Standard map for the installation of cement concrete pavements at traffic intersections. Road concrete - grades, composition, GOST Execution of concrete pavement

The road surface in Russia and abroad is different: in our country, highways for various purposes are made of asphalt, while in Europe and the USA they are mainly made of concrete. This is the obvious difference in their quality. In Russia, concrete roads have not become widespread due to their significant cost - after all, the country’s vast expanses and updating the road surface will cost the population another increase in taxes. However, no one forbids homeowners to build car parks and driveways from durable concrete.

Why are concrete roads needed?

The construction of concrete roads is advisable in places where there is no possibility of frequent repairs and there is a need for a durable road surface. In Russia it is:

• Autodromes;
• Runways and landing pads at airports;
• Parking of cars and other equipment;
• Pedestrian paths and sidewalks in cities;
• Coastal roads and embankments where high humidity and exposure to water prevail.

The service life of a concrete slab exceeds the service life of asphalt by up to 2-3 times. For this reason, it is advisable to replace asphalt concrete road pavements that cannot withstand climatic conditions with cement concrete ones everywhere, which is gradually happening in the USA.

The difference between asphalt and concrete

Why is asphalt road surface not as durable as concrete road surface? It's all about the quality of the basic materials:

• Asphalt is a composite of sand, crushed stone, mineral fillers, and their binder is bitumen polymers.
• Concrete is a sand and gravel mixture mixed with cement and additives.

The main difference between concrete and asphalt is the binder in their compositions. Bitumen, unlike cement, does not form a strong stone, sags under weak soils when loaded, softens in the sun and does not winter well. Concrete, if the technology of preparation and installation is followed, is free from these disadvantages.

The road surface consists of several layers:

1. The underlying is crushed stone, draining water from the ground, and sand, compensating for loads coming from above and below from the ground.
2. Strengthening – this is a layer of low-grade concrete that binds the bedding.
3. The main road surface is a layer of concrete.

When laying highways with large traffic of heavy vehicles, the road must be made of unstressed and stressed reinforced concrete, the reinforcement cage in which does not allow the stone to crack under the weight of heavy trucks.

In private construction, as well as when organizing road surfaces on or with water-saturated soils high level waterproofing for the road surface is laid on the sand and gravel embankment (roofing felt materials can be used). The layer prevents constant wetting of the concrete and, as a result, corrosion of the stone and reinforcement frame.

Types of canvas

The concrete road is good for both high-traffic highways and village driveways. For these cases choose different types canvases differing in quality and cost:

• A high-quality single-layer coating for roads of any purpose, suitable for laying top and bottom layers;
• Concrete for the bottom layer of the canvas is cheap - it has low strength, its components are subject to minimum requirements. A coating made of such material can be used in arranging adjacent areas with a low flow of passenger cars;
• Base concrete with average characteristics for heavy and advanced coatings. Can be laid on village roads;
• The organization of roads with ready-made concrete slabs can be included in a separate group.

Materials for filling the canvas

The universal material for laying roads is M400 concrete. Its strength is sufficient to withstand the pressure of the wheels of cars and trucks on city and village driveways.

The basis of the concrete is Portland cement, resistant to water (1 part). Plasticizers are also introduced into the solution, increasing the hydrophobicity of the coating and its strength. The working solution also includes:

• Crushed stone – 5 parts;
• Sand – 2 parts.

For concreting a road, it is rational to order ready-made concrete from a factory - even for a small site you will need a lot of mortar, which must be poured quickly, without allowing individual batches to set.

Road surfacing materials may differ in properties depending on the expected load and installation conditions.

Requirements for the quality of concrete roads

When choosing components for preparing road concrete, they are guided by SNiP 3.06.03-85 “Highways”. The document regulates the quality requirements for the finished fabric:

• Resistance to mechanical loads is the main requirement for a road surface. For roads for different purposes, the indicator is determined individually.
• No cracks in the coating after installation and during operation. Compliance with the technology for constructing concrete roads and the correctly selected composition of the working solution helps solve the problem.
• Water resistance and resistance to chemical reagents. Highways are located in different conditions relief and soil quality, and in the absence of organized drainage (if construction technology is violated), water accumulates on the canvas, worsening its quality.

Concrete requirements

The quality of the fabric is determined by the constituent components, which must also undergo careful selection in accordance with relevant GOST standards. For example, the strength of crushed stone, capable of ensuring reliable and long-term operation of the road, is at least 1200 kg/cm 2. For a pillow, less durable crushed stone 800-1000 kg/cm 2 will do.

Mobility concrete mortar– 2 cm when testing with a cone. A large number of mineral inclusions of different fractions helps to avoid deviations from this parameter.

Another requirement for concrete is high bending strength; for this purpose, plasticizers are introduced into the solution and the canvas is additionally reinforced with reinforcement.

Pros and cons of concrete roads

Compared to asphalt roads, concrete roads have a number of advantages:

• High strength and rigidity of the coating;
• Resistance to heat and temperature changes;
• Long service life without the need for repairs;
• Good adhesion of the road surface and car wheels increases traffic safety.

The roads have fewer disadvantages, but they are significant:

• High construction cost;
• The need for strict adherence to technology when preparing solutions and selecting components;
• The need for the concrete to fully gain strength before starting the road.

Construction of a concrete road

Let us consider in detail the stages of constructing concrete roads, since the service life of the coating depends on compliance with the laying technology.

Excavation work is one of the most expensive and complex. Before they begin, a detailed project is drawn up based on geological research relief. If possible, the laying plane of the road is made horizontal - the mounds are removed, and a board is made into the recesses with rock compaction.

