You are afraid of pits. And the pits are afraid of us - the specialists of the Asflt-Kachetsvo LLC company. After our arrival, their miserable life will be interrupted in an instant. And, most importantly, they will have no chance of revival. By performing pothole repairs in Moscow and the region, we give people real value.
We specialize in the construction of new roads, but in 2016 alone we completed 13,140 m2 of asphalt patching.
Best Methods and Practices
The choice of method depends on several factors: weather, density and type of current asphalt concrete pavement, as well as customer requirements for cost and speed of work. Let's look at the existing pothole repair methods used by our company.
Hot mix asphalt concrete. A mixture consisting of bitumen, mineral powder, crushed stone and sand is used. The so-called "asphalt". The advantage of this method is high quality, because The material from which the road itself is made is used. Materials react differently to changes in temperature and pressure from vehicles. If the material is homogeneous, the deformation and compaction will be the same, which reduces the likelihood of local cracks and potholes.
Cast asphalt concrete mixture. The temperature of cast asphalt also reaches 250 C during installation. The increased bitumen content (about 10%) makes the mixture liquid. Therefore, it is laid without a roller, the mixture is smoothly distributed over the base. State of aggregation makes the coating of cast asphalt elastic, monolithic and hydrophobic. More often used for leveling the bottom layer of road pavement in bridge structures. Pothole repair of coatings cast asphalt concrete will cost more. The price per m2 is usually 40-60% more expensive than conventional mixtures.
Polymer bitumen mixture. Polymer-Bitumen binder is a mixture consisting of petroleum bitumen, polymers, plasticizers and an adhesive attachment. Polymers play the main role here. Their physical properties eliminate rutting on roads in summer and the appearance of cracks at cold temperatures. Therefore, PMB mixtures are one of the best road materials. However, you may not like the price of such material in contrast to its quality. If you are interested in patching roads of categories I and II, we recommend considering this mixture.
Cold asphalt. Here we can also say about cold mixtures based on bitumen and liquefied emulsions, however, our company does not use this method, because the price/quality ratio has no practicality. In this case, sometimes it is necessary to use recycled asphalt or asphalt chips- milled asphalt concrete. Such a coating will not be durable, but can serve as a temporary solution in case of a limited budget.
You can often see a road crew on city streets repairing asphalt pavement by filling holes and potholes. Such repairs are carried out at any time of the year.
The main causes of damage to asphalt pavement
It is necessary to carry out when the asphalt covering is partially destroyed. It can be caused by various factors:
- long-term and intense load on the road surface (large daily traffic flow);
- the composition or structure of the asphalt pavement does not correspond to the loads on it;
- damage to asphalt from mechanical impact;
- the coating is damaged due to repairs and restoration work public utilities (replacement of communications, elimination of pipe breaks);
- roots of nearby greenery;
- destruction of asphalt from regular exposure to fuels and lubricants.
Partial “delamination” of the asphalt pavement can be caused by impaired production technology of the composition. This may be due to an insufficient amount of bitumen in the mixture or violations were made when laying the asphalt pavement.
It is necessary to carry out “hole-and-patch” repairs so that the coating does not deteriorate even more, which will lead to a complete replacement of the asphalt covering of an entire section of the road.
Technological process of pothole repair
Such repairs are quite simple and consist of several stages: marking the area, cutting down and cleaning the hole, paving potholes.
Preparatory work:
- First, the areas of damage are marked; for this purpose, a schematic map is drawn up for repairing the holes. The areas of the damaged section of the road where asphalt replacement is needed are identified with rectangular figures.
- Then the marked rectangles are cut down and cleaned to a depth of 15 cm using jackhammers and seam cutters. In cases where the damage is extensive, equipment designed for these purposes is used.
- After cutting down, the quality of laying the coating is checked, possibly main reason destruction in a poorly laid base or its complete absence. When the base is there, just add crushed stone and compact it. If there is no “cushion” of crushed stone, the pothole is cleaned of dirt and the base is made anew. Before filling potholes, their edges are treated with bitumen to better bond the old asphalt layer to the new one. If a large area of the road is damaged, cutting and dismantling is carried out using an excavator.
The process of asphalting pits
If the pothole is small, it is repaired manually, filling the asphalt mass with special rakes. Compact and level the area covered with asphalt using hand rollers or vibrating plates. Large potholes are filled with an asphalt paver and compacted with a roller.
The road surface is 30-40% more than full asphalting of the road due to the use of manual labor.
13.4. Pothole repair of asphalt concrete and bitumen-mineral materials. Basic methods of patching repairs and technological operations
The task of pothole repair 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 method or another depends on the size, depth and number of potholes and other coating defects, 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 cutting off 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 it. To give the pothole a rectangular shape, use small cold milling machines, circular saws, hammer drills.
Asphalt concrete mixtures that require compaction are predominantly used as repair materials, and small-sized rollers and vibratory rammers are used as mechanization tools.
When carrying out work in conditions of increased moisture, potholes are dried with compressed air (hot or cold) before priming, as well as using infrared burners. If the coating is being repaired in small areas (up to 25 m2), 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 reserve for compaction. When the depth of potholes is 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 for high quality repairs, 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 m2 or more are repaired using the surface treatment method using fine crushed stone.
The repair method involving 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 allows you to obtain high quality repairs, saves material, simplifies the technology of work, but has significant restrictions on weather conditions (wind and air temperature). It is used in the repair of all types of coatings made from asphalt concrete and bitumen-mineral mixtures.
The method of repair by filling potholes, pits and subsidence without cutting out or heating the old coating is to fill these deformations and destruction with a cold polymer-asphalt concrete mixture, cold asphalt concrete, a wet organic-mineral mixture, etc. The method is simple in execution and allows work to be done in cold weather with damp and wet pavement, but does not ensure high quality and durability of the repaired pavement. It is used for repairing surfaces on roads with low traffic volumes or as a temporary, emergency measure on roads with high traffic volumes.
Based on the type of repair material used, there are two groups of pothole repair methods: cold and hot.
Cold ways are based on the use of cold bitumen-mineral mixtures, wet organic-mineral mixtures (BOMC) or cold asphalt concrete as repair materials. They are mainly used for repairing black crushed stone and cold asphalt concrete surfaces on low-category roads, as well as when it is necessary to urgently or temporarily fill potholes in larger areas. early dates on roads of high categories.
Pothole repair work using 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 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, and the bottom and walls of the potholes are heated using burners 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 this, repair material is laid and compacted.
The formation of a coating at the repair site using a cold method occurs under traffic for 20-40 days and depends on the properties of liquid bitumen or bitumen emulsion, the type of mineral powder, weather conditions, intensity and composition of traffic.
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 mixer outlet of 90-120 °C. Mixtures can be stored in stacks up to 2 m high. summer period they can be kept in open areas, in the autumn-winter period - in closed warehouses or under a canopy.
Repair work can be carried out at a lower air temperature, repair material can be prepared in advance. The cost of work using this technology is lower than with the hot method. The main disadvantage is the relatively short service life of the repaired surface on roads with 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 sand mixtures, cast asphalt concrete, etc. The composition and properties of the asphalt concrete mixture used for repairs must be similar to that from which the coating is made. The mixture is prepared using conventional technology for preparing hot asphalt concrete. Hot methods are used to repair roads with asphalt concrete pavement. Work can be performed at an air temperature of at least +10°C with a thawed base and dry coating. When using a heater for the coating being repaired, it is allowed to carry out repairs at an air temperature of at least +5°C. Hot methods of pothole repair can ensure higher quality and longer service life of the repaired coating.
As a rule, all pothole repair work is carried out in early spring as soon as weather conditions and surface conditions permit. In summer and autumn, potholes and pits are repaired immediately after they appear. Technology and organization of work in various ways have their own characteristics. However, for all methods of pothole repair 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 for work sites, road signs and lighting if work is carried out at night;
marking repair locations (maps);
cutting, breaking or milling damaged areas of the coating and removing the removed material;
cleaning potholes from residual material, dust and dirt;
drying the bottom and walls of the pothole if the repair is carried out using a hot method with a wet surface;
treatment (priming) of the bottom and walls of the pothole with bitumen emulsion or bitumen.
