The evenness of the road surface is one of the main factors of traffic safety. But during operation, a track inevitably appears that prevents safe movement. What is the reason for its formation, how to avoid its occurrence, is it possible to control the process of rutting and prevent it - we talked about this and much more with the largest professional in this field, professor at the Rostov State Civil Engineering University, chairman of the board of directors of Avtodor-Engineering LLC Sergei Konstantinovich Iliopolov.
- Sergey Konstantinovich, what is the reason for the formation of a rut on the highway?
- The main cause of rutting is explained by the accumulation of residual deformations in the elements of the road structure, that is, in each layer of the pavement and in the upper road layer. This is the so-called plastic track. The second and main reason is the wear of the top layer of the coating as a result of the combined effect of wear and premature non-standardized destruction of the asphalt concrete layer under the influence of external factors, which include, along with the impact of wheels, precipitation, temperature changes and solar radiation. This track of destruction and wear is formed only in the upper, closing layer of the pavement. And it's good that the sectoral regulations issued last year in the ODN, which regulate the period for the restoration or replacement of the upper layers of the coating, as well as in the GOST, which is being prepared, introduced the concept of a wear layer. Therefore, it is more correct to say that the second type of track is formed during the premature destruction and wear of the pavement layer, that is, the upper layer. In real conditions of operation of the road, both of these factors also act together and significantly affect traffic safety. But they must be separated not only in order to understand the reasons for the formation of rutting, but also in order to know how to deal with this rutting.
- Is it possible to get away from the plastic track in general and solve this issue in a normative manner?
– It is absolutely impossible to get away from the plastic track. Even if we take into account all the factors involved, we cannot change the existing nature of the material. For example, any asphalt concrete is inherently an elastic-viscous plastic material that has all the main manifestations characteristic of this category of material: both load perception fatigue and redistribution of the main frame material - crushed stone, which is part of asphalt concrete, since the main element of asphalt concrete is dispersed asphalt-binder structure, giving it the properties of an elastic-viscoplastic body. This is not an elastic body, it will accumulate residual deformations as it is loaded. The only difference is that the elastic-plastic properties and the properties of the accumulation of residual deformation of asphalt concrete are somewhat dependent on temperature.
I want to note the absolute disregard for the physical nature of asphalt concrete in the calculation of non-rigid pavement, where each body taken into account is taken as having elastic properties, which in its essence is not. This also eliminates permanent deformation after loading. As you know, when a load is applied, the body deforms, and when it is removed, it must be restored to its previous dimensions. Here, asphalt concrete under cyclic load, being an elastic-viscoplastic body, cannot recover to the same parameters, it will recover, but a little less. This difference is called permanent deformation.
– Is it possible to control the process of rutting on our roads?
- Under the existing regulatory framework, it is impossible. Asphalt concrete, as well as other materials present in non-rigid pavement, as already mentioned, are accepted as rigid, not being such in fact.
- Is there a way out in this situation?
– It is necessary to improve the design standards for non-rigid pavements by introducing two additional controllable criteria into the calculation: the accumulation of design of non-rigid pavements for the accumulation of permanent deformation and the formation of fatigue cracks. Asphalt concrete in the existing regulatory framework is considered as a material that can withstand any number of loads for the billing period, which is laid down in the regulations. Until recently, depending on the road-climatic zone and road category, this period was 18 years, today it is 24 years. These are the overhaul periods during which it is assumed that an absolutely elastic body, which is asphalt concrete, should work without breaking its continuity, more precisely, without the formation of fatigue cracks. This is a myth that anyone understands. Even if steel, a much more solid body, has fatigue, upon the occurrence of which the metal breaks, then what can we say about asphalt concrete. In the current regulatory framework, there is no difference for which road we are designing: with a traffic intensity of more than 110,000 vehicles per day or 20,000 vehicles per day. It is clear that the effectiveness of asphalt concrete in different conditions will be different. The service life of the pavement is determined by the category of the road and the existing loads taken into account, but nowhere are there requirements for the resistance to fatigue failure of asphalt concrete, on the basis of which the service life is not calculated or, for a given service life of the pavement, the period of operation is not determined and calculated, after which fatigue failures in order to plan repair activities. It is precisely for this purpose that it is necessary to develop one of the two criteria that I named above.
If the formation of rutting is an obvious fact, then cracks are that insidious factor that is not always evident, but its influence and the need to take it into account in the calculation are sometimes more significant.
