Cold regeneration (cold recycling) is a method of restoring a road with defects in the form of thermal and fatigue cracking, cracks formed as a result of aging, ruts, potholes and bumps, as well as with loss of coating integrity, delamination, washing out and loss of bonding agent between layers.

Technology cold regeneration  Is the recycling of old coatings and materials pavement  to new foundations with simultaneous strengthening of bearing capacity, re-profiling, and reinforcement of curbs. The binder based recycling layer is strong enough to hold the load from traffic  and flexible enough to prevent the penetration of reflected cracks from the base to the top layer.

Main advantages of the cold regeneration method:

• cost savings due to the recycling of existing materials road construction;
• reduction of terms of work;
• environmental conservation;
• increased evenness of the coating;
• load bearing capacity;
• the formation of a protective waterproof top layer;
• the elimination of the formation of reflective cracks, the correction of the profile and the strengthening of curbs.

Unlike hot recycling, the characteristics of old bitumen do not deteriorate when it is heated, which also affects the service life of the coating. Cold recycling is especially attractive in areas remote from asphalt plants.

The cold regeneration process includes several successive stages: grinding the cohesive layers of the coating and base by cold milling; introduction to the resulting loose material - asphalt granulate, the distribution of the resulting mixture over the underlying layer of pavement.

All these technological operations are carried out, as a rule, on the road by a link of specialized machines. The optimal machine is the Roadtec universal milling cutter, complete with the RX ‑ 700‑4 CIR cold recycling kit. The main working body of cold recyclers is a milling and mixing drum with a large number of special cutters.

When the machine is moving with a rotating milling and mixing drum, water is injected into its mixing chamber, supplied from a tank truck through a flexible hose. The amount of water is precisely dosed by a microprocessor-controlled pump, the rotating drum mixes it well with the material crushed by the milling drum, so that the moisture content of the mixture is optimal for compaction.

Liquid binders are added directly to the mixing chamber in the same way. The binder enters the mixing chamber through a separate, specially designed distribution rail. Powder binders are usually distributed in front of the recycler with a layer applied to the surface of an existing road.

The recycler, milling the existing pavement together with a powder binder, mixes it with crushed material and added water in one pass. The mixture obtained during the cold milling process is laid using an asphalt paver. Compaction of the material requires a roller with vibration of one or both smooth bandages of its rollers. At its end, the pneumatic skating rink performs the final processing of the layer to obtain a uniform texture of its surface.

There are several types of surface treatments. roadbed:

• the correct movement of the recycler and the width of the overlap;
• recycling depths;
• the addition of water and binders, the costs of additives;
• mixture quality;
• recycler operating speed (from 6 to 12 m / min);
• humidity and appearance of the material behind the recycler;
• cross seams and cross section.

Acceptance checks and tests are carried out for:

• the strength of the material of the recycled layer, which is determined by laboratory tests of a sample taken from the recycler, or cores from pavement, on which the values \u200b\u200bof the compressive and / or tensile strength are determined;
• the thickness of the finished layer, which is checked by punching holes with a small diameter drill with still fresh material, ideally at the end of the finish. Also for this purpose, core samples with a diameter of 150 mm can be taken from stabilized layers after a set of strength material, after 28 days;
• the density of the compacted material in the dry state, which is determined at each point where the degree of compaction was checked.

The technology of cold regeneration of structural layers of pavement consists in grinding the coating (in some cases with the capture of part of the base) mainly by cold milling; introducing into the resulting asphalt concrete granulate, if necessary, a new skeletal material, a binder and other additives; mixing all components to obtain an asphalt-granular concrete mixture; its distribution in the form of a structural layer and compaction, after which the AGB mixture is converted into regenerated asphalt concrete.

The technology of cold regeneration implies the regeneration of asphalt concrete without additional heating of the asphalt granulate.