Marking of repair locations (repair maps) is carried out using a stretched cord or with chalk using a lath. The repair site is delineated with straight lines parallel and perpendicular to the axis of the road, giving the contour the correct shape and capturing the intact surface 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 to the thickness of the destroyed coating layer, but not less than 4 cm throughout the repair area. Moreover, if the pothole in depth 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 of durable, undamaged asphalt concrete along the entire marked contour. These edge strips of the pothole cannot be left unremoved, since the solidity of the asphalt concrete here is weakened due to the formation of microcracks, loosening and spalling of individual crushed stones from the walls of the pothole (Fig. 13.10, a). Water collects in the pothole, which, under the dynamic influence of car wheels, penetrates into the interlayer space and weakens the adhesion of the upper layer of asphalt concrete to the lower one. Therefore, if you leave the weakened edges of a pothole, then after laying the repair material after some time, the weakened edges may collapse, the newly laid material will lose contact with the strong old material and the development of a pothole will begin.
Rice. 13.10. Cutting a pothole before laying repair material: a - cutting weak spots; b- cutting the edges of the pothole after milling; 1 - weakened pothole wall; 2 - peeled part of the coating; 3 - destroyed part of the pothole bottom; 4 - chopped or beveled pothole wall
The walls of the edges of the pothole after cutting should be vertical along the entire contour. Cutting down and breaking up the coating can be done using a pneumatic jackhammer or crowbar, a concrete breaker, a seam cutter and ripper, or using a road milling machine.
When a road mill is used to cut a pothole, it creates rounded front and back walls of the pothole that must be cut with a circular saw or jackhammer. Otherwise, the upper part of the laid layer of repair material at the junction with the old material will be very thin and will quickly collapse (Fig. 13.10, b).
The loosened material of the old coating is removed from the pothole manually, and when using a road milling machine, the removed material (granulate) is fed into a dump truck by a loading conveyor and removed. The map is cleaned using shovels, compressed air, and, if the map area is large, using sweepers. The bottom and walls of the card are dried as necessary by blowing with hot or cold air.
Treatment of the bottom and walls of potholes with a binder (primer) is carried out in the case of laying hot mix asphalt concrete 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 bitumen emulsion with a flow rate of 0.8 l/m 2 . In the absence of mechanization means, bitumen is heated in mobile bitumen boilers and distributed over the base using a watering can.
Filling a pothole with repair material can only be done after all preparatory work. The installation technology and sequence of operations depend on the method and volume of work performed, as well as on the type of repair material. If the volume of work is small and there are no means of mechanization, the laying of repair material can be done manually.
Temperature hot asphalt concrete mixture delivered to the place of installation should be close to the cooking temperature, but not lower than 110-120°C. It is most advisable to lay the mixture at a temperature when it is easily processed, and during the laying process waves and deformations do not form during the passage of the roller. Depending on the type of mixture and its composition, this temperature is considered: for a poly-crushed mixture - 140-160 ° C; for medium crushed stone mixture - 120-140°C; for a low-gravel mixture - 100-130°C.
The mixture is laid in the card 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 bottom layer, and only a fine-grained mixture with a fraction size of up to 20 mm can be placed in the top layer.
The thickness of the laying layer in a loose body must be greater than the thickness of the layer in a dense body, taking into account the safety factor for compaction, which is accepted: for hot mix asphalt concrete 1.25-1.30; for cold asphalt concrete mixtures 1.5-1.6; for wet organic-mineral mixtures 1.7-1.8, for crushed stone and gravel materials treated with binder, 1.3-1.4.
When laying repair material using a mechanized method, the mixture is fed from a thermos hopper through a rotary tray or flexible hose of large diameter directly into the pothole and is evenly leveled over the entire area. Laying asphalt concrete mixtures when sealing maps with an area of 10-20 m2 can be done with an asphalt paver. In this case, the mixture is laid over the entire width of the card in one pass in order to avoid an additional longitudinal seam for mating the laying strips. The asphalt concrete mixture laid in the bottom layer of the coating is compacted using 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 vibrating roller (first two passes along the track without vibration, and then two passes along the track with vibration) or light-type static smooth-timber rollers weighing 6-8 tons up to 6 passes along one track, and then with heavy rollers with smooth rollers weighing 10-18 tons up to 15-18 passes along one track.
The compaction coefficient should be no lower than 0.98 for sandy and low-crushed asphalt concrete mixtures and 0.99 for medium- and high-crushed mixtures.
Compaction of hot asphalt concrete mixtures begins at the highest possible temperature at which deformations do not form during the rolling process. The compaction must ensure not only the required density, but also the evenness of the repair layer, as well as the location of the repaired coating at the same level as the old one. To better mate the new coating with the old one and form a single monolithic layer when laying hot mixtures, the joint along the entire contour of the cutting is heated using a line of burners or an electric heater. Pothole seal joints protruding above the surface of the coating are removed using milling or grinding machines. The final work is the removal of the remaining waste from the repair, loading it into dump trucks and removing fences and road signs, restoring 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 all technological operations (Fig. 13.11).
Rice. 13.11. The sequence of basic patching operations: a - correct; b- incorrect; 1 - pothole before repair; 2 - cutting or cutting, cleaning and treatment with binder (priming); 3 - filling with repair material; 4 - seal; 5 - view of a repaired pothole
The most important requirements are the following:
repairs must be carried out at an air temperature not lower than permissible for a given repair material on a dry and clean surface;
when cutting down the old covering, weakened material must 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 vertical, and the bottom is level; the entire surface of the pothole must be treated with a binder;
repair material must be laid when optimal temperature for this type of mixture; the thickness of the layer should be greater than the depth of the pothole, taking into account the margin for the compaction coefficient;
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 card is not allowed to avoid shocks when a car hits and rapid destruction of the repaired area.
The result of a correctly performed 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 old coating material, long service life of the repaired coating. The result of incorrectly performed repairs may be unevenness of the compacted material when its surface is higher or lower than the surface of the coating, arbitrary shapes of the card in plan, insufficient compaction and poor connection of the repair material with the material of the old coating, the presence of protrusions and sagging on the edges of the card, etc. Under the influence of transport and climatic factors, areas of such repairs are quickly destroyed.
Pothole repair of black crushed stone or gravel surfaces. When repairing such pavements, simpler materials and repair methods can be used to reduce the cost of maintaining roads with black crushed stone and black gravel pavements. Most often, these methods are based on the use of cold bitumen-mineral mixtures or materials treated with bitumen emulsion as repair materials. One such material 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. When using liquid bitumen or tar, cement or lime is used as an activator.
So, for example, to repair potholes up to 5 cm deep, a repair mixture is used consisting of: crushed stone 5-20 mm - 25%; sand - 68%; mineral powder - 5%; cement (lime) - 2%; liquid bitumen - over weight 5%; 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), mix;
add the calculated amount of water and mix;
an organic binder is introduced, heated to a temperature of 60°C, and finally mixed.
The amount of water introduced is adjusted depending on the intrinsic moisture content of the mineral materials.
When making the mixture, mineral materials are not heated or dried, which significantly simplifies the preparation technology and reduces the cost of the material. The mixture can be prepared for future use.
Before laying the mixture, the bottom and walls of the pothole are not primed with bitumen or emulsion, but rather moistened or washed with water. The laid mixture is compacted and movement is opened. The final formation of the layer occurs under the movement of traffic.
Pothole repairs using wet bitumen-mineral mixtures can be carried out at positive temperatures not higher than +30°C and at negative temperatures not lower than -10°C in dry and damp weather.
Patch repair of black crushed stone coatings using impregnation method. Crushed stone is used as a repair material, 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, cut off its edges, scrape up the old coatings and remove the loosened material, treat the bottom and walls of the pothole with hot bitumen at a flow rate of 0.6 l/m2. Then black crushed stone of a fraction of 15-30 mm is laid and compacted with a manual tamper or vibratory roller; bitumen is poured at a flow rate of 4 l/m2; lay a second layer of black crushed stone of fractions 10-20 mm and compact it; crushed stone is treated with bitumen at a consumption of 2 l/m2; stone screenings of fractions of 0-10 mm are scattered and compacted with a pneumatic vibrating roller. Using the same technology, repairs can be made by impregnation and using crushed stone not treated with bitumen. At the same time, bitumen consumption increases: during the first spill - 5 l/m 2, during the second - 3 l/m 2. Distributed bitumen impregnates the layers of crushed stone to the full depth, resulting in the formation of a single monolithic layer. This is the essence of the impregnation method. For impregnation, viscous bitumens 130/200 and 200/300 are used at a temperature of 140-160°C.
