gravel and gravel coverings. During their repair, periodic repair profiling is carried out, potholes, ruts and subsidence are eliminated, and dust removal measures are also taken. Repair profiling of the coating with the addition of new material is carried out by motor graders or graders at optimal moisture content (from 10 to 15%, depending on the composition of sandy-clay fractions), corresponding to such a state of gravel or crushed stone material, when it is well cut, moved and compacted (Table 12.4 .one).
Table 12.4.1
Repair profiling of gravel (crushed stone) pavements with the addition of new material (per 1000 m of pavement)
| Type of work | Coverage width, m | Number of circular passes | The composition of the link | Labor intensity, man-hour |
| Scarifying the pavement with a scarifier mounted on a motor grader | Machinist of the 5th category - 1 | 0,59 0,63 | ||
| Road worker of the 2nd category - 1 | ||||
| Motor grader moving additional gravel material from the shoulder, leveling across the entire width of the pavement | Machinist of the 5th category - 1 | 0,77 | ||
| 0,66 | ||||
| Motor grader mixing of boiled and newly added material with collection in a measuring shaft | Machinist of the 5th category - 1 | 0,51 | ||
| 0,44 | ||||
| Leveling and leveling of the material over the entire width of the coating | Machinist of the 5th category - 1 | 0,77 | ||
| 0,66 | ||||
| Watering the planned gravel material with water (norm up to 0.9 m 3 per 100 m 2) | 6-7 | - | Machinist of the 4th category - 1 | 0,75 |
| Compaction of the material with a self-propelled roller (8-10 tons) in 4 passes on one track | 6-7 | - | Machinist of the 5th category - 1 | 2,2 |
| Regulation of movement along the width of the pavement and maintenance of that pavement within 3 days with rearrangement of fences | 6-7 | - | Road worker of the 2nd category -1 | 1,38 |
To be repaired boil up. After removing the boiled material, the pothole is covered with gravel material, in composition close to the material of the upper layer of the coating with grains no larger than 20 mm, 1 ... 2 cm above the coating level. Scoured material can be used to seal potholes, but only after it has been screened.
At large volume works, gravel material is compacted with self-propelled rollers on pneumatic tires or rollers weighing 5 ... 10 tons, and with a small amount of pneumatic, electric or manual rammers weighing 25 ... 30 kg. Seal from the edges to the middle of the potholes. For better compaction, the material is watered with water at the rate of 1.5 ... 2 l / m 2 for each centimeter of the depth of the pothole. Instead of water, it is advisable to use a 30% aqueous solution of calcium chloride CaCl 2 or a 30-40% aqueous solution of technical lignosulfonate.
Repair of potholes or subsidence of crushed stone pavement built by the wedge method is carried out by the same method, and pavements from a mixture of optimal composition - as well as gravel pavements (Tables 12.4.2 and 12.4.3).
Table 12.4.2
Cost of materials for repairs
Table 12.4.3
The composition of the link and labor costs
Ruts and small ridges formed under the influence of traffic are leveled with heavy rollers, after moistening the coating. This method is used to eliminate small irregularities on a fairly durable coating. In other cases, ruts are eliminated by patching.
Crushed stone and gravel coatings treated with organic binders. In the process of repair, potholes, damage and uneven edges, bumps and sagging, small breaks and subsidence of the coating are eliminated.
Patching is carried out mainly with cold crushed stone (gravel) mixtures treated with organic binders.
In some cases, it is allowed to use cold or hot asphalt concrete mixtures or the direct or reverse impregnation method. In cold mixes, liquid (or viscous) bitumen, coal tar, bitumen emulsions are used as a binder.
Repair is carried out: in a cold way, if the air temperature is not lower than 5 ° C and in a hot way, if the air temperature is not lower than 10 ° C.
cold way it is advisable for potholes up to 3 cm deep, and hot - for potholes deeper than 3 cm.
With any of the above methods, the repaired site is prepared, including trimming (scribing) the edges, cleaning from dust and dirt, treating the cleaned surface with an organic solvent (solar oil, kerosene) at a rate of 0.1 ... 0.15 l / m using spray guns or sprayers and applying liquid bitumen, residual bitumen (tar) with a viscosity of 20-70 or tar in the amount of 0.3 ... 0.5 l / m 3 heated to 60 ° C on it.
Immediately after priming, the pothole is filled with repair material, the layer thickness of which is determined taking into account the compaction coefficient.
When using hot mixes, the material is laid in one layer when the depth of the potholes does not exceed 5 cm, and in two layers if the depth is more than 5 cm, and carefully compacted in layers. If the impregnation method is used, crushed stone no larger than 0.8 of the depth of the pothole, but not smaller than 16 mm, is placed in the prepared pothole, and compacted. Then viscous bitumen or tar is poured at the rate of 0.8-1.0 l/m 2 for each centimeter of the depth of the pothole. The temperature of the binder during filling should be: bitumen grades BND 200/300, BND 130/200 - 120...160°C. Spilling binder, crushed stone of fraction 5...15 mm is distributed and compacted. Small repaired areas are compacted with rammers.
Plots of pavement damaged by numerous potholes are repaired with cards. Damaged sections of the edges of the pavement at the interface with the shoulders are corrected by the above methods of patching, ensuring proper support from the side of the curb.
Asphalt concrete pavement. The main work on the repair of asphalt concrete pavements include the restoration of worn upper layers, elimination of damage in the form of potholes, cracks, individual waves, bumps and sagging, breaks and uneven edges, surface treatment, protective layers and wear layers. These works are started in the spring with the onset of warm and stable weather. Repair work begins with patching potholes using patching methods using cold milling of the coating. Milling is carried out using cold milling machines. Technical characteristics of a number of cutters firm "Wirtgen" are given in table. 12.4.4.
Table 12.4.4
Technical characteristics of milling cutters "Wirtgen"
| Parameters | Mill brand | ||||
| W 350 | W 500 | W 600 D C | W 1000 F | W 1200 F | |
| Milling width | 350 mm | 500 mm | 600, 500, 400 mm | 1000 mm | |
| Milling depth | 0...100 mm | 0...160 mm | 0...300 mm | 0...315 mm | 0...315 mm |
| Engine power | 35 kW (48 hp) | 19 kW (107 hp) | 123 kW (167 hp) | 185 kW (252 hp) | 185 kW (252 hp) |
| Operating weight | 4400 daN (kg) | 7400 daN (kg) | 12030 daN (kg) | 17300 daN (kg) | 17300 daN (kg) |
| Milling drum drive | mechanical | hydraulic | mechanical | mechanical | mechanical |
| Number of wheels | 3 (optional equipment 4) | ||||
| ground drive | guide / front wheels | guide / front wheels | guide / front wheels | guide / front wheels | guide / front wheels |
When repairing, the general technological sequence is observed, which includes preparing the damaged area, preparing, laying and leveling the mixture, and compacting.
Hot and cold asphalt mixtures, poured asphalt, crushed stone and gravel materials treated with an organic binder serve as repair materials. Hot asphalt mixes and cast asphalt are mainly used on non-roads of categories I and II.
Repair of coatings using hot asphalt mixes is carried out in dry and warm seasons at an air temperature of at least 10°C. Molded asphalt can also be laid at low air temperatures - down to -5°C.
The preparation of the repaired site is carried out in the following order: the boundaries of the potholes are outlined in straight lines, capturing the undamaged part of the coating by 3-5 cm, several small potholes, closely spaced from each other, are combined into one common map; old asphalt concrete is removed along the outlined contour, the pothole is cleaned and (if necessary) dried; the bottom and its walls are primed with a bitumen emulsion with liquid or viscous bitumen heated to 60 ° C, at a rate of 0.3-0.5 l / m 2.
After preparatory work fill the pothole with repair material, taking into account the safety factor for sealing. If the depth of potholes is up to 5 cm, the mixture is laid in one layer, more than 5 cm - in two layers.
Small potholes isolated from one another are compacted with electric or pneumatic rammers, manual vibratory rollers, and large areas are compacted with smooth-roller rollers weighing 4-10 tons. The best results are achieved when using rollers with rubber-coated rollers.
Compaction is carried out from the edges to the middle, while the surface of the repaired places after compaction should be at the level of the coating. Approximate indicators of work are given in table. 12.4.5.
