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GOU VPO TYUMEN STATE

ARCHITECTURAL AND CONSTRUCTION UNIVERSITY

Department of Building Materials

TEST

By discipline

"Standardization, metrology, certification"

on the topic: "Normative service life and wear of road structures"

Tyumen 2011

Literature

Chapter 1. Elements of pavement, basic terms and definitions

Road pavement is a multi-layer artificial structure, limited by the carriageway of a motor road, consisting of a road surface, base layers and an underlying layer, perceiving the repeatedly repeated impact of vehicles and weather and climatic factors and ensuring the transfer of traffic load to the upper part of the subgrade.

Non-rigid pavements include pavements with layers made from various types of asphalt concrete (tar concrete), from materials and soils reinforced with bitumen, cement, lime, complex and other binders, as well as from weakly cohesive granular materials (crushed stone, slag, gravel, etc.). ).

There are the following elements of pavement:

Coating - the upper part of the road pavement, which perceives the forces from the wheels of vehicles and is directly exposed to atmospheric factors.

On the surface of the coating, layers of surface treatments for various purposes (layers to increase roughness, protective layers, etc.) can be arranged.

Foundation - a part of the pavement structure located under the pavement and providing, together with the pavement, the redistribution of stresses in the structure and the reduction of their magnitude in the soil of the working layer of the subgrade (underlying soil), as well as frost resistance and drainage of the structure.

DEFINITIONS

A road structure is an engineering structure consisting of a pavement and the upper part of the subgrade within the working layer.

Strength (bearing capacity) of a road structure is a property that characterizes the ability of a road structure to perceive the impact of moving vehicles and weather and climatic factors.

The operability of a road structure is the property of a road structure to maintain a margin of safety for the repeatedly repeated impact of automobile loads within the calculated, overhaul periods of service.

The service life of a road structure is the period of time within which its strength and reliability decrease to the design level, the maximum allowable under traffic conditions.

Reliability of pavement - the probability of failure-free operation of pavement within the estimated (normative) overhaul life.

The level of pavement reliability is a quantitative indicator of reliability, defined as the ratio of the length of strong (non-deformed) sections of the road to its total length.

Regulatory overhaul period of pavement - the time period established by the current norms from the moment of construction to the overhaul or between overhauls.

Chapter 2

When designing pavement, the following principles should be followed:

a) the type of pavement and the type of pavement, the design of the pavement as a whole must meet the transport and operational requirements for the road of the corresponding category and the expected composition and traffic intensity in the future, taking into account changes in traffic intensity during the given overhaul periods and the expected conditions of repair and maintenance;

b) the design of clothing can be adopted as a standard or developed individually for each section or a number of sections of the road, characterized by similar natural conditions (soil of the working layer of the subgrade, its moisture conditions, climate, availability of local road-building materials, etc.) with the same design loads . When choosing a clothing design for given conditions, preference should be given to a typical design that has been proven in practice in given conditions;

c) in areas insufficiently provided with standard stone materials, it is allowed to use local stone materials, industrial by-products and soils, the properties of which can be improved by treating them with binders (cement, bitumen, lime, active fly ash, etc.). At the same time, we must strive to create a structure that is as least material-intensive as possible;

d) the design must be technological and provide the possibility of maximum mechanization and industrialization of road construction processes. To achieve this goal, the number of layers and types of materials in the structure should be minimal;

e) when designing, it is necessary to take into account the actual conditions of construction work (summer or winter technology, etc.).

Pavement should be designed with the required level of reliability, which is understood as the probability of failure-free operation during the overhaul period. Structural failure in terms of strength can be physically characterized by the formation of longitudinal and transverse surface irregularities of the pavement associated with structural strength (transverse irregularities, ruts, fatigue cracks), followed by the development of other types of deformations and fractures (frequent cracks, a network of cracks, potholes, subsidence, breaks etc.). The nomenclature of defects and the methodology for their quantitative assessment are determined by special standards used in the operation of roads.

Normative service life - the operational overhaul period (from the moment the road is put into operation until the first major overhaul) - is a parameter that is set at the design stage. Depending on it, building materials are selected that perceive various design loads.

In the absence of regional norms, the estimated service life of pavement may be assigned in accordance with the recommendations of Table 2.1

	Pavement type	Service life in road-climatic zones Т sl, years
	Capital
	Capital
	Capital
	Lightweight
	Capital
	Lightweight
	Lightweight
	transitional

The service life of pavement is the period of time within which the bearing capacity of the road structure decreases to a level that is maximum allowed by traffic conditions.

Repair of pavement is carried out when the calculated level of pavement reliability and the corresponding limit state of the pavement in terms of evenness are reached during operation.

The reliability of pavement is understood as the probability of failure-free operation of the structure during the entire period of operation before repair. Quantitatively, the level of reliability represents the ratio of the length of strong (undamaged) sections to the total length of the pavement with the corresponding value of the strength factor.

Regulatory overhaul periods of pavement service and the corresponding standards of reliability levels are taken according to Table. 2.2

road automotive coating overhaul

Table 2.2 Norms of overhaul (calculated) service life (T o) and norms of reliability levels (K H) of non-rigid pavements

	traffic intensity,	Pavement type	Road-climatic zone
		capital
		capital
		capital
		lightweight
		capital
		lightweight
		transition
		lightweight
		transition

Notes

1. Intermediate values ​​are taken by interpolation (for K H and T o).

2. When calculating the layers of reinforcement of capital and lightweight pavements, a reduction by 15% of the service life norm from the minimum values ​​is allowed while maintaining the reliability level norm.

When solving practical problems related to the assessment of the actual service life of non-rigid pavements and the transport and operational qualities of roads, they are guided by the maximum permissible operating conditions of the pavement in terms of evenness "i", depending on the level of pavement reliability.

The service life of the pavement is the period of time within which the adhesion properties of the pavements (capital and lightweight pavements) decrease or the wear of the pavement surface (transitional and lower pavements) increases to the values ​​​​maximum allowed by traffic conditions.

The norms of the overhaul service life of pavements (T p) on roads with capital and lightweight pavements are taken depending on the intensity of traffic in the first year after construction or work on the device of rough surfaces during road repairs (Table 2.3).

Table 2.3

Traffic intensity on the busiest lane, avt./day	Road-climatic zones	Norms of overhaul service life of road surfaces (T p)
from 200 to 2500
from 200 to 2000
from 200 to 1500
from 2500 to 4500
from 2000 to 4000
from 1500 to 3000
or 4500 to 6600
from 4000 to 6000
from 3000 to 5000

Chapter 3

3.1 Assessment of the quality and condition of the road

The quality of the road is the degree of compliance of the entire complex of indicators of the technical level, operational condition, engineering equipment and arrangement, as well as the level of maintenance with regulatory requirements that change during operation as a result of the impact of vehicles, meteorological conditions and the level of maintenance. Consumer properties of the road - a set of its transport and operational indicators (TEP AD), which directly affect the efficiency and safety of road transport, reflect the interests of road users and the impact on the environment, must be preserved in such a way that it loses its capacity to a minimum by the end of the calculated operational period. Consumer properties include those provided by the road: speed, continuity, safety and convenience of movement, traffic capacity and level of traffic congestion; the ability to pass cars and road trains with axle loads permitted for movement. To preserve consumer properties, it is necessary to carry out diagnostics of highways, for timely intervention and prevention of limit states of road characteristics. Diagnostics includes the examination, collection and analysis of information about the parameters, characteristics and conditions of operation of roads and road structures, the presence of defects and the reasons for their occurrence, the characteristics of traffic flows and other information necessary for assessing and predicting the condition of roads and road structures in the course of further operation. The assessment of the quality and condition of roads is carried out by:

* when putting the road into operation after construction in order to determine the initial actual transport and operational condition and compare it with regulatory requirements;

* periodically during operation to monitor the dynamics of changes in the state of the road, predict this change and plan repair and maintenance work;

* when developing an action plan or project for reconstruction, overhaul or repair to determine the expected transport and operational state, compare it with regulatory requirements and evaluate the effectiveness of the planned work;

* after performing works on reconstruction, overhaul and repair in the areas of these works in order to determine the actual change in the transport and operational condition of the roads.

To assess the condition of roads and road structures, it is necessary to collect and analyze a significant amount of basic initial information on the following indicators, parameters and characteristics:

1. General information about the road:

Number and title of the road, area of ​​its location;

Management body and service organization;

Assessment of the level of road maintenance for the last 12 months.

2. Geometric parameters and characteristics:

The width of the carriageway, the main fortified road surface and fortification strips;

Shoulder width, incl. fortified; type and condition of roadside reinforcement; longitudinal slopes;

Cross slopes of the carriageway and roadsides;

Radii of curves in the plan and the slope of the turn;

The height of the embankment, the depth of the excavation and the slopes of their slopes; state of the subgrade;

The visibility distance of the road surface in plan and profile.

3. Characteristics of pavement and pavement:

Pavement design and type of pavement;

Strength and condition of pavement and pavement (presence, type, location and characteristics of defects);

Longitudinal evenness of the coating;

Transverse evenness of the coating (rutting);

Roughness and coefficient of adhesion of the coated wheel.

4. Artificial structures:

Location, type, length and dimensions of bridges, overpasses, overpasses, tunnels;

Load capacity of bridges, viaducts and flyovers;

The presence and height of curbs;

Type and condition of the bridge deck;

Availability, material, type, size and condition of pipes.