A simplified method of pothole repair involving impregnation of crushed stone with bitumen emulsion or liquid bitumen is widely used in France for filling small potholes on roads with low and medium traffic intensity. Such potholes are called "chicken's nest".
The repair technology consists of the following operations:
first, potholes or pits are manually filled with large-sized crushed stone - 10-14 or 14-25 mm;
then, as it is filled, small crushed stone of fractions 4-6 or 6-10 mm is scattered until the road profile is completely restored;
pour the binder: bitumen emulsion or bitumen in a ratio of 1:10, i.e. one part binder per ten parts crushed stone by weight;
compaction is performed manually using a vibrating plate.
The binder penetrates into the crushed stone layer to the base, resulting in the formation of a monolithic layer. The final formation occurs under the influence of moving cars.
In addition to direct impregnation, the reverse impregnation method is used for patching repairs. 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 hot bitumen spill, 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 tamper.
When a mineral material that 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/m2, covered with a thin layer of crushed stone and compacted.
If the pothole depth is up to 6 cm, all fillings are carried out in one layer. At greater depths, filling is carried out in layers 5-6 cm thick. Pothole repair work can also be carried out using this method negative temperature air. However, the service life of the repaired areas in this case is reduced to 1-2 years.
Pothole repair using crushed stone treated with bitumen emulsion has a number of advantages: there is no need to heat the binder to prepare the mixture; can be laid at positive ambient temperatures, i.e. from the beginning of spring to the end of autumn; rapid disintegration of the cationic emulsion, which promotes the formation of a repair layer; there is no cutting of edges, removal of material or priming.
To perform the work, a repair vehicle is used, which includes: a base vehicle with a thermally insulated emulsion tank with a capacity of 1000 to 1500 liters; distribution device for emulsion (compressor, hose, nozzle); bunkers of crushed stone fractions from 2-4 to 14-20. The cationic emulsion used must be fast disintegrating, contain 65% bitumen and be in a warm state at a temperature of 30°C to 60°C. The surface to be treated must be clean and dry.
The technology for repairing deep holes of more than 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 onto a layer of crushed stone 10-14; laying the 3rd layer of crushed stone 6-10; spraying binder onto a layer of crushed stone 6-10; laying the 4th layer of crushed stone 4-6; spraying binder onto a layer of crushed stone 4-6; laying the 5th layer of crushed stone 2-4 and compacting.
It is important to ensure the correct dosage of the binder when spraying the emulsion on crushed stone. Crushed stone should only be covered with a film of binder, but not buried in it. The total consumption of binder should not exceed the ratio of binder: crushed stone = 1:10 by weight. The number of layers and size of crushed stone fractions depends on the depth of the pothole. When repairing small potholes up to 10-15 mm deep, repairs are performed in the following order: laying a layer of crushed stone 4-6; spraying binder onto crushed stone 4-6; crushed stone distribution 2-4 and compaction.
These methods are applicable when repairing black crushed stone 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 appearance The patch follows the contours of the pothole.
Pothole repair of asphalt concrete pavements using an asphalt heater. The work technology is greatly simplified in the case of performing pothole repairs 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 surface 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 and the height of the burners above the coating from 10 to 20 cm.
After heating, the asphalt concrete coating is loosened with a rake to the entire depth of the pothole, a new hot asphalt concrete mixture from a thermos bunker is added to it, mixed with the old mixture, distributed over the entire width of the map in a layer greater than the depth by 1.2-1.3 times, taking into account the compaction coefficient and compact from the edges to the middle of the repaired area using a manual vibratory roller or self-propelled roller. The interface between the old and new coatings is heated using a line of burners included in the asphalt heater. The line of burners is a movable metal frame with infrared burners mounted on it, which are supplied with gas from cylinders according to flexible hose. During repair work, the coating temperature should be within 130-150°C, and by the end of compaction work - not lower than 100-140°C.
The use of an asphalt heater significantly simplifies the technology of pothole repair and improves the quality of work.
The use of gas-powered 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 gas will flow from them, 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 using special pothole repair machines or road repairers. The most effective and high-quality type of pothole repair is repair performed using special machines called road repairers. Road repairers are used as a means of comprehensive mechanization of road repair work, since with their help not only pothole repairs are carried out road surfaces, but also sealing cracks and filling joints.
The technological scheme for pothole repair using a road repairman includes conventional operations. If the repairman is equipped with a heater, the repair technology is greatly simplified.
Simplified methods of pothole repair (injection methods). In recent years, simplified methods of pothole repair using special machines such as “Savalco” (Sweden), “Rasko”, “Dyura Petcher”, “Blow Petcher”, etc. have become increasingly widespread. In Russia, similar machines are produced in the form of special trailed equipment - sealer brand BCM-24 and UDN-1. Pothole repair using the injection method is performed using a cationic emulsion. Cleaning of potholes for repair is carried out using a jet of compressed air or using the suction method; primer - emulsion heated to 60-75°C; filling - crushed stone blackened during injection. With this repair method, trimming the edges is not necessary.
Crushed stone of a fraction of 5-8 (10) mm and an emulsion of the EBK-2 type are used as repair materials. A concentrated emulsion (60-70%) is used on BND 90/130 or 60/90 bitumen with an approximate consumption of 10-11% by weight of crushed stone. The surface of the repaired area is sprinkled with white crushed stone in a layer of one crushed stone. Traffic opens after 10-15 minutes. Work is carried out at an air temperature of at least +5°C on both dry and wet surfaces.
Pothole repair using the injection method is performed in the following order (Fig. 13.12):
Rice. 13.12. Pothole repair using simplified technology: 1 - cleaning potholes by blowing compressed air; 2 - priming with bitumen emulsion; 3 - filling with crushed stone treated with emulsion; 4 - applying a thin layer of untreated crushed stone
the first stage - the area of the hole or patch is cleaned with a jet of air under pressure to remove pieces of asphalt concrete, water and debris;
the second stage is priming the bottom, walls of the pothole and the surface of the adjacent asphalt concrete pavement with bitumen emulsion. The emulsion flow is controlled by a control valve on the main nozzle. The emulsion enters the air stream from the spray ring. The emulsion temperature should be about 50°C;
the third stage is filling the pothole with repair material. Crushed stone is introduced into the air flow using a screw conveyor, then enters the main mouthpiece, where it is covered with an emulsion from the spray ring, and from it the treated material is thrown into the pothole at high speed and distributed in thin layers. Compaction occurs due to forces resulting from high velocities of 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, which controls the flow of the emulsion, is turned off.
It should be noted that the exclusion of preliminary cutting of the edges of the pothole leads to the fact that old asphalt concrete with a damaged structure remains in the edge zone of the pothole, which, as a rule, has reduced adhesion to the underlying layer. The service life of such a patch will be shorter than with traditional technology. In addition, the patches have irregular shapes, which worsens the appearance of the coating.
Pothole repair using cast asphalt concrete mixtures. A distinctive feature of cast asphalt concrete mixtures 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, for repair work, a sand cast asphalt concrete mixture is used, consisting of natural or artificial quartz sand in an amount of 85% by weight, mineral powder - 15% and bitumen - 10-12%. To prepare 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 installation is carried out in special mobile boilers of the Kocher type or in thermos bunkers.
The delivered mixture is poured into the prepared pothole at a temperature of 200-220°C and easily leveled using wooden trowels. The easily moving mixture fills all the unevenness and, thanks to its high temperature, heats the bottom and walls of the pothole, resulting in a strong connection of the repair material on the coating side.