Table 12.4.5
Labor costs and output during pavement repair
When filling potholes deeper than 5 cm, when not only the upper, but also the lower layer of asphalt concrete is removed, the work procedure does not change: a coarse-grained mixture is placed in the lower layer and compacted, then a fine-grained mixture is placed in the upper layer and compacted. If the pothole is up to 8 cm deep and there is no coarse-grained mixture, a medium-grained mixture is laid in two layers. Fine-grained or sandy mixture is used only for the top layer.
When using infrared burners, the pothole, having cleaned of dust and dirt, is heated to 140-170 ° C, the heated edges are scraped to a depth of 1-2 cm, the bottom of the pothole is loosened, and the boiled material is distributed along the bottom and the required amount of a new mixture is added, compacted (if it is not a cast mixture) to the required density. The amount of the added mixture is set according to the size and depth of the pothole, taking into account the settlement during compaction (Table 12.4.6).
Table 12.4.6
The need for a mixture
| Hollow depth, mm | The amount of the added mixture, kg with the area of the pothole, m 2 | ||||||||
| 0,1 | 0,2 | 0,3 | 0,4 | 0,5 | 0,6 | 0,7 | 0,8 | 0,9 | |
When sealing potholes that are dangerous for traffic in early spring or autumn period when the coating is wet and the air temperature is above 0°C, it is recommended to use crushed stone materials treated with bitumen with surfactants. For the same purpose, the mineral material is treated with activators - lime or cement - 1.5 ... 2% by weight of the mineral material.
Influxes, waves and shifts on the coating are eliminated by patching or cut off with a motor grader knife (after they have been preheated) with subsequent surface treatment. For heating, self-propelled asphalt heaters with infrared burners (operating speed 0.5 ... 3.0 m / min) are suitable. Cracks in the coating are closed when they are open - in dry and warm weather, the temperature is not less than 5 ° C. Cracks with a width of 5 mm or more are sealed with mastic, and small ones are filled with bitumen and sprinkled with stone fines. Separate cracks with a width of more than 5 mm are sealed as follows: they are cleaned of dust and dirt with compressed air, a brush or metal hooks; moistened with an organic solvent (solar oil, kerosene) at a rate of 0.1 ... 0.15 l / m 2 using spray guns or spray guns with a small spray angle; poured bituminous mastic(Table 12.4.7). Cracks are filled with excess. After removing the excess mastic, the crack is sprinkled with hot stone cuttings or sand. Cracks with destroyed edges are cut by cutting or milling asphalt concrete with a strip of 10 ... 15 cm on each side for the entire thickness of the deformed layer. Cutting down the material can be replaced by heating with infrared burners.
| Road-climatic zone | Mixture number | Composition of the mixture, % by mass | |||
| bitumen grade BND 90/130 or BND 60/90 | mineral powder | rubber crumb | asbestos crumb | ||
| II | |||||
| II and III | - | ||||
| - | |||||
| III and IV | - | ||||
| - | |||||
| IV and V |
On coatings containing organic binders, including asphalt concrete, during repairs, a single or double surface treatment is arranged or a thin layer of asphalt concrete and similar mixtures is laid (Table 12.4.8). Prior to performing these works, the coating must be cleaned of dust and dirt, potholes eliminated and cracks repaired.
Table 12.4.8
Single surface treatment device on asphalt concrete and other black surfaces (per 1000 m 2 of coating)
| Type of work | The composition of the link | Labor intensity, man-hour |
| Cleaning the coating from dust and dirt in six passes mechanical brush | Machinist of the 4th category - 1 | 0,25 |
| Having solved bitumen with an asphalt distributor (norm 0.5 ... 1.1 l / m 2) | Machinist of the 5th category - 1 | 0,43-0,45 |
| Distribution of measured crushed stone by the T-224 distributor (norm 15 ... 30 kg / m 2) | Driver of the 5th category - 1, road workers of the 3rd category - 2 | 0,39 |
| Compaction (rolling) of black crushed stone with a light roller (5 ... 6 tons) in 5 ... 6 passes along one track | Machinist of the 5th category - 1 | 2,1 |
| Compaction of black crushed stone with a heavy pneumatic roller (10 ... 16 tons) in 5 ... 6 passes along one track | Machinist of the 5th category - 1 | 1,5 |
The repair of asphalt concrete pavements also includes work to restore the continuity and evenness of the upper layer using thermal profiling technology based on the principle of regeneration (restoration of lost properties).
Improving the adhesion properties of asphalt concrete and cement concrete pavements is carried out mainly by means of a double surface treatment device. The technology for performing work is described in Section 4.
For surface treatment on cement concrete pavements, it is advisable to use a rubber-bitumen binder: bitumen BND 60/90 or BND 90/130 from 85 to 91%; coal oil - 6...10%; crumb rubber - 3...5%.
Bituminous binder is prepared in boilers with a paddle mixer. First, dehydrated and heated to 150-160 ° C bitumen is loaded into the mixer in the amount of 10% of the required volume, then the calculated amount of dehydrated and heated to 40 ... 70 ° C coal oil and the mixture is thoroughly mixed for 10 ... 15 minutes . In the bitumen liquefied in this way, a predetermined amount of dried rubber crumb, sifted through a mesh with 3 mm holes, is added in small portions. The mixture is stirred for 1.0...1.5 h at a temperature of 150-160 °C. Then, without stopping mixing, the rest of the dehydrated and heated to 160 ° C bitumen is loaded. All components are finally mixed for 30 minutes at a temperature of 160 °C. Surface treatment device technology is described in section 4.
The scope of work on the arrangement of wear layers, as well as indicative indicators of work are given in table. 12.4.9
Table 12.4.9
Construction of a wear layer 1.5-3 cm thick from asphalt concrete and similar mixtures on black coatings (per 1000 m 2 of coating)
| Type of work | The composition of the link | Labor intensity, man-hours |
| Cleaning the coating from aching and dirt with a mechanical brush | Machinist of the 4th category - 1 | 0,25 |
| Priming of the coating with liquid bitumen distributed by an asphalt distributor (norm 0.5 l / m 2) | Machinist of the 5th category - 1 | 0,24 |
| Asphalt paver DS-181 | Machinist of the 6th category 1, asphalt concrete workers: 5th category - 1, 4th category - 1, 3rd category - 3, 2nd category - 1, 1st category - 1 | 21,6 (2,7) |
| Pre-compaction of the layer with light rollers in 5-8 passes on one track | Machinist of the 5th category - 1 | 5,2 |
| Compaction of the layer with heavy rollers on pneumatic tires in 10-12 passes along one track | Machinist of the 5th category - 1 | 7,6 |
Thermal profiling of asphalt concrete pavements. To restore the top layer of asphalt concrete pavements, technology based on the regeneration of pavements with the help of special machines is increasingly being used.
Regeneration is performed by various methods of thermal profiling, the main operations of which are: heating the coating; loosening (milling) it to a depth of 2-5 cm; loose mix planning; seal. Thermal profiling methods have varieties: thermal planning; thermohomogenization; thermal styling; thermal mixing; thermoplasticization.
Thermal planning method- the most simple, involves the implementation of only the basic operations indicated above. The average loosening depth of the repaired pavement depends on a number of factors, including the type of asphalt concrete and air temperature (Table 12.4.10).
Table 12.4.10
Average loosening depth
In the thermal planning mode, sandy asphalt concrete pavements are repaired with water saturation not exceeding 3% by volume (1.5% for areas with excessive moisture).
When repairing a pavement made of fine-grained asphalt concrete with a water saturation not exceeding 4% (3% for areas with excessive moisture), or sandy with a water saturation of more than 3% (up to 4% inclusive), thermal planning is combined with surface treatment or a wear mat. In this case, correction of the transverse slope is achieved. coverage up to 4%.
In other cases, after thermal planning, a protective layer of a new asphalt concrete mixture is laid on the pavement. It is most efficient to carry out this operation in one thread with thermal planning. The paver moves 15-20m or thermal profiler. Due to the fact that the final compaction of the old and new mixtures is carried out in one layer, its density increases. In addition, the thickness of the protective layer of the new mixture can be reduced to 1-2 cm versus 3 cm in the traditional way. This mode is a variation of the heat styling method.