First reason. Asphalt concrete is included in the calculation of pavement with certain specified physical and mechanical properties, primarily its modulus of elasticity. And even in everyday life we always call the strength of a certain structural element, consisting of asphalt concrete, the elastic modulus of asphalt concrete. And therein lies another root of evil. For pavement, the parameters and strength of not the material, but the layer, are extremely important. Thus, the performance of even non-rigid pavement is primarily influenced by the elastic modulus of the asphalt mix or asphalt concrete layer. As soon as fatigue cracks form in this layer, discontinuity occurs. And with the same modulus of elasticity as a material, we get a sharp decrease in strength, since when broken into blocks, the load distribution system fundamentally changes, and all lower layers will experience a much greater load in the crack zones. It would seem that they are elementary things, but no one talks about them today, they are the scourge of our highways.
The second reason. Getting fatigue cracks, we get non-standard condition of non-rigid pavement. Under these conditions, the design schemes laid down in the regulations no longer work, and the pavement should continue to work.
For highly loaded highways with a traffic intensity of over 100 thousand vehicles with four lanes, that is, roads of the first category, and often the second category, the package of asphalt concrete layers should usually consist of three layers. And these three layers in total should not be less than a certain thickness - 28 cm. By the way, in the regulatory framework of the Russian Federation there is no criterion that would determine the recommended thickness of asphalt concrete layers and what it depends on. Today you will not find anywhere any explanatory material that could point to the factors that make it possible to determine the minimum thickness of the package of asphalt concrete layers. We are approaching the development of this regulatory document, which will answer the question why the package of asphalt concrete layers cannot be less than a certain value. This value is determined by the composition and intensity of traffic and the need for this package to absorb the high-frequency part of the dynamic spectrum of the impact of the car. This criterion, in my opinion, is very important. The most high-frequency energy-intensive part of the spectrum of the dynamic impact of cars should be absorbed by asphalt concrete, since it, having a certain continuity, contains asphalt binder, that dispersed part in which these frequencies of the impact of the car are absorbed as in a viscous substance. What is frequency? This is a certain effect, determined by the wavelength. We must absorb that part of the dynamic spectrum, the wavelengths of which are comparable to the thickness of the pack of asphalt concrete layers. With a decrease in this thickness, a significant part of the spectrum falls lower, into those layers that are not capable of resisting a given energy impact at long frequencies. And if crushed stone is even further away, this will mean a significant excess of abrasion of the material and its transformation into stone flour within 5–7 years, with a pavement service life of 24 years. On this topic, too, there are no recommendations, no criteria.
– Why are fatigue failures more dangerous than plastic ones?
– Accounting for fatigue failures and preventing their occurrence is very important. Fatigue cracks are formed on the lower face of the last layer of asphalt concrete from the top in the package of asphalt concrete layers, since it is this face that experiences maximum tension. Consequently, we can get fatigue cracks on the bottom face of the last, third layer. The upward propagation of a crack is very fast. Within six months we will get a sprouting crack, and with each subsequent layer, the rate of its formation will be higher, because an ever smaller mass of asphalt concrete will resist tensile stress, especially since the edges have always served as a stress concentrator. Thus, cracks appear on the surface of the coating, and they can be strictly transverse, and at an angle, and longitudinal, and networks of cracks. The problem is not even that this creates discomfort during movement, with the formation of a network of cracks, fragmentation of the asphalt concrete of the top layer of the pavement is quickly achieved, moisture will penetrate into the resulting crack, but that the continuity of the package of asphalt concrete layers is broken, which at the same time radically change their distributing ability to the lower layers. And the lower layers of the base begin to experience those stresses for which they are not designed by their physics. As a result, we drastically reduce the resource of the underlying layers, the working resource of which significantly exceeds both 20 and 30 years. We are simply destroying this resource. Therefore, fatigue failures are of fundamental importance from the point of view of the durability of non-rigid pavements.
The way out of this situation is very simple. You cannot talk about certain things and phenomena until you control them. Neither rutting nor fatigue failure today in the Russian Federation is regulated anywhere and no one controls this process, because it can be controlled only when you know how to calculate it, you know the laws of its formation.
Thus, it is urgent to develop two new criteria. The first is the calculation of flexible pavements for their operational durability, or reliability, which would allow calculating the accumulation of residual deformations in the form of transverse unevenness or plastic rutting during the design service life of flexible pavement. The second criterion is the calculation of non-rigid pavements for the accumulation of fatigue failures. Until, at the design stage, we get two graphs of the accumulation of residual deformation of fatigue failures by years of the life cycle, we will not only control these processes, but we will not even be able to meaningfully state the very fact of the existence of these problems.
