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Mass of reinforced concrete sleeper. How much does a concrete sleeper weigh. How to build a foundation of reinforced concrete sleepers correctly

A sleeper is a support for railroad rails, maintaining their relative position unchanged. It takes the pressure from their weight and transfers it to the sleeper base, consisting of a layer of ballast of crushed stone or concrete, then to the ground. It is made of wood, plastic, steel, reinforced concrete. They are installed on each kilometer of tracks in the amount (three options): 1600 on secondary roads, 1840 or 2000.

Reinforced concrete products have found especially wide application in the construction of jointless (velvet) railway tracks. These are roads on which the distance between rail joints is much greater than the length of a standard rail (25 m). Such tracks differ from the usual ones by a higher cost of installation work due to the weight of the elements, but they provide the maximum speed of trains, convenience for passengers, and reduced maintenance costs.

Sleepers are solid beams (beams) of variable section with platforms for rail installation. They are made from prestressed concrete. It is a structure with prestressed (prestressed) steel reinforcement inside. It differs from ordinary reinforced concrete products in the ability to withstand significant tensile loads, to prevent the appearance of cracks and splits under their influence. Such material is also called prestressed (PNZhB marking). Its use allows the use of smaller products, saves on reinforcement, concrete and transportation costs, and simplifies installation. Weight of 1 pc - 270-285 kg (depending on the weight and number of reinforcing bars).

The production of rail supports is carried out in accordance with the requirements of GOST 10629-88 and 54747-2011. Standard dimensions of a reinforced concrete support: length - 2700 mm, width - 300, height - 230, height in the middle section - 160 mm, height at the ends - 185 mm.

Concrete is used with strength grades from B40 (M500) and higher, frost resistance of at least F200. As a filler for the mixture, only crushed stone from natural stone or gravel with a grain size of 5-20 mm is taken. By agreement with the buyer, in order to reduce the unit cost, it is allowed to add a fraction of 20-40 mm in an amount not exceeding 10% of the volume of the main one (5-20).

For reinforcement in the production of these reinforced concrete structures, carbon steel products of a periodic profile or smooth ones are used:

cold-formed wire with a diameter of 3 to 8 mm;
cold-formed bar reinforcement with a diameter of 8 to 10;
hot-rolled and heat-treated rod reinforcement from 8 to 10;
reinforcing ropes from 6 to 14.

Smooth reinforcement can only be used in conjunction with end anchors.

Advantages and disadvantages

Advantages of reinforced concrete sleepers:

long service life - at least 30 years;
lack of rotting and corrosion;
resistance to atmospheric and mechanical influences;
high resistance to movement;
ease of installation technology;
dimensional accuracy, weight stability;
the ability to use on the most loaded sections of the track;
dismantling and reinstallation.

Disadvantages of reinforced concrete supports:

weight of 1 piece - not less than 270 kg;
the need to use special equipment;
relatively high price of a new product;
increased rigidity, require special elastic gaskets;
the possibility of destruction of concrete, the need for periodic inspection;
high electrical conductivity, the use of insulation.

Kinds

On the platform for installing the rails (under the rail platform) there are holes for fastening to the rail and connecting to the adjacent support.

According to the type of rail fastening, sleepers are distinguished:

Sh-1-1 - separate terminal-bolt mounting type KB, with an angle of inclination of the thrust edges of the under-rail platforms of 55°;
Sh-1-2 - separate terminal-bolt, with an angle of inclination of the thrust edges of the under-rail platforms of 72 °;
Sh-2 - inseparable terminal-bolt fixation with bolt fastening to the gasket or rail;
Sh-3 - inseparable terminal-bolt fixation with bolt fastening to the rail;
Sh-5-DF - screw-dowel fastening;
ShS-ARS - anchor rail;
Pandarol-350 (Fastclip) - have a special anchorage developed by the British company of the same name for high-speed (350 km / h) and heavy traffic of railway transport.

According to the features of application and installation, the following types of reinforced concrete rail supports are distinguished:

pavement (M) - for laying on bridges;
shuttle (H) - for shuttles on bridges;
for curved sections (K) - radius less than 350°;
Sh-3-D 750 - for the children's railway (for a track width of 750 mm with rails of the R-43 type);
transformer - for the arrangement of paths for rolling power transformers at electrical substations, differs from other types in that it has a rectangular cross-section along the entire length;
bars for turnouts;
half sleeper - for rail tracks designed to move cranes along them;
for sections with a combination of two different gauges - two varieties: for three or four rail threads.