5. Arrangement and equipment of roads:

Kilometer signs and signal posts;

Road signs, their location, condition and compliance with the rules and regulations of placement;

Road marking, its condition and compliance with the norms and rules of application;

Fencing, their design, location, length, condition, compliance with the norms and rules of installation;

Lighting;

Junctions, intersections with roads and railways, their type, location, compliance with design standards;

Bus stops and pavilions, recreation areas, parking and parking areas, their main parameters and their compliance with regulatory requirements;

Additional lanes of the carriageway and transitional speed lanes, their main parameters.

6. Characteristics of driving on the road:

Traffic intensity on characteristic stages and the dynamics of its change over the past 3-5 years;

The composition of the traffic flow and the dynamics of its change, highlighting the share of cars and trucks of various carrying capacities, buses, and other vehicles;

Data on traffic accidents for the last 3-5 years, linked to mileage and highlighting the number of accidents by road conditions.

In addition to the basic initial information for various management tasks and the formation of a common automated road database (ATDB), additional information can be collected during the diagnostic process, in particular:

The final result of the assessment is a generalized indicator of the quality and condition of the road (P d), which includes a comprehensive indicator of the transport and operational condition of the road (KP D), an indicator of engineering equipment and arrangement (K OB) and an indicator of the level of operational maintenance (K O):

P d \u003d KP D K OB K E. (3.1)

Indicators P d, KP D, K OB, K e are the criteria for assessing the quality and condition of the road. Their standard values ​​for each category are taken in accordance with the current regulatory and technical documents. A road condition is considered to be normative, in which its parameters and characteristics provide the values ​​of the complex indicator of the transport and operational condition not lower than the standard one (KP D KP N) during the entire autumn-spring period. Acceptable, but requiring improvement and increase in the level of maintenance, is considered such a condition of the road, in which its parameters and characteristics provide the value of the complex indicator of the transport and operational condition in the autumn-spring period below the standard, but not below the maximum allowable (KP N > KP D > KP P).

Table 3.1 Normative values ​​of KP N (numerator) and maximum allowable KP P (denominator) values ​​of a complex indicator of the transport and operational condition of roads

	Basic design speed, km/h	On the main stretch	On difficult terrain
			crossed

Note. The criteria for identifying difficult sections of rough and mountainous terrain are adopted in accordance with note 1 to clause 4.1 of SNiP 2.05.02-85. Inadmissible, requiring immediate repair or reconstruction, is considered such a state of the road, in which the value of the complex indicator of the transport and operational state of the road in the autumn-spring period is below the maximum permissible (KP D< КП П).

3.2 Formation of an information data bank on the state of roads

Based on the results of road diagnostics, an automated road data bank (ARDB) is formed and systematically updated. RTSA is an essential element of the road condition management system. It is an automated information and analytical system containing periodically updated information about roads, artificial structures, vehicle traffic, road accidents, service facilities, etc. a set of issues related to the management of the state of roads. Depending on the tasks to be solved, the traffic police are divided into industry-wide and local. Industry-wide data banks operate in the system of the state road management body and contain mainly technical data on roads and artificial structures, as well as information on the movement of vehicles, road accidents, service facilities, etc. A set of calculation and analytical programs that are part of the structure of industry-wide banks data, is focused mainly on solving issues related to managing the state of the federal highway network, including the planning of repair work and the distribution of funds allocated for road work. Local data banks operate in various road management bodies and include technical data on individual roads (road sections) and artificial structures, as well as information on the movement of vehicles, accidents, and service facilities on these roads. In addition, these data banks may contain specific modules responsible for certain areas of administrative and economic activities of road organizations.

Table 3.2 Enlarged composition of the sectoral automated road data bank (ABDD) (name of databases)

General information on the road	Traffic intensity	Accident data	Coating evenness	Coupling properties of the coating	Pavement strength	A/B coating defects
defects of the c/w coating		road-climatic zone	plan curves	carriageway width	visibility in plan	longitudinal slope
road section marker	culverts	road markings	road signs	communications	road clothes	boundaries (regions, etc.)
road sections located in settlements	stationary points of automated traffic accounting	reconstructed road sections	distance between kilometer marks	subgrade elements and drainage systems	service stations	anti-noise and anti-dazzle screens
signal bollards	bridge structures		forest belts	interchanges	fences	weather stations
bus stops	footpaths and sidewalks	snow protection structures	junctions and intersections	road buildings and structures		road lighting
	underground passages	stationary traffic police posts	calling communication	food outlets	development	repair work
medical aid points	campsites	bus stations		recreation areas	stationary points of weight control	service objects

3.3 Road maintenance planning

Table 3.3 Types of road works depending on partial coefficients K pc i

Partial coefficient K pc i	Influence accounting	Type of road repair work at K pc i< КП Н
	Shoulder widths and conditions	Roadside strengthening
	The intensity and composition of traffic, the width of the actually used reinforced pavement surface	Widening of the roadway, installation of fortification strips, strengthening of roadsides, widening of bridges and overpasses
	Longitudinal slope and visibility of the road surface	Softening the longitudinal slope, increasing visibility
	Radius of curves in plan	Increasing the radii of curves, the device of turns, straightening the section
	Longitudinal evenness of the coating	The device of a leveling layer with surface treatment or the restoration of the upper layer by the methods of thermal profiling and regeneration (repair of the coating with E f E T r). Repair (strengthening) of pavement at E F< е тр
	Coupling qualities of the coating	The device of a rough surface by the method of surface treatment, embedding crushed stone, laying the top layer of multi-crushed asphalt concrete
	Cross evenness of a covering (rut)	Gauge elimination by overlapping, filling, milling
	traffic safety	Measures to improve traffic safety in hazardous areas

Repair planning based on "compliance indices"

The "compliance index", assigned by an expert, is understood as the level of compliance of the condition of road sections with traffic safety requirements in combination with compliance with the regulatory requirements for grip and evenness of the pavement, the presence of a turn and reinforced shoulders in these sections.

The use of the "conformity index" does not replace the economic criterion, but serves as a tool for analyzing the results of diagnostics, primarily in areas of concentration of road accidents and planning road repair work in conditions of insufficient funding.

When determining the priority of repair work, they are guided by Table 3.4, using which a weighted average indicator of the priority of repair work can be established.

Table 3.4

The order of repair work	The condition of the site in terms of road safety	The indicator of the order and condition of the site
	Very dangerous or dangerous and with an unsatisfactory friction coefficient
	Very dangerous or dangerous and with unsatisfactory evenness, and/or lack of a turn, and/or with an unpaved shoulder
	Slightly hazardous and non-hazardous and with an unsatisfactory coefficient of adhesion
Fourth	Slightly dangerous and non-hazardous and with unsatisfactory evenness and (and) the absence of a turn, and (and) with an unpaved shoulder
	Other areas in need of repair

Note. Areas that do not require repair are assigned a priority or condition score of 5.

Chapter 4

Table 4.1

	Parameters and elements	federal roads	Local roads (territorial)
		Trunk
	Geometrical parameters of the plan and profile (width of the carriageway and shoulders, longitudinal and transverse slopes, radii of horizontal curves, width of the dividing strip, etc.)	During the primary diagnostics of exploited roads. When re-diagnosing only in areas of change in geometric parameters after the appropriate repair measures or reconstruction
	Evenness of the road surface: in areas with unsatisfactory evenness	Annually	Once every 2 years	Once every 3 years
	in other areas	Once every 2 years	Once every 3 years	Once every 3 years
	Coupling properties of road surfaces	Annually	Once every 2 years	Once every 3 years
	Visual registration of pavement and pavement defects in order to determine their condition	Annually	Annually	Annually
	Strength of pavement, assessment of the condition and drainage system:
	* in areas with to pr< 0,80	Annually	Annually	Once every 3 years
	* in other areas	Once every 3 years	Once every 4 years	Once every 5 years
	as well as after repair and reconstruction works
	The state of road devices and road conditions (rest areas, parking lots, bus stops and car pavilions, road signs and indicators, fences, etc.)	Once every 3 years	Once every 4 years	Once every 5 years
	Condition of culverts	Once every 3 years	Once every 4 years	Once every 5 years
	Accounting for traffic intensity and composition of traffic flow	Annually	Once every 3 years	Once every 5 years
	Collection of information on accidents with the identification of areas of concentration of accidents and their detailed examination	Annually	Annually	Annually
	Formation and updating of a data bank on the state of roads	Annually	Annually	Annually

Literature

1. VSN 41-88 Norms of overhaul service life of pavements

2. ODN 218.046-01 Design of pavement

3. ODN 218.0.006 Rules for the diagnosis and assessment of the condition of roads

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The most commonly used asphalt concrete mix for the construction of the top layer of the pavement on roads with high traffic intensity is crushed-stone-mastic asphalt concrete, produced in accordance with GOST 31015-2011 (ShMA-20). Due to the high content of rationally selected fractional crushed stone, including along the screening boundaries, a more stable skeletal structure is formed in it, thanks to which the SMA layer perceives loads better and shows good resistance to operational deformations.

Under dynamic and thermal loads and deformations, it is the quality of the binder that ensures the creation of a "monolith" that has all the required performance characteristics. In our opinion, very little attention is paid to the quality of the original bitumen and checking the characteristics of a / b for crack resistance and shear resistance at low temperatures and water saturation, including after freezing and thawing, resistance to the formation of plastic rutting.

A logical result is a high risk of non-compliance with the warranty periods of operation during construction and repair and seasonal restriction of the movement of trucks "to dry", that is, additional losses for all subjects of the Russian economy. Consider our step towards solving this problem.

The use of bitumen obtained by oxidation technology, which meet the requirements of GOST, as practice shows, does not provide the required durability of road surfaces. The main reason for this is the insufficient deformability of oxidized bitumen, poor adhesion to mineral materials (especially acidic ones), and low resistance to aging processes. Asphalt concretes made on the basis of non-oxidized bitumen have hydrophobic properties, and hydrophobicity is already directly related to water resistance. In turn, increased water resistance increases the durability of the pavement.