Since a fine-grained or sand cast mixture creates a surface with increased slipperiness, it is necessary to take measures to improve its adhesion qualities. For these purposes, immediately after distributing the mixture, black crushed stone 3-5 or 5-8 is scattered over it with a consumption of 5-8 kg/m2 so that the crushed stone is evenly distributed in a layer of one crushed stone. After the mixture has cooled to 80-100°C, crushed stone is rolled with a hand roller weighing 30-50 kg. When the mixture has cooled to ambient temperature, excess crushed stone that has not been sunk into the mixture is swept away and movement is opened.
Laying cast asphalt concrete mixtures during patching can be done manually or with a special asphalt paver with a heating system. The advantage of this technology is that the operations of priming the repair card and compacting the mixture are eliminated, as well as the high strength of the repair layer and the reliability of the joints connecting new and old materials. The disadvantages are the need to use special mixers, heated mobile rollers and mixers or thermos-hoppers, viscous refractory bitumen, as well as increased safety and health requirements when working with a mixture that has a very high temperature.
In addition, cast asphalt during operation has significantly greater strength and less deformability compared to conventional asphalt concrete. Therefore, in the case when a coating made of conventional asphalt concrete is repaired with cast asphalt, after a few years this coating begins to collapse around the cast asphalt patch, which is explained by the difference in the physical and mechanical properties of the old and new material. Cast asphalt is most often used for pothole repair of city roads and streets.
One of the ways to simplify the technology of work and increase the construction season is to use cold asphalt concrete mixtures with polymer bitumen binder (PBB) 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.
The asphalt concrete mixture using PMB is prepared in mixers with forced mixing at a temperature of 50-60°C. The mixture consists of fine crushed stone of fractions 3-10 in an amount of 85% by weight of mineral material, screenings 0-3 in an amount of 15% and binder in an amount of 3-4% of the total weight mineral material. Then the mixture is 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, maintaining 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 a car body or from a road repairman’s hopper is manually or using a hose fed into the pothole and leveled, after which traffic is opened, under the influence of which a road layer is formed. The entire process of pothole repair takes 2-4 minutes, since the operations of marking a map, cutting and cleaning the pothole, as well as compaction with rollers or vibratory rollers are eliminated. The adhesive properties of the mixture are preserved even when it is laid in potholes filled with water. Repair work can be carried out at negative air temperatures, the limit of which requires clarification. All this makes this method of pothole repair very attractive for practical purposes.
However, it also has a number of significant disadvantages. 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 if there is water in the pothole, some of the moisture may 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 interface between new and old materials can be initiated. The second disadvantage of this repair method is that the irregular external shape of the pothole remains after repair, which worsens the aesthetic perception of the road.
Availability large quantity Pothole repair methods make 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 pothole repair, 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.
ODM 218.3.060-2015
INDUSTRY ROAD METHODOLOGICAL DOCUMENT
Preface
1 DEVELOPED by the Federal State Budgetary educational institution higher professional education "Moscow Automobile and Highway State Technical University (MADI)"
2 INTRODUCED by the Department of Scientific and Technical Research and Information Support of the Federal Road Agency
5 INTRODUCED FOR THE FIRST TIME
1 area of use
1 area of use
2 Normative references
Temperature cracks occur as a result of cooling and the coating's resistance to thermal shrinkage. Vertically, these cracks develop from top to bottom, from the surface of the coating to the base.
Fatigue cracks that occur when a monolithic layer bends under repeated transport loads develop from bottom to top from the base to the surface of the coating.
Reflected cracks replicate the seams or cracks of cement concrete pavements and are most characteristic of asphalt concrete layers laid on a cement concrete pavement. When the temperature drops, deformation of the cement concrete coating occurs in the form of shortening of the slabs. As a result, the seams or cracks in the cement concrete pavement expand, causing the overlying layers of asphalt concrete to stretch and rupture, forming reflected cracks. To these tensile stresses are added the own tensile stresses from the decrease in the temperature of the asphalt concrete. This is a time-cyclic process that leads to the destruction of the asphalt concrete pavement.
Based on their width, cracks are classified into narrow (up to 5 mm), medium (5-10 mm) and wide (10-30 mm). This classification is typical for temperature and fatigue cracks. For reflected cracks, this approach is incorrect, due to the presence of temperature deformations of the underlying cement concrete pavement, causing movement of the crack edges depending on temperature, the length of the cement concrete slab, the thickness of the asphalt concrete pavement and other factors.
Depending on the width and type of cracks, the technology for their repair and the composition of the equipment used are chosen. The main task when repairing cracks is to prevent water from penetrating through them into the underlying layers of the pavement. Waterproofing cracks is achieved by sealing them with special mastics and repair mixtures.
6.1.3 When choosing mastics, it is necessary to focus on their basic physical and mechanical properties. One of the most important indicators for the selection of mastics is adhesive strength, the requirements for which must comply with GOST 32870-2014.
6.1.4 Sealing narrow temperature or fatigue cracks on the surface of asphalt concrete layers laid on a cement concrete pavement does not require complex technological operations. The cracks are cleaned by blowing with compressed air, dried, heated and filled with bitumen emulsion or mastic with high penetrating ability.
6.1.5 On thin temperature or fatigue cracks (2-5 mm), heated polymer-bitumen mastic can be applied in the form of a tape that prevents chipping of the coating at the edges of the crack. It is smoothed with a special heating iron (shoe) and sprinkled with fractionated sand. The coating in the crack zone is pre-dried with a heated stream of compressed air.
6.1.6 If a crack has destroyed edges, the repair technology should begin with the operation of cutting it, that is, artificial expansion of the upper part of the crack to form a chamber in which optimal tensile performance of the sealing material is ensured during the period of crack opening.
6.1.7 The width of the chamber must be no less than the destruction zone of the crack edges. To create the best working conditions for the sealant in the chamber, the ratio of the width and depth of the chamber is usually taken as 1:1. In addition, when determining the geometric dimensions of the chamber, it is necessary to take into account the maximum possible crack opening and the relative elongation of the sealing material used. Typically the chamber width is in the range of 12-20 mm.
6.1.8 If a temperature or fatigue crack is not cut to its full depth (the thickness of the cracked coating exceeds 10 cm), then before sealing, a special sealing cord made of an elastic material that is thermally and chemically resistant to the sealant and environment. When using a sealing cord for pressing in, it must be taken into account that its diameter should be 1.2-1.3 times greater than the width of the cut crack chamber.
The depth of the groove after pressing the sealing cord (the upper free part of the chamber) is taken depending on the properties of the sealant.
Instead of a sealing cord, a layer of bituminized sand or a layer of rubber crumb laid on the bottom of the chamber, with a thickness equal to an average of 1/3 of its depth, can also be used, after which the chamber is filled with sealant.
When using bituminized sand, coarse and medium sand is used that meets the requirements of GOST 8736-2014 and GOST 11508-74 *.
Rubber crumbs must have particle sizes in the range of 0.3-0.5 mm and meet the requirements *.
________________
*See section. - Database manufacturer's note.
Depending on the temperature of stickiness and resistance of the sealant to wear under the influence of car wheels, it should be filled with underfilling, flush or with the formation of a patch on the surface of the coating.
6.1.9 In the case where the edges of a temperature or fatigue crack have not been subjected to destruction and it is possible to qualitatively seal the crack without cutting it, this operation can be excluded from the technological process.
6.1.10 The most important condition ensuring the quality of crack sealing is the presence of good adhesion of the sealant to the walls of the uncut crack or milled chamber. In this regard, much attention is paid to preparatory work on cleaning and drying the crack. To improve adhesion, the walls of the milled chamber are primed with a primer - a low-viscosity film-forming (adhesive) liquid.
6.1.11 The main technological operation when repairing temperature or fatigue cracks is their filling hot mastic. The mastic is preheated to a temperature of 150-180°C, after which it is fed into a built-in chamber or directly into the crack cavity. In this case, depending on the equipment used, it is possible to seal either the crack itself, or simultaneously with filling with mastic, place a plaster on the surface of the coating in the crack area. This patch, 6-10 cm wide and 1 mm thick, allows you to strengthen the edges of the crack and prevent their destruction.
It is advisable to use sealing with adhesive for cracks with significant destruction of the edges (10-50% of the crack length), because in this case, defects on the coating surface in the crack zone are healed.