Thermohomogenization method differs from thermal planning in that, in addition to the main operations, it also provides for the regeneration of asphalt concrete by mixing the old asphalt concrete mixture. At the same time, the homogeneity of asphalt concrete increases and the compaction of the layer improves, which makes it possible to somewhat expand the scope of this method compared to the previous one.
Coatings with water saturation not exceeding 4% are repaired by the thermohomogenization method. Thermohomogenization is carried out using thermal profilers equipped with a stirrer in the form of one machine or a set of machines.
heat laying method, in addition to the basic operations, it provides for the addition of a new mixture in the form of an independent layer over the loosened old mixture.
This method, unlike the previous ones, has a wider scope, since it allows repairing pavements with large amplitudes of irregularities, deeper ruts, significant pitting, unsatisfactory transverse slopes and higher water saturation. In addition, this method is effective when, for some reason, the coating cannot be loosened to a depth equal to or greater than the minimum allowable.
Heat laying can be used to repair coatings with water saturation up to 6%. The amount of added new mixture depends on the evenness of the repaired coating, the degree of its wear and is usually assigned within 25...50 kg/m 2 . If it is necessary to correct the transverse slope of the pavement by more than 4%, the consumption of the added asphalt concrete mixture is increased (Table 12.4.11).
Table 12.4.11
Increasing the consumption of the added mixture
The advantage of the heat laying method is the possibility of simultaneous compaction of the old and new mixture in one layer, which increases its density. Thermal laying is carried out using a thermal profiler equipped with equipment for receiving and distributing a new mixture in the form of a single machine or a set of machines. You can also use an equipment kit that includes a paver to add new mix.
thermal mixing method unlike thermal laying, it involves mixing the new added mixture with the old one and laying the resulting mixture in one layer.
Its advantage is the possibility of correcting to a certain extent the composition of the old mixture and its regeneration. When performing work in this way, no requirements are imposed on the old coating that limit its water saturation. The flow rate of the added mixture is set depending on the evenness of the repaired pavement, the degree of its wear and the desired change in the properties of the old asphalt concrete. Thermal mixing is carried out using a thermal profiler, equipped, in addition to the equipment for thermal laying, also with a stirrer.
Thermoplasticization method differs from the previous ones by adding a plasticizer to the old mixture in an amount of 0.1-0.6% by weight of the latter. This operation must be accompanied by mixing. The method has all the advantages of thermoplanning and thermohomogenization, since it does not require the addition of a new mixture. In addition, it allows you to regenerate old asphalt concrete, expands the scope of this method, extending it to pavements with water saturation exceeding 3%. (The only limitation on the applicability of the thermoplasticization method is the presence of large irregularities on the coating and heavy wear, requiring the addition of a mixture. Thermoplasticization is carried out by the same machines as thermohomogenization, provided that they are equipped with a plasticizer injection unit. It is advisable to use oils of petroleum origin containing aromatic hydrocarbons as a plasticizer not less than 25% by weight.The most accessible renobit is a plasticizer proposed by GiprodorNII.It is also possible to use extracts of selective purification of oil fractions of oil, motor oil.Indicators of the physical properties of plasticizers must meet the requirements:
Kinematic viscosity at 50°С, m2/s........(25...70) 10 6
Flash point in an open crucible, °С, not less....100
Mechanical impurities, % mass fraction, not more than... 2.0
Water, % mass fraction, no more...................4,0
Fuel, % mass fraction, no more.............6,0
The plasticizer consumption depending on the depth of loosening of the coating and the speed of the thermal mixer is given in Table. 12.4.12.
Table 12.4.12
Plasticizer consumption rates, l/min
| Loosening depth, cm | Dosage of plasticizer, % by weight of asphalt concrete mix | |||||||||||
| 0,3 | 0,5 | 0,7 | ||||||||||
| Machine speed, m/min | ||||||||||||
| 1,5 | 2,0 | 2,5 | 3,0 | 1,5 | 2,0 | 2,5 | 3,0 | 1,5 | 2,0 | 2,5 | 3,0 | |
| 0,8 | 1,1 | 1,3 | 1,5 | 1,3 | 1,8 | 2,2 | 2,5 | 2,3 | 2,6 | 3,0 | 3,5 | |
| 1,2 | 1,5 | 2,0 | 2,3 | 2,0 | 2,5 | 3,3 | 3,8 | 2,8 | 3,5 | 4,7 | 5,4 | |
| 1,6 | 2,0 | 2,6 | 3,1 | 2,7 | 3,3 | 4,3 | 5,2 | 3,7 | 4,7 | 6,1 | 7,2 | |
| 2,0 | 2,6 | 3,3 | 3,8 | 3,3 | 4,3 | 5,5 | 6,3 | 4,6 | 6,1 | 7,7 | 8,9 |
Thermal profiling without the use of an additional asphalt heater for all methods (except for the third one with a consumption of a new mixture of more than 25 kg/m3) is carried out at an air temperature of at least 15 °C; in the third method, at a flow rate of a new mixture of 25 ... 50 kg / m 2, work is carried out at an air temperature of 10 ° C and above, and at a flow rate of more than 50 kg / m 2 - 5 ° C and above.
With the use of an additional asphalt heater, work by all means can be performed when the air temperature is not lower than 5 °C.
Thermal profiling works are carried out at a wind speed of not more than 7 m/s. The temperature on the surface of the heated asphalt concrete pavement should not exceed - 180°C during the first and third methods of thermal profiling (the consumption of a new mixture is less than 25 kg/m2).
The temperature of the mixture in front of the tamper bar in all thermal profiling methods (except the fifth one) should not be lower than 100°С, in the fifth method - not lower than 85 °С.
The specialists of the Ministry of Construction of Ukraine have established the following duration of heating of the layer of asphalt and tar concrete coating to an average temperature of 110 and 80°C, respectively (Table 12.4.13).
Table 12.4.13
Coating heating time
Note.In the numerator- heating time of asphalt concrete to an acceptable temperature of 200°C, and the denominator - tar concrete to an acceptable temperature of 125°C.
Estimated resource requirement for various ways repair of asphalt concrete pavements (per 1000 m) is given in Table. 12.4.14.
Table 12.4.14
Resource requirement
Repairfromusing cast asphalt and cold organo-mineral mixtures. IN In accordance with the provisions of the current regulatory documents, repairs using poured asphalt type V can be carried out almost throughout the year (at temperatures down to -10 °C) [54].
Preparatory work is carried out in accordance with established requirements. In winter, the preparatory work includes cleaning the repaired maps from sand and salt deposits, snow, ice, and removing water.
Transportation of the mixture to the place of work is carried out in special self-propelled units with a thermos boiler or bunker, equipped with heating and a mixer. During transportation, continuous mixing and a temperature of the mixture of 180-240 ° C should be ensured, and, if necessary, batch unloading with varying the speed of the mixture.
Before loading, the thermos boiler (bunker) is heated for 10 minutes by two heaters or a nozzle to 180-190°C. The lid of the feed opening must be opened no earlier than 5 minutes before loading the boiler with the mixture.
It is forbidden to turn on the agitator drive clutch before starting the engine, as well as the agitator drive until the hopper is warmed up and if there are residues of a hardened (non-heated) mixture in it that prevents the movement of the agitator blades. During transportation, the total mixing time of the mixture in a mobile unit should be at least 20 minutes.
Arriving at the place of laying, the self-propelled unit is installed in front of the prepared pit in such a way that the outlet tray, when the boiler (bunker) is tilted, is directed directly into the pit. The mixture is unloaded when the outlet chute is tilted with simultaneous operation of the paddle mixer in the boiler. Works on the distribution of the mixture with distribution to the edges of the card and removal of excess, as well as smoothing and grouting of interface points, are performed manually.
A separate operation is the distribution of black (or untreated) crushed stone over the surface of a freshly laid cast mixture to ensure the required adhesion properties in the repaired areas.
Crushed stone with a size of 3-5 (8) or 5-8 (10) mm is delivered to the place of repair work by dump trucks in the amount necessary for uninterrupted operation. The scattering of crushed stone is carried out in a uniform layer into one crushed stone immediately after the distribution of the mixture. The approximate consumption of crushed stone for a mixture of type I is 5 ... 8 kg / m 2. After the coating has cooled down to a temperature of 80-100 ° C, it is allowed to roll the distributed crushed stone with a hand roller weighing 30-50 kg. After the laid layer has cooled to the outside temperature, the unburned gravel should be swept away.