Based on the well-known principle that the property of asphalt concrete is determined mainly by the quality of bituminous binders, researchers and road practitioners in many developed countries have come to the conclusion that it is expedient to replace conventional bitumen with polymer-modified bitumen (BMP).

Starting from the 60s, this area of ​​bitumen technologies has been developing quite intensively, but haphazardly: various polymers were used (at the first stage, production waste), there was a search for technologies for their optimal combination with bitumen. Thus, the scientific and production experience accumulated up to this time indicates the advantages of asphalt concrete based on polymer-modified bitumen, compared to conventional asphalt concrete, in terms of: strength and, in particular, shear resistance; brittleness and crack resistance temperatures (with appropriate polymer content); stability in the aquatic environment and, ultimately, the durability of asphalt polymer concrete pavements. At the same time, the provision of these advantages requires the complication of the technological preparation of bituminous binders, which leads to their rise in price due to the high cost of polymers. At the same time, a significant additional consumption of energy resources is inevitable, which is necessary for carrying out all technological processes at temperatures 15-25 ° C higher than in the case of the practice of using traditional bitumen and asphalt concrete. Compensation for the costs of application can be ensured by lengthening the time between repairs of the asphalt-polymer concrete pavement and reducing the volume of its repair.

Developing in a given direction, Innovative Technologies LLC conducted a set of laboratory studies and full-scale practical tests in the period from 2013-2016, as a result of which the possibilities and requirements for the use of the Dorflex BA® material were determined. The polymer modifier "Dorflex BA" is a bulk material in the form of granules with a diameter of 2-6 mm. Secondary polymers - polyolefins modified with organoelement compounds - are used as feedstock for Dorflex BA composition.

The increase in the durability of road surfaces is determined by the ability of the top layer of the road surface to perceive static and dynamic loads in all operating conditions without destruction and deformation, this is achieved by increasing the cohesive strength of the adhesive of the binder with asphalt concrete and maintaining its "elasticity" to the maximum.

Butadiene and styrene thermoplastic elastomers of the SBS type, the most common in road construction, are distinguished by the ability to highly elastic deformation due to the work of a spatial structural network formed due to physical bonds between blocks of butadiene and styrene macromolecules. With the use of the modifier "Dorflex BA" there is an increase in the resistance of asphalt concrete to shear deformations, associated with the formation of a spatial polymer structural network in a bituminous binder, close to that obtained using a polymer-bitumen binder (PBV). Physical and mechanical characteristics on the example of ShMA-20 modified with the additive "Dorflex BA" in comparison with the reference brand of the mixture are shown in the table.

Table Physical and mechanical characteristics of crushed stone-mastic asphalt concrete ShMA-20.

No. p.p.	The name of indicators	Requirements GOST 31015-2002 for ShchMA-20	ShMA-20 gabbro-diabase, BND 60/90 (stab. add. 0.47% in 100%) reference	Actual figures with additive
				ShMA-20 gabbro-diabase, BND 60/90 (stable add. 0.47% in 100%, 0.2% Dorflex BA (over 100%)
	Average density, g/cm²		2,65	2,66
	Water saturation, % by volume	1.0 to 4.0	2,10	1,48
	Tensile strength at 20°C	Not less than 2.2	2,78	3,40
	Tensile strength at 50°C	Not less than 0.65	0,77	1,05
	Shear resistance according to the coefficient of internal friction	Not less than 0.93	0,97	0,97
	Shear stability in shear adhesion at a temperature of 50°C, MPa	Not less than 0.18	0,19	0,26
	Crack resistance, tensile strength at split at 0°С	At least 2.5 No more than 6.0	3,65	4,84
	Binder flow rate at 170°C, wt %	Not more than 0.20	0,14	0,13

The use of secondary polymers as a modifier in road construction solves the problems of increasing the thermal stability of asphalt concrete, saving bitumen, recycling solid domestic waste, as well as related environmental problems and environmental protection. The mechanism of the modifying effect of the additive on road bitumen, as part of an asphalt concrete mixture, consists in filling the mass of bitumen with a finely dispersed polymer phase, that is, in structuring. Naturally, with an increase in the degree of filling of the binder mass with a dispersed polymer phase, the cohesive strength and density of the composition increase. Since the basis of the modifier is a thermoplastic linear polymer - polyolefin, which makes the bitumen-polymer system sufficiently rigid, as evidenced by a sharp increase in the viscosity of the modified bitumen, it can be assumed that the abrasive effect of solids on the surface of the polymerized bitumen-polymer system (wear from studded rubber) does not will have a destructive effect on the molecular bonds of the latter.

The duration of the preparation of the asphalt concrete mix does not change, thereby maintaining the productivity of asphalt concrete plants and eliminating the need for significant costs for the installation of additional equipment. The dosing of Dorflex BA can be done manually or automatically by means of a dosing device consisting of a small hopper for the granular modifier, a screw conveyor and a weighing batcher. The temperature of a traditional asphalt mix using Dorflex BA at the outlet of the mixer should be in the range of 150-155 °C, of ​​a crushed stone-mastic mixture 160-165 °C.

Together with NCC-road, studies were carried out to find the optimal composition of asphalt concrete mixtures using Dorflex BA and a series of comparative tests were carried out with different content of the polymer additive in the preparation of asphalt mixtures with their subsequent compaction during the operation of the road surface on the test site. It has been established that the most effective summation of technical and economic factors for SMA and hot mixes is the content of "Dorflex BA" in an amount of about 0.2% of the mineral part of asphalt concrete. A scientific and technical research base has been formed, design and technological documentation has been developed for the use of Dorflex BA as a modifying additive for hot asphalt mixes of all types.

To confirm the theoretical data, and determine the effectiveness, tests were carried out for resistance to the formation of plastic rutting on the asphalt concrete pavement analyzer (APC), as well as tests for wear resistance from studded rubber by the Prall method according to SFS-EN 12697-16.

As a result of tests for rutting, it was found that the modifier "Dorflex BA" significantly reduces the susceptibility of asphalt concrete to plastic deformation. A comparative analysis of the results showed that the values ​​of the track indicators when using Dorflex BA are close to those when using PBB 60.

Due to the introduction of the modifier into the asphalt concrete mix, an improvement in wear resistance indicators is recorded on average by 5-7% from the reference grades of mixtures according to GOST 31015 and GOST 9128. If we analyze the results of the wear resistance of asphalt concrete according to the Prall method (SFS-EN 12697-16), with the characteristics of reference mixtures, the modifier practically increases this indicator by one class.

Summarizing the above, we propose to pay attention to the modifying additive "Dorflex BA", we are sure that our work will reduce the likelihood or completely eliminate cases of non-compliance with the warranty period for the operation of the roadway.

A.V. Ivkin,
Technical Director
LLC "Innovative Technologies"

Asphalt laying is a rather complicated and time-consuming process, but at the same time an effective way of paving. The range of work performed includes: excavation, foundation, asphalt laying, landscaping.

The work performed at a professional level will allow you to create not only a reliable and stable road surface, but also ensure its long-term service life. Specialists START CITY GROUP will help you choose the best option for the base and material for laying asphalt, based on your wishes.

Characteristic

Asphalt (or asphalt concrete mixture) is a rationally selected mixture based on mineral materials, which include sand, crushed stone, mineral powder, liquid bituminous substance. All substances are selected in the optimal amount and mixed in a heated state.

Crushed stone, which is part of the mixtures, must comply with the requirements of GOST 8267 and GOST 3344. It is allowed to use gravel or crushed stone produced according to foreign standards, provided that their quality complies with established Russian standards.

The scope of application of asphalt concrete is wide: the construction of roadways, squares, sidewalks, parking areas, park areas for cyclists, airfields, flooring in industrial buildings and many other areas.

Today, asphalt concrete mixtures, depending on the mineral component, are divided into:

• sandy;
• crushed stone;
• Gravel.

The structure of each type has its own characteristics, which determine the effectiveness of the use of the selected material.

Also, asphalt concrete mixes are classified depending on the size of mineral grains:

• Fine-grained - less than 2 cm;
• Coarse-grained - up to 4 cm.
• Sandy - up to 1 cm.

The amount of solid filler in the mixture depends on which group the asphalt concrete belongs to. There are 3 groups: A, B, C.

Stacking technology. Stages. materials

To date, two technologies for the construction of the roadway are used:

• hot asphalting;
• cold asphalt.

Each of them has its pros and cons:

• Hot asphalt. The mixture is prepared from viscous and liquid petroleum bitumen. Laying can be carried out in winter. The temperature of the mixture should not be less than 120 degrees. Before laying asphalt, a piece of the road, on which the asphalt concrete mixture will be applied, is dried with special equipment.
• Cold paving. The mixture is prepared from liquid petroleum road bitumen. Laying works are carried out only in the warm season, since this technology does not dry the water. Cold asphalting is often used for patching.

Professional paving works require significant financial investments. After all, for this it is necessary to attract special equipment and experienced qualified specialists.

Asphalt laying consists of several stages:

1. Development of design estimates

Each site is individual: it has its own size, topography and configuration, soil characteristics, remoteness and features of access roads. Based on these criteria, after the departure of the specialist, the total area, volume and preliminary cost of the work are determined.

2. Territory development, excavation

Preparation of the territory for the installation of an asphalt canvas begins with the removal of the top layer of soil. As a rule, bulldozers and loaders are involved to remove a large soil layer. Graders are used to level the surface of the base. According to the given marks, the formation of a road "trough" is carried out with its further compaction.

If there is an old coating on the asphalted area, then it is destroyed by a road mill. With proper recycling, the old coating can be reused.