To ensure insulation, sleeper manufacturers offer products with special hollow-forming inserts.

Depending on the accuracy of dimensions, the quality of the concrete surface and the resistance to cracking, rail supports are classified into two grades. The products of the second can be purchased for use on access, station, other lightly loaded tracks of the 5th class and intra-factory roads of industrial enterprises.

Before buying a batch of reinforced concrete rail supports, it is recommended to inspect several sleepers. On the top surface of a quality product there should be a stamp with a marking. It contains a trademark or an abbreviated name of the manufacturer. On the end part they put a mark on the inspection of the quality control department and the batch number. On every fifth element indicate the last two digits of the year of issue.

Products of the second grade (in terms of crack resistance and geometry) are supplied only at the request of the buyer. At both their ends, a transverse line 1.5-2 cm wide is applied with indelible paint. If there are two such strips on each side, it means that the sleeper does not meet the requirements of the standard even for the second grade.

Be sure to evaluate the number and nature of defects. It is allowed to have:

prints from welds on the longitudinal edges of the under-rail platforms;
traces on the ends - no more than 5 mm deep.

Not allowed:

nodules in the channels for the bolts, preventing their installation and free rotation;
influxes on under-rail platforms;
turning bolts;
cracks;
protruding reinforcement bars (if wire was used for reinforcement, then its ends should extend beyond the end by no more than 2 cm).

Maximum allowable dimensions of shells and rims on reinforced concrete sleepers of the first grade:

For the second grade, defects with dimensions twice as large as those of the first are acceptable.

Reinforced concrete sleepers are special beam structures that are used in the construction of a railway track as supports for rails along which a typical rolling stock moves with loads and speeds established for a common railway network, without restrictions on traffic density. The sleepers ensure the invariance of the relative position of the rail threads, perceive the pressure that comes from the rails and the vehicles passing along them, from the intermediate fasteners, and transfer it to the sleeper base (in railway construction, this is usually a ballast layer, in the subway - a concrete base).

The first mention of track roads made of rails and sleepers dates back to the middle of the 16th century. The rails were wooden beams and were used in mines and coal mines, along which trolleys moved. The wooden beams wore out quickly, causing wagons passing along the rails to go off track. In order to reduce wear, wooden rails were reinforced with strips that were laid across the track. The service life of wooden rails and sleepers, depending on the type of wood, external conditions and intensity of operation, ranged from seven to forty years. Despite such advantages as elasticity, good adhesion to crushed stone ballast, ease of processing, there was a main drawback - the wood in the places where rails and sleepers were attached simply rotted due to accumulated moisture. The first railway track made entirely of cast iron appeared in the 18th century in Petrozavodsk.

However, given the development of railway transport (the emergence of high-speed trains, increasing travel speed), engineers were faced with rapid wear of the cast-iron gauge. With the discovery of new metal-based alloys, it has been found that steel rails wear less and more evenly than other metals. From that time to the present, only steel rails have been used all over the world. During the Great Patriotic War (1941-1945), the development of railways was suspended. However, after it, in the course of the work on the restoration of railway transport, innovations were proposed to strengthen the railway tracks - a jointless track, which reduces the specific resistance to train traffic, electricity and fuel costs, and reinforced concrete sleepers, the service life of which reaches about 60 - 70 years . Today, in the construction of railways, only reinforced concrete sleepers are used.

What are the advantages of reinforced concrete as a material for the manufacture of sleepers? Firstly, the durability of reinforced concrete, which allows the sleepers to be subjected to long-term operation. Secondly, a high degree of mechanical strength, due to which reinforced concrete sleepers have an increased bearing capacity and can resist numerous and prolonged loads without losing their original physical properties. In addition, reinforced concrete sleepers are resistant to aggressive environmental factors, including moisture and decay. The simplicity of the designs is high-tech - they can be reused. Compared to other materials (wood, metal), sleepers easily cope with a high degree of load density. These are the main and obvious reasons for the high relevance of reinforced concrete in the construction industry.