Motion road transport on the finished coating opens when the coating reaches the outside temperature, but not earlier than 3 hours after completion of work.
With small volumes of repair with cards up to 3 m 2 (most often emergency), it is advisable to use cold organo-mineral mixtures. In the construction season, at an air temperature above 5 ° C, a mixture of brand I is used for repairs, in winter time- II mark. Unlike the previously described repair methods with small cards, in this case it is allowed to lay the mixture even in rainy weather [54]. As with repairs using poured asphalt, there is no need to treat the prepared maps with bituminous materials. The need for special compaction of the laid organic-mineral mixture is also excluded.
The mixture is distributed into the prepared card manually with a compaction safety factor of 1.25-1.30. After distribution, it is enough to roll the mixture with the wheel of any car, including cars, in one pass along one track. It is possible to use vibrating plates for this purpose.
Traffic on the repaired area can be opened immediately after rolling. The final formation of the organo-mineral mixture layer occurs during the operation of the road surface under the influence of the traffic load.
Repair of coatings using organo-mineral mixtures in the areas of acceleration and deceleration of vehicles (crossroads, public transport stops) due to the peculiarities of the formation of the layer can only be a temporary measure, for example, emergency repairs in rainy or winter periods. A longer service life of such cards (directly proportional to the intensity of vehicle traffic) is noted in the haul sections.
Abroad with current repair with the use of such materials, it is allowed to lay them directly into potholes (without preparing maps) with a minimum depth equal to the size of coarse aggregate.
Based on the results of a survey of repaired sections at federal road network facilities, it was found that the optimal layer thickness in a dense body should be considered to be at least two diameters of coarse aggregate.
The main condition for the correct assignment of the repair method is to determine the cause of the crack formation, the degree of destruction of the base and coating materials, the reasonable timing of the repair work and the economic feasibility of the cost of repair work.
Planned work on sealing temperature cracks should be carried out during periods of their maximum opening. The most optimal periods are spring with the onset of dry and warm weather or late autumn, when night frosts cause compression of the asphalt concrete of the road surface, but during the day it is relatively warm (not lower than 5...10 °C).
When sealing cracks, in addition to their sealing, a “soft hinge” should be created from the repair material between the layers of asphalt concrete separated in a horizontal plane. Therefore, in the warm season, when the cracks are opened to a smaller width, it is recommended to additionally cut them with the formation of a deformation chamber (reservoir).
Table 12.4.15
Parameters of deformation chambers
Calculation of the chamber width can be performed using a simplified formula
IN= 100 b · TO one · T/l , (12.4.1)
where b- distance between cracks, established during visual examination of the coating, mm;
TO 1 - coefficient of linear thermal expansion of asphalt concrete, taken depending on the brand and type of asphalt concrete, the type of stone materials and binders used, degrees (approximately 2.1 ´10 ° for asphalt concrete types "A" and "B"; 3.3 ´10 ° - asphalt concrete type "B" and "G");
T- the difference between the air temperature during the period of work and the minimum possible temperature in the winter, ° С;
l- limiting relative elongation of the repair material at the minimum air temperature, % (according to the relevant regulatory documents, less than 50%).
In case of destruction of the edges of thermal cracks, the width of the chamber is taken not less than the width of the destruction.
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Full repair of the road should begin in cases where the number of general defects and damage reaches 12-15%. If there are fewer various deformations, cracks, chips, peeling, chipping and potholes, the so-called patching is carried out, the purpose of which is to ensure road safety. To do this, use different methods, tools, materials.
The main causes of road violations are low quality materials used and violation technological processes, the most common of which is insufficient compaction. As a rule, road repairs are carried out in the warm season in dry weather, but sometimes there is a need for urgent restoration of the roadbed, and then work is carried out in almost any weather conditions.
Construction technology is constantly being improved, which makes it possible to make roads of the highest quality and increase their service life. The additives used in the composition of the asphalt concrete mixture allow the formation of a minimum number of cracks. As for the latter, they tend to increase in size by spring. And this is explained by the properties of water, which, getting into even the smallest crack in winter, freezes and expands.
Hot and cold mixes
The main percentage of pavement is asphalt concrete pavement, therefore, most often, when repairing them, they resort to using a hot mix of asphalt and concrete. Starting materials sand, crushed stone, bitumen and mineral powder are used to prepare the mixture. This material is characterized high properties terminations.
hot asphalt mix and cast asphalt are used in the repair of roads of the first and second categories. The temperature of the hot mix is approximately +150°C. They deliver it to the place of repair in special bunkers that maintain heat. According to the standards, the mixture, the temperature of which is below +110 ° C, is considered a marriage. Thermos hoppers with a capacity of up to 4 m3 are able to provide a mixture of approximately 100 holes with a size of 100x100 cm and a depth of 5 cm.
Depending on weather conditions, cold bituminous mixtures, materials based on bitumen emulsions and thinned bitumen can be used. Cold technologies are relevant for roads of the third and fourth categories, since the strength and water resistance of such mixtures are approximately three times lower than those of hot ones.
As for bitumen emulsions, they are actively used in road repair in many countries, primarily because they are highly economical, not demanding on weather conditions, and their service life is quite long. For emergency repairs, minor repair of defects, less common and non-traditional mixtures based on polymer, cement, polymer-bitumen and other binders can be used.
Recycling technology and jet-injection methods
This technology provides for the recycling of asphalt concrete material and its use for repairing the road surface directly on site. Pieces of asphalt, scrap and milling products are heated and thoroughly mixed in a special machine - a recycler. Gravitational mixing takes place in a cylindrical drum with blades and a burner. It is most efficient to process asphalt crumb, which is subsequently added with bitumen. The resulting mixture is immediately applied to the prepared place. Thus, it is possible to reduce repair costs by up to 60%.
The jet-injection technology, in which necessary operations performed by one machine. The essence of the technology is high-speed air blowing, instant flushing and application of bitumen emulsion. In this case, breaking and milling of asphalt concrete may not be carried out. The pothole is filled with crushed stone of a fine fraction, mixed with a bituminous emulsion (rapidly decomposing cationic or anionic 60% concentration). High speed air environment provides good compaction and no need to use vibratory plates and vibratory rollers.
Stages of proper preparation before patching
At correct execution patching and proper preparation pavement lasts up to 5 years. To do this, the basic requirements must be met and the results taken into account practical experience and new developments. Preparation consists of several stages.
- Markup. Potholes are indicated by straight lines along the axis of the road and across. In this case, the margin of the undestroyed layer should be approximately 3-5 cm. If several potholes are located side by side, they are combined with one contour.
- Removing small potholes. The process takes place with the help of a jackhammer (possibly pneumatic) with an appropriate nozzle.
- Removal of long and narrow potholes larger than 3 m2, large cracks. In this case, a cold cutter works (it can be self-propelled, trailed, mounted), which removes the coating over its entire thickness of the layer along the outlined contour, resulting in the formation of well-shaped pits with vertical walls. Some models of cold milling machines feed the cut material into a special loader bucket or body, reducing the amount of manual work.
- Cleaning new pits from crumbs, small pieces, dust, treating the walls and bottom with liquid bitumen or a bitumen-containing emulsion. The amount of lubricant should not be excessive, otherwise the quality of adhesion of the new layer of the road surface to the old one is reduced. For lubrication, small-sized installations are most often used, which spray the mixture with a small pressure from a hose.
The choice of one or another method of patching must always meet certain criteria and requirements. As a result, the repaired site will serve for a long time.
Roads and streets general rule, are perceived as transport arteries, ways of communication. But it often happens that they turn into a kind of construction site, where work is underway on a fragmentary replacement of the asphalt concrete pavement - patching.
Causes of asphalt destruction. The need for patching asphalt arises in the event of its partial destruction. The reasons can be very different:
- intensive or long-term operation of the roadway;
- discrepancy between loads and coating composition;
- mechanical damage;
- excavations carried out by public utilities during the repair of underground utilities;
- roots of closely growing trees;
- regular hit on asphalt of fuels and lubricants.
The fragility of asphalt can be caused by violations in the technology of its manufacture (insufficient bitumen content) or violations in the technology of its laying (insufficient compaction, work with a cooled asphalt concrete mixture, poor-quality base). Whatever the specific reasons for patching an asphalt concrete pavement, it is just as necessary to do it as it is to go to the dentist when caries appears: if you miss out on a small thing, you can lose in a big one.