The method of remediation of medium and wide temperature or fatigue cracks of asphalt concrete layers laid on cement concrete is divided into five stages:
1. Cutting cracks. In this case, special crack separators are used. To avoid damage to the edges when cutting a crack in an asphalt concrete pavement, it is necessary when choosing cutting tool take into account the composition of asphalt concrete. For crushed stone grain sizes of 20 mm or more, it is recommended to use diamond tool, and when the aggregate size is up to 20 mm, cutters with carbide surfacing can be used.
2. Removal of destroyed asphalt concrete. For this, a high-performance compressor is used. For thorough cleaning both from dust resulting from cutting, and to remove deposits remaining deep in the crack.
3. Drying and warming up. The cut cavity of the crack is dried and heated with a so-called heat lance.
The parameter for stopping heating is the appearance of melted bitumen on the crack walls. Under no circumstances should a crack be overheated; burning out the bitumen will lead to a sharp decrease in adhesion and further destruction of the coating around the crack.
In this regard, heating the crack with open-flame burners is unacceptable.
4. Filling the crack cavity with sealant. Immediately fed into the cleaned, dried and heated cavity of the cut crack bitumen mastic from a melting and casting machine.
Modern pourers, in general, are a heated tank mounted on a frame equipped with wheels. Heating can be carried out using coolant oil, gas or a burner with diesel fuel. The sealing material is loaded into a tank, where it is heated to operating temperature, and then, using a pump, it is fed through heat-resistant hoses into the prepared crack.
Cracks are directly sealed through various nozzles, the size of which depends on the width of the crack being filled. If necessary, the filling nozzle can be equipped with shoes for installing a mastic plaster on the coating surface in the crack zone.
To reduce the dynamic load on the seam and reduce the adhesion of the sealant to the wheel of a passing car, it is necessary to fill only the internal cavity of the crack without spilling onto the edges.
5. Powder. Immediately after filling the crack with sealant, the repair area is covered with sand or a mixture of fine crushed stone and mineral powder.
6.1.12 For powdering, special equipment is used - a distributor. The equipment is a bunker mounted on three wheels. Moreover, the front piano wheel allows you to move exactly in the direction of the crack, and a dosing roller is mounted on the axis of the rear wheels inside the hopper. The distributor is moved manually along the sealed crack, immediately behind the pourer, while the wheels rotate the roller, dispensing crushed sand or fine crushed stone onto the surface of the mastic poured into the crack.
The powder serves to restore the overall texture and roughness of the coating, prevents mastic from sticking to the car wheels, and reduces the fluidity of the sealant immediately after filling the crack.
6.1.13 When carrying out crack rehabilitation work, it is necessary to ensure the continuity of the technological process. Allowable time gaps between individual technological operations should not exceed the following values: 1 - crack cutting - up to 3 hours; 2 - crack cleaning - up to 1 hour; 3 - heating of the side walls of the crack - up to 0.5 min; 4 - crack sealing - up to 10 minutes; 5 - sprinkle the surface of the sealant with sand or fine crushed stone with mineral powder.
6.1.14 The crack rehabilitation technology is implemented by a set of equipment consisting of:
A crack separator with a diamond tool for road pavement aggregate size over 20 mm; for aggregate size up to 20 mm, cutters with carbide surfacing are used;
A mechanical brush or a wheeled tractor with a mounted brush (in cases where it is necessary to rehabilitate fairly wide and heavily contaminated cracks, they can be cleaned with disk brushes with metal bristles, brushes with a disk with a diameter of 300 mm and a thickness of 6, 8, 10 or 12 mm, the thickness should be 2-4 mm less than the width of the crack being cleaned);
Compressor;
Gas generator or heat lance. The principle of operation of the heat lance is based on the fact that compressed air from a compressor with a capacity of 2.5-5.0 m/min with a pressure of 3.5-12 kg/cm is mixed with natural gas and, in the form of a gas-air mixture, enters the combustion chamber, where it is ignited . Air heated to a temperature of 200-1300°C is supplied through a nozzle at a speed of 400-600 m/sec to the zone of the crack being treated. Gas consumption in this case is 3-6 kg/hour. A high-speed flow of compressed air, in addition to heating, effectively cleans the cavity of the crack itself and, in addition, pulls out individual destroyed particles of the coating from the area adjacent to the crack;
Melting and casting machine mounted on a vehicle chassis;
Equipment for filling a sealed crack.
6.1.15 When repairing reflected cracks, first of all it is necessary to determine whether the crack being repaired is of the reflected type. Visually reflected cracks are easy to distinguish from temperature and fatigue cracks, since they pass over the seams of the underlying cement concrete coating, as if “copying” them.
If there are cracks in the cement concrete itself, then such reflected cracks can be identified on the surface of the asphalt concrete layer using a georadar survey.
6.1.16 One of the ways to repair reflected cracks is to artificially expand its upper part to form a chamber, the width of which takes into account the maximum possible opening of the crack (usually at least 1 cm) and the relative elongation of the sealing material used.
The technology for carrying out repair work of this type is discussed in clauses 6.1.6-6.1.8.
6.1.17 Another method is to repair reflected cracks using reinforcing geogrids in combination with continuous non-woven geotextiles. In this case, the geogrid is included in the work of tension during bending, preventing the crack from opening, and the geotextile acts as a damping layer that absorbs the stresses that arise in the crack zone during temperature movements of the cement concrete slabs.
The following requirements are imposed on the geogrid: it must have high heat resistance, low creep with sufficient high temperatures laying asphalt concrete mixture (120-160°C) and good adhesion to bitumen. The cell sizes are taken depending on the composition of the asphalt concrete mixture and ensuring good adhesion between the coating layers (about 30-40 mm when using hot asphalt concrete mixtures on viscous bitumens).
The following requirements are imposed on the non-woven layer of geotextile: the density of the layer should be no more than 150-200 g/m, tensile strength 8-9 kN/m, elongation at break 50-60%.
6.1.18 Repair of reflected cracks using reinforcing geogrids in combination with non-woven geotextiles is carried out using the following technology:
Organization traffic at the work site, installation of fencing;
Cleaning the coating from dust and dirt;
Milling of the existing asphalt concrete pavement in the crack zone to a width of 30-50 cm and to the depth of the repaired layer (but not less than 5 cm);
Subpriming of the milled asphalt concrete surface with cationic bitumen emulsion in an amount of at least 1 l/m2 in terms of bitumen;
Laying a layer of geotextile to a width of 30 cm strictly symmetrically to the axis of the crack being repaired (when laying a strip of geotextile, its pre-tension of at least 3% must be ensured. The fabric is stretched by 30 cm with a strip length of 10 m);
Laying a layer of coarse-grained asphalt concrete mixture on the geotextile layer to the width of the milled crack, followed by layer-by-layer compaction with a layer thickness of 5-6 cm. If there are lower layers, compaction is carried out by tamping, the upper layer - by small rollers or vibrating plates so that the compacted surface of the asphalt concrete is flush with existing coating;
Subpriming the surface of the laid layer of asphalt concrete with bitumen emulsion in an amount of at least 0.6 l/m in terms of bitumen for a laying width of the geogrid of 150-170 cm;
Laying the geogrid sheet strictly symmetrically to the axis of the crack being repaired;
Repeated pouring of binder over the entire width of the coating surface;
Laying and compacting the top layer of a dense, fine-grained asphalt concrete mixture in a layer of at least 5-6 cm over the entire width of the pavement being repaired.
6.1.19 One of the ways to repair reflected cracks is their rehabilitation by sealing the crack with a hot, fine-grained asphalt concrete mixture with bitumen-rubber binder. This makes it possible to significantly dampen the stresses that arise above the seams of the cement concrete pavement and absorb internal plastic deformations. Rubber crumbs in the binder act as particles of the polymer component, which provide dispersed elastic reinforcement of asphalt concrete.
Asphalt concrete mixtures based on bitumen-rubber binder should be designed, depending on the type and purpose of asphalt concrete, in accordance with GOST 9128.
Technical requirements for composite bitumen-rubber binders must meet established requirements.