Is there a way to solve these problems? In what direction should you move?
- Over the past five years, the Avtodor State Company has repeatedly stated at all levels that such criteria are necessary. Moreover, the main difficulties in developing these criteria are not even that we have to admit the imperfection of the methods for calculating pavements. We need new criteria for the level of operational condition of roads during the operation of non-rigid pavements. The biggest problem that the State Company proposed to take on was those methods, those knowledge, scientific schools that can implement and solve it. These are calculation methods, development of criteria on the basis of which the methods will work. Today we have scientific schools that are not only able to solve this issue, but are already working for the Avtodor State Company to resolve these problems. And I really hope that by the end of 2018 these criteria will be submitted for testing. This will allow us to manage the processes that we are talking about, because today even the technical elite of the road industry does not have a clear understanding that all problems with the top layers of the pavement, including extended turnaround times, cannot be solved with the top wear layer alone. There is an integral cumulative indicator of the health of the entire road structure.
Each element of the road structure, including the subgrade, contributes to the formation of plastic ruts or unevenness. The evenness of the upper layer of non-rigid pavement should begin with the evenness of the upper layers of the subgrade, the lower underlying layers, the lower asphalt concrete layers of the package, and the evenness of the upper, closing layer is their integral, summing indicator. So, all the problems that drivers face on our roads are fatigue damage, rutting resulting from the destruction of the upper layer, because all these parameters do not have not only criteria, but even an internal understanding of the need to take them into account.
– What are the main factors in determining the durability of pavements?
“It's about accumulation. If we are talking about rutting, then remember that two factors contribute to it: the accumulation of residual deformation in each element of the road structure plus the destructive and abrasive effect of the car wheels, for which the structure of the upper closing layer is primarily important. In order to control these processes, as I have already noted, it is necessary to create methods that take into account the accumulation and formation of residual plastic deformation in non-rigid pavement. Humidity and temperature are of paramount importance for each item of clothing. Humidity, for example, for subgrade soil or sand and gravel is important because the strength of the subgrade is directly proportional to its density, and the density is inversely proportional to moisture. Humidity will necessarily be taken into account in these criteria. The same is true for asphalt concrete: at 20°C it works in a completely different way than at 60°C. All these factors should be included in the methodology for calculating non-rigid pavement for the accumulation of residual deformations. As well as fatigue, it is significantly dependent on the moisture content of the subgrade soil, since when waterlogged, the bearing capacity is generally lost and asphalt concrete will work in much more severe conditions, since there is practically nothing to rely on. Therefore, all these factors are essential in determining the durability of pavements.
Chapter 18
18.1. Assessment of the nature and identification of the causes of rutting
Sections of roads with formed ruts are identified in the process of diagnosing the condition of the roads. At the same time, the depth of the track is measured and the degree of its influence on the speed and traffic safety is assessed, on the basis of which a fundamental decision is made on the need to eliminate it.
Guided by the Classification of work on the repair and maintenance of roads, the type of repair is preliminarily assigned. In order to justify the type of repair and determine the scope and scope of work, it is necessary to identify the causes of rutting in each characteristic area. To do this, it is necessary to carry out detailed surveys of each section of the road on which repair work is planned.
The track is formed as a result of heavy vehicle traffic at high air and pavement temperatures in summer and at high humidity of subgrade soils in spring; insufficient shear resistance of the layers of asphalt concrete pavement or base, as well as soils of the active zone of the subgrade. In this case, abrasion of the top layer of the coating in the rolling strip, additional compaction or reconsolidation of the pavement layers (with or without crushed stone destruction), peeling or chipping of the upper layer, plastic deformation of the pavement layers occur.
The accumulation of residual deformations and structural damage can occur in one or several layers of the road structure at once. The top layer of the coating is located in the zone of maximum temperature effects and perceives the greatest load from the wheels of the vehicle. Therefore, it is subject to deformations to the greatest extent and more often than others is the cause of rutting. Any of the underlying layers can also be the cause of rutting.
The track can be formed as a result of deformation of the transverse profile of the carriageway in the form of recesses along the rolling lanes with or without ridges. The total depth of the track is the sum of the height of the uplift and the depth of the depression (Fig. 18.1).