Patching Technology not very "smart". In any case, you need to start by marking the damaged areas, for which they draw a patching map, taking into rectangles all sections of the canvas to be replaced. Cutting of damaged areas of asphalt is carried out to a depth of 5-15 cm (depending on the dimensions of the hole, crack, etc.): the contour is cut with a seam cutter, and the middle is dismantled using jackhammers. In cases where the replacement of asphalt needs to be performed on a sufficiently large area, and it is difficult to do it manually, special equipment is used.
It is necessary to check the quality of the base under the removed fragments of asphalt: perhaps it was because of this that the need for repair arose. It's one thing if the "root of evil" is in a thin or poorly compacted base, then it will be enough to add crushed stone and carefully compact it. Another case is when there is simply no foundation under the asphalt. Instead, there are pieces of clay, soil, or even just dirt. Here you will have to work more carefully, performing a full-fledged crushed stone base in accordance with all the rules.
Immediately before laying the asphalt "patch", the edges of the pit are treated with bitumen: binders are poured, providing better adhesion and adjoining the new layer to the old one.
Separately, we will dwell directly on the process of asphalting. In cases where the thickness of the asphalt is more than 6-7 cm, laying is carried out in 2 layers. One layer of asphalt general practice- should be 4-6 cm. Asphalt is poured out, leveled (planned), then rolled (compacted). At this stage, the professionalism of asphalt workers is very important. It is necessary to correctly calculate the amount of uncompacted asphalt mix, so that after its compaction, the level of the restored pavement coincides with the level in the adjacent areas. During compaction, the asphalt “squats” by about 1.5 times.
Equipment and tools for patching. The destruction and selection of old asphalt and underlying layers is carried out with the help of seam cutters, jackhammers, and even excavators. In the event that the dismantling of old asphalt over large areas is required, special machines are used - road milling machines. Sometimes, on the contrary, small amounts of work, associated with various kinds of constraints, force the use of manual labor.
The layout of the asphalt concrete mixture during patching is carried out exclusively by hand - with the help of rakes (they look like mops). Vibratory plates, vibrorammers, small hand rollers are used to compact the base, and even the asphalt concrete mixture in small areas. Very convenient for patching are manual vibratory rollers weighing about half a ton.
Cast asphalt: pros and cons. The technology of patching with the help of cast (liquid) asphalt has become quite widespread. This technology is regulated by GOST R 54401-2011. Such an asphalt concrete mixture is distinguished by a high content of bitumen. It is transported to the place of laying in special machines with a closed body, which provide heating and mixing. The main advantage of the poured asphalt technology is that poured asphalt does not require compaction. It is distributed in the gaps to be repaired with the help of strokes, after which it spreads and hardens. This is, of course, easier and faster. However, this technology also has disadvantages. Firstly, the higher cost, and, secondly, the fact that in summer, at high temperatures, the poured asphalt coating melts, spreads, and sags.
Pothole repair cost. Pothole repair of asphalt concrete pavement and sidewalks is not at all the same as simple asphalt laying. And the volume of such work is small, and the space on which it is performed is much smaller. But share manual labor- much higher. These circumstances make patching a rather expensive item: its cost is 30-50% higher than conventional asphalting.
13.4. Pothole repair of asphalt concrete and bituminous materials. The main methods of patching and technological operations
The task of patching is to restore the continuity, evenness, strength, grip and water resistance of the coating and ensure normative term refurbished site services. When patching, various methods, materials, machines and equipment are used. The choice of one or another method depends on the size, depth and number of potholes and other defects in the coating, the type of coating and the materials of its layers, available resources, weather conditions, requirements for the duration of repair work, etc.
The traditional method involves trimming the edges of the pothole to give it a rectangular shape, cleaning it from asphalt concrete scrap and dirt, priming the bottom and edges of the pothole, filling it with repair material and compacting. To give the pothole a rectangular shape, small cold milling machines, circular saws, and punchers are used.
As a repair material, asphalt concrete mixtures that require compaction are mainly used, and from the means of mechanization, small-sized rollers and vibrorammers are used.
When working in conditions of increased moisture, potholes are dried before priming with compressed air (hot or cold), as well as using infrared burners. If the coating is repaired with small cards (up to 25 m 2), the entire area is heated; when repairing large maps - along the perimeter of the site.
After preparation, the pothole is filled with repair material, taking into account the margin for compaction. With a pothole depth of up to 5 cm, the mixture is laid in one layer, more than 5 cm - in two layers. Compaction is carried out from the edges to the middle of the repaired areas. When filling potholes deeper than 5 cm, a coarse-grained mixture is placed in the bottom layer and compacted. This method allows you to get a high quality repair, but requires a significant number of operations. It is used in the repair of all types of coatings made of asphalt concrete and bitumen-mineral materials.
Small potholes up to 1.5-2 cm deep on an area of 1-2 m 2 or more are repaired according to the method of surface treatment using crushed stone of fine fractions.
The repair method with heating the damaged pavement and reusing its material is based on the use of special equipment for heating the pavement - an asphalt heater. The method makes it possible to obtain a high quality of repair, saves material, simplifies the technology of work, but has significant limitations due to weather conditions (wind and air temperature). It is applied at repair of all types of coverings from asphalt concrete and bituminous mixes.
The method of repair by filling potholes, pits and subsidence without cutting or heating the old pavement consists in filling these deformations and destructions with cold polymer-asphalt concrete mix, cold asphalt concrete, wet organo-mineral mix, etc. The method is simple to perform, allows you to work in cold weather with a wet and wet coating, but does not provide high quality and durability of the repaired coating. It is used when repairing pavements on roads with low traffic volumes or as a temporary, emergency measure on roads with high traffic volumes.
According to the type of repair material used, there are two groups of patching methods: cold and hot.
cold ways are based on the use of cold bitumen-mineral mixes, wet organic-mineral mixes (VOMS) or cold asphalt concrete as a repair material. They are mainly used for the repair of black gravel and cold asphalt concrete pavements on low-grade roads, as well as, if necessary, urgent or temporary filling of potholes in more early dates on high grade roads.
Work on patching by this method begins in the spring, as a rule, at an air temperature of at least + 10 ° C. If necessary, cold mixtures can be used for patching and at a lower temperature (from +5°С to -5°С). In this case, before laying, cold black crushed stone or cold asphalt concrete mixture is heated to a temperature of 50-70 ° C, with the help of burners, the bottom and walls of potholes are heated until bitumen appears on their surface. In the absence of burners, the surface of the bottom and walls is coated with bitumen with a viscosity of 130/200 or 200/300, heated to a temperature of 140-150°C. After that, the repair material is laid and compacted.
The formation of the coating at the place of repair in a cold way occurs under the traffic for 20-40 days and depends on the properties of liquid bitumen or bitumen emulsion, type of mineral powder, weather conditions, traffic intensity and composition.
Cold asphalt concrete layers for patching are prepared using liquid medium thickening or slow thickening bitumen with a viscosity of 70/130, using the same technology as hot asphalt concrete mixtures, at a bitumen heating temperature of 80-90 ° C and a mixture temperature at the outlet of the mixer 90-120 °C. Mixtures can be stored in stacks up to 2 m high. In the summer, 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, and repair material must be prepared in advance. The cost of work on this technology is lower than with the hot method. The main disadvantage is the relatively short service life of the repaired pavement on roads with the movement of heavy trucks and buses.
hot ways are based on the use of hot asphalt concrete mixtures as a repair material: fine-grained, coarse-grained and sandy mixtures, poured asphalt concrete, etc. The composition and properties of the asphalt concrete mixture used for repair should be similar to that of which the coating is made. The mixture is prepared according to the usual technology for the preparation of hot asphalt concrete. Hot methods are used in the repair of roads with asphalt concrete pavement. Works can be carried out at an air temperature of at least +10°C with a thawed base and a dry coating. When using a heater of the repaired coating, it is allowed to carry out repairs at an air temperature of at least +5°C. Hot patching methods provide higher quality and longer service life of the repaired pavement.
As a rule, all work on patching is carried out in early spring as soon as weather and surface conditions permit. In summer and autumn, potholes and pits are sealed immediately after they appear. Technology and organization of work in various ways have their own characteristics. However, for all methods of patching there are common technological operations that are performed in a certain sequence. All these operations can be divided into preparatory, main and final.