3. Foundation preparation

It is the turn of the formation of a "road pillow". To do this, two layers of the road “pie” are poured: first, sand or a sand-gravel mixture is laid, and to give the entire coating special strength, crushed stone of a large fraction is poured on top, and then a fine fraction is poured to minimize voids. Each layer of the base is leveled by a grader and carefully compacted. A side stone is installed along the edges of the site. In order for the asphalting to be of high quality, before laying the asphalt, the surface of the site is shed with bitumen.

4. Asphalt paving

The final layer consists of asphalt concrete. This material is delivered by dump trucks or is prepared directly on the road construction site itself. The standard composition of ABS includes: mineral powder, sand, crushed stone and liquid bitumen.

The mixture is evenly distributed over a given area. For laying the last layer of the mixture, asphalt pavers are used. Asphalt rolling is carried out by several rollers for the best consistent compaction. Our company has formed its own material basis - a modern fleet of special equipment, which has about 40 units of equipment, which fully provides the entire process of road construction.

It should be noted that the technology of laying asphalt concrete and the materials used may have some differences depending on further operating conditions. So, for example, to extend the life of highways, new technologies are used - modified gel-like petroleum bitumen (MAK bitumen).

Road time

It should be noted that asphalt paving is a seasonal work and directly depends on weather conditions. It is recommended to carry out all work in dry weather.

In autumn and spring, the temperature should not be less than +5 degrees. After all, the delivered mixture is a hot product. Therefore, all manipulations with it should occur as quickly as possible so that it does not have time to cool. Otherwise, it will be impossible to lay asphalt.

Service life

The service life of an asphalt pavement directly depends on the loads, traffic intensity, weather conditions, adherence to laying technologies and the quality of the materials used.

The guaranteed service life is approximately 7 - 10 years. But you need to take into account the fact that with intensive use, the specified period can be reduced. Timely repair work of the roadway, which includes the elimination of pits, subsidence, cracks and irregularities, will help to extend the operational life.

Asphalting today is the easiest, fastest and most economical way to build roads and carry out repairs. For the production of new asphalt, asphalt chips formed during dismantling are used.

Requirements for asphalting roads

Asphalting of roads must be carried out in strict accordance with all the technical requirements of the project documentation. All actions performed by workers must comply with the documentation, otherwise there is a risk of violating the technology and obtaining poor-quality results.

Asphalt should be laid at an air temperature of at least +5 degrees in autumn and +10 degrees in spring. Asphalting should not be done in rain, snow and other precipitation. Careful dismantling of the old asphalt pavement must be carried out before laying the new one. Only if all requirements are met can a quality result be guaranteed. BiK specialists always comply with all technical requirements, which ensures high quality of road works.

What determines the expiration date

The service life of an asphalt pavement depends primarily on the observance of technology during its laying and the use of high-quality materials. The guaranteed service life of asphalt is about ten years. However, during operation under the influence of natural and man-made factors, this period may decrease. Under bad weather conditions and heavy use of the pavement, the life of asphalt can be reduced to five years, even with careful observance of all technical requirements for its installation.

How to extend the service life

Timely repair, elimination of pits, irregularities and cracks as they appear can extend the life of the pavement. Repair work does not require large financial and time costs, unlike laying new asphalt.

High-quality asphalting of roads from the company "BiK"

Employees of our company have extensive experience in road works. We always have a wide range of all necessary special equipment available, which allows us to perform any work at a high level of quality. Therefore, we offer our customers a wide range of road works: road asphalting, repair work, overhaul, dismantling of the old asphalt pavement, laying paving slabs and other activities.

www.bik-stroy.ru

Asphalt pavement in modern construction remains the most reliable and in demand. The service life of the canvas is at least 7 years, subject to the rules of laying and operation. The evenness of the finished asphalt, the relative cheapness of the coating and the long service life are the main differences from other types of road construction.

Types of asphalt

Hot mix asphalt consists of sand, bitumen, gravel, mineral additives. The composition is prepared from ingredients taken in a certain proportion, heated to a temperature of 120 ° C. Asphalt should be used within 4 hours from the date of manufacture. Raw materials are transported in special containers to ensure a constant temperature. Asphalt paving is carried out with the help of heavy equipment: asphalt pavers, rollers and vibrating plates. Ambient temperature is allowed not lower than 5°С during asphalt laying. In hot weather, the asphalt pavement can collapse if the rules for operating the road are violated. You can fully use the strip covered with asphalt after 6 hours from the time of laying.

hot mix asphalt
hot mix asphalt
hot mix asphalt

Cold asphalt uses liquid bitumen and a number of special additives to give the product strength. The road can be operated almost immediately after laying. For ramming, hand tools are used along with special equipment. High quality is maintained when working in temperatures ranging from -20° C to +40° C. Many customers are stopped by the rather high cost of the product with the same quality indicators as hot asphalt.

cold mix asphalt
cold mix asphalt

Asphalt crumb - the removed and crushed layer of the old coating - is used mainly for patching roads.

Asphalt crumb
Asphalt crumb
Asphalt crumb

Asphalt paving

In order to properly lay the asphalt canvas, ensuring the proper quality of the future road, it is necessary:

• make a marking of the site for asphalting: determine the boundaries;
• identify a place for water flow after natural precipitation;
• bypass underground utilities so that in case of repair they do not destroy the road surface; remove the roots of large trees;
• determine the intended purpose of the asphalt pavement in order to correctly calculate the depth of the pit and the cost of the material;
• provide construction with special equipment or devices;
• calculate the required slope of the road, which ensures the flow of rainwater into the drainage system.

Asphalt laying technology:

• remove the top layer of soil using an excavator or similar equipment. The depth of the excavation is calculated depending on the purpose of the road;
• limit the width of the pavement to ensure a decent quality of the road lane;
• fill the pit and compact first with crushed stone 40-60 mm in size, and then with a fraction of 20-40 mm. You can use broken bricks, stones or concrete slabs;
• a layer of river sand is poured on top and carefully compacted. For better precipitation, the layers can be moistened;
• the final stage is the laying of the asphalt itself with a layer corresponding to the intended operation of the road.

Each layer is compacted individually to ensure decent quality and durability of the finished coating.

kayrosblog.ru

Warranty period of pavement operation

The bill on the establishment of a warranty period of service was submitted to the State Duma. If adopted, road construction or repair companies will have to resurface at their own expense in the event of a roadbed failure before the warranty period expires.

In this case, the duration of the guarantee will be established by the regulations. So the bottom layer of the coating should last at least five years, the base - at least seven years. For earthen pavement, the service life will be from 10 years, and asphalt pavement will have to be calculated for at least 4 years. The transitional and lower type of the top layer should last at least 3 years.

In addition, the guarantee for bridges, overpasses and various overpasses will be over 8 years, barrier fences will last more than 5 years, and signal posts will become unusable only after 4 years. Road signs will stand without replacement for 3 years. Road markings should serve at least 9-15 months, with the exception of temporary markings. The warranty period begins to operate from the date of delivery of works. In the event that a defect has been discovered, the warranty period will begin to operate from the moment it is eliminated.

Currently, quality requirements and guarantees are specified in the documentation when concluding a contract. It is expected that in this way builders will be more responsible for their work and provide the proper quality of services to meet the requirements. The rate of deterioration of roads in Russia today shows that most contractors are negligent in their obligations to build or repair roads or various structures, so the government decided to legislate the responsibility of road services Source: jcnews.ru

carddefence.ru

Asphalt paving technology

Asphalt laying is a rather complicated and time-consuming process, but at the same time an effective way of paving. The range of work performed includes: excavation, foundation, asphalt laying, landscaping.

The work performed at a professional level will allow you to create not only a reliable and stable road surface, but also ensure its long-term service life. START CITY GROUP specialists will help you choose the best option for the base and material for asphalt laying, based on your wishes.

Characteristic

Asphalt (or asphalt concrete mixture) is a rationally selected mixture based on mineral materials, which include sand, crushed stone, mineral powder, liquid bituminous substance. All substances are selected in the optimal amount and mixed in a heated state.

Crushed stone, which is part of the mixtures, must comply with the requirements of GOST 8267 and GOST 3344. It is allowed to use gravel or crushed stone produced according to foreign standards, provided that their quality complies with established Russian standards.

The scope of application of asphalt concrete is wide: the construction of roadways, squares, sidewalks, parking areas, park areas for cyclists, airfields, flooring in industrial buildings and many other areas.

Today, asphalt concrete mixtures, depending on the mineral component, are divided into:

• sandy;
• crushed stone;
• Gravel.

The structure of each type has its own characteristics, which determine the effectiveness of the use of the selected material.

Also, asphalt concrete mixes are classified depending on the size of mineral grains:

• Fine-grained - less than 2 cm;
• Coarse-grained - up to 4 cm.
• Sandy - up to 1 cm.

The amount of solid filler in the mixture depends on which group the asphalt concrete belongs to. There are 3 groups: A, B, C.

Stacking technology. Stages. materials

To date, two technologies for the construction of the roadway are used:

• hot asphalting;
• cold asphalt.

Each of them has its pros and cons:

• Hot asphalt. The mixture is prepared from viscous and liquid petroleum bitumen. Laying can be carried out in winter. The temperature of the mixture should not be less than 120 degrees. Before laying asphalt, a piece of the road, on which the asphalt concrete mixture will be applied, is dried with special equipment.
• Cold paving. The mixture is prepared from liquid petroleum road bitumen. Laying works are carried out only in the warm season, since this technology does not dry the water. Cold asphalting is often used for patching.

Professional paving works require significant financial investments. After all, for this it is necessary to attract special equipment and experienced qualified specialists.