Rice. 18.1. General view of the outer track: 1 - track base (bottom); 2 - a crest of a rut; 3 - design surface of the coating; IN To- track width; H To- total track depth ( H To =h y +h G);h G- height of the ridge; h y- depth of depression (recess); 4 - lane boundary; 5 - middle of one lane
Field work on the survey of sections with a track is most expedient to be carried out in late summer or early autumn, after the cessation of high summer temperatures. Surveys must be completed at least 6-8 months before the start of the repair. Field surveys are carried out in two stages: visual surveys; instrumental examinations.
A visual inspection of the site is carried out from a car moving at a speed of not more than 20 km / h or on foot. Stops are made in places that require detailed inspection and examination. Inspection of roads with separate carriageways is carried out in forward and reverse directions. At each site determine: the intensity and composition of traffic; coverage condition; roadside condition; condition of drainage structures and subgrade.
The description of the external nature of the track is carried out according to the following criteria: general information; the shape and outline of the edges of the track (pronounced or smoothed); the presence of ridges of vypor and their nature; track depth (small - less than 20 mm, medium 20-40 mm, deep - more than 40 mm); track width; the presence of plastic deformations or signs of abrasion of materials; types of defects on the surface of the coating; heterogeneity of color and quantity of components on the surface (bitumen spots, lack of binder, protrusion of crushed stone, excess sand, etc.); track development dynamics (track develops quickly or slowly); the condition of the coating around the track (a network of cracks, sagging, peeling, etc.); picket position and length of the section with a track (beginning and end of the track), direction of movement and lane number.
A preliminary conclusion on the condition of the road section and the reasons for the formation of a rut is made on the basis of the results of a visual inspection and general data. In conclusion, the planned methods for eliminating the rut are indicated. If the reason for the formation of a rut cannot be unequivocally established during a visual examination, instrumental examinations are prescribed, during which the following are established:
geometrical parameters of the track (depth and width of the track, height and width of the ridges);
geometrical parameters of the road (width of the carriageway, number of traffic lanes and width of each lane, shoulder width, longitudinal and transverse slopes);
evenness of road surfaces;
adhesion of coatings to a car wheel;
pavement strength.
The measurement of the geometric parameters of roads with a gauge by geodetic methods is used at the stage of survey and development of a technical project for road repair (if necessary, milling, leveling layers or widening of the roadway).
In each diameter, 5 points are marked (Fig. 18.2): the edge of the carriageway on both sides TO 1 and K 2 middle of the carriageway WITH 1 and WITH 2 on each side; road axis O.
Rice. 18.2. The layout of the control points on the surface: TO 1 and K 2 - the edge of the carriageway on each side; WITH 1 and WITH 2 - the middle of the carriageway on each side; 1 1 and 1 2 - the bottom of the right track in each lane; 2 1 and 2 2 - the top of the right track; O - axis of the road
The geometric parameters of the road are measured every 10 m along the length of the road. On a road section with a track in the transverse profile, two additional points are obtained that characterize the depth of the track: the bottom of the track (point 1) and the top of the track (point 2). Measurements are carried out along the outer, right track (closer to the roadside) for each lane on which there is a track. The track depth is calculated as the difference between the marks of points 2 and 1.
Elevation marks of additional points 1 and 2 are determined after 20 m, to link the track to the longitudinal and transverse profiles of the road and draw up a milling cartogram or leveling layers. If data on the track depth obtained by other methods are available, the track depth is measured by geodetic methods at least once for every 100 m. In the picket log, the coordinates of the beginning and end of the section with the track are noted.
The assessment of the pavement strength is carried out on sections of the road with a track depth of more than 35 mm or in the presence of a grid of cracks, indicating a possible loss of strength by one or more layers of the pavement. Work is carried out according to the method ODN 218.1.052-2002 spring. To draw up the project, diagnostic data taken from the data bank obtained as a result of previous surveys of this site can be used. Examination of the pavement and pavement is carried out by sampling with rectangular cuttings measuring 300300 mm or by drilling cores with a diameter of 100 mm. It is most advisable to drill samples using a special drilling rig. A breakdown is considered at least two core samples taken at a distance of not more than 0.5 m from one another (two cores - one sample).
Sampling is carried out in order to determine the cause of rutting in the pavement (search for a weak layer) and to assess the possibility of recycling materials.
The sampling depth depends on the type and nature of the track:
with a surface character of the track, the core sampling depth is assigned equal to the thickness of the asphalt concrete layers in the pavement;
with a deep gauge, the core sampling depth is assigned equal to the thickness of the entire pavement. In this case, it is necessary to take soil samples from the active zone of the subgrade.