Railway reinforced concrete sleepers are solid beams of a special profile with a variable cross section. The design of the sleepers provides for special platforms that allow the installation of rails, as well as holes for installing fixing bolts for rail and sleeper fastening, which also allows the use of intermediate fastenings of reinforced concrete sleepers. Recently, anchoring has been increasingly used to fasten rails and sleepers.

Sleepers, depending on the type of rail fastening, are divided into:

type I - for separate terminal-bolt rail fastening with threaded attachment of the rail and lining to the sleeper;
type II - for inseparable anchor rail fastening with threadless attachment of the rail to the sleeper;
type III - for inseparable terminal-bolt rail fastening with threaded attachment of the rail to the sleeper.

Reinforced concrete sleepers are divided into classes according to the presence or absence of electrical insulating characteristics and the type of prestressed reinforcement used. According to the electrical insulating parameters, reinforced concrete sleepers are produced in the following types:

isolated. It is supposed to install special liners of an insulating type, which are called blank formers;
uninsulated. Inserts are not provided.

By applicability in curved sections of a railway track of different radii, sleepers of all types are classified into two types:

for straight and curved sections of the railway track with a radius of 350 m or more;
for curves of small radius (less than 350 m) and transition curves.

Also, the main features by which the classification of products is carried out are the degree of crack resistance, quality, as well as the accuracy of the geometric parameters of this type of reinforced concrete products. It is customary to distinguish sleepers of the 1st and 2nd grade. Sleepers made of reinforced concrete of the second grade have a lower degree of crack resistance, lower requirements for the geometric parameters of the product, reduced workmanship, which makes it possible to use only for the arrangement of access and intra-factory railway tracks of the fifth grade, which are characterized by a low degree of load and intensity of operation.

Reinforced concrete sleepers are made in accordance with the norms and requirements established by GOST 10629-88 and GOST R 54747-2011, from heavy concrete of a compressive strength class of at least B40 (according to GOST 26633). The actual strength of concrete (at the design age, transfer and temper) must comply with the requirements of GOST 13015.0. The normalized transfer strength of concrete should be taken equal to 32 MPa (326 kgf/cm2). The release strength of concrete is taken equal to the transfer strength of concrete. The frost resistance grade of concrete must be at least F200. For concrete sleepers, crushed stone from natural stone or crushed stone from gravel of a fraction of 5–20 mm in accordance with GOST 10268 should be used. It is allowed, by agreement between the manufacturer and the consumer, to use: crushed stone of a fraction of 20–40 mm in an amount of not more than 10% of the mass of crushed stone of a fraction of 5–20 mm according to GOST 10268; crushed stone from natural stone fraction 5 - 25 mm in accordance with GOST 7392, subject to its compliance with all other requirements of GOST 10268.

Reinforced concrete sleepers are reinforced with prestressed rebar to provide the extra strength needed for high dynamic railway tracks.

According to GOST 10629-88, steel wire of a periodic profile of class Br with a diameter of 3 mm according to GOST 7348 and TU 14-4-1471-87 is used as reinforcement for sleepers. The nominal number of reinforcing wires in a sleeper is 44. The location of the wires, controlled at the ends of the sleeper, must comply with the project. The vertical distance in the light between pairs or individual wires, in case of their deviation from the design position, should not be less than 8 mm. It is allowed to turn pairs of wires by 90° while maintaining the above distance. Separating spacers remaining in the concrete body of the sleeper can be used to ensure the design arrangement of the wires. It is allowed, upon agreement between the manufacturer and the consumer, to use spacers that differ from the design ones.

According to GOST R 54747-2011, for reinforcing sleepers, the following should be used: steel cold-deformed wire, smooth and of a periodic profile with a diameter of 3 to 8 mm, not lower than strength class B1200; cold-formed reinforcement, smooth and with a periodic profile with a diameter of 8 to 10 mm, not lower than the strength class 1400K; hot-rolled and thermomechanically hardened smooth reinforcement and periodic profile with a diameter of 8 to 10 mm, not lower than strength class A1200K; reinforcing ropes with a diameter of 6 to 14 mm, not lower than the strength class K1500K. Smooth reinforcement can only be used with end anchors. The diameter and strength class of reinforcement, the number and arrangement of reinforcing elements, deviations from the nominal number of reinforcing elements and the value of the initial tension of all reinforcement must be indicated in the technical documentation for the product. It is allowed, in agreement with the customer, to use other types of fittings.

