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The logs were laid across the streets and covered with boards on top, laid in the direction of traffic. Or the upper parts of the logs were cut off, forming a flat surface. The Zemstvo Prikaz collected “bridge money” from city residents – a tax for street improvements.
Wooden pavement of the 17th century, found during excavations in Istorichesky Proezd, 1988.
Over time, wooden pavements became dirty, overgrown with soil, and subsequent ones were built on top of the soil layer. Judging by archaeological excavations, such layers reached 50 centimeters.
Plan "Kremlengrad" 1602. It’s hard to imagine, but back in the 16th and 17th centuries, Red Square was still unpaved. Wood flooring They led only from the streets - Nikolskaya, Ilyinka to the Nikolsky and Spassky Gates of the Kremlin, respectively.
Fragment of Sigismund's plan of 1618. Chertolskaya street, paved with wood, is shown - today's Volkhonka and Prechistenka.
Moscow 17th century. Towers of the White City. Reconstruction by restorer Sukhov. This is what streets paved with wood might have looked like.
One of the Kremlin streets under reconstruction by Appolinary Vasnetsov. Here the artist depicted a type of wooden pavement with longitudinal boards with which the logs were sheathed on top.
A fragment of an engraving by the Dutch master Pieter Picart, 1707. On the other bank you can see a wooden pavement leading from the Moskvoretsky Gate of China Town to the “living” floating bridge across the Moscow River.
First experiments with stone
The first stone pavement in Moscow appeared in the Kremlin in 1643. Master Mikhail Ermolin paved the territory of the Patriarchal Court with stone, for which he received good money for those times - 4 rubles.
They began to pave the streets with stone only under Peter I. They started in the 1690s; in 1700, the authorities ordered “to collect paving money from all Moscow courtyards to the Streletsky Prikaz.” In 1705, a decree was issued to collect money from all cities of the country. The peasants were obliged to mine and bring wild stone to Moscow, and so that each one was no smaller than a goose egg.
In 1718, several decrees were issued regulating the paving of streets. The maintenance of the pavements was entrusted to Moscow homeowners:
“Every resident should sprinkle sand and stone opposite his yard, pave it smoothly, as will be indicated by the masters, and so that the drains are along the streets, closer to the courtyards, and at the ends of the streets, make drains towards rivers and ponds, so that they are firmly established, so that in the spring and It didn’t drift when it rained.”
In the central regions, it was prescribed that streets and alleys should be completely paved with stone: “in the Kremlin and China, everyone should pave stone bridges in front of their house.”
However, back in the mid-18th century, most Moscow streets were paved with wood; many of these pavements survived until the fire of 1812.
Cobblestone street in Krivokolenny Lane in a painting by Karl Baudry, 1843.
Until the introduction of municipal management in the 1860s, homeowners were responsible for maintaining and renovating pavements. Not all owners had the money for this, so in 1823 a capital was established, from which loans were provided to low-income homeowners.
One can imagine how the obligation of the inhabitants to maintain the pavements affected their quality. One updated, but his neighbor postponed this matter. One did it well, the other did it poorly. The street surface became increasingly uneven, and holes and potholes became commonplace.
Another problem until the mid-19th century was the imperfect technology of stone laying. In most cases, cobblestones were paved without a backing, directly on the ground. As a result, it was necessary to change the coating several times a year. Only in some places they made a pillow: first they laid logs and boards, sprinkled crushed stone, garbage, coal and ash on top, then added a layer of earth, and only after that they laid a stone on top. But this did not always save.
Painting by artist Pyotr Vereshchagin, 1879. The roadway has cobblestone pavement, and the sidewalk along the edge of the embankment is made of stone slabs, most likely sandstone.
G. Vasilich writes about the quality of roads in Moscow in the mid-19th century:
“There was no cleanliness on the streets at all, the pavements were disgusting... In winter, the snow and accumulated manure were not removed, and by spring Moscow was full of potholes, which, when the melting began, turned into traffic jams, and the moment came when the prudent man in the street sat at home, because the passage was neither on wheels nor on a sleigh. ... They also note the stench that hovered over Moscow, which became especially unbearable in the lower part of Tverskaya, near Okhotny Ryad, where poultry and cattle were slaughtered for a long time ... "
Money from the city budget for pavements began to be allocated in the 1860s; roads were finally transferred to the maintenance of the city only in 1874. But this only applied to the roadways of the streets; sidewalks still had to be laid and repaired by the owners of the properties.