Recommended sampling locations in one lane are shown in fig. 18.3. Point 1 is located at the bottom of the outer track (closer to the roadside) approximately in the middle of the outer track. Point 2 is 0.2-0.3 m away from the road axis or from the line separating the traffic lanes. Point 3 is located at the top of the upstream ridge. Point 3 is optional. Regardless of the type of track, in each characteristic section, one control sample is taken from point 1 for the entire thickness of the pavement.
Rice. 18.3. Scheme of sampling from the pavement: 1, 2, 3 - places (points) of sampling located in the same alignment, on the same lane
With the surface nature of the track, samples are taken from points 1 and 2. Point 1 is located at the bottom of the outer track, and point 2 is removed from the axis of the road or from the line dividing the traffic lanes by 0.2-0.3 m. ) it is necessary to take two samples (4 cores). The maximum distance between sampling sites along the length of the road is no more than 500 m.
In case of a deep rut, accompanied by extrusion of material from the layer with the formation of upstream ridges, an additional core sample is taken at the highest point of the rut - point 3 (upstream ridge) after 1000 m or one sample for each characteristic section (if the length of the section with a track is less than one kilometer) . The selected samples are tested in 4 stages: they are tested for the destroyed core; each core layer is tested in its natural state; testing reshaped samples of asphalt concrete; determine the properties of mixtures and their components.
Core testing is carried out at the sampling site in a mobile laboratory. In its absence, after visual inspection and marking (sampling location, date of sampling, section, sample and core numbers), the samples are delivered to the laboratory and tested on the day of sampling. If the core could not be taken for the entire depth of the pavement (one or several layers may crumble), it is necessary to collect all the material of the destroyed layer in a separate bag and record the thickness of this layer in the structure (based on the measurement of the layer thickness in the drilled hole).
The thickness of the layer in the structure is measured using a depth probe. In the process of testing unreformed cores, the thickness of the layers is determined based on the results of measuring the thickness at 3 points with an accuracy of 0.5 mm. The arithmetic mean of three measurements is taken as the layer thickness.
The cores are divided into separate layers and determine the adhesion strength between the layers and the average density of the pavement layers in the cores
- average density of the layer in the structure, kg/m 3 ;
m- mass of the sample in air (weighed to the nearest 0.01 g);
V- sample volume (determined by hydrostatic weighing or calculated, m 3.
Then determine the moisture content of the layer in its natural state (with an accuracy of 0.01%) and calculate the water saturation and swelling of the layers. After that, the reshaped samples are tested in accordance with the current regulatory documents.
The material of each layer of asphalt concrete (one sample of 2 cores) is heated in a thermostat and cylindrical samples are made in accordance with clause 6 GOST 12801-98, during testing of which the average density of asphalt concrete is determined; calculate the compaction coefficient of each layer; determine water saturation and swelling of asphalt concrete, compressive strength at temperatures of +50°C, +20°C and 0°C, tensile strength at splitting, tensile strength in bending and deformability indicators, shear resistance characteristics and water resistance. It is allowed to carry out tests by the accelerated method in accordance with GOST 12801-98, item 21.
After testing, the reshaped samples are heated in a thermostat to 80°C, converted into a mixture, and the following are determined: the true density of the mixtures by the pycnometric method, the average density of the mineral part, the porosity of the mineral core and residual porosity, the quality of adhesion of the binder to the mineral part of the asphalt concrete mixture.
The composition of the asphalt concrete mixture is determined and the quality of the constituent components is assessed. To do this, perform the extraction of bitumen from the asphalt mixture. The amount of bitumen in the mixture and the grain composition of the mineral part of the asphalt concrete mixture are determined.
After the end of extraction (extraction of bitumen from the asphalt mixture), the extract (dissolved bitumen) is dried and the components of the mixture are weighed. At the same time, the following are determined: the content of bitumen in the mixture from the coating with an accuracy of 0.1% and the grain composition of the asphalt concrete mixture after extraction.
The quality of the bitumen after extraction from the mixture is determined by the following tests: the depth of penetration of the needle according to the method GOST 11501-78*; extensibility according to the method GOST 11505-75*; softening temperature for the ring and ball according to the method GOST 11506-73*; brittleness temperature according to Fraas according to the method GOST 11507-78*; adhesion of bitumen to marble or sand according to the method GOST 11508-74*.
The quality of crushed stone and sand in the asphalt concrete mixture and structural layers of pavement after extraction is determined in accordance with the requirements of current standards. Compile summary statements of the condition of the pavement and the properties of materials, in which the arithmetic averages of all tested properties are entered.