The fertile soil layer is removed: when large construction motorways completely, for private styling adjoining areas are sufficiently 15-20 cm. The lower ones are compacted with rollers and vibrating plates with a large weight. This is one of the most critical stages - the rigidity and integrity of the coating under intense dynamic loads depends on the strength level of the base.

At the stage preparatory work with the soil, they think over a drainage system to remove ground and rain water. To do this, the base is made not in an ideal plane, but at a slight angle of 2-4%. Concrete gutters or natural slopes, through which water flows into the receiver or into the ground.

Laying the bedding layer

Crushed stone and sand are poured onto the compacted soil. They perform the function of load compensator and water drainage.

The thickness of the bedding layers depends on the type of relief and the properties of the foundations and fluctuates around 20-40 cm. When laying intercity roads, geotest is often laid between sand and crushed stone - it does not allow the factions to mix and the embankments perform their functions better.

On foundations with a high groundwater level, it is rational to make the crushed stone mound thicker - it does not wash out and drains water well. Sand must be placed under layers of concrete - it forms a dense cushion.

Both sand and crushed stone layers must be compacted with a roller or vibratory pits to achieve high cushion strength.

For convenience, the bedding layer is sometimes covered with a thin concrete screed up to 5 cm thick, and a waterproofing sheet is laid on top.

Concrete is weak to bending loads, so the use of reinforcement is never superfluous - the choice of its type again depends on the characteristics of the base. In some cases, reinforcement may not be used at all.

The diameter of the reinforcement for the concrete sheet is taken only structurally according to calculations. Usually these are rods from 10 mm, welded into a mesh with a cell from 150 mm. The reinforcement products are laid in a concrete layer at a height of at least 4 cm from the bottom plane. It is important that the mesh is in the lower part of the slab, since it is there that the destructive load is concentrated and cracks form.

The easiest way to make formwork is to use thick boards with a cross-section of 50x150 mm (the choice of height depends on the design layer of the concrete base and coating). Thick plywood will also work. Boards and plywood are fixed with reinforcing pegs stuck into the ground with outside canvases. When laying paths for pedestrians and parking lots for cars, the formwork can be replaced by curb stone installed at the stage of preparation for pouring.

Laying concrete pavement

Pouring the road with concrete must be carried out continuously, so the materials for the roadbed are prepared immediately in the required quantity. It is advisable to order concrete from the factory during construction major roads Temporary mobile workshops for the production of mortar are installed near the sites, which reduces delivery costs.

If necessary, low-grade concrete (for example, M200) is laid on the base with bedding, then with finishing mortar M400 with additives.

Laying the top covering occurs in 2 stages: first, a 30-40 mm substrate is poured, reinforcing mesh is laid on it and the remaining thickness is poured.

The total layer thickness is about 12 cm, sometimes more or less.

Concrete is poured for preparation without interruption and the surface is immediately leveled. Material is constantly being delivered, work goes on around the clock.

After laying, the concrete must be compacted using vibrocompression. The procedure expels air bubbles and compacts the structure of the finished coating.

Cutting and sealing expansion joints

The construction of a concrete road includes cutting the road surface into segments. This is possible, then the concrete will gain sufficient strength of 50-60% and will withstand the weight of a person and cutting equipment.

Seams are needed to compensate for thermal expansion, which varying degrees collapses concrete stone. When the volume of slabs changes seasonally, cracks do not form in the road surface.

Sawing is carried out with a special tool - a jointer.

Expansion joints are made at a distance determined by calculations. One of the determination formulas is coating thickness × 30.

To prevent water from penetrating into the slab through the seams, they are filled with bitumen-polymer sealants.

Care and prevention of concrete pavement

To ensure that the work does not go in vain, according to technology, a concrete road can be opened for traffic only after the concrete has fully gained strength, that is, after 28 days.

To prevent destruction of the canvas, it is protected with polymer impregnations, which form a waterproof film on the surface. True, these reduce the roughness of the road and its grip on the wheels. This negative quality for expressways, so in most cases the roadbed is left as is. If the soil preparation and laying technology have been followed, the seams are cut correctly, nothing threatens the integrity of the slabs for a long time.

Another way to prevent and repair concrete roads is to lay a wear layer. Asphalt is applied to the concrete, which provides traction between the wheels and the surface, and extends the service life of the highway itself several times. In addition, repairing asphalt concrete pavement is much cheaper.

If cracks appear, it is necessary to take measures to eliminate them. To repair small damage, special putties are used, and to repair deeper damage, concrete mortar is used. In all cases, the crack is cleaned and moistened before introducing the filler.

If a fault occurs, the entire section of the canvas will have to be removed. The cause of such deformations is insufficient compaction of the soil base or embankment.

7.1. For concrete and mortars, Portland cement of a grade of at least 400 should be used.

7.2. Brand of mosaic concrete and cement-sand mortar for coatings should be at least 200.

7.3. For light-colored coatings, white or bleached gray Portland cement should be used, and for colored coatings, colored white or bleached Portland cement with the addition of no more than 15% by weight of an alkali-resistant, light-resistant mineral pigment.

7.4. For whitewashing, stone powder of a fraction of no more than 0.15 mm from white or light stone materials with a compressive strength of at least 20 MPa (200 kgf/cubic cm) should be added to ordinary Portland cement. The amount of whitener should be 20-40% by weight of cement. The use of gypsum and lime for whitening cement is not allowed.