Sandstone pavement in the Kremlin on Cathedral Square.
Sandstone sidewalk in the Kremlin, 1900s.
1890s. Podsosensky lane. The roadway is made of cobblestones and the sidewalks are made of sandstone slabs. There is no such thing as a border.
Presnenskaya outpost, 1910s. The area is entirely paved with cobblestones.
In the 19th century, already at the end of October, Moscow was covered with snow, and the carts were exchanged for sleighs. Before Soviet times, every winter there was an order not to clear snow from the moment it fell until March 22. Over the winter, up to 50 cm of compacted snow accumulated on the roadway. Excess snow was cleared off into snowdrifts on the side of the road. During thaws, snow from these snowdrifts was scattered across the bare pavement. The sidewalks were cleared, and they turned out to be much lower than the roadway. So the sled could fall onto the sidewalk if you drove too close to the edge of the road.
1900s Petrovka in winter.
Until the mid-20th century, most Moscow streets still retained cobblestone surfaces. In the magazine "Behind the Wheel" in 1928, a detailed article was published about the state of the pavements at that time:
“Indeed, by the end of May of this year, the area of Moscow city passages, paved in one way or another, was equal to 11½ million square meters. meters, of which cobblestone pavements - 10,998,383 sq. meters or 95.7%. If we remember the well-known truth that a meter is one ten-millionth of a quarter of the Parisian meridian, then we can easily understand that if a strip one meter wide is paved with Moscow cobblestones, then more than a quarter of the globe can be walked along it. This is already grandiose and, it seems, this is the only advantage of the Moscow cobblestone street.”
“Bus traffic contributes to the appearance of abysses on the cobblestone pavement (Butyrsky Kamer-Kollezhsky Val).” (Magazine “Behind the Wheel”, 1928).
1971 Cobblestone street in Bolshoi Vatin Lane. Still from the film “12 Chairs” by L. Gaidai.
By 2016, the only place in Moscow where the cobblestone pavement remains is the Krutitskoye Compound.
Krutitskaya street
When did asphalt first appear in Moscow?
In the 1870s, it became clear that you couldn’t go far with cobblestones alone; it seemed to be a very outdated type of surface, especially for main streets. An unprecedented innovation – asphalt – was gaining more and more popularity in major cities around the world.
The first asphalt pavement in Moscow appeared in 1873 on Nikolskaya Street. However, the city did not have a hand in this; it was a private initiative. The rich and progressive merchant Alexander Porokhovshchikov, who built the Slavic Bazaar restaurant, decided to demonstrate an outlandish novelty and rolled the street along his property into asphalt.
Asphalt on Nikolskaya Street, 1910s.
The city didn’t give up either. Clever engineers were sent to learn from experience abroad, to Europe to see the technology of laying modern pavements, and to Baku to study the extraction and production of asphalt.
In addition to the detailed report, engineer Petunnikov brought to Moscow a statement that: “Moscow must once and for all abandon cobblestone, recognizing it as a stone unsuitable for paving.” Instead, he offered asphalt and stone paving stones.
In 1876, the City Duma allocated 50,000 rubles for experiments with new types of coating. In the same year, 5 test sections of different pavements appeared on Tverskaya Street.
The first section is pressed asphalt bricks, the second is pressed asphalt hexagonal blocks, the third is cast Syzran asphalt, the fourth is pressed Sessel asphalt and the fifth is wooden end paving according to the Nicholson system.
Cast Syzran asphalt and, unexpectedly, wooden end paving have proven themselves best.
Asphalt on Tverskaya Street, 1876. There was still a cobblestone road in Maly Gnezdnikovsky Lane.
By 1896, the area of asphalt pavements in Moscow reached 5,505 square fathoms (2.5 hectares). But for the most part, these are small plots along private estates, built with the funds of wealthy entrepreneurs. Moreover, some homeowners laid asphalt along their houses to muffle the noise from iron wheels and horse shoes.
1900s. Exchange Square. The roadway of Ilyinka is paved with cobblestones, and on the left there is a pedestrian crossing rolled into asphalt.