Analysis of the state of the layers of the road structure. The analysis of the state of the road structure is carried out in four stages. At the first stage, the analysis of the uniformity of the thickness of each layer within the same alignment at points 1, 2 and 3 is carried out. Changes in the thickness of the layers are noted. A layer in which a spread of properties in one section of more than 10% is noted is considered unstable, subject to plastic deformations. Mark the number of the section and the layer in which unstable properties are marked.
At the second stage, an analysis of the uniformity of the properties of the unstable layer along the length of the section is carried out. To do this, evaluate the uniformity of properties in samples of the same name (the bottom of the track or the border of the lanes, or the crest of the track riser) along the length of the section. The homogeneity of properties at the same points along the length of the section confirms the revealed instability or allows one to judge the randomness of the result.
At the third stage, the reasons for the loss of stability of the pavement layers are determined by analyzing the compliance of the properties, pavement layers and their components with the requirements of standards and regulatory documents.
When analyzing the grain composition of mixtures, changes in the composition of mixtures of one section and deviations in composition from the design values are noted. Layers in which crushed stone crushing is noted, or the quality of materials does not meet the requirements of regulatory documents by more than 5%, are considered weak, in need of strengthening or replacement (full or partial).
A list of unstable pavement layers is compiled, in which the location of the section on the road, the number of the layer and the properties by which this layer is recognized as unstable are noted. Make a list of the location of areas whose material is not suitable for reuse.
The final stage of the survey of sections of roads with a track is drawing up a conclusion on the quality of materials in the layers of pavement and their compliance with the requirements of regulatory documents. In conclusion, it is necessary to indicate the places of the track where unstable layers were found, indicate the possible reasons for the loss of stability and the possibility of further operation of the layer in the road structure. It should be noted the possibility of recycling materials of defective layers in pavement and suggest ways to repair a section of the road with a track.
On the basis of the data obtained in the course of field surveys and laboratory tests, the calculation and forecasting of the possible development of rutting is carried out, the results of which make it possible to justify decisions on the method and methods for eliminating the rut.
What causes ruts on asphalt? Many motorists believe that the main reason is studded tires. Let's talk about the main points of the formation of ruts on roads. Who is guilty?
Main reasons
If you completely prohibit the operation of cars with studded tires, this will not eliminate the appearance of ruts on the roads. But why thorns are considered the main source, because there are other reasons. Tracks from studded tires are in the form of narrow strips. And from freight transport and a large flow of cars - in the form of deformation of the roadway. As a result, wide depressions appear on the roads, with elevated edges.
Namely, this type of track is most common. And the destruction from studded tires, compared with the deformation from a large flow of cars, is minimal.
It turns out that the important reasons for the appearance of the track are the imperfection of road construction works and the poor quality of the asphalt concrete mixture. According to the technical requirements, the roadway should consist of two layers, each of which must be left alone for three days. It often happens the other way around - the road builders will lay only one layer of asphalt, which is able to withstand the load of only 300 cars a day. And where can you find such roads in a large city with such low traffic?
In addition, when applying each layer of asphalt, it must be allowed to dry for 72 hours. In our country, everything is done the other way around, as soon as asphalt is laid, a stream of cars will immediately be allowed to pass through it. And who does not mind, from motorists, "fly" on the new smooth asphalt with a breeze.
Another reason for imperfection
When repairing an old road with deep ruts, only the top layer of asphalt is often removed, and a new one is applied in its place. This is certainly cheaper than building it again, but it's of little use. After a while, ruts form again.
When a rut is formed, the entire roadbed is deformed. To get rid of them, you need to rebuild the road anew, and not just replace the top layer. By the way, in Europe, the surface repair of the road, because. little sense from him.
It is clear that the main reason for the formation of a rut is the poor quality of the roadway and road works. Their contribution to the destruction of asphalt is minimal against the background of exposure to cold, heat, wind, heavy trucks. Of greater importance is the quality work of builders. If done correctly, a smooth and even road surface will delight drivers for decades. But, many motorists continue to argue that the spikes on the wheels are to blame. And often, they refer to the European experience.
Studded tires have been banned in Germany since 1975, but this is not related to road destruction. The reason for the ban is a longer braking distance car with studded tires on dry pavement.
Can bad roads be redone?
The layout of the streets of large cities and the heavy workload will lead to the fact that during the overhaul, entire areas will be covered by a transport collapse. Cutting and replacing the upper damaged layer does not give the desired effect, because the deformation of the coating as a whole occurs, and not just the few centimeters removed. A year will pass, and the new surface will show the defects of the old one. For example, in Europe such a scheme is not applied. If the road needs repair, it is completely closed. It costs more, but the result is more profitable ...