7.5. The size of crushed stone and gravel for concrete pavements and marble chips for mosaic-concrete pavements should not exceed 15 mm and 0.6 of the coating thickness.

7.6. For mosaic coverings, fractionated marble chips should be used in a volume ratio of 1:1:1, respectively, fractions 2.5-5 mm, 5-10 mm and 10-15 mm.

7.7. Crushed stone, gravel and marble chips in terms of strength they must meet the requirements given in table. 1.

Table 1

7.8. For alkali-resistant concrete and cement-sand coatings, crushed stone, gravel and sand from dense limestone (serpentinites, porphyrites, limestones, dolomites) or igneous rocks (diabase, granites, etc.), or basic blast furnace slag should be used. The use of pure quartz sand is allowed.

7.9. Samples of materials used for alkali-resistant coatings must withstand at least 15 cycles of alternating saturation with sodium sulfate solution and subsequent drying without the appearance of signs of destruction. Tests should be carried out in accordance with GOST 8267-93.

7.10. Cement consumption (regardless of brand) for concrete alkali-resistant coatings must be at least 500 kg/cub.m., and for mortars - at least 600 kg/cub.m.

7.11. For non-sparking concrete, mosaic and cement-sand coatings, crushed stone and sand should be used, prepared from pure stone materials such as limestone, marble, etc., which do not form sparks when struck by steel or stone objects. The absence of sparks must be verified by testing concrete (mortars) and their aggregates on a standard grinding wheel.

7.12. The consumption of large aggregates (crushed stone, gravel, marble chips) for all types of concrete must be at least 0.8 cubic meters. per 1 cubic meter concrete, and sand - within 1.1-1.3 of the volume of voids in the coarse aggregate.

7.13. Concrete and mortars should be laid on a moist, but without accumulation of water, base in strips (sections) limited by lighthouse slats (wooden blocks, rolled metal, etc.)

7.14. The strips are laid one at a time. When concreting intermediate strips, previously concreted strips are used as guides and formwork.

The width of the stripes is selected taking into account technical characteristics the equipment used and the distance between columns in the building.

7.15 . In coatings carried out without vacuuming, compaction should be carried out using vibrating laths until the movement of concrete or mortar stops and moisture appears uniformly on the surface.

Smoothing the surface should be completed before the concrete or mortar begins to set.

7.16 Vacuuming of concrete should be carried out in accordance with paragraphs. 3.6 and 3.7 of the Recommendations.

7.17. The first smoothing of evacuated concrete should be done with a machine equipped with a leveling disc immediately after the mixture has been evacuated. The final smoothing should be done using a machine with a paddle smoothing device 3-4 hours after the first.

7.18. The installation of a reinforced top layer can be carried out over a coating made as in the usual way, and with the use of vacuum.

Work on hardening the surface should begin when the concrete reaches a strength at which it can withstand the weight of a person.

Before applying the dry mixture, the concrete must be smoothed to soften the crust formed on the surface. After moisture appears on the smoothed concrete surface, it is necessary to apply a strengthening mixture to the concrete manually or using a mechanical spreader.

The application of the strengthening mixture should be carried out in 2-3 steps. In the 1st dose, apply 2/3 of the total amount of the mixture. The mixture must be completely and evenly saturated with moisture sucked from the concrete, as judged by the uniform darkening of the color of the mixture. Adding water to the strengthening mixture is prohibited.

The surface is smoothed using a machine with a disk, the edges of which must be flat to avoid the formation of bubbles and cavities. Areas that cannot be smoothed by machine must be smoothed by hand. After applying the remaining mixture, smoothing is repeated.

The final processing of the hardened surface should be carried out using a machine with blades.

When constructing concrete pavements using vacuum, the strengthening mixture is applied directly to the evacuated and smoothed concrete surface.

7.20. For hardening concrete floor coverings performed traditional way, concrete of the following compositions, wt., is recommended. h.:
- concrete class B30 (400 kgf/sq.cm.)
- cement M400 -1.0
- crushed stone up to 20 mm -1.7
- sand -1.0

using vacuum:
- concrete class B22.5 (300 kgf/sq.m)
- cement M400 -1.0
- crushed stone up to 20 mm -2.4
- sand -1.4
- water content -0.4-0.42 (including water contained in additives)

To increase the crack resistance of the coating, it is advisable to introduce an aqueous rubber dispersion (TU 33.108.004-82) in an amount of 15% of the cement mass into concrete mixtures.

The amount of water should be specified in test batches so that the mobility concrete mixture, measured by the draft of a standard cone, was 10-12 cm.

7.21. For the preparation of dry strengthening mixtures, the composition of which is selected laboratory method are used:
- cement grade not lower than 400;
- metal-containing material or stone materials (granite, crushed gravel, quartz).

7.22. Multi-color mosaic coverings should be installed with dividing veins made of metal, glass or polymer materials.

In places where the coverings adjoin columns and pilasters, veins or spacers made of roofing material should be installed.

7.23. Grinding of coatings should be carried out until the maximum exposure of the aggregate is achieved when the concrete reaches a strength at which the possibility of chipping of the aggregate is excluded.

7.24. To facilitate grinding, moisten the concrete surface with water with the addition of a surfactant. The wetted liquid should cover the surface to be treated in a thin layer.

7.25. If specifically indicated in the project, the mosaic coating should be polished.

7.26. Before resuming concreting, the hardened vertical edge of the previously laid concrete must be cleaned of dirt and dust and washed with water. In areas of working seams, compaction and smoothing of concrete (mortar) should be carried out until the seam becomes invisible.