In the course of laboratory tests of our additive (stabilizer), we obtained the results of comparing the technologies of cold and warm regeneration of asphalt granulate. The results have almost the same physical and mechanical properties that reveal the advantages of cold technology over warm regeneration. When applying the technology of cold regeneration, there is no transportation and heating of asphalt concrete granulate at a stationary asphalt concrete plant, which significantly reduces cost costs.

Material obtained in the course of cold regeneration works meets the requirements of " Guidelines  AVTODOR recovery asphalt concrete pavement  and road bases by cold regeneration. OS-568-r dated 06/27/2002 ".

Scope of technology:

The application of cold regeneration technology, depending on the category of road, is possible for use as a lower bearing layer of the pavement structure, instead of a layer of asphalt concrete of hot grades; the device of the upper layer of asphalt concrete coating with surface treatment, with:

Repair of asphalt concrete pavements and bases;

Reconstruction of highways;

Recycling of asphalt concrete granulate in the construction of new roads, sites, landscaping.

The main advantages of the technology:

High physical and mechanical properties of regenerated asphalt concrete, fully meeting the requirements of the RF standards;

The possibility of reducing the estimated cost by more than 30%;

Ease of use of technology;

100% safety for both the environment and workers;

Increased service life;

Reducing the timing of work more than twice.

The main element of the technology is the additive (stabilizer) of soils and organic-mineral mixtures in the form of a solution. The action of the drug is aimed at carrying out a redox reaction in the soil, which in turn leads to the formation of large conglomerates with strong crystalline bonds. Additionally, a maximum compaction ratio is achieved. As an additional catalyst for the reaction, cement M400 is used in a proportional ratio, depending on the type of soil, road and climatic zone and the required physical and mechanical parameters.

Comparative analysis of the use of regeneration technology:

Repair example 1 km. Highways of the IV category S \u003d 6000 sq.m. using a recycler, regarding generally accepted regeneration technologies:

№	Comparison position	Cold regeneration technology	Conventional Technologies Using Conventional Technologies
1.	The thickness of the regenerated layer	10cm	\u003e 15cm
2.	Options for additional layers on top of the regenerated layer	Asphalt 5cm, Surface Finishing 2 cm	Asphalt\u003e 10cm
3.	The amount of materials used for repair	Stabilizer Cement from 50t to 90t Asphalt concrete 700t	Bitumen emulsion from 24t to 48t Asphalt concrete 1400t
4.	Cost of production, taking into account prices in Russia.	< 6.500.000 руб	\u003e 8.000.000 rub
5.	Quality assurance	7 years	5 years

Brief technological regulations for the production of works using the technology of cold recovery of asphalt concrete:

1. Preparation of an aqueous solution of a stabilizer by mixing the required amount of water and a stabilizer in a tank tank.

2. Distribution of the required amount of cement over the structural layer.

3. Milling of the structural layer with a recycler with the simultaneous introduction of an aqueous stabilizer solution into the asphalt mixture.

4. Profiling regenerated asphalt mix  using a grader.

5. Compaction of the regenerated asphalt mix with rollers.

6. Creating an additional coating layer of dense asphalt or surface treatment with crushed stone with an emulsion.

Technology of hot, warm and cold regeneration. Used machinery and equipment. Advantages and disadvantages.

Asphalt mixtures, depending on the temperature regimes of heating the asphalt granulate and the requirements for the minimum allowable temperature of the mixture during compaction, are divided into:

§ warm regenerated asphalt mixes prepared with a heating temperature of asphalt granulate from 120 ° C to 140 ° C and stacked with a temperature of the mixture not lower than 50 ° C;

§ hot regenerated asphalt mixes prepared with a heating temperature of asphalt granulate from 140 ° C to 170 ° C and stacked with a temperature of the mixture not lower than 90 ° C.