When restoring damaged pavement, rough asphalt is used. It has a longer service life, which means it needs less repair. But the noise from it is above average. When repairing, bypass technologies are used when the top layer is laid from gravel. Motorists themselves must "roll" it. In practice, this turns around, in the first days after the repair, with the departure of stones from under the tires, which often leads to chips on the glass.
In order for the road to last longer, all construction technologies must be observed. But the spikes in the destruction of asphalt are definitely not to blame ... The track is the result of non-compliance with the laying technology.
The problem of rutting on the road worries the vast majority of motorists, because the formed "rutting" causes accidents, and with quite serious consequences. There is an opinion that the main culprit for the appearance of the track is the motorists themselves, who “shoe” their vehicles in studded tires. But, is this really the case?
The main reasons for the appearance of a rut
The track from the spikes is formed in the form of a small narrow strip, but the wider strips formed, most likely appear from a large number of large vehicles and traffic. And, most likely, it is for this reason that “rutting” with hills and depressions appears.
From everything, one conclusion is drawn that the main reason why the problem of rutting on the road arises is rather not properly carried out road work, as well as the extremely low quality of the coating and material itself. If we pay attention to the technical documentation of the coating, we will find a clear wording that the canvas must be laid in two layers. Moreover, the time period between them should be at least three days. But, as a rule, even one layer cannot be put in good faith on domestic roads. And rarely it meets even the minimum indicators, and according to experts, most roads in Russia are designed for use with a traffic intensity of no more than 500 cars per day.
NOTE
In addition, even if they lay asphalt according to the technology, adhering to the norms and order, they do not even let it freeze for a day. Often, traffic is immediately opened along an unformed canvas, from which drops and ruts appear.
There is another reason, which is hidden in poor-quality repairs. Surely everyone noticed that when repairing a section of the road where there are already depressions, they simply remove the top layer of the canvas, without additional processing and strengthening the base. That is, the problem remains, and it is covered with new asphalt. Of course, this type of "repair" is much cheaper, but, as we see, there is little sense in carrying it out.
NOTE
It is not enough to remove the old coating layer, because when used, not only the upper canvas is deformed, but the entire “cushion”. Therefore, it is necessary to build the base again to avoid the appearance of a rut. An interesting fact about the construction of roads in Europe, patching and surface repairs have been prohibited there for quite a long time.
Therefore, it is clear that the low quality index of the material itself, the improper performance of official duties, becomes the fundamental reason for the appearance of a rut. Of great importance is the role of the workers and managers themselves, because the quality of the work performed will allow the road to remain smooth for many decades. But, still a large percentage of people see spikes as the culprit of the problem, even referring to the experience of their colleagues from Germany.
NOTE
Indeed, in Germany since 1975, a ban on the use of any tires with spikes has been introduced, but this is not due to damage to the canvas, but to the large braking distance and inertia of such cars.
A categorical question arises, is it really possible to completely remake disgusting roads into good ones? Of course, experience shows that all this is real, but local specifics must be taken into account. For example, high traffic congestion, street layout, with long-term repairs form a real collapse. But, at the same time, surface repairs will not give any positive results, the road will shine only for the first year, and maybe much less. Therefore, it is much cheaper to completely block a section of the road and carry out a major overhaul than to carry out patching every year.
NOTE
Today officials prefer to choose the lesser negative – bad roads. Summing up, I would like to remind you again that the spikes do not play any role in the destruction and formation of the rut. The fault is not the quality of work and material.
Methods by which the problem of rutting on the road can be eliminated
As we have already found out, for a quality repair it is important not only to eliminate the track itself, but also to remove the underlying cause. Therefore, it is important to carry out not only surface repairs, but also carefully revise the “cushion”. Identify shortcomings, determine the level of work and take appropriate measures.
In companies involved in laying roads, they divide repairs into two main subspecies:
- Asphalt repair.
- Concrete repair.
In the first case, the process involves the use of two technologies:
- The repair is carried out with the cutting of the road map, that is, such work allows you to completely remove the destroyed and damaged coating, followed by an analysis of the base. If the “cushion” is ready to last another season, then asphalt mixture is poured into the cutouts. The cold type is often used, because hot asphalt is difficult to compact in small sections.