7.27. Concrete, cement-sand and mosaic-concrete coatings must be kept in damp conditions (wet sawdust, plastic film, etc.) for 14 days after their installation.

7.28. Skirting boards where the floor meets walls, partitions, columns, etc. should be performed after the end of moistening.

Road reinforcement is carried out to enhance the bearing capacity of the road surface. Standard layers of sand and crushed stone distribute pressure evenly, but are not able to withstand heavy loads.

Reinforcement of the roadway imparts rigidity to the entire structure and distributes the total load over a large area, reducing point pressure on the ground. When constructing the base, both steel and fiberglass reinforcement with a diameter of 14-18 mm are used, metal fiber is also used, it increases the fracture resistance. Concrete is used depending on the climate and weather conditions; in the cold season, various chemical additives are used to provide the desired properties.

Manufacturing technology of reinforced concrete pavement

The construction of a reinforced roadway consists of several stages:

Faults and repairs of concrete foundations

If not observed technological process when reinforcing the roadway under concrete, damage and breakdowns may occur over time various types:

• cracks and swellings. Exposure to water and freezing of the coating can lead to cracks. To eliminate the effects of swelling and prevent further destruction, it is necessary to remove the layer over the entire defective area. If the cracks are not deep and do not reach the reinforced frame, they can be filled with bitumen or mastic. If the damage is deep, the concrete is cut through, the reinforcement is released with a hydraulic breaker, new links are added and everything is filled with new mortar.
• scattering When the road surface collapses, moisture gets inside. When using concrete with poor resistance to water, the base loosens and crumbles. In winter, the water inside the coating freezes, which leads to additional destruction. When repairing, a road milling machine is used to remove the damaged layer and fill it with new mortar. When performing road reinforcement work for heavy equipment, it is important to ensure sufficient waterproofing to avoid such failures.
• subsidence. When subsidence of a reinforced concrete base occurs, it is necessary to major renovation plot. In addition to restoring integrity, it will be necessary to eliminate the cause of soil subsidence.

Prevention

To increase the service life of roads, preventive maintenance is carried out on them. The coating is treated with various emulsions that form a thin film on the surface. This film protects the surface well from moisture penetration.

The only negative is the reduction in the adhesion of car wheels to the road surface.

The price of a reinforced road surface will be higher than a standard asphalt road, but its durability and operation without repairs will quickly pay for the costs.

Reinforcement of the roadway under concrete is carried out to increase the maximum weight load. In addition, reinforced fabric lasts much longer than usual and can last up to 30 years without repair. To achieve such indicators during construction, you need to carefully adhere to the technological process of reinforcing the roadway.

Related posts:

1. Soil stabilization: improving the quality of the canvas and saving resources

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Reinforced concrete pavement base

Reinforced concrete base (RBC) is used to increase the strength and rigidity of road pavement. Sand and crushed stone layers evenly distribute the load on the ground to small area, but are not able to impart the necessary rigidity. ABO increases the rigidity of clothing and allows vertical loads to be transferred over a larger area, reducing the specific pressure on the ground.

For the construction of the base, steel or fiberglass reinforcement with a diameter of 14-18 mm and various concretes are used. The composition of concrete depends on the climate, pouring conditions and expected road traffic. For filling in the cold season, various additives are used - urea, calcium chloride, and others.

To increase the performance properties of concrete, metal fiber is added to it along with reinforcement. This increases rigidity and fracture toughness.

Laying a reinforced concrete base

Work on the creation of ABO is carried out after laying a drainage layer of sand, crushed stone layers and, if necessary, an insulating layer.

• Creation of a reinforcing frame. The basis of the concrete base layer is a frame made of reinforcement. Concrete has very high compressive strength and extremely low fracture strength. Properly done reinforcement increases fracture strength many times over. This is due to the fact that fracture strength depends not only on the strength of the concrete itself, but also on the tensile strength of the reinforcement. To achieve maximum fracture strength, reinforcement is carried out from below and above the concrete layer. The reinforcement must be tied into a mesh. This will increase strength not only in the longitudinal but also in the transverse direction. Untied reinforcement can move during pouring and compaction of the layer, compromising its fracture strength. The use of metal fiber can further increase the fracture toughness.
• Installation of formwork. Before pouring, formwork is installed using wooden or metal panels, in some cases it is made from concrete road blocks. In this case, the top of the block acts as a border. Formwork is needed in order to give the base the desired shape and avoid overuse of concrete.

The reinforced concrete base increases the rigidity of the clothing and allows vertical loads to be transferred over a larger area, reducing the specific pressure on the ground.

• Concrete for pouring. For the base, concrete is used, prepared using crushed stone of durable rocks, fraction 20-40 mm. The ratio of sand, crushed stone, cement and additional materials depend on the temperature during installation, climatic conditions and expected road load. The delivery time of concrete from the plant should not exceed one hour. The time from loading the mixer or dump truck to pouring into the formwork should not exceed two hours. Exceeding this time reduces the strength of the finished reinforced concrete.
• Pouring the base. Pouring is carried out using pneumatic or tracked concrete placing machines. They allow not only laying an even layer of concrete, but also compacting it with vibrating plates.

The reinforced concrete base is poured using pneumatic or tracked concrete placing machines.