Preparatory work includes:
installation of fencing of work sites, road signs and lighting, if work is performed at night;
marking of places of repair (maps);
cutting, breaking or milling of damaged areas of the coating and cleaning of the removed material;
cleaning potholes from material residues, dust and dirt;
drying the bottom and walls of the pothole, if the repair is carried out in a hot way with a wet coating;
processing (priming) of the bottom and walls of the pothole with bitumen emulsion or bitumen.
The marking of repair sites (repair maps) is carried out using a stretched cord or chalk using a rail. The repair site is outlined with straight lines parallel and perpendicular to the axis of the road, giving the contour the correct shape and capturing the intact coating to a width of 3-5 cm. Several potholes located at a distance of up to 0.5 m from one another are combined into a common map.
Cutting, breaking or milling of the coating within the marked map is carried out for the thickness of the destroyed layer of the coating, but not less than 4 cm throughout the repair area. In this case, if the depth of the pothole has affected the lower layer of the coating, the thickness of the lower layer with the destroyed structure is loosened and removed.
It is very important to remove and remove the entire destroyed and weakened layer of asphalt concrete, capturing a strip of at least 3-5 cm wide from a strong, undestroyed asphalt concrete along the entire marked contour. These edge bands of the pothole cannot be left unremoved, since the solidity of the asphalt concrete is weakened here due to the formation of microcracks, loosening and chipping of individual gravel from the walls of the pothole (Fig. 13.10, a). Water collects in the pothole, which, under the dynamic influence of the wheels of cars, penetrates into the interlayer space and weakens the adhesion of the upper layer of asphalt concrete to the lower one. Therefore, if the weakened edges of the pothole are left, then after laying the repair material, after some time, the weakened edges may collapse, the newly laid material will lose its connection with the strong old material and the development of the pothole will begin.
Rice. 13.10. Cutting a pothole before laying the repair material: a - cutting weak spots; b- cutting the edges of the pothole after milling; 1 - weakened wall of the pothole; 2 - exfoliated part of the coating; 3 - destroyed part of the bottom of the pothole; 4 - chopped off or beveled wall of the pothole
The walls of the edges of the pothole after cutting should be vertical along the entire contour. The cutting and breaking of the coating can be carried out using a pneumatic jackhammer or scrap, a concrete breaker, a seam cutter and a ripper, or using a road milling machine.
When using a road milling machine to cut a pothole, rounded front and back walls of the pothole are formed, which must be cut with a circular saw or a jackhammer. Otherwise, the upper part of the laid layer of repair material at the interface with the old material will be very thin and will quickly collapse (Fig. 13.10, b).
The loosened material of the old pavement is manually removed from the pothole, and when using a road milling machine, the removed material (granulate) is fed into a dump truck by a loading conveyor and taken out. The cleaning of the map is carried out with the help of shovels, compressed air, and with a large area of the map - with the help of sweepers. Drying of the bottom and walls of the card is carried out as necessary by blowing with hot or cold air.
Treatment with a binder (priming) of the bottom and walls of potholes is carried out in the case of laying hot asphalt mixes as a repair material. This is necessary in order to ensure better adaptation of the old asphalt concrete material to the new one.
The bottom and walls of the cleaned card are treated with liquid medium-thickening bitumen with a viscosity of 40/70, heated to a temperature of 60-70°C with a flow rate of 0.5 l/m 2 or a bituminous emulsion with a flow rate of 0.8 l/m 2 . In the absence of means of mechanization, bitumen is heated in mobile bitumen boilers and distributed over the base using a watering can.
Filling the pothole with repair material can only be done after all the preparatory work has been completed. The laying technology and the sequence of operations depend on the method and volume of work performed, as well as on the type of repair material. With small volumes of work and the absence of mechanization, the laying of repair material can be done manually.
The temperature of the hot mix asphalt delivered to the place of laying should be close to the temperature of preparation, but not lower than 110-120°C. It is most expedient to lay the mixture at such a temperature when it is easily processed, and during the laying process, waves and deformations are not formed during the passage of the rink. Depending on the type of mixture and its composition, such a temperature is considered: for a multi-gravel mixture - 140-160 ° C; for medium crushed stone mixture - 120-140 ° C; for low gravel mixture - 100-130°C.
Laying the mixture in the card is carried out in one layer at a cutting depth of up to 50 mm and in two layers at a depth of more than 50 mm. In this case, a coarse-grained mixture with a crushed stone size of up to 40 mm can be laid in the lower layer, and only a fine-grained mixture with a fraction size of up to 20 mm can be placed in the upper layer.
The thickness of the laying layer in a loose body should be greater than the thickness of the layer in a dense body, taking into account the safety factor for compaction, which is taken: for hot asphalt mixes 1.25-1.30; for cold asphalt mixes 1.5-1.6; for wet organo-mineral mixtures 1.7-1.8, for crushed stone and gravel materials treated with a binder, 1.3-1.4.
When laying the repair material in a mechanized way, the mixture is fed from the thermos hopper through a rotary tray or a large-diameter flexible hose directly into the pothole and is evenly leveled over the entire area. The laying of asphalt concrete mixtures when embedding maps with an area of 10-20 m 2 can be carried out by an asphalt paver. In this case, the mixture is laid over the entire width of the map in one pass in order to avoid an additional longitudinal seam for conjugating the laying strips. The compaction of the asphalt concrete mixture laid in the bottom layer of the coating is carried out by pneumatic rammers, electric rammers or manual vibratory rollers in the direction from the edges to the middle.
The asphalt concrete mixture laid in the top layer, as well as the mixture laid in one layer with a pothole depth of up to 50 mm, is compacted with a self-propelled vibratory roller (first two passes along the track without vibration, and then two passes along the track with vibration) or light-type static smooth-roller rollers weighing 6-8 tons up to 6 passes along one track, and then heavy rollers with smooth rollers weighing 10-18 tons up to 15-18 passes along one track.
The compaction coefficient should be at least 0.98 for sandy and low-gravel asphalt concrete mixtures and 0.99 for medium- and high-gravel mixtures.
Compaction of hot asphalt mixes is started at the highest possible temperature at which deformations are not formed during the rolling process. Compaction should provide not only the required density, but also the evenness of the repair layer, as well as the location on the same level of the repaired coating with the old one. For better mating of the new coating with the old one and the formation of a single monolithic layer when laying hot mixes, the joint along the entire contour of the cutting is heated using a line of burners or an electric heater. The joints of potholes that protrude above the surface of the coating are eliminated by milling or grinding machines. The final work is the cleaning of the remaining repair waste with their loading into dump trucks and the removal of fences and road signs, the restoration of marking lines in the patching area.
The quality of the repair and the service life of the repaired coating depend primarily on compliance with the quality requirements for the performance of all technological operations (Fig. 13.11).
Rice. 13.11. The sequence of basic patching operations: a - correct; b- wrong; 1 - pothole before repair; 2 - cutting or cutting, cleaning and processing with a binder (priming); 3 - filling with repair material; 4 - seal; 5 - view of the repaired pothole
The most important requirements are:
repairs must be carried out at an air temperature not lower than that allowed for this repair material on a dry and clean surface;
when cutting down the old coating, weakened material should be removed from all areas of the pothole where there are cracks, breaks and spalling; the repair card must be cleaned and dried;
the shape of the repair map must be correct, the walls are sheer, and the bottom is even; the entire surface of the pothole must be treated with a binder;
repair material must be laid at the optimum temperature for this type of mixture; the layer thickness should be greater than the depth of the pothole, taking into account the margin for the compaction factor;
the repair material must be carefully leveled and compacted flush with the surface of the coating;
the formation of a layer of new material on the old coating at the edge of the map is not allowed to avoid shocks when a car runs over and the rapid destruction of the repaired area.
The result of a properly executed repair is the height of the laid layer after compaction, exactly equal to the depth of the pothole without unevenness; correct geometric shapes and invisible seams, optimal compaction of the laid material and its good connection with the material of the old pavement, long service life of the repaired pavement. The result of an incorrectly performed repair may be unevenness of the compacted material, when its surface is higher or lower than the surface of the pavement, arbitrary map shapes in plan, insufficient compaction and poor connection of the repair material with the material of the old pavement, the presence of protrusions and sags on the edges of the map, etc. Under the influence of transport and climatic factors, the areas of such repair are quickly destroyed.