In foreign literature, the regeneration of asphalt concrete pavements is defined by the term “recycling”. Two methods are distinguished at the place of regeneration:
  1) factory recycling;
  2) re-cycling on the road. remix

The process flow of regeneration at the plant is as follows:

Factory recycling material flow

1) removal of the old coating by cold or hot milling or rupture;
  2) delivery by road of old material to mobile or stationary asphalt plant;
  3) cooking new asphalt mix  from the material of the old coating with the addition of stone material and bitumen in accordance with the requirements of the formulation;
  4) delivery of a new asphalt mix by road to the repaired area;
  5) distribution of asphalt paver;
  6) seal.

The process flow of regeneration on the road is made by a special remixing machine. In one working stroke, the material of the old coating is heated, processed with or without the addition of new material, distributed and compacted (Fig. 4.2).

Workflow recycling material flow

There are four groups of cars for performing hot ris-kings on the road:
  1) a joint remixer 300 is used to close cracked joints on an old surface;
  2) mini remixer-1000 is designed to restore sections of roads of small area;
  3) the remixer-2500 is equipped with a vario system, which allows loosening the old pavement and laying a new one, and is used to repair road lanes up to 2.5 m wide;
  4) Remixer-4500 is designed for the complete restoration of roads up to 4.5 m wide in one working passage.

Fig. 19. The machine that works by the method of "remix"

1 - hopper; 2.15 - heating blocks; 3 - scraper inclined feeder; 4 - hopper dispenser; 5 - tank for liquefied gas; 6 - diesel engine; 7 - wheel chassis; 8 - tamper; 9 - rear distribution screw; 10 - bridges; 11 - heating block; 12 - dump; 13 - middle auger; 14 - rake type cultivator; 16 - paddle mixer

During reconstruction and overhaul highways, caused by a sharp decrease in the bearing capacity of the pavement, accompanied by its cracking and deep ruts, until the mid-80s, various methods were used to disassemble the old pavement using first pickers and then road mills. After layer-by-layer disassembly of the coating and the base, they were rebuilt. Moreover, already in those years, reinforced soils and stone materials treated with binders began to find more and more application in the bases of road pavements: crushed stone and crushed stone and sand mixtures. The emergence in the 80s of a new type of road machines - recyclers (regenerators) made it possible to abandon layer-by-layer disassembly. We can say that the recycler is a further development and combination of a road mill and a self-propelled soil mixer. It carries out cold (without heating) processing (grinding) of the required thickness of the coating layer or pavement (coating and part of the base) by milling, mixing the resulting mass with the addition of an organic, inorganic or complex binder and laying the resulting mixture in pavement as a base on the main and regional and as a coating on local roads. IN Russian Federation  such machines are not yet available. The most famous recyclers in the Russian Federation are the world's leading manufacturers: Caterpillar (USA), Terex-CMI (USA), Roadtec (USA), Wirtgen (Germany) and Bomag-JCB (Germany).

The main share of manufactured recyclers is occupied by models with a processing width of 2400-3000 mm, a significantly smaller proportion of machines with a processing width of 1500-2330, 3800 and 4200 mm.

The stroke drive of all machines is hydraulic, which ensures the selection of the required speed in operation.

The main working body of the recycler - the milling and mixing drum, as a rule, has a mechanical drive and rotates along the way (by rotation of the wheels of the machine) and vice versa. All Wirtgen recyclers except WR 4200 are equipped with one milling and mixing rotor. The WR 4200 recycler has three rotors: two front widths of 700 mm and one rear width of 2800 mm, which allows the width of the processing to be changed from 2800 mm to 4200 mm by extending the front rotors to the sides.

As a binder for processing the milled coating material and the base are used:

· Cement with the addition of water or a cement-water suspension;

Bitumen emulsion;

· Bitumen foamed;

· A complex of additives (cement slurry + water + foamed bitumen or bitumen emulsion).

Typically, the recycler is equipped only with distribution pipes (ramps) and pumps for introducing liquid materials - water and bitumen emulsion. To enter foamed bitumen on the distribution pipe, hot bitumen (with a temperature of up to 180 ° C), a small amount of water and compressed air are supplied to the nozzles. The surface of the foamed bitumen films is very large, and the viscosity of the bitumen decreases sharply, which contributes to the mixing of bitumen with the crushed material of the pavement.