Asphalt laying consists of several stages:

1. Development of design estimates

Each site is individual: it has its own size, topography and configuration, soil characteristics, remoteness and features of access roads. Based on these criteria, after the departure of the specialist, the total area, volume and preliminary cost of the work are determined.

2. Territory development, excavation

Preparation of the territory for the installation of an asphalt canvas begins with the removal of the top layer of soil. As a rule, bulldozers and loaders are involved to remove a large soil layer. Graders are used to level the surface of the base. According to the given marks, the formation of a road "trough" is carried out with its further compaction.

If there is an old coating on the asphalted area, then it is destroyed by a road mill. With proper recycling, the old coating can be reused.

3. Foundation preparation

It is the turn of the formation of a "road pillow". To do this, two layers of the road “pie” are poured: first, sand or a sand-gravel mixture is laid, and to give the entire coating special strength, crushed stone of a large fraction is poured on top, and then a fine fraction is poured to minimize voids. Each layer of the base is leveled by a grader and carefully compacted. A side stone is installed along the edges of the site. In order for the asphalting to be of high quality, before laying the asphalt, the surface of the site is shed with bitumen.

4. Asphalt paving

The final layer consists of asphalt concrete. This material is delivered by dump trucks or is prepared directly on the road construction site itself. The standard composition of ABS includes: mineral powder, sand, crushed stone and liquid bitumen.

The mixture is evenly distributed over a given area. For laying the last layer of the mixture, asphalt pavers are used. Asphalt rolling is carried out by several rollers for the best consistent compaction. Our company has formed its own material basis - a modern fleet of special equipment, which has about 40 units of equipment, which fully provides the entire process of road construction.

It should be noted that the technology of laying asphalt concrete and the materials used may have some differences depending on further operating conditions. So, for example, to extend the life of highways, new technologies are used - modified gel-like petroleum bitumen (MAK bitumen).

Road time

It should be noted that asphalt paving is a seasonal work and directly depends on weather conditions. It is recommended to carry out all work in dry weather.

In autumn and spring, the temperature should not be less than +5 degrees. After all, the delivered mixture is a hot product. Therefore, all manipulations with it should occur as quickly as possible so that it does not have time to cool. Otherwise, it will be impossible to lay asphalt.

Service life

The service life of an asphalt pavement directly depends on the loads, traffic intensity, weather conditions, adherence to laying technologies and the quality of the materials used.

The guaranteed service life is approximately 7 - 10 years. But you need to take into account the fact that with intensive use, the specified period can be reduced. Timely repair work of the roadway, which includes the elimination of pits, subsidence, cracks and irregularities, will help to extend the operational life.

start-city.com

Destruction of asphalt concrete pavement: causes and types

It is always convenient to travel in a car on a flat and smooth freeway, developing a high speed. Not infrequently, the quality of the track does not allow this, as the surface has a deviation from the norm and is unsuitable for a quality ride. Over time, under the pressure of the wheels of cars, especially large trucks, the influence of adverse natural conditions in the form of rain, hail, a sharp change in temperature, asphalt concrete flooring loses its original appearance. It is covered with small cracks, pits, potholes, which shortens the time of high-quality work of the highway. Driving on such worn-out roads leads to damage to cars and can even lead to an accident.

Causes of destruction

As a result of the use of asphalt concrete pavements, they are subjected to various deformations. Road wear is formed due to external and internal influences on asphalt concrete pavements. Defects on the coating from the influence of external factors include:

• power loads from automobile wheels;
• atmospheric precipitation (rain, temperature changes, thawing, snow, freezing).

The main causes of destruction are non-compliance with the technology of laying or repairing the roadway and the impact of cars.

Internal factors associated with the destruction of the asphalt concrete pavement arise as a result of improper design for roads, their construction and repair:

1. Incorrect design of an asphalt concrete highway leads to the destruction of the road surface. Inaccurate studies, calculations and errors made in determining the intensity of the flow of vehicles can contribute to the formation of defects on the road from asphalt concrete and lead to the destruction of the road structure, namely: the integrity of the asphalt layer on the road surfaces will be violated; the soil of the base will sag; the strength of the soil cushion will decrease; deterioration of the asphalt concrete floor will follow.
2. Old techniques are applied and poor quality materials are chosen when working with asphalt concrete pavement. More recently, for installation, laying asphalt mortar and repairing roads, hot mixes of asphalt concrete were used, which included low-quality bitumen. It caused damage to the road deck and worsened the strength characteristics of the finished mixture for asphalting the road surface. However, construction does not stand still, and even today the latest polymer-bitumen materials are being developed and introduced, which can significantly improve the properties of the material and the future route. Various additives to the mixture have gained great popularity for: improving adhesion, increasing resistance to water and cracking. Thanks to these additives, the resistance of the roadway to sub-zero temperatures is ensured. In order to avoid defects and wear of the roadway, it is necessary not only to use new mixes for asphalt paving, but also to choose new technologies that will stabilize and strengthen the weakened mobile base soils. To prevent the destruction of coatings, a reinforcing mesh is used, which will strengthen the road structure and increase the life of the asphalt road.
3. Defects and wear on the asphalt concrete pavement occur as a result of an incorrect technological process during the construction of the road structure. Destruction is formed due to mistakes made when laying asphalt and repairing the track. Violations of the rules for the transportation of asphalt concrete mortar contribute to the occurrence of defects, as a result of which the mixture is supplied at the wrong temperature. When compacting the laid mixture, air bubbles were not removed or, conversely, the solution was too compacted, then the asphalt canvas will begin to crack and delaminate. Destruction of the route may occur as a result of poor-quality preparation of the subgrade and work on laying the road structure.
4. Defects on the road surface are most often formed as a result of weather conditions, when during rains moisture penetrates the asphalt road, and the hot rays of the sun spoil the top layer of the route - the strength of asphalt concrete deteriorates, which leads to the formation of potholes. During sub-zero temperatures, the collected moisture in the layers of asphalt concrete can increase in volume and thereby destroy the structure and compaction of the asphalt.
5. As a result of heavy loads from vehicles, the roadway is destroyed. High loads on the surface of the route are due to the intensive flow of vehicles, as a result of which the throughput rate for 24 hours is exceeded and, as a result, the resource of the road bed is reduced. An increase in the axial load due to the operation of the road surface by heavy-duty vehicles leads to the destruction of the asphalt concrete pavement, the formation of ruts and cracks.

Damage to asphalt concrete pavement can occur due to the complex influence of external and internal factors.

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Main types of defects

Typical defects of highways.

Asphalt damage is of the following types:

• Break. It is a slot on the paved area where the flow of vehicles passes. If cracks are not patched in time, they can grow in size and turn into a large-diameter breach.
• Service life expiration. The destruction associated with the long-term operation of the roadbed, which was not repaired, affects the thickness of the asphalt concrete layer.
• Reducing the strength of asphalt concrete. As a result of heavy loads from heavy trucks, canvas subsidence and destruction of the upper coating layer in the form of bumps, potholes and ruts are formed.
• potholes. Pothole failures are depressions with a sharp edge break that occur due to improper asphalt concrete laying using poor quality materials.
• Peeling. The formation of peeling on the road surface due to the separation of particles from the top layer of the coating. It is formed due to constant variable effects on the road surface of frost and thaw.
• Climatic influences. During the melting of snow masses, a large amount of liquid is formed, which is capable of destroying the roadbed, which entails a decrease in the strength characteristics of asphalt concrete.
• Chipping. This type of damage occurs due to a violation of the laying or repair of the roadway, namely, work in precipitation or sub-zero temperatures.
• Cracks. Cracks form on the road surface as a result of a sharp change in temperature.
• Drawdown. Settling occurs due to poor quality paving materials selected, as well as insufficient compaction of the asphalt mix or soil.

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How to prevent road damage?

The measures taken will prevent further destruction of the road.

Prevention of destruction of asphalt concrete pavements includes comprehensive measures to eliminate problematic sections of the route. Timely detection of damage will prevent further formation of potholes, faults and improve the strength characteristics of the asphalt pavement.

Damage control methods help maintain the desired transport and operational performance of the track, preserve the integrity of the structure and surface, and also increase the life of the automobile surface. These methods include:

• Use of the latest materials, equipment and technology for laying asphalt on highways. Polymer mixtures are used, which are added to the solution at the stage of its manufacture, which are necessary to increase heat resistance in the hot season, when the coating is exposed to direct sunlight and high temperatures. The polymers in the asphalt mix reduce the formation of cracks during periods of low air temperatures, and prevent the formation of potholes during the use of the track.
• In the process of paving, all the rules and requirements for installing a highway should be followed: thoroughly compact the soil and asphalt mixture, add a binder-bitumen component to the solution in the required proportions to ensure the desired adhesion and improve the roughness of the coating.
• To avoid the formation of road damage, it is important to carry out repairs not only as needed, but also for preventive purposes. Untimely work worsens the condition of the roadway and leads to an increase in costs to give the road surface a standard condition. Delayed repair of the roadbed leads to the use of more reinforced thick layers of the road surface and high costs for repairing the pavement.

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Conclusion

People come across asphalt concrete roadbed every day, so this part of the road structure should not only have high strength and quality, but also be easy to use. Various potholes, cracks, ruts and other road damage that can cause a lot of trouble for both pedestrians and vehicles.

In order for the road surface not to deteriorate, it is important to follow the technological methods and recommendations for its installation, carry out repairs on time and prevent the increase in existing damage.

kladembeton.ru

Asphalt laying according to SNIP and GOST

Asphalt road surfaces are common and extremely popular. This is primarily due to the durability and strength of this option. For these conditions to be fully met, a number of conditions must be met. The technology of laying asphalt is notable for certain difficulties, but if everything is done correctly, the costs will pay off with impeccable coverage and trouble-free operation.