At the beginning of the 20th century, asphalt got everything greater distribution. In 1912-1914, 57% of the new pavement area was laid with granite paving stones, 18% with asphalt and 22% with cobblestones.
By this time, Petrovka from Teatralnaya Square to Stoleshnikov Lane had already been rolled into asphalt, as was Stoleshnikov Lane itself.
The roadway and sidewalk are made of asphalt. Petrovka, 1915.
Curb stones were still a rarity; the edges of sidewalks were paved with cobblestones. The sidewalks on the central streets were paved, and some properties still had large slabs of sandstone left.
Tverskaya. 1900s. The roadway is made of cobblestones; asphalt on this section of the street is currently only on sidewalks.
1927 Laying asphalt at the beginning of Tverskaya.
Surprisingly, in 1928 it was still possible to drive on a tree:
“You can find wooden pavement in small quantities in Moscow. The wooden ends of recent times are very bad and do not satisfy the requirements technical requirements(large-layered, knotty, rotting); therefore, the service life of the end pavement was reduced by two years compared to the pre-war period.” (Magazine “Behind the Wheel”)
It’s hard to believe now, but in the late 1920s they couldn’t even imagine asphalt everywhere:
“They proposed to fill all of Moscow with asphalt; of course it would be neat and elegant. But try to climb one of the seven notorious Moscow hills on this asphalt in icy conditions and you will abandon your project. And it’s a bit difficult to build asphalt pavement on a steep slope.”
Less than half a century had passed before the whole of Moscow was, in fact, poured into asphalt.
When did paving stones appear in Moscow?
Paving stones appeared in the 1870s as a type of experimental pavement, along with asphalt.
1913 The entire 1st Tverskaya Street, from Triumfalnaya Square to Tverskaya Zastava, was paved with paving stones.
1925, Tverskaya street in the section from the Boulevard Ring to the Garden Ring. Experimental small paving stones - “Klein-plaster”, a square block on a concrete base.
From the magazine “Behind the Wheel”, 1928:
“For significant movement, paving stones are quite good. In Moscow, it is used in three types: 1) normal paving stones 15-16 centimeters high, placed on a sandy base; Lightweight paving stones with a height of 12-14 cm are used on tram tracks; 2) brutkenstein or lowered paving stones laid on a layer of concrete; 3) kleinpfläster or mosaic with cubes 8-10 cm high (for example, on Tverskaya, in the form of circular arcs), on a concrete base with a sand layer between the concrete and the mosaic.”
1971, paving stones on Vorontsovo Pole street. Still from the film “12 Chairs” by L. Gaidai.
To date, there are several streets left in Moscow with paving stones laid at the end of the 19th or early 20th centuries.
Paving stones on the Kuznetsky Bridge, still preserved. Photo from the 1980s.
Paving stones on Barrikadnaya Street, photograph by A. Slyusarev, 1981
Paving stones on Barrikadnaya Street, 2010s.
Paving stones from 1927 on the Komissariatsky Bridge near Novokuznetskaya
When did paving stones appear on Red Square?
Red Square, 1910s. An asphalt path in the middle of cobblestones.
1925 The pavement of Red Square is still cobblestone.
Until the 1920s, Red Square remained paved with cobblestones, and only for the opening of Lenin's stone mausoleum in 1930, the cobblestones were replaced with diabase paving stones. The stone was mined on the shores of Lake Onega and cut into bars weighing 8-10 kg.
1930 Laying paving stones on Red Square.
New paving stones along Srednye shopping arcades, 1930.
In 1974, the paving stones were completely renewed and laid on concrete base. These pavers are made from the ultra-strong igneous rock rock gabbro.
1974, reconstruction of Red Square.
Clinker pavements
As an experiment in the first third of the 20th century, it was decided to pave some streets and squares of Moscow with clinker bricks. This is a Dutch invention: a heavy-duty brick made from a special type of clay, fired until completely baked at a temperature of 1200 degrees. Clinker brick pavements are laid in a herringbone pattern.