For cement injection, tankers with attachments are usually used to dispense and distribute cement over the surface of the processed pavement.

The Wirtgen company on the WR 2500SK recycler installs an integrated cement distributor with a 4 m 3 hopper. The company produces a WM 1000 mobile (trailed) mixing unit for recycling equipment for receiving and transferring cement-water slurry to the recycler via a hose. This eliminates dust formation at the place of work, increases the accuracy of dosing and the quality of mixing of the crushed material. This installation is equipped with a cement hopper with a capacity of 25 m 3 and a water tank with a capacity of 11 m 3. To ensure the best quality of mixing the material of crushed road pavement with a binder, a longitudinal two-shaft paddle mixer is installed next to the milling and mixing drums on the WR 4200 recycler.

Typically, the mixture obtained in the recycler is distributed using the rear wall of the casing of the milling and mixing drum and, in some cases, additional profiling is carried out using a grader. However, when processing thin coating layers (40-60 mm), this is not enough to ensure the constancy of the thickness and evenness of the processed coating layer.

Recycler WIRTGEN WR 2500 S

Cold Regeneration AB Mixture

Scope of technology:

The application of cold regeneration technology, depending on the category of road, is possible for use as a lower bearing layer of the pavement structure, instead of a layer of asphalt concrete of hot grades; the device of the upper layer of asphalt concrete coating with surface treatment, with:

Repair of asphalt concrete pavements and bases;

Reconstruction of highways;

Recycling of asphalt concrete granulate in the construction of new roads, sites, landscaping.

The main advantages of the technology:

High physical and mechanical properties of regenerated asphalt concrete, fully meeting the requirements of the RF standards;

The possibility of reducing the estimated cost by more than 30%;

Ease of use of technology;

100% safety for both the environment and workers;

Increased service life;

Reducing the timing of work more than twice.

The main element of the technology is the additive (stabilizer) of soils and organic-mineral mixtures in the form of a solution. The action of the drug is aimed at carrying out a redox reaction in the soil, which in turn leads to the formation of large conglomerates with strong crystalline bonds. Additionally, a maximum compaction ratio is achieved. As an additional catalyst for the reaction, cement M400 is used in a proportional ratio, depending on the type of soil, road and climatic zone and the required physical and mechanical parameters.

Brief technological regulations  works using the technology of cold recovery of asphalt concrete:

1. Preparation of an aqueous solution of a stabilizer by mixing the required amount of water and a stabilizer in a tank tank.

2. Distribution of the required amount of cement over the structural layer.

3. Milling of the structural layer with a recycler with the simultaneous introduction of an aqueous stabilizer solution into the asphalt mixture.

4. Profiling of the regenerated asphalt mix using a grader.

5. Compaction of the regenerated asphalt mix with rollers.

6. Creating an additional coating layer of dense asphalt or surface treatment with crushed stone with an emulsion.

A brief process schedule for the production of warm regenerated asphalt mixes with the use of batch-type ABZ:

2. Under the action of an open flame of the dryer drum burner, the AG is heated to a temperature of 130 ° C (+/- 10 ° C). At the same time, any processes of sticking of bitumen to the walls of the drying drum ABZ or burnout of bitumen does not occur.

3. Hot AG through the heat of hot materials is discharged from the dryer drum to the bucket elevator and transported to the upper discharge point.

4. Hot AG, bypassing the vibrating screen, is dispensed through the hopper of hot materials to the hopper. To prevent material from sticking to the vibrating screen, a 5mm sieve is removed or the material is fed through the bypass hopper (if this option is available at the ABZ).

5. The dosed material is discharged into the hopper mixer ABZ.

6. In the bunker, the mixer is dosed with an aqueous solution of the stabilizer "ANT" in an amount of 5% by weight of the asphalt mix (50 l per 1 t).

