with this mixture.

An equally interesting and useful development for patching pavements, including emergency ones, was once made at SoyuzdorNII: stored asphalt concrete mixtures (SAC) on viscous bitumens that can be stored, laid and compacted in cold form.

They are prepared on viscous bitumen with enhanced thixotropic properties, which is achieved by introducing special plasticizers into them (summer autotractor diesel fuel LTD and SB oil feedstock for the production of viscous road bitumen). But the situation with the practical use and implementation of the SAS remains the same as with the VOMS, that is, not very satisfactory.

If the asphalt is laid according to all the rules, then it should serve for more than one year. But that's in theory. In our life, everything is different. As a rule, the first pits on the roads appear within a few months after the renewal of the road surface.

Why it happens? The main reasons, of course, are negligence and violation of asphalt laying technology. For the sake of economy (I want to get more money and spend less), road builders add less bituminous emulsion to the mixture, save on sand and gravel. Because of this, the asphalt becomes brittle and as a result, breaks, cracks and pits appear.

Current regulations do not allow road services to wait for good and comfortable weather to carry out repairs. Judge for yourself, the existing GOST R 50597–93 " Car roads and streets. Requirements for the operational state permissible under the conditions for ensuring road safety "sets the maximum allowable dimensions for pits on the roads: along the width of the road - no more than 60 cm, along the length - 15, in depth - 5.

And in case of identifying problem areas, immediately notify the road builders. Those, in turn, are obliged to promptly repair the roadway. After all, if a car gets into such a hole, it is the organization serving this section of the road that will have to answer.

That is why, despite the rain and snow, the asphalt rolls into holes. After all, according to the standards, the elimination period is a maximum of 10 days. Is it correct?

Road work on laying asphalt (including patching) is carried out in accordance with SNIPs and GOSTs. When repairing patching, as a rule, a cold laying method is used. In this case, the asphalt mix seizes very quickly and almost immediately you can drive along the repaired area.

There is another hot way. It is used mainly in the construction of new roads and the reconstruction of old ones. Here they use a hot bituminous mixture and roll it until it cools completely. Occasionally, hot laying is also resorted to during patching. More often in warm weather, when the temperature outside is not lower than 10ºС. However, there are so-called cast mixtures that allow hot styling even at sub-zero temperatures. Such a mixture is brought to the place of repair in a special thermos trailer. The composition is in liquid state like thick glue. The temperature of the mixture is under 200ºС. Observing the technology, it can be laid even in harsh winter conditions. From high temperature moisture from the pit simply evaporates. After the mixture hardens, the road section can be exploited. Pleasure is quite expensive. Therefore, this type of repair is used for serious damage to the canvas, when it is necessary to quickly restore traffic in an emergency section.

So, if hot styling is used in the warm season (+10ºС and above), cold styling is limited to slight frosts (not lower than -5ºС), and cast mixtures are more suitable for cold weather, already at -10ºС, for example. It is clear that, if necessary, road builders will patch up the road at lower temperatures. If a pit (fault, etc.) suddenly forms on the highway, traffic is blocked, and it’s minus 30 on the street, you won’t wait for spring warming. In general, any winter asphalt laying repairs, in fact, are emergency. Their task is to make sure that the repaired area lasts until it gets warm, when restoration can be done in earnest.

As you can see, roads can be repaired in winter as well. The main thing is to follow the technology. That's just in our realities about quality repair few people think of roads. Indeed, for most road services it is more important to have a good and constant income from the repair and maintenance of roads. If you do everything qualitatively, you won't get money from the budget. The problem is that we have not yet established guarantees for the service life of the road surface. If such a period existed, then the road builders would eliminate all the pits at their own expense. And so they built the road, got the money. Potholes appeared - they patched them up, they got money again. As a result, we are simply doomed to drive through pits and potholes.

Well, for example, some numbers. Last year, the repair of the road and street network was spent: in Kazan - 2.87 billion rubles, in Vladivostok - 2 billion, in the Moscow region - 12 billion, in the capital - 22.4 billion. This is for comparison. Now imagine how much you could save if the roads after laying (reconstruction and overhaul) did not require repairs for at least four years.