In the 1910s, part of Theater Square was laid out with clinker, but the issue was raised seriously in 1928. From the magazine “Behind the Wheel”:
“In particular, the commission believed that clinker could be a suitable material for paving outskirts and generally streets with insignificant traffic. It is necessary to immediately begin studying the suitability of clays near Moscow for clinker, and if the decision is positive, raise the question of building clinker factories near Moscow.”
In 2015, during the reconstruction of Pushechnaya Street, a completely preserved clinker brick covering was revealed.
This pavement was in danger of being completely destroyed.
But fortunately, a fragment of the roadway was moved to the sidewalk, and now it is a local landmark.
So in today’s Moscow, in addition to Sobyaninka tiles and the ubiquitous asphalt, you can walk on cobblestones, paving stones and clinker. But wooden pavements are now much more difficult to find.
The publication was prepared by Alexander Ivanov
Asphalt is a natural or artificial multicomponent material based on surface (formed when reaching the surface of the earth) or petroleum (obtained as a result of oil refining and subsequent processing of tar remaining in the sediment) bitumen containing mineral fillers - gravel, crushed stone different breeds, sand.
In fact, applying the term “asphalt” to road asphalt concrete mixtures is incorrect. The content of asphalt as a mixture of bitumen in the total mass is several times less and depends on the type of material.
Start of using asphalt for road construction
The first mention of the use of natural asphalt for laying roads dates back toXVIcentury and South America. The production of artificial cast asphalt mixtures appeared in the United States only at the end ofXIXcentury, bitumen-mineral compositions came to the streets of Europe a little earlier - in 1830-40. paved sidewalks and roadways in cities in France, Austria, Great Britain and Russia began to be replaced by asphalt surfaces.
The first trial and larger-scale asphalt paving experiment was carried out in St. Petersburg, but only by 1980. the new road material spread to other major cities. At the same time, our own plant was not built in Russia right away - for three decades, the then progressive product was purchased abroad.
America was again the pioneer in mechanized laying. It was here that a tarmacrator, from which hot bitumen poured, was first used to build a road.
Composition of natural and artificial asphalt
Natural asphalt is extracted from rare deposits - Peach Lake in Trinidad, the Dead Sea in Israel, Alberta in Canada, the Orinoco Belt in Venezuela, US states, Iran, and Cuba. The composition includes a mixture of bitumen up to 70%, inorganic inclusions and organic compounds.
Artificial asphalt concrete mixtures consist of two main components. The role of the binding component is viscous, low-viscosity or liquid petroleum, modified bitumen and PBB (polymer-bitumen binders). Crushed stone/gravel of different fractions from 5-10 mm to 20-40 mm, sand and mineral powder are used as fillers to improve strength, toughness and fill voids.
Asphalt concrete is a monolithic road surface obtained by laying and compacting an asphalt concrete mixture.
Asphalt production technology
The main steps in the production of any asphalt concrete mixture are preparation of components, mixing and storage in a bunker. Manufacturing is carried out at stationary and mobile (located near the road construction site) factories.
General technological steps:
- Preparation of mixture components. Mineral fillers are crushed and separated into fractions using a screen, dried, heated, dosed and fed into the mixer.
- Preparation of bitumen. The heated bitumen is fed to the bitumen melting plant, kept with constant stirring, adding a surfactant and raising the temperature until the moisture evaporates, and is sent to working boilers and to the mixer dosage.
- Mixing components. Prepared crushed stone/gravel and sand are fed into a forced-action asphalt mixer for “dry” mixing with the addition of mineral powder and subsequent addition of heated bitumen and mixing until a homogeneous mixture.
- Overload ready mixture. The hot asphalt mixture is sent to a storage bin or loaded into dump trucks for transportation to construction site. The cold mixture is cooled and transported to a warehouse for storage.
Heating of crushed stone and bitumen during the production of hot mixtures is carried out to a temperature of 165…175 0 C and 140…155 0 C, when producing cold mixtures - up to 65...75 0 C and 110…120 0 C accordingly.
Classification of asphalt concrete mixtures is carried out according to residual porosity, type of mineral materials, their fraction and percentage, bitumen binder and laying temperature.
Certain types of asphalt concrete mixtures
In addition to traditional and widely used asphalt concrete mixtures, there are more advanced road materials that differ from the former in composition and laying conditions.
These include:
- Crushed stone-mastic mixtures ShchMA with stabilizing additives.