7. Produce forced mixing of the components of the mixture in the bunker-mixer for 10-15 seconds.

8. The warm regenerated asphalt mixture is discharged from the mixer hopper into the finished materials hopper or dump truck.

9. Within 3 hours from the time of preparation, the warm and regenerated mixture is laid and compacted. The minimum allowable temperature of the mixture during installation and compaction is 50 ° C.

Comparative analysis of the use of regeneration technology:

Repair example 1 km. Highways of the IV category S \u003d 6000 sq.m. using a recycler, regarding generally accepted regeneration technologies:

№	Comparison position	Cold regeneration technology	Conventional technologies using generally accepted technologies (hot and warm regeneration)
1.	The thickness of the regenerated layer	10cm	\u003e 15cm
2.	Options for additional layers on top of the regenerated layer	Asphalt 5cm, Surface Finishing 2 cm	Asphalt\u003e 10cm
3.	The amount of materials used for repair	Cement stabilizer from 50t to 90t Asphalt concrete 700t	Bitumen emulsion from 24 t to 48 t Crushed stone Asphalt concrete 1400 t
4.	Cost of production, taking into account prices in Russia.	< 6.500.000 руб	\u003e 8.000.000 rub
5.	Quality assurance	7 years	5 years

Typically, there are several options available to repair a damaged road, and it is often difficult to determine which is the best. However, the answer to two important questions is designed to help determine which option is optimal according to the cost / effectiveness criterion:

- What is integral to existing pavement?

A quick inspection to visually assess the condition of the road in combination with some basic tests (e.g. deviation measurement) is usually sufficient to assess the fracture mechanism. It is important to determine if damage is limited by the trailing layer (or the top layers of the pavement) or if the structure of the pavement is damaged;

- What does the road owner really want?

Is, for example, a 15-year estimated life expectancy of the road, or are there lower capital costs, only to maintain the existing rate of deterioration and maintain the required quality of pavement for a further, say, five years?

These issues have one single purpose: determining the most cost-effective solution to a particular problem within the framework of the project requirements.

Surface restoration

Surface restoration is limited to the upper layers of pavement to a depth of 100 mm. Damage here is usually associated with bitumen aging and cracking, which starts from the surface under the influence of heat.

- Laying thin  (about 40 mm) layer of hot asphalt over a damaged surface. This is the easiest way to surface repair. For the preparation of asphalt, modified binders are often used to increase the service life of the end layer. However, repeated deposition of the wear layer over the existing layer increases the height of the roadway and can create problems with passage through it and drainage.

- Shredding Damaged  layer and its replacement. Using this method, a damaged asphalt concrete layer is removed and replaced with a layer of new hot asphalt mix, often with a modified binder. This method is relatively fast due to the high performance of modern road milling machines. Destruction is removed along with the asphalt layer, and the height of the road is preserved. But at the same time there are expenses for transportation and disposal of the remote layer.

- Recycling  with the addition of a bitumen emulsion to the material of the existing pavement (recycling to a shallow depth). New, cold material is prepared from the crushed material of old clothes in a regenerator-mixer at the place of work. This type of recycling aims to introduce fresh bitumen emulsion into existing asphalt concrete. In addition, the quality of the final asphalt mix was purposefully changed by the addition of an emulsion.

Strengthening Pavement

Repairing pavement damage is usually done as a long-term solution. Sealing granular material is actually an improvement, since the higher the density of the material, the better its strength characteristics.

- Complete reconstruction. This is an option when restoration is combined with reconstruction. Essentially, reconstruction involves re-building the road. Where traffic flows are large, it is sometimes more advisable to build a new road along a separate highway.

- Application of additional layers (from granular material and / or asphalt) over an existing surface. Thick, laid on top layers of asphalt concrete are often the easiest solution to problems with paving under heavy loads. However, increasing the height of the road often requires separate drainage and creates problems with road traffic.