Faults in reinforced concrete foundations

• Looseness. If the integrity of the pavement is damaged, water gets inside the pavement. If concrete with weak water resistance was used to create ABO, then water that gets inside will lead to the formation of looseness. This, in turn, will lead to the formation of cracks and depressions on the surface of the coating. The water will flow stronger and stronger. During the winter months, concrete will begin to crack and crumble. Water that gets inside the concrete turns into ice, expands and breaks the concrete. To eliminate looseness, it is necessary to cut out the base in a sufficient area, remove the loose ABO layer with a road milling machine, restore the level of the base surface, lay a new coating, and ensure high-quality waterproofing.
• Cracks and heaving. The ingress of water into the concrete and frost, leading to freezing of the base, will lead to heaving and deep cracks in the concrete layer and coating. To eliminate the effects of heaving and prevent re-occurrence, it is necessary to remove the coating on an area sufficient for repair and conduct an inspection of the ABO. If the cracks have not reached the reinforcement, they can be filled with bitumen or polymer mastics. If the cracks have reached the reinforcement, the damaged piece must be cut out with a joint cutter or concrete cutting machine and removed. Then use a hydraulic hammer or jackhammer to release the reinforcement, attach a new one to it, forming a tied mesh from it, and fill it with new concrete. After that, be sure to lay a heat-insulating layer that can withstand the load, and restore the coating using cast asphalt concrete.

If freezing and heaving occurs in several places, the entire road needs reconstruction because it does not correspond to the climate.

• Subsidence of the base. When subsidence occurs, it is necessary not only to restore the integrity of the foundation, but also to eliminate the cause of the subsidence. That is, to carry out major repairs on a small section of the road.

Compliance with the requirements of GOST and SNiP during the design, construction, maintenance and repair of reinforced concrete pavement base will allow the road to serve for many decades.

roadmasters.ru

Concrete roads: materials used. Installation of formwork and reinforcement. Concrete pouring and finishing

Concrete roads in the USA are an almost integral element of the landscape: the use of effective technologies for preparing the base and pouring the road surface makes it possible to obtain a fairly durable road surface that can withstand heavy traffic loads.

In Russia, the situation looks somewhat different: cast concrete and concrete slabs are considered rather as an alternative, used where it is impossible to lay asphalt. And yet, new technologies are gradually being introduced, so the appearance of such routes is also not far off.

With the right approach, concrete can also be made of high quality

Preparing for work

Materials for filling the canvas

When laying industrial tracks in our country, standardized concrete road slabs are most often used. On the one hand, the use of such elements significantly speeds up the work, but on the other hand, the quality of the canvas is relatively low, and therefore the surface wears out very quickly (read also the article “Asphalt concrete road mixtures: all their types, varieties and grades provided for by the standards”).

This is how it is formed asphalt concrete pavement roads on an industrial scale

Note! Particular problems are caused by joints, which over time become deformed and turn into large potholes.

That is why in private construction the technology of pouring a monolithic coating is most often used. This is what we will focus on in our article.

The estimate for constructing a concrete road using poured technology includes the following items:

• First, we need high-quality concrete. To lay highways, it is necessary to use cement meringue compositions M400 (B30) and stronger, but for the access road to a private house M300 (B22.5 - B25) is sufficient.
• Preparation of the base is carried out with the obligatory addition of sand and gravel.
• To provide the material with sufficient elasticity, it is reinforced with steel bars or reinforcing mesh. Metal parts with a cross section of 10-12 mm are used here.
• To function effectively and prevent deformations, concrete road surfaces must be divided into several sections using expansion joints. When making such seams, special sealants are used.

In addition, we will need materials for installing the formwork: boards with a thickness of at least 50 mm, fasteners, steel corner covers, pins for fixing the frame.

Road slabs with steel reinforcement

Pre-treatment of the area

The technology of concrete roads, described in TR 147-03 “Technical recommendations for the construction of road structures from cast concrete mixtures”, provides for the mandatory preparation of the base:

• We apply markings to the site selected for construction.
• According to the markings, we select the soil, removing the top fertile layer of soil and going deeper by about 60 cm in relation to the planned level of the future canvas.

• Then we pour a layer of gravel with a fraction of 40 millimeters or more onto the earthen base. The thickness of such a layer should be about 30 cm.
• We lay a gravel-sand cushion on top, bringing it to the required level. We carefully compact the bedding using tamping machines, constantly moistening and adding new portions of material.
• To check the quality of the seal, we use a steel rod with a diameter of about 10 mm. When stuck into the base, it should be deeply buried by 60-70 cm. If the rod passes the top layer with resistance, and then goes easily, you need to continue tamping, since loose areas will shrink sooner or later.

Work methodology

Installation of formwork and reinforcement

Formwork diagram

• Before starting installation, we determine the level at which the road surface will be located. It is desirable that it be slightly higher than the ground level - then dirt will not accumulate on the roadway.
• Also, when designing a driveway to a house, it is advisable to include a small slope in the structure for water drainage. The optimal slope is 2-3 cm per 1 m.
• Then we install the formwork, the strength of which directly depends on the parameters of the cement layer being poured. For a road with a thickness of 100 mm, the boards should be no thinner than 50 mm, and the road surface with a thickness of 150 mm or more is erected in formwork from timber 100 mm thick.

In parallel with the formwork, we are engaged in reinforcement and installation of expansion joints:

• Along the edges of the road surface we install ribs made of steel strip.
• We lay a welded mesh with a cell size of 150x150 mm into the road itself at a distance of about 40 mm from the base.
• With our own hands we install expansion joints every 10-12 meters. For laying we use a strip of fiberboard or similar material impregnated with bitumen, as well as rubber, plastic, etc. You can put a special cover on top of the strip, which is adjusted exactly to the level of the road.

Photo of an expansion joint in an asphalt concrete route

Note! After polymerization of the cement, the cover must be removed, and the groove in its place must be filled with elastic sealant.