Types of asphalt pavement

Bituminous materials (resins) and reinforcing filler are used in the production of asphalt mix. Its role is played by coarse sand and mineral rocks of a certain fraction. All materials must be of good quality, and depending on the type and purpose of the coating, other ingredients are added to the composition.

Asphalt types:

1. First class coverage. Used for laying tracks, able to withstand heavy loads. The technology involves the use of mineral filler up to four centimeters in size. Such coatings can withstand the weight of loaded vehicles and heavy use.
2. Coatings of the second class. They are used for asphalting squares, sidewalks and pedestrian roads. The largest inclusions of the asphalt mix reach 25 mm.
3. Coatings of the third class. The priority in this case will be the plasticity of the mixture. Mineral particles of the minimum size (up to 15 mm), which allows you to get a snug fit of the composition. Such coverage equips places of non-transport use (private yards, territories of institutions, sports grounds).

Proportions and manufacturing standards are regulated by GOST, but many manufacturers ignore this rule and use cheap substitutes. This is not displayed in the best way on the quality of the asphalt mix, therefore it is preferable to order this product from really trusted companies, for example, representatives of the Road Technologies company.

Application technologies:

• Hot asphalt. Its laying technology requires the use of special equipment, as well as the observance of a number of conditions. First of all, this is the temperature of the finished mixture and the ambient air. It is unacceptable to lay cooled asphalt, as well as perform work at low temperatures. The second important point is the speed of laying hot asphalt. If the work is not performed in accordance with GOST, the quality of the coating will be poor. Hot asphalt is used to build new roads and sidewalks. After application, the coating should be left unused for some time to ensure a sufficiently strong bond.
• Cold asphalt. Its nomes are also regulated by GOST and SNIP, but other grades of bitumen are used in production, which harden faster and do not require a certain temperature. It is possible to lay cold asphalt in a wider range of ambient temperatures (up to -5ºС is allowed). Most often, this method is used when performing patching roads, or to perform asphalting on their own.

You can buy cold asphalt not only directly from the manufacturer, but also in hardware stores. Hermetic packaging allows you to save its characteristics for up to several months. However, in terms of strength and service life, the cold mix is ​​significantly inferior to the alternative, so the use on busy roads or places of active use is somewhat limited.

Preparatory work before laying asphalt

An important condition for proper laying is compliance with the requirements of GOST and SNIP for surface preparation. These standards provide for several stages, on which the quality of the future road will also depend.

How to prepare the surface:

1. Clear and mark the asphalt area. If necessary (marshy area, possible problems with the soil), geodetic surveys are carried out.
2. The top layer of soil is removed completely. For motorways, it is possible to build a special embankment, but for an asphalt pedestrian road, this is not required.
3. A sand "cushion" is poured at the bottom of the trench, after which it is necessary to install a special material - geotextiles. It will prevent the displacement of building materials of large fractions into the sand.
4. Crushed stone of different sizes must be poured into the resulting pit. The fraction of the material will depend on the purpose of the coating. The largest crushed stone is used for laying highways. The layers are arranged in descending order - from large to fine-grained materials.
5. The number of preparatory layers also depends on the further use of the road. After installation, the material is well pressed down with a special roller. This will ensure a reliable hitch, eliminating possible operational problems.
6. To strengthen and prevent the appearance of cracks on the finished coating, a reinforcing mesh is used.

GOST for laying asphalt regulates all possible nuances associated with the implementation of such a coating. This process is complex, because even with special equipment, most of the work still requires manual labor.

How is asphalting done?

The rules for laying asphalt for the most part depend on the type and purpose of the pavement, but some standards cannot be changed. Such rules are clearly spelled out in GOST and SNIP, and it is they that ensure the durability and quality of future roads and sidewalks.

According to the requirements of GOST, asphalting of roads and sidewalks should be carried out under suitable weather conditions. The production of the mixture is also determined by the standards of these documents. Asphalt laying SNIP (building norms and rules) also determines the quality of finished work, from the stage of preparatory work to the final cycle.

The main requirements of the standards:

• Immediately before asphalt is laid, heated bitumen or bitumen emulsion is applied to the prepared surface.
• Laying of hot asphalt should be carried out exclusively at positive air temperature (not lower than 5 degrees).
• The mixture must be at a certain temperature, therefore, before application, it is maintained in a hot (not lower than 100 degrees) state.
• The thickness of the asphalt mixture layer is determined by the purpose of the coating. Asphalt is applied in sections of a certain length, after which it is leveled and compacted.
• Compaction of the layer must begin immediately after backfilling. For this, special equipment is used - a skating rink, a vibropress or an asphalt paver.
• The applied layer should harden for at least a day, but for cold asphalt this time can be only a couple of hours.

Modern additives - plasticizers allow styling even at low temperatures. This mixture is called asphalt concrete. It is quite expensive and is most often used for emergency road repairs in winter.

Final works

After asphalting, a special impregnation must be applied to the section of the future road. It provides a tight grip with asphalt and gives the coating an attractive appearance.

There are the following impregnation options:

1. asphalt emulsion. Among all types, this is the most affordable, but not always a mixture that lives up to expectations. Most often used for road sections without heavy traffic or sidewalks.
2. Coal tar. A reliable base, which, in addition, gives the finished coating an aesthetic appeal. It is not affected by oil products and has a long service life.
3. acrylic polymers. Adding special components to the mixture allows you to get an elastic and durable coating. It is even possible to change the coloring, which is used for additional decoration of the territory.

When choosing a finish layer, it is worth considering not only the financial issue, but also the main purpose of the project. How intensively the road surface is used should be taken into account when choosing a mixture.

The creation of asphalt pavement is an important process, because it determines the quality and durability of future roads and sidewalks. The classification of mixtures and the application process is determined by the requirements of GOST and SNIP, as well as types of road works. In order for the coating to last the maximum period even under heavy load, it is important to choose a reliable manufacturer. "Road Technologies" guarantee the speed of execution and compliance with all quality requirements.

nsk-asfalt.ru

Assessing the fatigue life of asphalt concrete pavements under real operating conditions

In the conditions of modern high-speed heavy traffic, asphalt concrete pavements are subjected to multi-cyclic impact of vehicles, which is dynamic in nature and is one of the main factors in reducing the transport and operational state of road pavements and their destruction. It is known that the destruction of asphalt concrete under the action of multiple loads is due to fatigue processes, i.e. the formation and accumulation of microdefects with a gradual decrease in strength over time.

The works of Sall A.O., Radovsky B.S., Rudensky A.V., Bakhrakh G.S. are devoted to the study of fatigue life of asphalt concrete pavements. and others. Increased interest in the issues of fatigue failure of road surfaces is explained by the increasing traffic flow every year, on the one hand, and the decrease in the actual service life of asphalt concrete pavements, on the other hand. That is why, in a number of foreign methods for designing pavements, the calculation of the fatigue of the material of the bending layer is considered the main one in determining the required thickness of the layers of the structure (the method of the Shell oil company, Finnish design standards, etc.). An important conclusion was obtained during the development of the “Guidelines for the mechanical-empirical design of new and reconstructed pavements” (USA), in which much attention is paid to the issues of fatigue cracking (two types of fatigue cracking are considered: ascending and descending). It consists in the fact that asphalt concrete pavements with a thickness of 7.6 - 12.7 cm (3-5 inches) are subject to the greatest fatigue failure. Increasing or decreasing the thickness of an asphalt concrete pavement leads to an increase in its fatigue life. Taking into account that in the Russian Federation on roads of III, IV technical category the thickness of a two-layer asphalt concrete pavement is 10-12 cm, increased attention should be paid to the development of measures to increase the resistance of asphalt concrete to fatigue failure.

The method used in our country for calculating non-rigid pavement for strength provides for the assignment of the thicknesses of individual structural layers, based on the calculation of the structure as a whole according to the allowable elastic deflection with checking the resistance of monolithic layers to fatigue failure from stretching in bending and shear resistance by soils of weakly cohesive structural layers. At the same time, the calculation of the structure for the resistance of monolithic layers to fatigue failure, in our opinion, has a number of disadvantages: - discrepancy between the period of the year, during which the number of applications of the calculated load is summed up, and the calculated parameters of asphalt concrete layers. So, for example, for the region of the European part to the south of the Rostov-on-Don-Elista-Astrakhan line, according to Table. Clause 6.1. ODN 218.046-01 the number of settlement days in a year is 205, which covers a period with various temperature and humidity factors. At the same time, the calculated values ​​of the elasticity modulus of asphalt concrete during the calculation of tensile stresses in the lower layer of asphalt concrete correspond to low spring temperatures; the estimated total number of applications of the design load over the service life is determined taking into account the number of design days per year, which does not correspond to the actual conditions for the occurrence of fatigue phenomena in asphalt concrete pavements, because according to clause 6.1. ODN 218.046-01 "the calculated day is considered to be the day during which the combination of the state of the subgrade soil in terms of moisture and temperature of the asphalt concrete layers of the structure provides the possibility of accumulating residual deformation in the subgrade soil or weakly cohesive layers of the road pavement", and fatigue damage accumulates over the entire period operation;

the values ​​of tensile stresses arising in the asphalt concrete layer during the passage of vehicles change throughout the year depending on the temperature regime of the coating and the moisture content of the subgrade soil. This means that when calculating asphalt concrete layers for resistance to fatigue failure, it is necessary to take into account the climatic factors of the region, and in the current regulatory document, the calculated values ​​of the elastic modulus of asphalt concrete are assumed to be the same for all road climatic zones.