Sleepers are marked with brands in accordance with the requirements of GOST 23009. The sleeper brand consists of two alphanumeric groups separated by a dash. The first group contains the designation of the sleeper type. In the second group indicate the version of the under-rail platform.

Reinforced concrete sleepers

Reinforced concrete sleepers in Russia. Today, there is a certain upward trend in the market for the production and sales of reinforced concrete sleepers, even despite the global economic crisis. According to marketers, the positive dynamics of demand for concrete sleepers expected in the future. The competition between enterprises will also increase - competition for new orders and new customers. This competition forces us to be as attentive as possible to proposals for the supply of reinforced concrete sleepers. We are not chasing extra profit, therefore, by contacting our company, you will receive the most advantageous offer that corresponds to the present time. Our prices are of the greatest relevance when supplying reinforced concrete sleepers to the central regions of the Russian Federation.

These reinforced concrete sleepers are designed for the construction of a common railway network with a gauge of 1520 mm and are produced in accordance with GOST 10629-88. Reinforced concrete sleeper sh1 (1Sh 27-VR1500-KBshz) is used with rails of the R75, R65, R50 type with rail fastening of the KB type (separate clamp-and-bolt fastening) with a gasket bolted to the sleeper (separate type Sh1). The sleepers are reinforced with VR II wire with a cross section of 3 mm.

Technical characteristics of reinforced concrete sleepers type 1Sh 27-VR1500-KBshz:

Product weight - 0.270 tons.
The volume of concrete is 0.108 cubic meters.
Concrete class - B40
Concrete grade for frost resistance - F200
Length - 2700 mm, width - 300 mm, height - 230 mm.

Sleeper manufacturers: a modern factory of reinforced concrete sleepers offers supplies of its products!

A modern factory of reinforced concrete sleepers offers supplies of its products at competitive prices. Sleeper manufacturers ship these products by rail, the loading rate of one gondola car is 240 pcs and 256 pcs.

Reinforced concrete sleepers

Attempts to use reinforced concrete sleepers on domestic roads date back to 1903, but in most cases the designs of sleepers were unsuccessful and excluded from use. Design and experimental work on reinforced concrete sleepers was resumed in 1947 using prestressed reinforced concrete. Experimental batches of such sleepers were laid on the road in 1948-1953; since 1957, their mass production began.

By the beginning of 2002, more than 40% of the total length of the main tracks on the railways of the Russian Federation was laid on reinforced concrete sleepers. Until September 1971, string-concrete solid-slab sleepers (GOST 10629-63) of three types were laid on the track: S-56-1, S-56-2, S-56-3. Sleepers of these types allowed laying rails R50, R65, R75 with a mass of 250 kg. Sleepers of the S-56-1 type have not been produced since 1967, since the wooden bushings in which the screws were installed did not ensure the stability of the gauge, failed much earlier than the end of the service life of the sleepers themselves, and their replacement was very laborious.

On July 1, 1972, GOST 10629-71 was introduced for reinforced concrete sleepers, which was valid until 1978. In accordance with this standard, four types of square string-concrete sleepers were manufactured: S-56-2, S-56-2M, S- 56-3, S-56-ZM, designed for the use of R-50, R-65, R-75 rails with intermediate rail fastenings KB and ZhB on straight and curved sections (with a radius of at least 350 m). Reinforced concrete sleepers S-56-2 and S-56-2M corresponded to intermediate fastenings KB-50 and KB-65 (separate terminal-bolt with a flat lining); sleepers S-56-3 and S-56-ZM - fastenings ZhB-50 and ZhB-65 (inseparable terminal-bolt with spring terminals without lining).

The design of reinforced concrete sleepers of all types is basically the same: only the shape of the under-rail platforms, parts corresponding to various designs of intermediate rail fastenings, and the shape of the lower bed of the middle part of the sleepers are different.

The sleepers, in the designation of the types of which the letter W was added, had a middle part not with a flat lower bed, but with a wedge-shaped shape. It was believed that with this form, the possible reaction forces of the ballast decrease if the sleeper is supported by its middle part, but the stress in the sleeper increases when torsional forces appear.