Concrete pouring and finishing

Since concreting roads requires large quantity material, a solution for this purpose is usually ordered from large enterprises. On the one hand, the price of the material increases slightly, but we will be able to fill a large area in one go, without interruption and avoiding the formation of stressed areas.

The filling process itself goes like this:

• Using gutters, we evenly distribute the solution from the mixer inside the formwork.
• Using rules on long handles and shovels, we perform preliminary leveling of the plane, filling areas along the ribs and removing large air cavities.
• Then, using a long rule (a flat board or a steel U-shaped profile), we finally level the surface. To make the work easier, we select a rule that is slightly larger than the width of the road - so its edges can be rested on the formwork.

Scheme of operation of the rule

• Finally, we use the so-called “bull trowel” - a wide board with a long handle. With it we remove all unevenness, while simultaneously compacting the top layer of coating.

Then we let the concrete set.

After this we perform finishing:

Jointing for material shrinkage

• To avoid cracking of the fabric during drying, we cut shrink seams. For cutting, we use a special tool - jointing, going deep to at least 1/3 of the thickness of the concrete layer.

Advice! The pitch of the shrink seam is determined by multiplying the thickness of the fabric by 30.

• After jointing, we apply a relief to the surface of the material using a road brush. This way we not only improve the adhesion of the coating to the wheels, but also promote water drainage. Thanks to this treatment, the concrete road will last much longer!

Types of road brushes

Conclusion

The construction of concrete roads using the technology described above can be done independently. Of course, the project will be large-scale, and the costs will be very significant - but it can still be implemented without the involvement of professionals (see also the article “Road concrete: main characteristics and application features”).

If this method of pouring a monolithic coating interests you, we also recommend watching the video in this article containing Additional information.

rusbetonplus.ru

Construction of a concrete road

It is known that there are two obvious problems in Russia, as a classic once said. These are fools and roads. There is absolutely no desire to think about fools, but you can develop quite interesting thoughts about roads. First of all, those that allow you to solve an existing problem. And if the problem of teaching a person depends on both the object and the subject of the activity, then with roads the situation is easier - you can make their repairs, having only the desires, strength and materials for arranging roads located at least on the territory of the entrance to your house or on its territories.

The quality of the soil that lies under the road under construction determines the technology by which the construction and further repair of concrete will take place, and how long and efficiently it will serve you and the guests passing along it.

The most popular type is a concrete road, the technology of which is capable of withstanding extremely heavy loads and functionally serving not only as an entrance to the territory of a private house, but also as a road for highways. Repairs of which, as you know, are not carried out very often. And the point here is not at all a lack of funds, it just turns out that repairs are not required for a long time. If you decide to start building or repairing a driveway, it is extremely important to decide which concrete laying technology is suitable for your particular case.

Materials for the device

Construction and subsequent repairs are possible if the following materials are available:

• sand;
• gravel;
• sealant;
• plastic;
• concrete mixture for pouring slabs;
• reinforcing mesh;
• boards;
• pins;
• retainers.

Construction and repair

Properly selected soil and a properly laid foundation under concrete roads will ensure effective drainage of concrete slabs and eliminate frequent and very unpleasant repairs of concrete roads and their covering.

The quality of the soil that lies under the road under construction determines the technology by which construction and further repairs will take place, and how long and efficiently it will serve you and the guests passing along it. General technology, to which both the construction procedure and the repair of concrete roads are subjected, suggests that directly under the concrete there is a two-hundred-millimeter layer of gravel base, which, in turn, rests on a layer of larger stones, the size of which reaches 40 mm, laid to a height of 20-30 cm. Below is a bed of natural soil. Naturally, the technology, depending on the type of soil cushion, also affects the thickness of each layer laid under the concrete road. The best option Such a cushion will be gravel or, at most, sandy soil, which brilliantly contribute to the natural drainage of water coming from the surface. This soil can only be thoroughly compacted and the construction of the foundation can begin.

If the bed under concrete slabs consists of the following natural compounds, like peat, clay, or is an alluvial soil, characterized in that it is capable of retaining moisture in large volumes and for a long time. Which completely denies the fact that natural drainage technology is present here. This problem will have to be solved using some technology. It will be needed in order to remove the soil, in a layer of up to 15 cm. Determine the type of soil and its bearing capacity Specialists will help, whose solution can speed up construction, if, of course, it contains data on soils that do not contain liquid.

Properly selected soil and a well-laid foundation will ensure effective drainage of concrete slabs and eliminate frequent and very unpleasant repairs of concrete roads and their coating. After earthworks run out, you need to start profiling concrete roads to the required height, the size of which can be slightly lower or higher - 25 mm. In order for the drainage technology to function even better, you need to try to maintain the slope, the construction of which is being carried out to create a comfortable entrance to the house. Experts recommend making the following slope - one mm for every 5 cm.

Drainage and soil compaction

Ready-made concrete must be manually distributed along the edges of the road and all voids that appear must be scrupulously filled.

In those places where concrete slabs are laid in the gaps between the house and the garage, it is better to start building a storm drain to ensure drainage. In this case, the device storm sewer implies the use drainage pipe, the diameter of which is more than 10 cm. Its function is to discharge incoming water outside or into an organized storm drain collector. The soil compaction device on which concrete for a road or slab will be laid must have a high level of strength, which depends on how much it is compacted. Check this characteristic bed can be done by inserting a smooth steel rod no more than 12 mm thick. These actions must be carried out over a short distance. The proper density of the soil for constructing a concrete road, as shown by construction technology, does not allow the rod to be pushed to a depth lower than 60-70 cm.