For composite bitumen-rubber binders, petroleum road viscous bitumens of the BN, BND grades in accordance with GOST 22245 and liquid bitumen of the MG and MGO grades in accordance with GOST 11955 are used as starting materials.
Fine crumb rubber is used, which is crumbs from general-purpose rubber, including rubber obtained by crushing worn-out car tires or other rubber technical products. The crumb must have particle sizes in the range of 0.3-0.5 mm and meet the requirements.
6.1.20 The technology for repairing reflected cracks using hot fine-grained asphalt concrete mixture with bitumen-rubber binder includes the following technological operations:
Crack cutting;
Mechanical cleaning of the crack;
Blowing out the crack with compressed air;
Warming up the side walls of the crack, priming the bottom and walls of the crack;
Sealing the crack with a hot fine-grained asphalt concrete mixture with bitumen-rubber binder;
Compaction of asphalt concrete mixture.
For compaction, a small-sized roller or vibrating plate is used.
The temperature of the asphalt concrete mixture on bitumen BND 40/60, BND 60/90, BND 90/130, BND 130/200, BND 200/300 with bitumen-rubber binder at the beginning of compaction should not be lower than 130-160 ° C for dense asphalt concrete types A and B and high-density asphalt concrete.
6.1.21 The technological sequence of work when repairing potholes consists of the following operations: cleaning the asphalt concrete surface from moisture, dirt and dust at the work site; marking the boundaries of repair work in straight lines along and across the axis of the road, including 3-5 cm of undamaged surface (if several closely spaced potholes are being repaired, they are combined into one contour or map); cutting - cutting or cold milling of repaired asphalt concrete along the outlined contour to the entire depth of the pothole, but not less than the thickness of the asphalt concrete layer. In this case, the side walls must be vertical; cleaning the bottom and walls of the repair site from small pieces of crumbs, dust, dirt and moisture; treating the bottom and walls with a thin layer of liquid (hot) or liquefied bitumen or bitumen emulsion, laying an asphalt concrete mixture; leveling and compacting the coating layer.
6.1.22 In the event of chipping in cement concrete pavement slabs, the resulting pothole in the overlying asphalt concrete layer can be significant in depth (more than 20-25 cm). Repair of such areas must be carried out with the removal of the entire thickness of the destroyed asphalt concrete layer, the width of the chipped surface of the cement concrete slab. Repair of a chipped surface of a cement concrete slab must be carried out in accordance with. After which the asphalt concrete mixture is laid and compacted.
6.1.23 For patching repairs of an asphalt concrete layer laid on a cement concrete pavement, it is recommended to use predominantly hot mix asphalt concrete or cast asphalt concrete of types I and II in accordance with the requirements of GOST 9128-2013 and GOST R 54401-2011, respectively.
It is recommended to use asphalt concrete mixtures that correspond in terms of strength, deformability and roughness to the asphalt concrete of the existing pavement. Hot fine-grained mixtures of types B and C should be used, since they are more technologically advanced for working with shovels, rakes and trowels in auxiliary operations than multi-crushed mixtures of type A.
To prepare hot fine-grained asphalt concrete mixtures, viscous road bitumens BND 40/60, BND 60/90, BND 90/130, BND 130/200, BND 200/300 are used in accordance with GOST 22245, as well as modified polymer-bitumen binders in accordance with OST 218.010- 98.
6.1.24 To perform edge trimming work, small milling machines, circular saws, and hammer drills are used.
Depending on the area of the repaired area, cutting of the coating is carried out in various ways. Small areas (up to 2-3 m) are contoured using a seam cutter equipped with special thin (2-3 mm) diamond discs with a diameter of 300-400 mm. Then the coating inside the circuit is dismantled with jackhammers. The asphalt concrete crumbs are removed and the area is prepared for laying the asphalt concrete mixture.
6.1.25 When preparing for the repair of narrow long potholes or areas of more than 2-3 m, it is advisable to use permanently installed, trailed or mounted cutters that cut the defective coating material with a width of 200-500 mm to a depth of 50-150 mm.
If the area is large, then special road milling machines are used. high performance with a large width of the cut material (500-1000 mm) and a maximum depth of up to 200-250 mm.
6.1.26 Primer of the bottom and walls of a contoured pothole, cleared of small pieces and dust, with a thin layer of liquid (hot) or liquefied bitumen or bitumen emulsion (bitumen consumption 0═3-0═5 l/m) can be done using: a mobile bitumen heater ═ asphalt distributor═ road repairman, etc.
Small-sized units (5 hp) that pump bitumen emulsion into the spray nozzle of a hand fishing rod with a hose 3-4 m long, and units that supply emulsion from a barrel with a hand pump are effective for lubricating a pothole being repaired.
For small volumes of work and small potholes, priming with emulsion can be done from portable containers (10-20 l) with spraying with compressed air using the spray principle.
6.1.27 Laying the asphalt concrete mixture is carried out manually or using small-sized asphalt pavers. When laying the mixture manually, leveling the asphalt concrete mixture is done using improvised means (rakes and trowels).
The pothole is filled with asphalt concrete mixture in layers of 5-6 cm, taking into account the safety factor for compaction. Among the means of mechanization, a small-sized roller or vibrating plate is used for compaction. The surface of the repaired area after compaction should be at the level of the existing coating.
6.1.28 To increase the efficiency of repairing potholes with hot asphalt concrete mixture, special repair machines are used. A thermal container for hot asphalt concrete mixture with thermal insulation and heating is placed on the base machine; tank, pump and sprayer for bitumen emulsion; a compressor for cleaning and dusting repair maps, a jackhammer drive for cutting off the edges of repair maps, a vibrating plate for compacting the asphalt concrete mixture.
6.1.29 When carrying out work in conditions of increased moisture, potholes are dried with compressed air (hot or cold) before priming.
6.1.30 Repair of potholes using the jet-injection method using cationic bitumen emulsion is carried out using special trailed equipment. The pothole is cleaned for repair using a jet of compressed air or the suction method, primed with an emulsion heated to 60-75°C, and filled with crushed stone blackened during the injection process. With this repair method, cutting off the edges does not need to be done (Fig. 6.1).
Figure 6.1 - Sequence of operations for the jet-injection method of filling a pothole: 1 - cleaning the pothole with a high-speed air stream; 2 - coating the surface of the pothole; 3 - filling and compaction; 4 - dry topping
Figure 6.1 - Sequence of operations for the jet-injection method of filling a pothole: 1 - cleaning the pothole with a high-speed air stream; 2 - coating the surface of the pothole; 3 - filling and compaction; 4 - dry topping
6.1.31 Crushed stone of a fraction of 5-10 mm and an emulsion of the EBK-2 type are used as repair materials. Use a concentrated emulsion (60-70%) based on bitumen BND 90/130 or BND 60/90 with an approximate consumption of 10% by weight of crushed stone. The surface of the “seal” is sprinkled with white crushed stone in a layer of one crushed stone. Traffic opens in 10-15 minutes. Work is carried out at an air temperature of at least +5°C, both on dry and wet surfaces.
6.1.32 On roads of categories III-IV and in cases of “emergency” repairs for higher categories of roads, repair of potholes in the asphalt concrete layer on a cement concrete pavement can be carried out using wet organic-mineral mixtures (MOMS). The repair method using VOMS involves cleaning the pothole, filling it with a mixture of moistened mineral material of a selected composition and liquid organic binder (tar or liquefied bitumen) and compacting the mixture. The thickness of the laid layer of material must be at least 3 cm.
The composition of VOMS consists of limestone or dolomite crushed stone of 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 6...7% and water. Instead of crushed stone, it is allowed to use crushed screenings of crushed slag. The mixture can be prepared for future use in conventional asphalt concrete plants, retrofitted with a water supply and dosage system.
VOMS can be used at air temperatures down to -10°C and laid on the damp surface of a pothole.
6.1.33 Another method of “emergency repair” of potholes is repair using cold asphalt concrete (repair) mixtures.
This type repairs are used for pothole areas up to 1 m. Potholes are repaired immediately after they are discovered; in some cases, work can be carried out without cutting off the pothole or milling it.
The repair cold mixture consists of a mineral filler, an organic binder with the introduction of special additives. Mixing of the mixture is carried out in forced-action installations.