- Cast asphalt concrete mixtures with an increased content of bitumen and mineral powder.
- Polymer-asphalt-ethony mixtures with the addition of polymers (elastomers).
- Colored hot and cold mixtures with coloring pigments.
- Glass-asphalt-ton mixtures with the inclusion of broken glass.
- Rubber-asphalt concrete and rubber drainage mixtures with rubber crumbs and polymer additives.
- Sulfur asphalt concrete mixtures with the presence of technical sulfur.
Each type of material has a specific area of application, determined by the characteristics and operational properties of the resulting coating.
is a heavy, dark brown or black mineral substance, one of several mixtures of hydrocarbons called bitumen. Asphalt is a strong, versatile and chemically resistant binder that adapts to various types its applications. Asphalt binds crushed stone and gravel (commonly called aggregate) into a durable road surface. Asphalt, also known as mineral tar, is obtained from natural sources such as native asphalt or breya, or as a by-product oil industry(petroleum asphalt).
Interesting fact! Prehistoric animal skeletons have been entirely preserved in natural asphalt deposits, one of the most famous of which is the La Brae Tar Pits, in Los Angeles, California.
Historical facts about asphalt
Asphalt is one of the oldest in the world engineering materials, which has been used since the beginning of civilization. The Sumerian peoples also knew what asphalt was. Thus, the Sumerians had a thriving shipbuilding industry, which produced and used asphalt for compaction and waterproofing. As early as 2600 B.C. the Egyptians used asphalt as waterproofing material, and also for wrapping mummies as a preservative. Ancient civilizations widely used asphalt as a mortar for building and paving blocks used in temples, irrigation systems, reservoirs and highways. The asphalts used by early civilizations were naturally occurring and were found in geological strata as both soft, workable solutions and hard, brittle black veins of rock (also called asphalt coal). Natural asphalt was formed when crude petroleum oils made their way through cracks onto the earth's surface. The action of the sun and wind dried out the light oils and gases, leaving a black residue. Natural asphalts were widely used until the early 1900s. With the discovery of the ability to process asphalt from crude oil and the growing popularity of the automobile, the asphalt industry expanded significantly. Modern petroleum asphalt has the same durable properties as natural asphalt, with the added benefit of being uniform and free of organic and mineral impurities.
What is asphalt made from? What does it consist of?
The raw material used in modern asphalt production is oil. Oil wells supply crude oil to refineries where it is separated into its various components or fractions through distillation of the fossil.
Asphalt production process
1. After fractionation, the oil is further refined into other products, which include asphalt, paraffin, gasoline, lubricating oil, kerosene and diesel oil. Because asphalt is the base or heavy component of crude oil, it does not evaporate or boil during the distillation process. Asphalt is essentially a heavy residue from the oil refining process.
2. The asphalt can then be mixed or "cut" with a volatile agent, resulting in a soft and workable product at a lower temperature than pure asphalt cement. When cutting asphalt is used for paving or construction, the volatile element evaporates when exposed to air or heat, leaving behind hard asphalt cement. Heated asphalt cement is mixed with residual asphalt oil from an earlier distillation process for slow-cure asphalt, with kerosene for medium-cure asphalt, and with gasoline or naphtha for fast-cure asphalt.
3. Asphalt cement can also be emulsified to produce a liquid that can be easily pumped through pipes, mixed with aggregate, or sprayed through nozzles. For emulsification, asphalt cement is crushed into globules of 5 to 10 microns or less (one micron is equal to one millionth of a meter). Then mixed with water. An emulsifier is added, which reduces the tendency of asphalt and water to decompose. The emulsifying agent may be colloidal clay, soluble or insoluble silicates, soap or sulfonated vegetable oils.
4. Asphalt can also be crushed to produce powdered asphalt. The asphalt is crushed and passed through a series of screens to ensure uniform granule size. Powered asphalt can be mixed with road oil and aggregate to construct sidewalks. The heat and pressure of the road slowly mixes the powder with the aggregate and the binding oil, and the asphalt cement substance hardens to a consistency similar to regular asphalt cement.
Important! There are two types of asphalt mixtures: hot mix and cold mix. Hot mix asphalt (HMA) is typically used for heavier traffic areas, while cold mix asphalt is used for secondary roads.