- Recycling to great depths, to the entire depth of the damaged pavement, thus creating a new thick homogeneous layer with higher strength characteristics. Additional layers can be laid on top of the recycled layer where the pavement needs to be substantially modernized. Stabilizers are added to the recycled material (bitumen emulsion, with necessary - high strength  crushed stone), especially where the material of the existing pavement is of insufficient quality and requires strengthening. The task of recycling is to maximize the restoration of existing pavement. In addition to reusing the upper layers of the existing pavement, material below the recycling level remains intact.

Cold recycling method

Constantly increasing traffic on public roads, as well as doubling the axle loads, requires an increase in the bearing capacity of existing road pavement.

Currently in the area road construction  along with traditional methods of repairing, reconstructing, and strengthening roads, fundamentally new technologies have appeared that meet the latest requirements of an ever-increasing intensity of traffic, based on the latest achievements of science and technology.

One of such technologies that best meets the requirements for reconstruction, repair and operating conditions of roads is the "Cold Regeneration Method" (recycling).

This method of repairing coatings is modern, well-established in road organizations, a method and one of a kind, because it provides restoration of the foundation of pavement in a way that allows the reuse of the old coating material. The use of this method allows to reduce the time of reconstruction, repair, significantly reduce costs. Cold regeneration works are carried out without stopping the movement.

The method of cold regeneration (recycling) is the strengthening (stabilization) of soils, stone materials and asphalt granulate binders  by pre-milling and mixing on the road. This achieves significant material savings. In addition, the destruction of the old coating allows you to eliminate the source of the occurrence of new reflected cracks. No disposal of old coating is required.

When carrying out regeneration work, a special mechanism is used: the RM-350B regenerator-mixer of the American company CATERPILLAR with a capacity of up to 1.6 km of a seven-meter road per shift. Which can perform all kinds of regeneration. The working scheme of the working body of the regenerator-mixer RM-350B is shown in the figure

Cold recycling application

When restoring damaged pavement, the most cost-effective repair methods are methods that take into account specific conditions, which is less typical in the construction of new roads. Each project is unique in terms of the structure of the existing pavement and the quality of the materials of its own and subgrade. Therefore, it is very important to choose the technology that most fully meets the conditions of this particular area of \u200b\u200bwork. The following factors should be considered:

Location. And the choice of the most effective solution for a given country or region is influenced by local environmental conditions: such as traffic on a city street requiring repair, the ability to perform work not only at night, but also during the day, the bearing capacity of a dirt road requiring urgent repair, etc. d. Already in these two cases, completely different solutions and requirements for the maintenance of roads are required. It is also important to know local standards for road construction, as well as the attitude of the local population to the quality of roads, which they regard as acceptable.

The physical environment.When choosing the optimal recycling method, topological and geological conditions should be taken into account. Very steep slopes may require recycling as much as possible in practice. Variations in climatic conditions are most important when choosing the optimal recycling technology: for regions with low rainfall, completely different technologies are needed compared to regions where this level is high. The effects of extreme temperatures, such as cracking caused by melting-freezing cycles, should also be considered when choosing the right technology.

Availability of materials.The feasibility of various recycling options is significantly affected by the availability of the right materials, especially stabilizers. They must be available in sufficient quantities and of the required quality. Modern recyclers require a large number of stabilizers, so from the very beginning it must be determined whether they can be supplied.

MostDorStroy owns the installation “AkzoNobel"Producing bitumen emulsions according to Swedish technology with a capacity of 40 tons per hour and a crushing and screening complex for the preparation of high-strength washed cuboid crushed stone" SvedalaArbra", As well as means of delivery of materials to the place of work:bitumen trucks for delivery of bitumen emulsion with a volume of up to 30 m 3, tractors (Freightliner) with semitrailers American trailer with a loading capacity of 38 tons.

Types of cold recycling

Deep recycling

Recycling to a great depth covers a wide range of applications of this technology: to reinforce damaged pavements in order to extend their service life by an appropriate time. Subsequent application of the closing layers on top of the recycled layer increases the operational properties of the restored road, such as skid resistance, etc. The typical recycling depth here exceeds 150 mm.