As an organic binder, bitumens of the BND 60/90 and BND 90/130 brands are used, meeting the requirements of GOST 33133-2014. The properties of bitumen are improved by introducing various additives with organic solvent(thinner).
Thinners used to impart a given viscosity to the original MG 130/200 bitumen (GOST 11955-82) must meet the requirements of GOST R 52368-2005 and GOST 10585-99. The amount of thinner is 20-40% by weight of the bitumen binder and is specified by the laboratory.
In the process of preparing repair mixtures, surfactants are used to increase the adhesion strength of the binder to the surface of mineral materials and ensure the specified properties.
The temperature of the mixture should not be lower than -10°C. It is allowed to lay the repair mixture on a frozen and wet base, but in the absence of puddles, ice and snow in the area being repaired.
When repairing potholes in the surface, depending on the depth of destruction repair mixture laid in one or two layers no more than 5-6 cm thick with careful compaction of each layer.
When eliminating potholes on the surface, observe technological sequence, which includes cleaning the damaged area, leveling and compacting the repair mixture.
Priming the surface to be repaired with bitumen or bitumen emulsion is not necessary.
The repair mixture is laid taking into account the reduction in layer thickness during compaction, for which the thickness of the applied layer should be 25-30% greater than the depth of the pothole.
When repairing potholes, depending on the area of the repaired area, the mixture is compacted with a vibrating plate, a manual vibratory roller, mechanical, and for small volumes of work - with a manual tamper. If the pothole size exceeds 0.5 m, the mixture is compacted with a vibrating plate. The movement of the compacting means is directed from the edges of the area to the middle. Compaction is considered complete if there is no trace of the sealant.
The mixture is usually packaged in plastic bags weighing 20, 25, 30 kg or other quantities as agreed with the consumer. Unpackaged mixture may be stored under a canopy in open stacks on concrete floor within 1 year. The mixture packaged in sealed bags retains its properties for two years.
6.1.34 One of the methods for repairing potholes is to seal them with cast asphalt concrete mixture. This mixture differs from the usual asphalt concrete mixture in the increased content of mineral powder (20-24%) and bitumen (9-10%) of the BND 40/60 grade. Crushed stone content - 40-45%. At a laying temperature of 200-220°C, the mixture has a cast consistency, which eliminates the need for compaction. The mixture is delivered to the work site by special vehicles with a heated container and the prepared card for pothole repair is filled with it.
After the mixture has cooled to 50-60°C, traffic is opened in the repaired area.
When installing new layers of asphalt concrete pavement, the use of cast asphalt concrete mixtures to repair potholes is not allowed. When laying new asphalt concrete layers, the cast asphalt repair cards on the underlying layers should be removed.
6.1.35 Individual defects on the surface of the asphalt concrete pavement in the form of chipping and peeling are eliminated using the jet-injection method, similar to pothole repair.
6.2 Surface treatment device on the road surface
6.2.1 The device of surface treatment on the road surface helps to increase its adhesion properties, as well as protection from wear and exposure to atmospheric factors. When applying surface treatment, the tightness of the coating increases and its service life increases. In addition, minor irregularities and defects are eliminated.
6.2.2 A single surface treatment is carried out on the surface of the asphalt concrete pavement if it has defects in the form of: peeling, spalling, cracks and small potholes.
Double surface treatment is carried out if there is a significant amount of destruction on the asphalt concrete pavement (more than 15% of total area coatings). In this case, a decision may be made to mill the top layer of the asphalt concrete pavement.
6.2.3 The installation of a single surface treatment is carried out in accordance with the Methodological Recommendations for the installation of a single rough surface treatment using equipment with synchronous distribution of bitumen and crushed stone.
6.2.4 Single surface treatment is carried out, as a rule, in the warm summer periods of the year, on a dry and sufficiently warm surface at an air temperature of at least +15°C.
Sequence of single surface treatment device:
Preparatory work;
Single surface treatment device;
Care of the surface treatment layer.
6.2.5 Preparatory work includes:
Elimination of coating defects;
Selection and preparation of crushed stone and bitumen;
Selecting the initial consumption rate of crushed stone and bitumen;
Selection and adjustment of equipment and machines that are part of a specialized detachment;
Education and training of operating personnel of machines and mechanisms.
6.2.6 In areas selected for single surface treatment, elimination of defects on the roadway is carried out in accordance with the requirements. Filling of potholes and cracks must be completed at least 7 days before the start of surface treatment.
6.2.7 The selection of the approximate consumption rate of crushed stone and bitumen for a single surface treatment device is carried out according to Table 6.1.
Table 6.1 - Selection of approximate consumption rate of crushed stone and bitumen for a single surface treatment device
|
Crushed stone fraction, mm |
Consumption |
|
|
crushed stone, m/100 m |
bitumen, kg/m |
|
6.2.8 For surface treatment, it is recommended to use machines with synchronous distribution of binder and crushed stone (synchronous method of distribution of binder and crushed stone, Fig. 6.2).
6.2.9 The surface treatment device is carried out in the following sequence:
Cleaning the surface from dust and dirt;
Clarification of material consumption standards;
Synchronous distribution of bitumen and crushed stone on the surface of the roadway;
Compaction of the freshly laid rough layer;
Surface treatment care.
6.2.10 Cleaning the surface of the coating from dust and dirt is carried out with specialized machines with a nylon brush, and in case of severe contamination of the surface - with a metal brush and watering equipment. The coating is cleaned in two to five passes along the track.
Figure 6.2 - Synchronous distribution of binder and crushed stone during surface treatment
Figure 6.2 - Synchronous distribution of binder and crushed stone during surface treatment
6.2.11 Compaction of the freshly laid layer is carried out immediately after the passage of the machine with synchronous distribution of binder and crushed stone. Carry out 5-6 passes of a self-propelled roller on pneumatic wheels on the surface with a wheel load of at least 1.5 tons and a tire pressure of 0.7-0.8 MPa, or a roller with rubber-coated metal rollers. The final formation of the layer occurs under the influence of passing motor transport with a speed limit of up to 40 km/h. The period of formation of a freshly laid layer should be at least 10 days.
6.2.12 Maintenance of freshly laid surface treatment includes the following operations:
Speed limit to 40 km/h;
Regulation of traffic across the entire width of the roadway using guide fences;
Cleaning up unrooted crushed stone with the brush of a watering machine no later than one day after completion of compaction;
Additional compaction with a roller.
6.2.13 When using a single surface treatment in a synchronous manner, the time interval between pouring bitumen and distributing crushed stone is less than 1 s. This provides a significant improvement in the adhesive quality of the binder, by penetrating it into the micropores of crushed stone. In this case, the crushed stone adheres well to the surface of the coating. With the synchronous distribution of binder and crushed stone, the quality of surface treatment is significantly improved, both when using hot bitumen and bitumen emulsion as a binder.
6.2.14 Work on installing double surface treatment is carried out on a clean, dust-free surface of the coating, dry when using bitumen and moistened when using bitumen emulsions. The air temperature when using bitumen as a binder should not be lower than +15°C, and when using bitumen emulsion - not lower than +5°C. In some cases, if it is impossible to ensure the required cleanliness of the milled coating, it is recommended to prime it by pouring liquid bitumen at a rate of 0.3-0.5 l/m.
6.2.15 The technological process of the double surface treatment device includes:
Milling of asphalt concrete pavement;
Cleaning the milled surface from dust and remaining asphalt chips;
Priming the coating surface (if necessary);
The first pouring of bitumen binder is 1.0...1.2 l/m and distribution of processed crushed stone of the 20...25 mm fraction in an amount of 20...25 kg/m, followed by rolling the layer with two or three passes of a light roller (5...8 t);
The second filling of binder at a rate of 0.8...0.9 l/m;
Distribution of processed crushed stone fraction 10…15 mm (13…17 kg/m) followed by compaction with four to five passes of a light roller.