Pothole repair of black crushed stone or gravel coatings. When repairing such pavements, simpler materials and repair methods can be used to reduce the cost of maintaining roads with black gravel and black gravel pavements. Most often, these methods are based on the use of cold bituminous mineral mixtures or materials treated with bitumen emulsion as a repair material. One of these materials is a mixture of organic binder (liquid bitumen or emulsion) with wet mineral material (crushed stone, sand or gravel-sand mixture), laid in a cold state. Cement or lime is used as an activator when using liquid bitumen or tar.
So, for example, to repair potholes up to 5 cm deep, a repair mixture is used in the composition: crushed stone 5-20 mm - 25%; sand - 68%; mineral powder - 5%; cement (lime) - 2%; liquid bitumen - in excess of 5% mass; water - about 4%.
The mixture is prepared in forced action mixers in the following sequence:
mineral materials are loaded into the mixer at natural humidity (crushed stone, sand, mineral powder, activator), mixed;
add the calculated amount of water and mix;
enter the organic binder, heated to a temperature of 60°C, and finally mix.
The amount of water introduced is adjusted depending on the intrinsic moisture content of the mineral materials.
During the preparation of the mixture, mineral materials are not heated or dried, which greatly simplifies the preparation technology and reduces the cost of the material. The mixture can be prepared ahead of time.
Before laying the mixture, the bottom and walls of the pothole are not primed with bitumen or emulsion, but moistened or washed with water. The laid mixture is compacted and movement is opened. The final formation of the layer occurs under the traffic.
Patching with the use of wet bituminous mineral mixtures can be carried out at a positive temperature not higher than +30°C and at a negative temperature not lower than -10°C in dry and damp weather.
Pothole repair of black gravel coatings by impregnation. As a repair material, crushed stone is used, pre-treated in a mixer with hot viscous bitumen in an amount of 1.5-2% by weight of crushed stone.
After marking the contour of the pothole, its edges are cut off, old coatings are scraped off and loosened material is removed, the bottom and walls of the pothole are treated with hot bitumen at a flow rate of 0.6 l / m 2. Then, black crushed stone with a fraction of 15-30 mm is laid and compacted with a manual rammer or vibratory roller; bitumen is poured with a flow rate of 4 l / m 2; lay the second layer of black crushed stone with fractions of 10-20 mm and compact it; crushed stone is treated with bitumen at a rate of 2 l/m 2 ; scatter stone screenings of fractions of 0-10 mm and compact with a pneumatic vibrating roller. Using the same technology, it is possible to carry out repairs by impregnation and using crushed stone not treated with bitumen. This increases the bitumen consumption: at the first spill - 5 l/m 2 , at the second - 3 l/m 2 . The distributed bitumen impregnates the layers of crushed stone to the full depth, as a result of which a single monolithic layer is formed. This is the essence of the impregnation method. For impregnation apply viscous bitumen 130/200 and 200/300 at a temperature of 140-160°C.
A simplified method of patching with impregnation of crushed stone with bitumen emulsion or liquid bitumen is widely used in France for patching small potholes on roads with low and medium traffic. Such potholes are called "chicken nest".
The repair technology consists of the following operations:
first, potholes or pits are manually covered with large-sized crushed stone - 10-14 or 14-25 mm;
then, as it is filled, small crushed stone of fractions of 4-6 or 6-10 mm is scattered until the road profile is completely restored;
binder is poured: bitumen emulsion or bitumen in a ratio of 1:10, i.e. one part binder per ten parts crushed stone by weight;
compaction is carried out manually using a vibrating plate.
The binder penetrates the crushed stone layer to the base, as a result of which a monolithic layer is formed. The final formation occurs under the action of moving cars.
In addition to direct impregnation for patching, the reverse impregnation method is used. In this case, bitumen with a viscosity of 90/130 or 130/200, heated to a temperature of 180-200°C, is poured onto the bottom of the prepared card. The thickness of the bitumen layer should be equal to 1/5 of the depth of the pothole. Immediately after the spill of hot bitumen, mineral material is poured: crushed stone of fractions 5-15; 10-15; 15-20 mm, ordinary crushed stone or gravel-sand mixture with a particle size of up to 20 mm. The mineral material is leveled and compacted with a rammer.
When the mineral material, which has natural moisture, interacts with hot bitumen, foaming occurs and the material is impregnated with bitumen from the bottom up. If the foam has not risen to the surface of the material, the binder is poured again at the rate of 0.5 l / m 2, covered with a thin layer of crushed stone and compacted.
With a pothole depth of up to 6 cm, all its fillings are performed in one layer. At a greater depth - filling is carried out in layers 5-6 cm thick. negative temperature air. However, the service life of the repaired sections in this case is reduced to 1-2 years.
Pothole repair using crushed stone treated with bituminous emulsion has a number of advantages: there is no need to heat the binder to prepare the mixture; can be laid at a positive ambient temperature, i.e. from the beginning of spring to the end of autumn; rapid disintegration of the cationic emulsion, which contributes to the formation of a repair layer; no edge trimming, material removal or priming.
To perform work, a repair vehicle is used, which includes: a base vehicle with a heat-insulated emulsion tank with a capacity of 1000 to 1500 liters; distribution device for emulsion (compressor, hose, nozzle); bunkers of crushed stone of fractions from 2-4 to 14-20. The cationic emulsion used must be fast disintegrating, contain 65% bitumen and be kept warm at temperatures between 30°C and 60°C. The surface to be treated must be clean and dry.
The technology for repairing deep pits over 50 mm of the "chicken's nest" type (French terminology) consists of the following operations: laying a layer of crushed stone of fraction 14-20; distribution of binder on a layer of crushed stone 14-20; laying the 2nd layer of crushed stone 10-14; spraying binder on a layer of crushed stone 10-14; laying the 3rd layer of crushed stone 6-10; spraying binder on a layer of crushed stone 6-10; laying the 4th layer of crushed stone 4-6; spraying binder on a layer of crushed stone 4-6; laying the 5th layer of crushed stone 2-4 and compaction.
It is important to ensure the correct dosing of the binder when spraying the emulsion over crushed stone. Crushed stone should only be covered with a binder film, but not drowned in it. The total consumption of the binder should not exceed the ratio binder: crushed stone = 1:10 by weight. The number of layers and the size of crushed stone fractions depends on the depth of the pothole. When repairing small potholes up to 10-15 mm deep, the repair is carried out in the following order: laying a layer of crushed stone 4-6; spraying binder on crushed stone 4-6; crushed stone distribution 2-4 and compaction.
These methods are applicable in the repair of black gravel and black gravel pavements on roads with low traffic volumes. The disadvantages of using such methods are that the presence of a layer of variable thickness can cause destruction of the edges of the patch, and appearance patch repeats the outlines of the pothole.
Pothole repair of asphalt concrete pavements using an asphalt heater. The technology of work is greatly simplified in the case of patching with preliminary heating of the asphalt concrete pavement over the entire area of the map. For these purposes, a special self-propelled machine can be used - an asphalt heater, which allows you to heat the asphalt concrete pavement up to 100-200 ° C. The same machine is used for drying repaired areas in wet weather.
The heating mode consists of two periods: heating the coating surface to a temperature of 180°C and further more gradual heating of the coating over the entire width to a temperature of about 80°C in the lower part of the heated layer at a constant temperature on the coating surface. The heating mode is regulated by changing the gas flow rate and the height of the burners above the coating from 10 to 20 cm.
After heating, the asphalt concrete pavement is loosened with a rake to the entire depth of the pothole, a new hot asphalt concrete mixture is added to it from the thermos hopper, mixed with the old mixture, distributed over the entire width of the map with a layer 1.2-1.3 times greater than the depth, taking into account the compaction coefficient and compact from the edges to the middle of the repaired area with a manual vibratory roller or a self-propelled roller. The junctions of the old and new coatings are heated using a line of burners that are part of the asphalt heater. The line of burners is a mobile metal frame with infrared burners mounted on it, which are supplied with gas from cylinders through a flexible hose. During the repair work, the temperature of the coating should be in the range of 130-150°C, and by the end of the compaction work - not lower than 100-140°C.
The use of an asphalt heater greatly simplifies the technology of patching and improves the quality of work.