Along with the above disadvantages, it should be noted that the current regulatory document on the design of non-rigid pavements is limited in the field of their design. Traditional design methods provide for the arrangement of layers with a decrease in the strength characteristics of the material with depth. At the same time, porous or highly porous asphalt concrete, which has the lowest resistance to fatigue failure, is placed in the lower layer of the coating. It is not possible to design pavement, the lower layer of which has a higher elastic modulus, since for such a design it is impossible to perform the calculation of the allowable elastic deflection in accordance with ODN 218.046-01. More than 25 years ago, A.O. Sallem, B.S. Radovsky and others proposed structures that are resistant to fatigue failure, in which the modulus of elasticity of the lowest layer of asphalt concrete is greater than that of the layer located above it. In 2000, a similar principle was observed in the design of pavement in Southern California on a highway with very heavy traffic. At the suggestion of a group of specialists from the University of California, headed by K. Monismith, the following pavement design was built: a wear layer of a highly porous drainage mixture (25 mm), a coating (75 mm) of a dense asphalt concrete mixture on a polymer bitumen binder, an intermediate layer (150 mm) of dense mix on high viscosity bitumen, the lower layer of asphalt concrete (75 mm) with the same grain composition and bitumen as the intermediate, but with a higher bitumen content.

The pavement and intermediate layer were chosen so as to ensure minimal rutting in the hot season, and a dense bottom layer with a high bitumen content should provide high bending fatigue resistance. especially non-cohesive bases) under conditions of intensive high-speed traffic does not provide the required service life of road structures, although it increases their overall modulus of elasticity. To improve the durability of road structures, it is necessary to search for new effective design solutions and their testing.

Our country has accumulated considerable experience in materials science solutions to improve the fatigue life of asphalt concrete pavements: reducing the porosity of asphalt concrete, increasing the viscosity of bitumen, introducing modifying, strengthening additives (polymeric, reinforcing, etc.), using reinforcing layers. However, the lack of methods and requirements for the fatigue strength of asphalt concrete mixtures under repeated loading in Russian standards excludes the possibility of targeted selection of compositions of asphalt concrete mixtures with increased fatigue strength, which sometimes leads to erroneous decisions when choosing the type of mixtures, justifying the expediency of using polymer and reinforcing additives.

In modern conditions of high-speed heavy traffic of vehicles, for an objective assessment of the durability of materials for the structural layers of pavement, it is necessary to switch to new methods of testing them, corresponding to the actual impact of the traffic flow in terms of loading conditions. Such test methods are currently being carried out in many countries. According to the draft European standards (prEN 12697-24), for example, the determination of fatigue strength is carried out at a loading frequency of 10 Hz, 25 Hz, and also in the frequency range from 1 to 60 Hz.

Thus, the solution to the problem of increasing the fatigue life of asphalt concrete pavements should be comprehensive and complex, including: at the design stage of non-rigid pavements, the calculation of the fatigue life of asphalt concrete pavements, taking into account the loading characteristics under given climatic conditions in different periods of the year; analysis of the effectiveness of design solutions to improve the fatigue life of asphalt concrete coatings; testing the fatigue strength of asphalt concrete mixtures under repeated loading to select compositions that provide the specified operational properties of asphalt concrete; at the stage of operation of roads, calculating the characteristics of the dynamic impact of vehicles, taking into account the actual evenness of road surfaces; calculating the fatigue life of asphalt concrete pavements in use and predicting the residual life of road pavements taking into account real loading; testing of fatigue strength asphalt concrete taken from the pavement. To assess the fatigue life (residual life) of asphalt pavements, we have developed a comprehensive experimental-theoretical method. Its essence is as follows:

– at the first stage, the calculation of the dynamic characteristics of loading of asphalt concrete pavements on a given road during the year is performed. The performance index of the evenness of the road surface and speed modes of movement determine the level and frequency response of the dynamic impact of vehicles. The calculation of the dynamic characteristics of the pavement loading is carried out using the developed mathematical models of the "road structure - soil" system for a given composition of the traffic flow. This takes into account seasonal changes in climatic factors characteristic of the region. This method (calculation-theoretical) can be implemented both in the design of new road structures to justify the most efficient and durable asphalt concrete pavements, and in the operation of highways to calculate the residual life of pavements under the real dynamic impact of traffic flow. For operated roads, it is advisable to use an experimental method, in which the dynamic characteristics of the loading of the asphalt concrete pavement are determined in the course of full-scale measurements using a vibration measuring complex;

- at the second stage, the calculation of the durability of asphalt concrete pavements is performed under the operational loading mode. Currently, DorTransNII RSSU has developed a laboratory facility for testing asphalt concrete for fatigue failure under dynamic (vibration) impact in a wide frequency range (from 0.5 to 100 Hz). The loading mode during laboratory tests is taken in accordance with the previously calculated loading characteristics of the asphalt concrete pavement. Fatigue fracture curves for various types of asphalt mixtures allow you to choose the type of mixture, select the composition and justify the feasibility of using polymer and reinforcing additives to increase the durability of the pavement. Fatigue failure tests of asphalt concrete pavement of operated roads under real loading conditions make it possible to predict the residual life of asphalt concrete pavements and reasonably assign the types and terms of repair work.

Conclusion

Under the conditions of modern high-speed heavy traffic, the impact of vehicles on the road structure has a significantly pronounced dynamic character, which leads to an increase in loads on road structures and a decrease in the fatigue life of asphalt concrete pavements.

The calculation of road pavements for the resistance of monolithic layers to fatigue failure, which is used in our country, has a number of disadvantages, which does not allow making optimal decisions at the design stage of pavements to increase the fatigue life of asphalt concrete pavements.

To increase the durability of road structures, it is necessary to search for and test new effective design solutions, which include, for example, the installation of lower layers of asphalt concrete pavements from dense mixtures with a high bitumen content, which provide high bending fatigue resistance; arrangement of reinforcing layers, etc. The absence of methods and requirements for the fatigue strength of asphalt concrete mixtures under repeated loading in Russian standards excludes the possibility of targeted selection of compositions of asphalt concrete mixtures of increased fatigue strength, which sometimes leads to erroneous decisions when choosing the type of mixtures, justifying the expediency of using polymer and reinforcing additives . For an objective assessment of the durability of the materials of the structural layers of the pavement, it is necessary to switch to new methods of testing them, corresponding in terms of loading conditions to the real dynamic impact of the traffic flow. The dynamic impact of the traffic flow on the road structure is due to the evenness of the road surface and speed modes. It is proposed to calculate the dynamic characteristics of the pavement loading on the basis of the developed model of the "car - road" system for a given composition of the traffic flow, or to determine them in the course of experimental measurements using the DorTransNII RSSU vibration measuring complex.

6. To assess the residual life (fatigue life) of asphalt concrete pavements, taking into account real dynamic loading, a complex experimental and theoretical method has been developed and proposed, based on the developed mathematical model of the stress-strain state of the "road structure - soil" system and experimental tests of fatigue failure of asphalt concrete under real loading conditions.

LiteratureRadovsky B.S., Merzlikin A.E. "Guidelines for the mechanical-empirical design of new and reconstructed pavements" (USA) / / Science and technology in the road industry. 2005, No. 1, p.32 - 33. ODN 218.046 - 01. Design of non-rigid pavement. -M., 2001. - 146 p. Sall A.O. On the issue of designing pavements with asphalt concrete bases / Tr. Soyuzdornia, no. 105. M, 1979, p. 142 - 155. Rudensky A.V. Road asphalt pavement. - M .: Transport, 1992. - 253 p. Iliopolov S.K., Seleznev M.G., Uglova E.V. Dynamics of road structures. - Rostov-on-Don: Yug Publishing House. 2002 – 260 pp. Iliopolov S. Investigation of dynamic transport impact in pavement design/ IX International Conference. Kielce. 2003, pp. 451 – 457 Frequency response of various types of vehicles Evenness of the road surface (microprofile) Average speed modes of vehicle movement Calculation of the dynamic impact of vehicles on the road (“car-road” model) Stage 1 Road construction dynamic stress-strain state of asphalt concrete pavement (“road structure – soil” model) Seasonal changes in climatic factors Calculation of dynamic loading characteristics of asphalt concrete pavement during the year Testing of asphalt concrete specimens for resistance to fatigue failure under a given loading mode Stage II coatings

DEPARTMENTAL BUILDING REGULATIONS

REGIONAL AND INDUSTRY REGULATIONS
SERVICE LIFE
FLEXIBLE TRAVELING
AND COATINGS
(VSN 41-88)

Agreed by Gosstroy of the RSFSR

Approved

Minavtodor of the RSFSR

Moscow 1999

Regional and sectoral norms of overhaul periods of service of non-rigid pavements and coatings (VSN 41-88) / Ministry of Highways of the RSFSR. - M.: GUP TsPP. 1999. The norms of overhaul periods of service of non-rigid pavements are developed in accordance with direction 02 of the Program for solving the scientific and technical problem 0.55. II-P "... To develop, improve and introduce progressive technical solutions and technologies for the repair and maintenance of highways and artificial structures for 1986-1900." The document is intended for specialists of road organizations involved in the design and operation of roads. Giprodornii of the RSFSR Minavtodor, the Leningrad branch of Soyuzdornia, MADI, Rostov, Sverdlovsk, Saratov and Khabarovsk branches of Giprodornia, SibADI, the Computing Center of the RSFSR Minavtodor, Azdorproekt and the Scientific Research Laboratory of the Minstroyavtodor of the AzSSR, NPO "Dorstroytechnika" of the Mindorstroy of the BSSR, Gruzgosorgdornia, the Kazakh branch of Soyuzdornia, KirgizavtodorKTI, Vilnius ISI and Orgtehdorstroy trust of the Ministry of Automotive Road of the Lithuanian SSR, Orgdorstroy trust of the Minavtodor of the Moldavian SSR, Central Asian branch of Soyuzdornia, KADI, Gosdornia and HADI. The list of participants is given in Appendix 2. When preparing the document, comments and suggestions from the road ministries of the Union republics were taken into account. 1. These standards are intended to develop standards for long-term planning of funding volumes for the repair of public roads, clarify the norms for the consumption of materials and cash costs for road repairs, as well as for use in calculating the strength of the designed pavement and reinforcement layers of structures in operation. 2. The service life of pavement is the period of time within which the bearing capacity of the road structure is reduced to a level that is maximum permissible under traffic conditions. Repair of pavement is carried out when the calculated level of pavement reliability and the corresponding limit state of the pavement in terms of evenness are reached during operation. Under the reliability of pavement is understood (in accordance with the Instruction for the design of non-rigid type pavement VSN 46-88 of the USSR Ministry of Transport and Construction) the probability of failure-free operation of the structure during the entire period of operation until repair. Quantitatively, the level of reliability represents the ratio of the length of strong (undamaged) sections to the total length of the pavement with the corresponding value of the strength factor. 3. Regulatory overhaul periods of pavement service and the corresponding standards of reliability levels are taken according to Table. one .