- The second type of work already takes into account the absence of a map cut, as such. The technology involves pouring the canvas with a cast mixture. Such a mixture does not even require mandatory compaction.
In the second case, the use of two technologies is also implied:
- In the same way, a part of the canvas, the so-called “card”, is cut out, after which the reinforcement is laid in pre-cut grooves. Before installation, fittings, coating, base are carefully processed and cleaned. After that, only proceed to direct pouring.
- Repair without cutting "cards" is carried out using special fillers. That is, the track is cleaned, debris and dust are removed, the surface layer is removed, as a rule, no more than 0.2 mm. Then it is processed with special solutions and emulsions based on cement.
Rutting Prevention
In Europe, for example, the main causes of rutting are caused by water ingress with subsequent destruction of the canvas. Of course, in our country there are also sections of roads that are built in accordance with all the rules. Therefore, it would be reasonable to carry out destruction prevention, to save the layer, using a variety of technologies.
The problem of rutting on the road can be solved with the help of special emulsions that are poured into the formed pores and provide protection against moisture ingress. The disadvantages of this method include only the need to periodically restore the protective layer every two years.
In addition to the use of various solutions and emulsions, the so-called wear layer is also used. This is a layer of asphalt canvas, consisting of 1 cm of asphalt and 1 cm of crushed stone recessed into the canvas. This coating protects the road from moisture, and also helps to improve traction with the wheels. According to its technical parameters, this type allows you to save the original appearance of the road, but on the condition that initially the work on the arrangement of the roadway was carried out taking into account all the rules and regulations.
Rutting on the roads: we are looking for the perpetrators and understand the reasons.
Each owner of motor transport, when driving on highways and highways of our beloved Motherland, has repeatedly encountered such an unpleasant phenomenon as rutting on the roads. A track is a type of deformation of the asphalt concrete pavement in the roadway. Rutting on the roads is one of the most common problems of domestic roads, and also the most dangerous, because it is often accompanied by road traffic injuries. Of course, we all dream of a perfect asphalt surface and no less perfect car suspension and often scold negligent road builders. Let's talk about who is to blame for the current quality of the road surface and what are the causes of rutting on the roads.
Rutting on the roads: causes of formation.
As a rule, rutting on the roads occurs due to the following reasons:
1. Violation of the technology for the construction of roads.
The quality of the base prepared for asphalt has an impact on the strength of the upper layers of the asphalt concrete pavement. These are works on the preparation of a sand and gravel base and other types of work. High-quality compaction of sand-gravel and natural base, maintaining the necessary proportions of components in accordance with regulatory documents, SNiP, GOST, compliance with asphalt laying technology - all these are important aspects of a good result.
Design documentation for the construction of roads should be developed taking into account the climatic, landscape and other features of the area. Also, categories and capacity of roads, etc., should be taken into account.
Therefore, it is necessary to produce only with the help of organizations with highly qualified employees who are able to fully complete all stages of work.
2. Poor quality of materials used for road construction.
An important role in the quality of asphalt concrete pavement is played by the materials used in the construction of pavement. If the materials do not meet the required technical parameters, there is an accelerated deformation of the pavement. Potholes, cracks, spalling, abysses, subsidence, ruts, as well as the collapse of roadsides can be observed on the roadway. Eliminates many deformations. Pothole repair can significantly extend the life of asphalt if it is carried out in a timely manner.
2. Deconsolidation of the pavement structure.
Decompression of the pavement structure can be observed in several cases:
- The ingress of precipitation into pavement;
- Production near the construction of pavement.
3. Improper road maintenance.
Often the roads are operated improperly, it is unacceptable on the roads:
- Violation of weight control. Overloading trucks has a deplorable effect on the asphalt concrete road surface;
- Violation of the terms of the current repair. The ingress of precipitation through cracks and pits leads to decompression of the pavement structure;
- Violation of conditions. With poor-quality road maintenance in winter, cars are forced to drive along the “knurled track”, as a result of which the load on a certain section of the road increases and a rut appears.
3. Climatic aspects.
Today, it is increasingly possible to meet climatic anomalies, weather phenomena atypical for a particular area. Excessive heat, or, conversely, frost, can seriously affect the road. Precipitation or its absence, landscape changes, groundwater and many other aspects of natural phenomena can affect the quality of the roadway.
Rutting on the roads: who is to blame?
Thus, it can be concluded that there may be many culprits here. These are road construction companies, material suppliers, service organizations, motorists themselves, accidental disasters, etc. After all, it is important not only to carry out road construction with high quality, but also to preserve the result of work.