The use of gas-fired asphalt heaters requires special attention and compliance with safety regulations. It is not allowed to operate gas burners at a wind speed of more than 6-8 m / s, when a gust of wind can extinguish the flame on part of the burners, and the gas from them will flow, concentrate in large quantities and may explode.
Asphalt heaters operating on liquid fuel or with electrical sources of infrared radiation are much safer.
Repair of asphalt concrete pavements with the use of special machines for patching or road repairers. The most effective and high-quality type of patching is the repair performed using special machines, which are called road repairers. Road repairers are used as a means of complex mechanization of road repair work, since they are used not only for patching road surfaces, but also for sealing cracks and filling joints.
The technological scheme of patching with the use of a road repairer includes the usual operations. If the repairer is equipped with a heater, the repair technology is greatly facilitated.
Simplified methods of patching (injection methods). In recent years, simplified methods of patching using special machines such as Savalco (Sweden), Rasko, Dyura Petcher, Blow Petcher, etc. have become more widespread. In Russia, similar machines are produced in the form of special trailed equipment. - sealer brand BCM-24 and UDN-1. Repair of potholes by injection is performed using a cationic emulsion. Cleaning the pothole for repair is carried out with a jet of compressed air or by suction; primer - heated to 60-75 ° C emulsion; filling - with blackened crushed stone in the process of injection. With this repair method, edge trimming can be omitted.
As a repair material, crushed stone of a fraction of 5-8 (10) mm and an emulsion of the EBK-2 type are used. A concentrated emulsion (60-70%) is used on bitumen BND 90/130 or 60/90 with an approximate consumption of 10-11% by weight of crushed stone. The surface of the repaired area is sprinkled with white gravel with a layer of one gravel. The traffic opens in 10-15 minutes. Works are carried out at an air temperature of at least +5 ° C, both on dry and wet surfaces.
Patch repair by injection is performed in the following order (Fig. 13.12):
Rice. 13.12. Pothole repairs according to a simplified technology: 1 - cleaning potholes by blowing with compressed air; 2 - priming with bituminous emulsion; 3 - filling with crushed stone treated with emulsion; 4 - applying a thin layer of raw gravel
the first stage - the place of the pit or patch is cleaned with a jet of air under pressure to remove pieces of asphalt concrete, water and debris;
the second stage - priming with a bitumen emulsion of the bottom, walls of the pothole and the surface of the asphalt concrete pavement adjacent to it. The emulsion flow is controlled by a control valve on the main nozzle. The emulsion enters the air stream from the spray ring. The temperature of the emulsion should be about 50°C;
the third stage is filling the pothole with repair material. Crushed stone is introduced into the air stream by means of a screw conveyor, then it enters the main mouthpiece, where it is covered with an emulsion from a spray ring, and from it the treated material is ejected at high speed into a pothole, distributed in thin layers. Compaction occurs due to the forces resulting from the high speeds of the ejected material. The suspended flexible hose is controlled remotely by the operator;
the fourth stage is the application of a protective layer of dry, untreated crushed stone to the patch area. In this case, the valve on the main nozzle that controls the flow of the emulsion is turned off.
It should be noted that the exclusion of pre-cutting the edges of the pothole leads to the fact that in the marginal zone of the pothole there remains old asphalt concrete with a disturbed structure, which, as a rule, has reduced adhesion to the underlying layer. The service life of such a patch will be less than with traditional technology. In addition, patches have irregular shapes, which impairs the appearance of the coating.
Pothole repairs using cast asphalt mixes. A distinctive feature of cast asphalt mixes is that they are laid in a fluid state, as a result of which they easily fill potholes and do not require compaction. Fine-grained or sandy cast asphalt can be used for repairs at low air temperatures (down to -10°C). Most often, a sandy cast asphalt concrete mixture is used for repair work, consisting of natural or artificial quartz sand in an amount of 85% by weight, mineral powder - 15% and bitumen - 10-12%. For the preparation of cast asphalt, viscous refractory bitumen with a penetration of 40/60 is used. The mixture is prepared in mixing plants with forced action mixers at a mixing temperature of 220-240°C. Transportation of the mixture to the place of laying is carried out in special mobile boilers of the Kocher type or in thermos bunkers.
The delivered mixture at a temperature of 200-220°C is poured into the prepared pothole and easily leveled with wooden trowels. The easily moving mixture fills all the irregularities, due to the high temperature it heats up the bottom and walls of the pothole, as a result of which strong connection repair material on the coating side.
Since a fine-grained or sandy cast mixture creates a surface with increased slipperiness, measures must be taken to improve its grip. For this purpose, immediately after the mixture is distributed, black crushed stone 3-5 or 5-8 is scattered over it with a consumption of 5-8 kg / m 2 so that the crushed stone is evenly distributed in a layer of one crushed stone. After the mixture has cooled down to 80-100°C, crushed stone is rolled with a manual roller weighing 30-50 kg. When the mixture has cooled to ambient temperature, the excess gravel that has not sunk into the mixture is swept away and movement is opened.
Laying of cast asphalt mixes during patching can be done manually or with a special asphalt paver with a heating system. The advantage of this technology lies in the fact that the operations of priming the repair card and compacting the mixture are excluded, as well as the high strength of the repair layer and the reliability of the joints of the interface of new and old materials. The disadvantages are the need to use special mixers, heated mobile rollers and mixers or thermos bunkers, viscous refractory bitumen, as well as increased safety and labor protection requirements when working with a mixture that has a very high temperature.
In addition, poured asphalt during operation has a significantly greater strength and lower deformability compared to conventional asphalt concrete. Therefore, in the case when poured asphalt is repairing a coating of conventional asphalt concrete, after a few years this coating begins to collapse around the patch of poured asphalt, which is explained by the difference in the physical and mechanical properties of the old and new material. Molded asphalt is most often used for patching city roads and streets.
One of the ways to simplify the work technology and increase the construction season is the use of cold asphalt concrete mixtures based on polymer bitumen binder (PBV) as a repair material. These mixtures are prepared using a complex binder, which consists of bitumen with a viscosity of 60/90 in an amount of about 80% by weight of the binder, a polymer modifying additive in an amount of 5-6% and a solvent, for example diesel fuel, in an amount of 15% by weight of the binder. The binder is prepared by mixing the components at a temperature of 100-110°C.
Asphalt-concrete mix on PMB is prepared in mixers with forced mixing at a temperature of 50-60°C. The mixture consists of fine crushed stone of fractions 3-10 in the amount of 85% by weight of the mineral material, screenings of 0-3 in the amount of 15% and a binder in the amount of 3-4% of the total mass of the mineral material. The mixture is then stored in an open stack, where it can be stored for up to 2 years, or loaded into bags or barrels, in which it can be stored for several years, retaining its technological properties, including mobility, plasticity, lack of caking and high adhesive characteristics.
The repair technology using this mixture is extremely simple: the mixture from the body of a car or from the bunker of a road repairer is manually or using a hose fed into a pothole and leveled, after which traffic is opened, under the influence of which the road layer is formed. The whole process of repairing a pothole takes 2-4 minutes, since operations for marking the map, cutting and cleaning the pothole, as well as compacting with rollers or vibratory rollers are excluded. The adhesive properties of the mixture are also preserved when it is laid in potholes filled with water. Repair work can be carried out at negative air temperatures, the limit of which needs to be clarified. All this makes this method of patching very attractive for practical purposes.
However, it also has a number of significant drawbacks. First of all, there is a possibility of rapid destruction of the repaired pothole due to the fact that its weakened edges are not removed. When performing work in wet weather or in the presence of water in a pothole, part of the moisture can get into microcracks and pores of the old coating and freeze when the coating temperature drops below 0. In this case, the process of destruction of the zone of conjugation of new and old materials can be initiated. The second disadvantage of this method of repair is the preservation of the irregular external shape of the pothole after repair, which worsens the aesthetic perception of the road.
Availability a large number methods of patching makes it possible to choose the optimal one based on specific conditions, taking into account the condition of the road, the number and size of coating defects, the availability of materials and equipment, the timing of repairs and other circumstances.
In any case, it is necessary to strive to eliminate pitting at an early stage of its development. After patching, in many cases it is advisable to arrange a surface treatment or lay a protective layer, which will give a uniform appearance to the coating and prevent its destruction.
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