Table 1

Norms of overhaul (estimated) service life (T 0) and norms of reliability levels (K n) of non-rigid pavements

	Intensity of traffic flow, vehicles/day	Pavement type	Road-climatic zone
				T 0 , years		T 0 , years		T 0 , years
		capital
		capital
		capital
		lightweight
		capital
		lightweight
		transition
		lightweight
		transition

Notes. 1. Intermediate values ​​are taken by interpolation (for K n and T 0). 2. When calculating the layers of reinforcement of capital and lightweight pavements, a reduction by 15% of the service life norm from the minimum values ​​is allowed while maintaining the reliability level norm. 3. When designing roads for the calculation of pavements, it is recommended to use the norms of the longest service life from the specified range for each type of pavement. 3.1. For existing roads: category III with transitional clothes, the overhaul periods and reliability levels are the same as for category IV roads; Category V with capital type clothes, the norm of the overhaul period of service should be increased by 20%, and the norm of the level of reliability should be reduced by 30% compared with the norms established for roads of category III with a similar surface; Category IV with lightweight clothing at a traffic intensity of 100-500 vehicles / day. normalized indicators are taken the same as for roads of category V. If the actual intensity of the traffic flow on the road exceeds the calculated one established for the considered category of roads, the norm of the overhaul life of the pavement is reduced by 20% while maintaining the norm of the level of reliability. When the traffic intensity is less than the standard, the reliability level is reduced to 15% while maintaining the service life rate. 3.2. When planning and performing repairs using the thermal profiling method, the level of pavement reliability is reduced by 10%. 3.3. In the regional conditions of the RSFSR, it is allowed to lower the norm of the level of reliability of pavements against the values ​​given in Table. 1. on: 2% - in the Urals (Perm, Sverdlovsk regions), East Siberian (Amur, Irkutsk, Chita regions, Buryat ASSR, Yakut ASSR) and West Siberian regions (Tomsk and Tyumen regions, Krasnoyarsk Territory, north Omsk region); 5% - in the Far East region (Primorsky, Khabarovsk Territories, Sakhalin, Kamchatka, Magadan Regions). 3.4. When solving practical problems related to the assessment of the actual service life of non-rigid pavements and the transport and operational qualities of roads, they are guided by the maximum permissible operating conditions of the pavement for evenness "δ i" depending on the level of pavement reliability.

K n
δ i , cm/km

The given data was obtained using the TXK-2 pusher installed on the UAZ-452 car. When using other car brands, a preliminary calibration of the device is required. 4. The service life of the pavement is the period of time within which the adhesion properties of pavements (capital and lightweight pavements) decrease or the wear of the pavement surface (transitional and lower pavements) increases to the maximum allowable values ​​for traffic conditions. 5. The norms of the overhaul service life of pavements (T p) on roads with capital and lightweight pavements are taken depending on the intensity of the traffic flow in the first year after construction or work on the arrangement of rough surfaces during road repairs (Table 2).

table 2

Traffic intensity on the busiest lane, avt./day	Road-climatic zones	Norms of overhaul service life of road surfaces (T p)
from 200 to 2500
from 200 to 2000
from 200 to 1500
from 2500 to 4500
from 2000 to 4000
from 1500 to 3000
from 4500 to 6500
from 4000 to 6000
from 3000 to 5000
over 6500

5.1. The service life rate of the coating may be reduced by: 20% - when used as a binder for surface treatments of tar and resins; 30% - when using crushed limestone. 5.2. In cases where the overhaul life of the pavement and pavement differ by more than 30%, the overhaul life of the pavement is taken equal to 50% of the normal life of the pavement. 6. Compensation for wear of transitional pavement coatings is provided with a frequency no later than after 3 years. 7. Road-climatic zones (DKZ) are established according to the map of road-climatic zoning of the USSR (see VSN 46-83).

Attachment 1

(not approved)

Features of the application of norms in the Union republics

1. Road-climatic zones within the republics

1. Azerbaijan SSR V 2. Armenian SSR V 3. Byelorussian SSR II, III 4. Georgian SSR V 5. Kazakh SSR IV, V 6. Kirghiz SSR III, IV, V 7. Latvian SSR II 8. Lithuanian SSR II 9. Moldavian SSR III, IV 10. Tajik SSR V 11. Turkmen SSR V 12. Uzbek SSR V 13. Ukrainian SSR II, III, IV 14. Estonian SSR II consider vertical zoning. When the road is located above sea level at an altitude of 1000 to 1500 m, the service life of the pavement and the reliability level should be reduced by 7% and 3%, respectively, from 1500 to 2000 m - by 10% and 4.5%, from 2000 to 2500 by 14% and 6% and over 2500 m - by 20% and 10% respectively. It is allowed to reduce the overhaul periods of up to 30% in conditions where deformations are observed associated with the loss of stability of the subgrade. 3. In the regional conditions of the Byelorussian SSR, the service life of surface treatments (road surfaces) on motor roads of categories IV-V should not exceed 3-4 years. 4. In the regional conditions of the Uzbek SSR, it is allowed to increase the service life of road surfaces up to 7-9 years for pavements of a capital type. 5. In the regional conditions of the Ukrainian SSR and the Moldavian SSR, the minimum service life of pavement surfaces for capital and lightweight types of clothing is assumed to be at least three years. 6. In the regional conditions of the Estonian SSR, in contrast to the norms recommended in Table. 2, the longest service life of pavements of lightweight and capital types is five years. With traffic intensity per lane from 1500 to 2500 and 2500 to 6500 vehicles / day. terms of service are four and three years, respectively.

Annex 2

List of participants in the development of standards

Apestin V.K. with the participation of Bolshakova I.V., Dudakov A.I., Ermakov M.Zh., Kulikov S.S., Stepanova T.N., Strizhevsky A.M., Tulupova E.V. (Giprodornii of the Minavtodor of the RSFSR - responsible for the implementation of research) Korsunsky M.B. (Leningrad branch of Soyuzdornia); Vasiliev A.P. with the participation of Tulaeva I.A. (MADI); Uglov V.A., Friedrich N.G., Rasnyansky Yu.I., Ivanov S.P. (Rostov-on-Don branch of Giprodornia); Roizin V.Ya., Naboka N.I., Yudina V.M. (Saratov branch of Giprodornia); Permin G.I. with the participation of Nechaeva Z.I. (Sverdlovsk branch of Giprodornia); Malyshev Alexey A., Malyshev Alexander A., ​​Khristolyubov I.N. (SibADI); Zakurdaev I.E., Voronin A.A., Kudimova L.I. (Khabarovsk branch of Giprodornia); Burenkov Yu.N. Ponomareva N.I. (Computer Center of the Minavtodor of the RSFSR); Musaev M.M. (Azdorproekt): Akhmedov K.M., Karaisaev N.M., Abramov Y.Kh. (NIL of the Ministry of Construction and Road of the AzSSR); Karapetyan A.A. (Technical Department of the Ministry of Highways of the Armenian SSR); Pasternatsky V.A. (NPO Dorstroytechnika); Shilakadze T.A., Gegelia D.I., Daneladze R.M., Surenyan E.A. with the participation of Babaradze M.A., Bernashvili G.K., Datunashvili T.S., Evtyukhina V.E., Kiknadze Ts.V., Korashvili M.U., Levit A.A., Nozadze A.I., Chigogidze G.E., Tsereteli Z.M., Tsiklauri L.M., Natsalishvili N.N. (Gruzgosorgdornia); Kotvitsky A.F., Krasikov O.A. (Kazakh branch of Soyuzdornia); Smatov T.Sh., Tyulegenov K.A., Turgunbaev A.T., Abekov T.U. (KyrgyzavtodKTI); Palshaitis E.L. (Vilnius ISI); Dranaitis E.A., Kazhdailis P. (Trust Orgtekhdorstroy of the Ministry of Transport and Transportation of the Lithuanian SSR); Kozhushko I.G (Trust Orgdorstroy of the Minavtodor of the Moldavian SSR); Butlitsky Yu.V., Pasynsky L.N. (Central Asian branch of Soyuzdornia); Sindenko V.M., Alemich I.D., Ivanitsa E.V., Titarenko A.M. with the participation of Bulakh A.I. (CADI); Kolinchanko N.N., Kazny A.S., Nosova N.V. (Gosdornia); Mikhovich S.I., Kudryavtsev N.M., Storazhenko M.S., Kolommets V.A. (HADI).