Deep recycling can be used to reinforce damaged pavements with thick and thin asphalt layers.

Immediately after recycling, a new trailing layer is required. For lightly loaded roads, this can be a layer of rubble or a thin layer of hot asphalt mix. High traffic loads may require styling asphalt concrete layers, and asphalt concrete layer  wear and tear.

Shallow depth recycling

Shallow depth recycling is usually performed to eliminate significant cracking of asphalt concrete layers and improve their operational quality. This type of recycling is often undertaken for the construction of roads with a short service life, but can also be used where the pavement is “healthy” and only the upper asphalt concrete layers are weakened. Recycling in this case is usually carried out to a depth of 80 to 150 mm.

Using recycling to a shallow depth, the design of pavement can be improved by laying then a trailing asphalt concrete layer. Due to the reduction of water penetration into the main layers, the service life of pavement is increased.

Reconstruction of dirt roads

Reconstruction of dirt gravel roads by strengthening them with an organic binder can be carried out by treating their gravel with a bitumen emulsion, followed by applying a thin crushed stone or other protective layer. The advantages of this method are the absence of dust from traffic in dry weather and safer driving conditions in rainy weather, with less chance of loss of stability by vehicles. In addition, mineral resources are much better used, since there is no need to regularly replace gravel (for dirt roads  common is the annual loss of 20 to 30 mm of gravel due to transport and weather conditions) This reduces environmental damage due to the constant need to open up new quarries and quarries for the extraction of gravel. The recycling depth of this type is usually between 100 and 150 mm.

It is important to note that it is also possible to strengthen gravel roads by adding cement to their material. But then a thicker recycled layer, about 200 mm, is needed. As a result, this case should be attributed rather to recycling to a greater depth.

Comparative analysis of road reconstruction methods

I.The list of necessary work carried out with traditional reconstruction methods:

• The device of a bypass (duplicate) road;
• Dismantling the construction of the roadway with bulldozers, excavators;
• Removal of materials received from disassembly and their disposal;
• Creating a longitudinal profile;
• Stabilization (compaction) of the road base with rollers impregnated with bituminous compounds;
• The device of the sandy base of the road;
• The device of crushed stone base - 3 layers (fractions) with compaction of each layer with rollers;
• Primer with bituminous compounds;
• The device of asphalt concrete pavement (as calculated);
• Arrangement of roadsides by adding soil with layer-by-layer compaction;
• A device for coating roadsides from gravel impregnated with bituminous compositions.

II.The list of necessary work carried out using the cold regeneration method:

• dry loosening to the calculated depth;
• grading of the roadway with graders;
• laying high-strength granite crushed stone on the road surface (if necessary, reinforcing the base);
• loosening to the calculated depth with the injection of bitumen emulsion;
• re-profiling of the roadway with graders;
• compaction;
• device of asphalt concrete pavement (as calculated);
• widening of shoulders if necessary.

Based on this analysis, it can be seen that the use of the cold regeneration method allows to exclude from technological process  a number of operations. There is no need to arrange a bypass road, work associated with disassembling the roadbed, removal and disposal of the materials obtained is excluded. The device of sand and crushed stone bases is not required since during regeneration, the existing base is not damaged. The amount of equipment involved in the work is significantly reduced.

* - the cost of work depends on the specific conditions determined by the terms of reference, and on the cost of materials at the place of work.

Savings when applying the cold regeneration method is " 25% .

Advantages of the cold recycling method

• - No pollution: due to the full use of the material of the old pavement. There is no need for dump sites, and the volume of imported materials is minimal. This reduces rural clogging, which is inevitable when opening new quarries. Transportation is very small. Energy consumption is thus significantly reduced, as is the destructive effect of vehicles on the road network.