In the sleepers of all four types, in contrast to the string-concrete sleepers (GOST 10629-63), the deepening of the under-rail platform was increased to 25 mm, the width of the lower bed in the under-rail parts was widened from 250 mm in the middle part to 300 mm towards the ends of the sleepers, which corresponds to the nature of the bending of the sleepers under load: towards the ends of the sleepers, their deflection, and consequently, the pressure on the ballast, increases.

In 1988, GOST 10629-88 “Prestressed reinforced concrete sleepers for 1520 mm gauge railways was approved and effective January 1, 1990. Specifications".

Depending on the type of rail fastening, the following types of reinforced concrete sleepers were installed:

Ш1- for separate terminal-bolt rail fastening (KB type) with bolted attachment of the lining to the sleeper;

SH2- for inseparable terminal-bolt rail fastening (BPU type) with bolted attachment of the lining or rail to the sleeper.

The main dimensions of the reinforced concrete sleeper are shown in fig. 5.6 and are given in table.

Sleepers are designated by marks, from two alphanumeric groups separated by a dash (see Table 5.14). The first group contains the designation of the type of sleeper (Ш1, Ш2), the second group indicates the option of using the under-rail platform (Table 5.14, second column).

Depending on crack resistance, accuracy of geometrical parameters, quality of concrete surfaces, reinforced concrete sleepers can be assigned to the first or second grade.

Since January 2001, a new industry standard "Reinforced concrete prestressed sleepers for 1520 mm gauge railways of the Russian Federation" - OST 32.152-2000 has been introduced. Reinforced concrete sleepers are designed for use on all railway lines in the main, station and other tracks, as well as in the sidings of industrial enterprises, on which standard rolling stock circulates with loads and speeds established for the general road network of Russia.

Reinforced concrete sleepers of the established types Sh1, Sh2, ShZ (Fig. 5.7 and Fig. 5.8) are designed for laying rails R75, R65 and R50.

The following definitions and designations are accepted:

W- prestressed reinforced concrete sleeper for railway tracks;

Under-rail platform - a section at each end of a sleeper, within which a rail and a rail fastening are located;

Under-rail section - the cross section of the sleeper in the middle of the under-rail platform;

Middle section - cross section of the sleeper in the middle of the section between the under-rail platforms;

Insert washers - metal parts concreted in a sleeper below the rail pads for attaching rail fastening bolts;

Slope - the slope of the under-rail platforms to a line lying in a vertical plane and passing through the longitudinal axis of the sleeper, connecting the centers of the under-rail platforms at different ends of the sleeper;

The sleeper propeller is the algebraic difference between the slopes of the under-rail platforms at different ends of the sleeper in the direction transverse to the axis of the sleeper.

Reinforced concrete sleepers are classified according to the following criteria that determine their types:

Type of rail fastening;

Type of prestressing reinforcement;

The presence of electrical insulating properties;

Manufacturing quality.

According to the type of rail fastening, the following types of sleepers are provided:

Sh1 - for separate terminal-bolt rail fastening of KB with bolted attachment of the lining to the sleeper;

Ш2 - for inseparable terminal-bolt fastening of the BPU with bolted attachment of the lining and the rail to the sleeper;

ShZ - for inseparable terminal-bolt fastening ZhBR-65 with bolted attachment of the rail to the sleeper.

Controlled sizes of sleepers Ш1, Ш2 and ШЗ are presented in the table:

According to the type of prestressing reinforcement, sleepers can be manufactured: with high-strength wire or rod reinforcement of a periodic profile.

According to the presence of electrical insulating properties that provide the necessary electrical resistance of the insulation of rail circuits in the railway track, the sleepers are divided into insulated sleepers, with special insulating inserts installed in them - void formers, and uninsulated, without insulating inserts.

According to the quality of manufacture, the sleepers are divided into the first and second grades. The sleepers of the second grade include sleepers with reduced crack resistance, with less accuracy of geometric parameters and reduced quality of concrete surfaces. Sleepers of the second grade are allowed for use only on low-traffic tracks of the 5th class and intra-factory tracks of industrial enterprises.

The slope of the under-rail platforms should be in the range from 1:18 to 1:22.

Propeller sleepers should not be more than 1:80. Angle (3 thrust edges should be 55° for sleepers types Ш1 and Ш2; for ШЗ - 60°

Deviations from the straightness of the top of the under-rail platforms along their entire length and width should not exceed 1 mm for sleepers of the 1st grade and 2 mm for the 2nd grade.