If, when pushing the rod into the ground, soil resistance is felt only in the first 20 cm, and then it enters the ground freely, then the lower layers of the soil do not have sufficient compaction. Such concrete roads will require frequent repairs, since the cushion will sag, crack, and sooner or later lead to destruction of the concrete for the road and the entire road surface. Moreover, both the base for concrete under and the bed itself must include in its design materials that prevent water from seeping upward, directly to the road. If moisture enters under slabs made of concrete, the accumulated moisture, when freezing in the cold season, will expand and ultimately lead to swelling of the slab. The role of such a material, saving the slab structure from destruction, will be brilliantly performed by crumbs of old concrete, which should be thoroughly compacted. The slope can be achieved when the technology of its construction includes the organization of formwork.

Formwork technology

After the stage of compacting the soil and base for installing a slab for a road made of a concrete mixture has been completed, you can proceed to the next stage, which is the installation of formwork. Here it is important to pay attention to the thickness of the concrete sheet, which directly determines what section of boards will be needed in the work. If the slabs are planned to be poured with a thickness of 100 mm, then the formwork will have to be made of lumber, the cross-section of which should not exceed 50 x 100 mm. And with a thicker layer of concrete for a road, for example, it will be equal to 150 mm, then the boards should have the following section - 50 mm by 150 mm.

Work progress

If concrete slabs for roads suddenly crack during operation, then ordinary pavement repair is unlikely to help.

The technology for fastening the formwork should be organized using metal poles. Any boards will be suitable for this, for example, those left over from you after you have made repairs. They can be pre-coated special composition, which will ensure their easy detachment from the concrete for the road as it hardens. After the formwork is completed, it will be necessary to level the soil layer at the base to the exact slope, after which the entire device will need to be compacted tightly. Then it is recommended to deepen the edges of the road being constructed a few centimeters. Adding thickness to the edges provided by thickening the entire perimeter of the slab will help increase the road's support area and provide protection to the soil adjacent to the road concrete from erosion. In order to strengthen the ribs of the slabs, the technology makes it possible to install reinforcement in them, the size and, accordingly, the level of strength, exceeding the standards required for road construction by two times.

Construction of seams

A good move during the pouring process would be to install expansion joints, which will ensure the movement of the concrete road slab being created, depending on weather conditions. These joints are also called expansion joints, and are made before the concrete laying stage. Such a device allows you to move both horizontally and vertically, this is facilitated by the properties of the concrete used for roads; it expands or contracts with temperature changes, because the soil conditions under the concrete for the road also change. In this regard, it is necessary to ensure complete separation of the filling sections.

In the case when the construction of a concrete road is organized on a private plot, different large sizes, expansion joints can be laid between the road under construction and the path leading to the house, which is located on the side.

Again, between the road and the area on which the garage or some other garden building is located, and, of course, between the slabs of this road, which are the main ones. And in the case when the road to which the access road will adjoin, that is, a public road, also has a concrete structure, then an expansion joint must also be installed between them.

This type of suture is made from a small layer of material that can absorb energy. For example, impregnated with bitumen fiberboard sheet, a layer of plastic, a wooden, cork or rubber version of the seam. It is advisable to close the seam arranged in this way from above, for example, with a plastic lid, which should be installed flush with the surface of the slabs. After all the concrete has hardened, plastic cover it will be possible to remove and fill the upper part of the expansion joint with sealant. When ensuring the installation of expansion joints that facilitate the movement of concrete slabs, in no case should we forget that the joints must be located at a maximum distance of 12 meters from each other.

If concrete slabs for roads suddenly crack during operation, then ordinary pavement repair is unlikely to help. The reason will lie much deeper - in the foundation on which concrete was poured for the road. After all, an insufficiently compacted cushion, with stones on its surfaces, will limit the movement of the slab and, accordingly, will lead to destruction of the slabs and the seams between them. It is also important to include expansion joints in the construction of roads because they can serve as shock absorbers at the junction of a concrete slab for a road that provides comfortable access for a car to a house with adjacent site structures, for example, a path and a garage or shed .

Selection of fittings

The reinforcement, the use of which involves the technology of this construction, should be a metal mesh with a cell area of ​​150 square meters. mm. This choice of reinforcement will avoid expansion and propagation of cracks in the concrete used for the road in the direction in the horizontal plane. It is necessary to lay the metal mesh during the process of pouring concrete for the road at a height of approximately 30-40 mm from the lower plane of the slab being installed. To do this, at this level you need to level the concrete and lay the existing reinforcing mesh over it; for convenience, you can use a device such as clamps. Then pour the remaining concrete you have. You can buy a completely new mesh or borrow it from friends who, having repaired their front garden, removed, for example, a chain-link fence.

Concrete requirements

Not only its appearance, but also how soon the pavement will have to be repaired depends on the quality of concrete used when the concrete road is being constructed. The quality of concrete is determined by a measurement scale that has quantitative indicators from 1 to 12. In this case, one corresponds to a dry concrete mixture and its moisture level increases with increasing numbers. An option with a moisture content of 4 or 5 is suitable as concrete for roads. The structure of this mixture will facilitate the process of laying concrete, and you will have to work with it quite quickly in order to prevent the concrete mixture from drying out. It is not recommended to add water in such cases, as this can significantly reduce the level of strength that it can initially guarantee.