• - The quality of the regenerated layer due to the consistent, high-quality mixing of locally obtained materials with stabilizers. Liquids are injected in exactly the right amount thanks to the microprocessor pump control system. Mixing meets the highest requirements, as the components are forcedly mixed in the working chamber.
• - Structural integrity of pavement. Cold recycling allows you to get bonded layers of large thickness. Which differ in the homogeneity of the material. Due to this, liquid binders between thin layers of pavement are not required, which is sometimes necessary in pavements of traditional designs.
• - Preservation of the integrity of the soil, since when recycling, damage to low-quality soil is less compared with the use of conventional road-building machines for the restoration of pavement. Usually, recycling is performed in one pass with the RM350B recycler on pneumatic tires, which exert little pressure on the ground and, therefore, deform it a little. Under the influence of conventional machines, the soil is repeatedly subjected to heavy loads, which often leads to the need for excavations and backfill with imported material.
• - Road safety. One of the most important advantages of this technology is the high level of road safety during recovery. pavement. All working machines performing regeneration are located within the width of one lane. Due to this, on two lane roads, one lane can be recycled first, and then the second, i.e. one of the lanes always remains for movement.
• - Increase in overhaul life.

MostDorStroy company has extensive experience in the field of road construction, repair and reconstruction of roads for various purposes, as evidenced by a number of concluded, including implemented, state contracts using the proposed technology.

Since 2001, MostDorStroy has performed work on the regeneration of more than 200 km of roads.

Hot regeneration  asphalt concrete pavement

TO  category:

Technique for the repair of roads

Hot asphalt pavement regeneration

In foreign literature, the regeneration of asphalt concrete pavements is defined by the term “recycling”. Two methods are distinguished at the place of regeneration:
  1) factory recycling;
  2) re-cycling on the road.

The process flow of regeneration at the plant has the following form (Fig. 4.1):

Fig. 4.1. Factory recycling material flow

1) removal of the old coating by cold or hot milling or rupture;
  2) delivery of old material by road to a mobile or stationary asphalt concrete plant;
  3) preparation of a new asphalt mixture from the material of the old coating with the addition of stone material and bitumen in accordance with the requirements of the formulation;
  4) delivery of a new asphalt mix by road to the repaired area;
  5) distribution of asphalt paver;
  6) seal.

Removing the old coating is advisable to carry out using mills company "Wirtgen" (Wirtgen).

Asphalt milled and crushed to granulate is transported by road to a stationary or mobile asphalt concrete plant. There, in strict accordance with the developed recipes, a new asphalt concrete mixture with the addition of stone material and bitumen is prepared.

Ready hot asphalt concrete must be delivered to the construction site. Motor vehicles designed to transport hot asphalt mixes must be equipped with tents to ensure that the temperature of the mixture provided by the technology is maintained.

Distribution and compaction of the delivered mixture is carried out according to traditional technology using modern pavers (Vogel, Dinapak) and pneumatic and smooth rollers.

The process flow of regeneration on the road is made by a special remixing machine. In one working stroke, the material of the old coating is heated, processed with or without the addition of new material, distributed and compacted (Fig. 4.2).

Fig. 4.2. Workflow recycling material flow

There are four groups of cars for performing hot ris-kings on the road:
  1) a joint remixer 300 is used to close cracked joints on an old surface;
  2) mini remixer-1000 is designed to restore sections of roads of small area;
  3) the remixer-2500 is equipped with a vario system, which allows loosening the old pavement and laying a new one, and is used to repair road lanes up to 2.5 m wide;
  4) Remixer-4500 is designed for the complete restoration of roads up to 4.5 m wide in one working passage.

When restoring roads with the Remixer-4500, four methods (methods) of regeneration can be used:
  1. Reshape (Reform) method - profiling.
  2. Repave method - profiling with restoration of the wear layer.
  3. Remix method - profiling with a change in the structure of the coating.
  4. The Remix-Plus method - profiling with a change in the composition of the mixture and the device layer of wear.

TO  Category: - Technique for the repair of roads