Very often, road construction managers, whose task is to lay the bitumen-concrete mixture, want to know what is the exact consumption of asphalt per 1 m2?
First of all, you need to consider the type of bitumen-concrete mixture.
The largest amount - about 25.5 kg per 1 cm of thickness - is typical for stone mastic asphalt mixture (SMAM). This can be explained by the SMAM particle size distribution curve (high degree of filling of the framework with grains of different sizes).
The quantity per 1 m2 of colored asphalt is 25 kg (thickness 1 cm).
The amount of coarse aggregate mixture is less - about 24 kg per 1 m2 (assuming a thickness of 1 cm), since their granular curve is intermittent, that is, the space between large grains is filled with sand, but not with fine fractional dust for stone screening, as is the case in case of SMAM,
For a sandy bitumen-concrete mixture, the amount is 23.5 kg per 1 m2, since the density of sand is lower than the density of crushed stone.
The above data is not exact and may vary up or down according to the type of crushed stone or sand that is used, as the density of mineral materials and their physical and chemical properties vary depending on where they are extracted.
Thus, if the plan is to cover a section of road with a total area of 1000 m2, 5 cm thick with SMA type bitumen-concrete mixture, the calculation should be made using a simple formula:
25 kg * 5 cm = 125 kg = 0.125 t - the amount of bitumen-concrete mixture required to cover 1 m2 of surface.
In our case, the surface area is 1000 m2, so multiplying this area by 0.125 tons, we get 125 tons cubic.
Result - 1 ton of bitumen-concrete mixture is enough to cover 8 square meters surfaces. These figures are purely individual, but as a guide they can be used for approximate calculations.
Asphalt is a mixture of mineral materials (gravel and sand) and bitumen. In the depths of the Earth it can be in both liquid and solid form. As the temperature rises, it softens and becomes liquid, and when the temperature decreases, it hardens again. Asphalt contains carbon and hydrogen, the latter, in turn, is part of crude oil.
Types of asphalt
There are two types: natural, which lies in deposits almost at the very surface of the earth, and artificial - it is produced in modern factories from crude oil. Natural asphalt has a high bitumen content - from 60% to 75%, while petroleum asphalt contains only 13-60%.
A very interesting fact is that the largest “lake of asphalt” is located on the island of Trinidad; it covers an area of forty hectares and goes more than thirty meters deep. When laying asphalt on the streets of Washington, the capital of the United States, most of it was taken from Trinidad.
Peach Lake Asphalt, Trinidad
Asphalt is used to cover roads, for roofing, for the manufacture of various varnishes, adhesives and putties, and is also used as an electrical and waterproofing material.
Background to the heyday
In the nineteenth century, city streets were initially paved with stones. In countries such as the USA, Switzerland, and France, from the mid-nineteenth century, bitumen-mineral mixtures began to be used for road surfaces. The first cast asphalt based on petroleum bitumen appeared in the USA in 1876. Asphalt concrete became the “pioneer” of paving in Paris in the 1930s during the laying and improvement of the Royal Bridge, and a little later for the bridge called Moran, which was thrown across the Rhone River in Lyon.
Road communications developed very rapidly and required new technologies and types that were built as quickly and easily as road surfaces.
The first road surface was created using an industrial method in the USA in 1892; it was 3 meters wide and made of concrete. And twelve years later, road structures were already produced using a tarmacrator, through which hot bitumen flowed freely.
The pioneer of mass production of asphalt in Russia was engineer I.F. Buttats. The first Russian plant to produce this road material was Syzran (back in 1873).
The advantages of asphalt in the modern world
As it turns out, asphalt is an ideal material for road surfaces because it has many advantages. Over time, it became smoother, which reduced wheel noise. Unlike cement concrete, which was used previously, asphalt concrete quickly dried, hardened, gained strength and “allowed” traffic to open almost immediately. Cement concrete needed twenty-eight days for this.
IN modern world Asphalt is widely used and is the most popular covering material for various areas. One of the many advantages of this bituminous substance is its ductility and ability to bend rather than break. This is very important when creating runways, since sometimes the weight of an aircraft can exceed 140 tons. This quality is also significant in the creation of highways along which huge trucks drive, weighing more than forty-five tons.