Cracks in concrete are not allowed in the sleepers (except for local shrinkage); local influxes of concrete on under-rail platforms.

The dimensions of the shells on concrete surfaces and the concrete around the edges of the sleepers should not exceed the values \u200b\u200bspecified in the table:

For sleepers of the 2nd grade, the maximum dimensions of the shells and around the concrete are allowed to be 2 times larger than those indicated in Table. 5.15.

The lower surface of the sleepers should have a roughness formed by coarse aggregate particles protruding from the concrete and provided by the sleeper manufacturing technology or special corrugation of the sole.

The electrical resistance of a sleeper of the ShZ type with electrically insulating inserts-hollow formers, measured between pairs of embedded bolts at different ends of the sleeper in a dry state, depending on the air temperature, should not be less than that indicated in the table:

On the bevel of the upper surface of the end part of each sleeper, when molded by stamping in concrete, a number (1,2 or 3) is applied, indicating the type of sleeper. On the bevel of the upper surface in the middle part, when forming the sleeper by stamping in concrete, the trademark of the manufacturer is applied - on each sleeper; year of manufacture (last two digits) - for at least 20% of the sleepers in the batch. At the end of each sleeper, on the top or side surfaces, an OTK stamp and a batch number are applied with indelible paint. Marking inscriptions are applied in font not less than 50 mm high. On the upper surface in the middle part of the sleepers to be repaired at the manufacturer, the quality control department temporarily puts a mark, which must be removed after the repair. At both ends of the sleepers of the second grade, a transverse strip 15-20 mm wide is applied with indelible paint.

At both ends of the sleepers, recognized as not meeting the requirements of this standard, two transverse strips 15-20 mm wide are applied with indelible paint. The marking scheme for reinforced concrete sleepers according to OST 32.152-2000 is shown in fig. 5.9.

Reinforced concrete sleepers should be transported and stored in working position (sole down). Sleepers are assembled in piles on wooden linings with a section of 150x200 mm or on substandard sleepers. The height of the stack should be no more than 16 rows of sleepers. The distance between stacks must be at least 1 meter. Between the rows of sleepers, wooden linings 40-50 mm thick should be laid, located in the recesses of the extreme under-rail platforms at a distance of 550-600 mm from the ends of the sleepers.

Sleepers of the 1st and 2nd grades are transported and stored separately.

In recent years, intermediate fastening ARS has been used, in which an anchor reinforced concrete sleeper is used - a string-concrete sleeper with two non-volumetric anchors enclosed in the under-rail zones of the sleeper (Fig. 5.10). Each of the two sleeper anchors replaces 11 parts of a typical KB-65 fastening (a metal under-rail pad, and two embedded bolts with nuts, two-turn spring washers, round black washers and embedded washers). Anchor heads protruding below the sleeper surface on each side of the rail base form a stable under-rail platform for the installation of a shock-absorbing rubber pad and rail base. In this case, each anchor head is designed to fix one terminal unit (on each side of the rail foot), consisting of a spring bar terminal, an insulating angle and a hexagonal regulator with an axis inserted into a cylindrical hole eccentrically located in the hexagon or made together with the regulator (Fig. 5.11 ).

The main defects of reinforced concrete sleepers, as well as measures for their prevention and elimination are given in Table. 5.17.

In this article we will talk about what these products are, as well as what are the features of their production and operation. Let's consider where reinforced concrete sleepers used are used, and what requirements are imposed on manufacturers of this type of material.

Initially, stone blocks were placed under the railroad tracks. A little later, the stone was replaced with wood, which not only had the best cushioning qualities, but was also easier in terms of machining. However, the situation changed dramatically only when the production of reinforced concrete sleepers began.

Ready-to-install sleepers

A bit of history

In the photo - wooden sleepers after long-term operation

As already mentioned, the history of railways has several varieties of props that fit under the rails. All solutions had a number of operational disadvantages. For example, the stone was extremely difficult to process and had low cushioning properties.

In addition, despite the apparent strength, these plates were not the most durable solution, because due to prolonged mechanical stress they cracked and became partially or completely unusable.

Slightly better was the situation with wood products. Such sleepers were tarred to protect against the negative impact of environmental factors. But wood, sooner or later, despite special treatment, rots. And, as a result, the railway tracks require repair.