After hot mixes, the second most common patching material is cast asphalt concrete. In composition, it differs from them in a larger proportion of bitumen and the use of fine mineral aggregate. In fact, it is an analogue of natural asphalt.

The advantage of repair using cast asphalt concrete mixtures is the greater strength and frost resistance of the embedded areas, as well as the possibility of performing work in winter time. Let's talk in detail and step by step about the technology of using cast asphalt concrete in patching roads with cutting maps.

Cutting cards for patching with poured asphalt does not differ from the same stage of work when using any other material and is carried out with the same tools and equipment. The requirements for cut cards are practically the same - the verticality of the edges, the complete removal of damaged asphalt, the absence of sharp corners. But there are two nuances:

• The area of ​​cards is limited to 2-3 square meters. This is due to the fact that poured asphalt has a smoother surface and lengthens the braking distance. It is especially dangerous if the car, when braking, hits the wheels of one axle on long sections with different coefficients of friction, it is automatically skidded. It is also undesirable to use cast asphalt concrete on bends. However, there is a way to get around this limitation - before the final solidification of the composition, cover the map with small gravel.
• Molded asphalt can adhere reliably even to wet surfaces. Therefore, if it is not possible, it is not necessary to dry the card to the end. But water still needs to be removed completely, since steam bubbles violate the structure of the hardened repair composition.

Requirements for a sliced ​​card: area up to 2-3 square meters, vertical edges, no sharp corners.

It should be noted that if the mixture is not brought from the factory, but is heated on site in a recycler, then it is advisable to cut and clean the cards during its heating. Thus, by correctly distributing workers so that they can prepare the right number of cards, which is filled with one load of the recycler, downtime can be completely avoided.

Paving of poured asphalt concrete

Unlike the use of other patching materials, the bottom and sides of the cards do not need to be primed before poured asphalt is applied. Its installation is extremely simple. Having received cast asphalt, which is transported in a thermos-bunker, we control the temperature, it should be at least 190-220 degrees. Machines for transporting this mixture are usually equipped with special trays from which you can unload required amount cast asphalt directly into the cut map. Then the composition is leveled with shovels and trowels and remains until the final hardening. Traffic on the repaired section of the road can be opened in an hour, and earlier in winter.

At the same time, it should be taken into account that overheated cast asphalt has increased plasticity and its surface tends to become strictly horizontal. The roadbed has a slight transverse slope. In order to prevent water from accumulating in the repaired place, the temperature of the material to be laid must strictly correspond to its passport, and the smoothers must be given the same level with the rest of the road surface.

The process of laying poured asphalt is simple: unload poured asphalt into a map, level it with trowels or shovels.

Preparation of poured asphalt concrete in a recycler

But most often, especially in winter, the mixture is not brought from the asphalt plant, but is prepared at the place of work in recyclers. These are devices that provide heating and mixing of the mixture. Most often they have a wheel drive and a towing device for towing.

The preparation of the mixture in this unit can be divided into several stages.

• The prepared asphalt concrete is loaded by turning the drum so that the loading hatch is at the top. It is recommended to introduce an additional small amount of pure bitumen into the composition.
• Then the hatch is closed and the nozzle is lit. The drum must constantly turn, making several revolutions in one direction or the other. During the operation of the recycler, the temperature of the mixture must be carefully monitored.
• When the poured asphalt is heated to the required value, the burner is turned off.
• The recycler is adjusted to the prepared cards, the drum is turned upside down. By opening the damper, the required amount of material is unloaded, then the laying of the mixture begins.

All laying processes are carried out in exactly the same way as during delivery. ready mix from the factory. When moving the recycler from card to card, continue to mix the heated mixture by rotating the drum. If the temperature drops, the burner is switched on again for a short time.

In winter, cast asphalt concrete is prepared at the work site in a recycler.

As with any other method of filling potholes, only complete and correct compliance with all technological requirements for repairs using poured asphalt concrete can achieve high quality.