Asphalt pavement is very practical, it can be easily repaired, adheres well to any road markings, is easy to clean and has a the required rigidity for wheel traction with the road.
Modern technologies do not stand still and continue to develop. This applies to both asphalt material and methods of covering it. The ability to withstand extreme heat and extreme cold without fear of temperature changes has long been added to the list of advantages.
It is a multicomponent mixture based on sand, stone and bitumen binder. The “correct” name of the material is asphalt concrete, which does not prevent the term “asphalt” from being used even in specialized publications.
Asphalt contains bitumen, sand, types of crushed stone or gravel, and mineral supplements and fillers. The only constant component is bitumen, and the remaining components can be added in various proportions.
Functions of fine components of asphalt mixture
Sand, contained in asphalt, plays the role of a filler and a fine base, helping to distribute pressure from the road to the ground. Without sand, the bitumen binder would leak out and crushed stone would be squeezed out onto the top.
In the case of special asphalts containing cement, sand participates in the cementation process and gives the coating additional hardness.
Mineral filler– is a rock (sandstone, limestone or chalk) crushed to a dusty state, intended to fill residual voids. Sandstone is the most versatile, as it is inert to almost any chemical attack. Calcium carbonates (limestone and chalk) are typically used on public roads, while sandstone can be used near chemical plants.
Rubber– added to asphalt in the form of rubber crumbs (1-1.5 mm), it gives the coating high water resistance and plasticity. Asphalts treated with rubber are much less likely to crack, which increases the period between repairs. The disadvantage of such roads is their high cost, so their use is limited to laying the most critical sections of highways.
Change in asphalt structure when adding mineral filler
Classification
One of the main parameters is the size of the crushed stone used, dividing asphalts into the following groups:
- dense– used for laying the top layer of coating and contains fine crushed stone. In the case of a crushed stone fraction of less than 5 mm, such asphalts are used for pavements with low loads (sidewalks and pedestrian crossings) and are called fine-grained. Larger fractions of crushed stone (5-15 mm) are suitable for creating the top layer of highways;
- porous– used in the lower part of a multilayer pavement and contain less bitumen than dense asphalts;
- highly porous– optimal quality bases for heavily loaded roads. In their production, the largest crushed stone of the 15-40 mm fraction is used. Such dimensions provide the necessary water permeability, creating drainage in lowlands and marshy areas. Larger grain size reduces the movement of the road base and indentation into the top layer of soil, reducing the risk of washout and subsidence of the pavement.
Manufacturing technology
The basis of any asphalt production is the preparation of the initial components, mixing high temperature and storage in special heated bunkers.
It is important that the plant is located close to the construction site, since the material must be transported for installation in a heated state. If the mixture cools down, it will be very difficult to compact and the resulting coating will not be strong enough. Let's look at the stages of asphalt production.
Preparation of components from which asphalt is made
This includes drying and sifting. Sand, crushed stone and rock usually arrive at the plant in a wet or air-dry state. The presence of residual moisture is fraught with a decrease in the strength of the coating and splashing of the hot bitumen mixture when water gets into it.
To eliminate possible consequences, the material is dried at a temperature of 150-160? C - this temperature allows you to get rid of moisture adsorbed in the pores of the material.
Screening of crushed stone is carried out using a screen. The mineral filler is pre-crushed in a crusher, after which it is also subjected to fractionation. Depending on the production technology, drying can be single or double, repeated after crushing or sifting.
Mixing components
Crushed stone and sand are fed onto a conveyor belt, which transports them to a common bunker. Mixing with filler and bitumen can occur simultaneously or be carried out after achieving a homogeneous crushed stone-sand mass.
After adding bitumen, the temperature is maintained at 160-170? C. After reaching the required consistency, the mixture (now asphalt) enters a storage bin, where it can remain heated for up to 4 days. During this period it must be shipped to the consumer to avoid loss of strength characteristics.
Asphalt modification with additives that impart useful performance properties is carried out simultaneously with asphalt mixing. When creating a rubber-asphalt mixture, crumb rubber is added to a heated, ready-to-use product.