Despite good shock-absorbing qualities, wood has one significant drawback - this is the high price of lumber, even taking into account the simplicity of their mechanical processing. The situation changed for the better in the second half of the twentieth century, when the first reinforced concrete sleepers were developed.

Despite the fact that wooden products are still used on secondary branches to this day, it is reinforced concrete structures that are rightfully considered the most modern and promising solution.

Main characteristics

Scheme and dimensions of reinforced concrete sleepers Ш1

Instructions for the use of reinforced concrete sleepers in the post-Soviet space have been tested for more than 40 years.

In accordance with GOST 23009, modern concrete sleepers are rail supports made in the form of beams with a variable size and sectional shape. The product is reinforced with reinforcing wire with a section diameter of 3-6 mm, depending on the modification.

During operation, the product is laid on top of the ballast layer. In relation to conventional tracks, large-sized crushed stone is used as a ballast embankment, and when arranging the subway, a slab-type concrete base is used.

Schematic representation of reinforced concrete products type Sh1

Prestressed concrete products used as under-rail supports are the optimal solution for both jointless and other categories of tracks.

The relevance of these designs is explained by a number of technical and operational advantages, including:

long operational resource;
optimal indicators of resistance to negative impacts of environmental factors;
non-susceptibility to rotting during the entire service life;
possibility of installation on tracks with any level of congestion;
relatively low price;
minimum costs required for operational maintenance;
ease of laying and installation, in comparison with wooden counterparts;
absolute identity of standard sizes of forms and weight that guarantees convenience of transportation and shipment.

In the photo - tongs for carrying sleepers

Are there any drawbacks that can negatively affect the use of these concrete products?

There are few such shortcomings:

Firstly, this is the probability of fatigue failure of the concrete structure and, as a result, the need for periodic inspection of the tracks.
Secondly, the weight of the reinforced concrete sleeper (270 kg) makes it impossible to install it yourself without the use of special equipment. Therefore, unlike wooden counterparts, concrete structures are installed using specialized sleepers.

Scope and conditions of application

Schematic representation of reinforced concrete sleepers type Sh3 and Sh3D

Sleepers made using prestressed concrete are widely used in the construction of railway transport links around the world.

Given the variety of climatic conditions in which these products are operated, as well as varying degrees of mechanical stress, increased requirements are placed on the production of sleepers, as well as on the quality of the finished product. As a result, depending on the favorable conditions of use, these concrete products can be used in for 30-60 years.

Reinforced concrete half sleeper for laying rail crane travel paths

The widespread replacement of the usual wooden supports with reinforced concrete counterparts is explained not only by strength and durability, but also by short production times.

For example, it takes only a few hours to produce ready-to-mount concrete products, which is very convenient when it comes to building a large branch and requires a constant supply of large volumes of building materials. Again, precast concrete can be repaired and adapted for operational needs by using diamond drilling in concrete.

Important: Sleepers manufactured by domestic manufacturers using prestressed reinforced concrete in accordance with the requirements of GOST are superior to foreign counterparts in terms of bearing capacity and material consumption.

Requirements for railway reinforced concrete sleepers

Installation of rails and reinforced concrete sleepers before laying on the embankment

As already mentioned, the operating conditions in which the sleepers are used place high demands on the technology for the production of these concrete products and, in particular, on the technology for the production of prestressed concrete.

The following requirements are imposed on the material and the finished product:

Strength, sufficient to transfer the prestressing force after a few hours (the time is set in accordance with the modification of the reinforced concrete products) at the end of the production process.
The highest possible degree of uniformity of consistency freshly prepared concrete.
Dimensional and shape accuracy- an order of magnitude higher than similar requirements for other categories of commonly used reinforced concrete and prestressed concrete structures.
These requirements include tolerances for the angle of inclination, length and width of individual structural elements. Particularly strictly controlled dimensions in the areas of junction with the rails.

Important: In Western Europe, the technical requirements that determine the quality of the raw material used in the manufacture of reinforced concrete sleepers are regulated by the EN 13230 standard.
The strength class of the starting material in domestic production is determined by the higher requirements given in GOST 26633.

Manufacturing technologies

Concrete pouring molds with prestress transfer bars

Regardless of whether the foundation is planned from reinforced concrete sleepers or concrete products will be used for their intended purpose, the strength of these structural elements will be guaranteed. The operational qualities of finished products are provided by production technologies.