6.2.16 The approximate costs of binder and crushed stone when distributed on the coating are given in Table 6.2.
Table 6.2 - Consumption of binder and crushed stone (excluding pre-treatment)
|
Crushed stone size, mm |
Consumption rate |
|||
|
crushed stone, m/100 m |
bitumen, l/m |
emulsion, l/m, at bitumen concentration, % |
||
|
Single surface treatment |
||||
|
Double surface treatment |
||||
|
First placer |
First bottling |
|||
|
Second placer |
Second bottling |
|||
|
Note - When using black crushed stone, the binder consumption rates are reduced by 20-25%. |
||||
6.2.17 The decision on pre-treatment of crushed stone with a binder in the installation (blackening of crushed stone) is made based on the results of laboratory studies of the adhesion of crushed stone to the binder in accordance with GOST 12801-98 *. For blackening, it is recommended to use bitumen grades BND 60/90, BND 90/130, BND 130/200, MG 130/200, MG 70/130.
6.2.18 The main pouring of the binder is carried out on half of the roadway in one go, without gaps or breaks. If it is possible to provide a detour, the binder is poured over the entire width of the roadway.
6.2.19 The temperature of the bitumen during its distribution should be within the following limits: for viscous bitumen grades BND 60/90, BND 90/130 - 150160°C; for grades BND 130/200 - 100130°C; for polymer-bitumen binders - 140-160°C.
6.2.20 When applying surface treatment using bitumen emulsions, cationic emulsions EBK-1, EBK-2 and anionic emulsions EBA-1, EBA-2 are used. When applying surface treatment using cationic bitumen emulsions, crushed stone is used that has not been pre-treated with organic binders. When using anionic emulsions - predominantly black crushed stone.
6.2.21 The temperature and concentration of the emulsion are set depending on weather conditions:
At an air temperature below 20°C, the emulsion should have a temperature of 4050°C (with a bitumen concentration in the emulsion of 55-60%). The emulsion is heated to this temperature directly in the asphalt distributor;
At air temperatures above 20°C, the emulsion does not need to be heated (at a bitumen concentration in the emulsion of 50%).
6.2.22 Immediately after scattering the crushed stone, it is compacted with smooth rollers weighing 6-8 tons (4-5 passes along one track). Then with heavy smooth rollers weighing 10-12 tons (2-4 passes along one track). For better manifestation of the rough structure, it is advisable to carry out the final stage of compaction using smooth rollers with rubber-coated rollers.
6.2.23 When using bitumen emulsions, work is carried out in the following sequence:
Wetting the treated coating with water (0.5 l/m);
Pouring emulsion over the coating in an amount of 30% of consumption;
Distribution of 70% of crushed stone from the total consumption (gap of no more than 20 m with a time interval of no more than 5 minutes from the moment of pouring the emulsion);
Pouring the remaining emulsion;
Distribution of the remaining crushed stone;
Compaction with rollers weighing 6-8 tons, 3-4 passes along one track (the beginning of compaction should coincide with the beginning of the disintegration of the emulsion);
Maintenance of the constructed surface.
6.2.24 When using cationic bitumen emulsions, vehicle traffic is opened immediately after compaction. Maintenance of double surface treatment is carried out for 10...15 days, by regulating traffic along the width of the road surface and limiting the speed to 40 km/h.
In the case of using an anionic emulsion, traffic should be opened no earlier than one day after the surface treatment device.
6.3 Installation of thin friction wear-resistant protective layers on the surface of the road surface
6.3.1 Construction of thin protective layers of cast emulsion-mineral mixtures
6.3.1.1 Thin friction wear-resistant protective layers made from cast emulsion-mineral mixtures (LEMS) are used as friction and waterproofing wear layers to increase the service life of road surfaces and improve driving conditions. Wear layers are primarily necessary to restore the performance of coatings.
6.3.1.2 When repairing asphalt concrete layers laid on a cement concrete pavement, the following options for using cast emulsion-mineral mixtures are possible:
1) laying LEMS on the top layer of asphalt concrete pavement;
2) laying LEMS on a milled asphalt concrete surface.
6.3.1.3 Before installing the LEMS layer, the coating is primed with emulsion or bitumen grades BND 200/300 at the rate of 0.3-0.4 l/m (in terms of bitumen).
6.3.1.4 Preparation and installation of LEMS is carried out using special single-pass machines that mix materials and distribute the mixture over the surface of the coating.
It is recommended to use crushed stone of various fractions up to 15 mm from igneous and metamorphic rocks with a strength of at least 1200. The sand fraction of 0.1 (0.071)-5 mm consists of crushed sand or a mixture of natural and crushed sand in equal parts. For mineral powder (preferably activated) from carbonate rocks, it is assumed that the total number of particles finer than 0.071 mm contained in the mixture is 5-15%. The binder is used in the form of cationic bitumen emulsions of the EBK-2 and EBK-3 classes, containing 50-55% bitumen. The compositions of LEMS are given in Table 6.3.
Table 6.3 - Compositions of cast emulsion-mineral mixtures
|
Mixture type |
Number of components,% by weight |
|||||||
|
granite crushed stone, mm |
mine- |
Portland- |
water for pre- |
bitumen emulsion (in terms of bitumen) |
||||
|
crushed |
nature |
|||||||
|
Crushed stone |
||||||||
|
Sandy |
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|
[email protected], we'll figure it out. | ||||||||
MINISTRY OF TRANSPORT OF THE RUSSIAN FEDERATION
STATE ROAD SERVICE
(ROSAVTODOR)
CENTER
ORGANIZATION OF LABOR AND ECONOMIC
MANAGEMENT METHODS
(TSENTRORGTRUD)
COLLECTION OF CARDS
LABOR PROCESSES FOR REPAIR AND
MAINTENANCE OF HIGHWAYS
Work process map
Pothole repair of asphalt concrete pavements
with pothole depths up to 50 mm
using ED-105 machines
KTP-1.01-2001
Second edition, revised and expanded.
(Issue 1)
Moscow, 2001
Maps of labor processes are intended to improve the organization of labor of workers engaged in the repair and maintenance of highways.
The maps determine the progressive technology of work, the rational use of working time, the technological sequence of work based on advanced techniques and labor methods.
Maps can be used in the development of organizational and technological documentation for the repair and maintenance of highways (PPR and others), work planning, as well as for educational purposes in the training of highly qualified workers.
A collection of maps of labor processes prepared by engineers A.I. Anashko, E.V. Kuptsova,
T.V. Insurance.Responsible for the release A.A. Morozov.
. Scope and effectiveness of the card
Note: The labor costs on the map include time for preparatory and final work - 5% and rest - 10%.
Using the methods and techniques recommended by the map will increase output by 8%.
. Preparation and conditions for performing processes
3.3 . Working clothes and safety footwear.
1 . Cotton overalls 4
2 . Leather boots 4 pairs
3 . Canvas mittens 3 pairs
4 . Combined mittens 1 pair
5 . Canvas knee pads 3 pairs
6 . Signal vest 3 pcs.
3.4 . Requirement for materials per 10 m 2 of repaired area with pothole depths up to 50 mm: hot fine-grained asphalt concrete mixture ( GOST 9128-84 ) - 1.19 t; liquid bitumen - 5 l; diesel fuel.
4. Process technology and labor organization
4.1 . Work on pothole repair of asphalt concrete pavements using ED-105 machines for repairing asphalt concrete pavements is carried out in the following technological sequence:
Installation and removal of fences and worker crossings at a distance of up to 50 m;
Breaking and cutting off the edges of the covering of the hole being repaired with a jackhammer;
Cleaning pits from dust, dirt and debris;
Lubricating the edges of the coating and base with bitumen;
Laying and leveling of asphalt concrete mixture;
Rolling the mixture with a vibrating manual roller;
Warming up bitumen with bitumen boiler maintenance;
Compressor and generator maintenance.
4.3 . Workplace organization diagram
M 1, A 1, A 2, A 3 - locations of workers; 1 - inventory barrier; 2 - road sign; 3- guide cones; 4 - potholes on the surface; 5 - road sign; 6 - road sign; 7 - machine for repairing black coatings; 8 - cutting map filled with asphalt concrete mixture. The arrow indicates the direction of movement of the link.
Layout of road signs for repair work(detour along the roadway).
Breaking and cutting off the edges of the coverings of the hole being repaired with a jackhammer