Delivery
Transportation of asphalt concrete to the construction site is carried out by motor transport. Most often, conventional dump trucks with a body resistant to hot asphalt are used. For transportation over long distances, kochers - vehicles with special heat-saving containers - can be used. They are designed to preserve the properties of asphalt concrete for 2 days.
The video will tell you how asphalt is made at a factory and whether it is possible to make it yourself:
How to check the parameters of the road surface and raw materials for its production
To avoid purchasing low-quality asphalt concrete, you should ask the seller for a certificate of product conformity. It is issued only after passing a set of tests corresponding to GOST or SNiP (depending on the scope of application).
In the quality control market, there are a number of regional laboratories that conduct sampling and testing of asphalt pavements. During the study, an average sample is selected from the total mass of the material. Analysis of the road surface is carried out by examining a core, which is an asphalt core obtained by drilling the road with a special hollow drill.
DIY cold asphalt
Let’s immediately make a reservation that cold asphalt is only laid independently, and its production is carried out only at the factory. The technology itself differs from traditional coating in lower operating temperatures (70-110 °C) and the addition of a complex of protective and polymer additives to its composition. The latter are necessary to impart greater strength and form a protective antioxidant film on the surface of the bitumen.
Despite the name, cold asphalt will still have to be heated in cold weather in order to convert the bitumen into a plastic state. At the same time, you need to use a burner to heat the place where the asphalt will be laid. Depending on the manufacturer, work with cold mixtures can be carried out even with negative temperatures(up to -20...-10 °C).
The advantage of cold asphalt is its long shelf life. Unlike classic asphalt concrete, it does not need to be used immediately after purchase. The disadvantages include lower strength, which is almost 2 times less than that of hot asphalt.
To compact the coating, use a vibrating plate or improvised means - thick wooden beam, car wheel. The final finishing of the surface occurs after repeated passage of vehicles. It is not recommended to make entire sections of the road from cold asphalt, since they are destroyed under the pressure of a vehicle weighing over 3.5 tons.
Modified cold asphalt:
Recycling old asphalt
The high cost of creating a road forces us to look for ways to save money. One of them is recycling - processing waste asphalt for the purpose of its reuse. Processing is carried out in stationary conditions or in mobile recyclers.
The process is carried out in several stages:
- Removing a layer of old asphalt is done with a remixer, which removes the road surface by milling;
- crushing the milled layer to the size of crushed stone. The resulting product is called granulate and can be used for laying roads and preparing crushed stone-sand building mixtures;
- heating in an oven without direct contact with fire (to avoid ignition);
- adding a fresh portion of bitumen and polymer additives, if necessary.
Recycling technology is of industrial importance and is usually used in the construction of urban and intercity highways. If the opportunity arises to buy recycled asphalt for private purposes, do not hesitate - there is no difference in performance properties, while the price will be significantly lower.
Mobile asphalt recycling plants
Installation No. 1 Installation No. 2
Modernization of asphalt concrete pavements
Although quite practical, road surfaces can be improved. One way is to use special mastics for asphalt. They contain bitumen or bitumen emulsions containing rubber polymer additives.
Conventional bitumen mastics are used in a hot state, and emulsions - in a cold state. The principle of operation of mastics is to seal cracks and pores on the surface of the canvas. This prevents water from getting inside the road and destroying it - water contributes to cracking of the coating during freezing and water hammer when vehicles pass.
Advantages and disadvantages of the material
It is worth noting the following:
- For light-duty applications, asphalts are not very expensive, unlike the multimillion-dollar cost of laying highways;
- With proper quality, asphalt is irreplaceable in any weather.
- Numerous defects that are clearly visible to pedestrians are rarely visible from a car window;
- The production of heated and viscous mixtures is not a simple task, despite the automation of the process;
- The difficulty of using heated mixtures is partly compensated by the appearance of cold asphalt;
- Asphalt paths in the garden are not made precisely for the reason unpleasant odor bitumen, although over time the mixture hardens and causes inconvenience only in hot weather.
Existing alternatives to asphalt are currently too expensive and not as practical. Unlike others building materials, the improvement of asphalt occurs not through the development of new materials, but through the modernization of old ones.
The widespread introduction of polymer modifiers makes it possible to fundamentally improve the properties road surfaces and expand the limits of their technological application, which is confirmed by numerous tests of the material.