While many sleeper manufacturing methods have been tried and tested over the course of more than fifty years, four of the most common manufacturing techniques that meet international standards are now widely used.

Carousel technology with delayed mold removal.
The peculiarity of this technological process is that the finished mixture is poured into molds and compacted. The removal of the product from the mold is carried out only after reaching the optimal strength indicators sufficient to apply the prestressing force.
In the manufacturing process, specialized collapsible cassette molds are used, which can accommodate up to six units of the product. Due to the use of special tensioning mechanisms, the pre-stressing of the reinforcing bars is ensured, which is subsequently transferred to the concrete and provides optimal adhesion to it.
After the reinforced concrete sleeper is ready, the form can be dismantled and immediately used for the next production cycle.
The name of the method is explained by the type of production process and the design features of the molds used, which are located on the carousel-type transport system. This method has become widespread in Western Europe and is considered the most promising and technologically advanced.
Linear technology.
Regardless of whether a reinforced concrete half sleeper for rail cranes or a full-sized product is being manufactured, the production process can be implemented on the basis of linear technology.
During the production process, a conveyor with a number of sequentially arranged forms is used. The total length of the chain, as a rule, is at least 100 meters.
At the ends of the forms, special devices are used that not only close the form, but also transfer the prestress to the reinforcing bars. As the mixture dries, the force is transferred to the concrete.
Technology of removal of a form with the subsequent tension.

In the photo - a modern line for the production of sleepers of the Western European standard

In this case, templates are inserted into the forms, which will determine the location of the metal reinforcement. The concrete is then poured into molds and compacted.

As it solidifies, metal pins are introduced into the thickness of the mixture, on which mechanical force is exerted. After a short period of time, the form is dismantled and the templates are removed. The advantage of this method is that the process is essentially continuous, and therefore a limited number of forms are needed to obtain the desired result.

Pre-stress mold removal technology.
In this case, the form is removed as quickly as in the previous method. The only significant difference of this technological process is that the tension force is transmitted to the product not through pins, but through frames.

Features of installation, repair and disposal of reinforced concrete sleepers

In the photo - the operation of a mobile sleeper

Laying of railway tracks using reinforced concrete sleepers has a number of characteristic features.

Rails and concrete sleepers, during the construction of railways, are mounted on an initially prepared canvas based on earth soil, sand and crushed stone backfill. .

Laying is carried out by means of mechanized complexes, which allow minimizing the degree of use of physical labor. As a result, the cost of the installation process is reduced, and in addition, the time for laying the track as a whole is reduced.

As previously mentioned, the operational resource of reinforced concrete sleepers is limited to 30-60 years. But such durability parameters are possible only if the state of the tracks is regularly inspected for breakages and partial deformations.

For example, the operational state of reinforced concrete products is affected by the state of the screws that fasten the lining to the sleeper. If the screw is broken and the problem is not detected in a timely manner, it is likely that the lining will hit the concrete during the passage of the composition, causing fatigue stresses in it. (See also the article Curing Concrete: Features.)

If the problem is not eliminated after the screw head breaks off, microcracks appear in the thickness of the concrete in a relatively short period of time, which lead to the partial or complete destruction of the sleeper.

In the photo - the work of a mechanized complex for the disposal of solid construction waste

After the expiration of the service life or due to natural destruction, the sleepers must be replaced. At the same time, non-usable concrete products are subject to disposal.

Since cutting reinforced concrete with diamond wheels for the purpose of grinding seems to be an unreasonably expensive process, processing is carried out using special mechanized complexes. The main working element of the complex is a jaw crusher, which grinds reinforced concrete to a consistency of medium or small crushed stone. (See also the article Strengthening concrete: how to do it.)

The recycled sleepers can later be used as backfill materials for excavations or for the formation of embankments.

Now you know how much a reinforced concrete sleeper weighs, how it is made and what its operational features are. It must be assumed that the use of these reinforced concrete products will be relevant and in demand for a long time.

Indeed, even despite the development of completely plastic sleepers in Japan, it is the compliance with GOST for reinforced concrete sleepers that guarantees the optimal combination of strength, durability and acceptable cost. You can find more useful and interesting information by watching the video in this article.