Ready-made concrete must be manually distributed along the edges of the road and all voids that appear must be scrupulously filled. Try to rake the concrete to the highest point in the formwork, from where it will move on its own to those areas where the mixture is still needed. Now start leveling the surface of the concrete road. This must be done very carefully, not forgetting to manually trim the ribs from time to time.

Then you will have to wait until all moisture disappears from the surface of the slab being created and make sure that the concrete is strong enough to support the weight of one worker. His task, standing on knee pads, will first be to mark and cut the shrinkage seams, which distinguish weak spots, so that cracks form only along the seam, and not in a random order. After the coating finishing stage is completed, you will need to spray a mixture of hardening sealant over the resulting surface. It will protect the road from too rapid evaporation of water, allowing it to dry evenly and gradually. This will increase the strength of the final coating and in this case you will be able to avoid making repairs for a long time. Moreover, concrete, with this method of drying, will not absorb moisture from the atmosphere during the hardening period.

Too frequent repairs of roads and highways indicate that the quality of the concrete mixture used in their construction is not good enough. Perhaps it’s not a matter of quality at all, but of violations in the process of its design. Anyway, redecorating tracks are made almost every year, but this does not completely solve the problem. What else could cause such frequent road repairs? No one will probably answer this question objectively and it will remain open forever.

Concrete floors are simply necessary in some facilities: in warehouses, terminals, garages and others. That is, where a high load on the floor is expected, which another coating simply cannot withstand. The popularity of this coating is also explained by the fact that the installation of concrete floors, although it requires adherence to technology, is quite possible to do independently.

Stages of installing a concrete floor

TO concrete floors there are a number of requirements that they must meet: durability, high chemical resistance, tightness, resistance to stress, lack of dust.

In order to obtain a concrete coating that meets all these requirements, two conditions must be met: use high-quality materials and strictly adhere to the technology, which includes four main stages:

• preparation of the base;
• laying concrete in a screed;
• surface finishing;
• cutting seams and sealing them.

The floor can be laid either on an existing cement concrete base or on a dirt base.

The installation of a concrete floor on the ground, although an economical, but rather labor-intensive method of arranging a floor. It is advisable to equip it in places where it is dry enough. A high-quality ground floor has a layered structure.

There are several options, but most often the floor pie on the ground looks like this:

• compacted soil base;
• a layer of river sand bedding;
• a layer of crushed stone or expanded clay;
• waterproofing;
• concrete screed (rough);
• vapor barrier;
• insulation;
• reinforced screed (finish).

If necessary, adjustments are made to this scheme, depending on the tasks and conditions. The technology for constructing concrete floors also depends on this. This type of floor requires careful preparation of the base.

Preparing the base

When laying on an old concrete base, careful preparation is carried out: the cracks are widened and filled with a repair composition made from a cement-sand mixture or polymer. In places where the base cannot be repaired, it is completely removed and new concrete is laid. Elevation differences are leveled, dust is thoroughly removed.

Preparation of the soil base begins with leveling, which allows you to estimate the volume of upcoming excavation work and determine the floor level. Then the soil is compacted using special machines, which helps to avoid subsidence and cracking of the floor in the future. Next, a “cushion” of river sand is laid and also compacted using rollers or vibratory tamping machines. To ensure that the density of the cushion is sufficient, 25% more sand is laid, then moistened and only then compacted to the desired thickness. A layer of gravel or expanded clay is poured on top of the sand.

Waterproofing

Waterproofing on one side should prevent moisture from being absorbed by the base concrete screed, and on the other hand, it prevents the penetration of moisture from the soil. It is produced using polymer membranes or rolled materials; sometimes thick polyethylene is used without damage.

The waterproofing is laid overlapping with an overlap on the walls (15-20 cm), the joints are taped.

Laying a concrete base (rough)

This layer acts as a basis for waterproofing materials. The rough screed is made from so-called “lean concrete”, using crushed stone (fraction 5 – 20). The requirements for it are not too high, so it is installed quite simply. The thickness should be at least 40 mm, horizontal differences should be no more than 4 mm.

Laying vapor barrier

A layer of vapor barrier materials (the optimal solution would be polymer-bitumen membranes, but other options are also suitable) is laid on a rough concrete base.

Floor insulation

It is very important to evaluate how necessary this procedure is and what material is best to use for floor insulation. As insulation, you should prefer materials that are resistant to moisture, or provide them good waterproofing. The most commonly used insulation materials are polystyrene foam, extruded polystyrene foam, and mineral wool.

Laying the finishing screed

Laying the finishing screed occurs in several stages:

• Reinforcement (can be done using a road mesh, and for increased loads it is better to use a frame made of rods from 8 mm in diameter).
• Pouring concrete mixture (it is better to use the services of rented special equipment).
• Installation of beacons (beacon slats are installed approximately two meters from each other, so that the ends of the rule can be supported on them).
• Filling the floor (carried out 1.5 cm above the installed beacons).
• Leveling and compacting concrete using a vibrating screed or rule.

Surface finishing

After completing the process of laying and compacting concrete, a technological break is taken so that the concrete can gain strength. Depending on the air temperature and its humidity, it can be at least 3 hours, but no more than 7 (the depth of the mark left on it should be 2-3 mm). During this period, rough grouting of the floor is carried out using trowels or discs. A little later, when the depth of the mark left is 1 mm, finish grouting is performed.

Sometimes, to get a stronger and more durable base, they use topping, a special mixture based on cement and other substances, which is rubbed into the concrete. The use of special polymer impregnations allows us to solve the problem of dusting.

Cutting joints in concrete

Screed concrete is a rather fragile material, strange as it may sound, and is prone to cracking. In order to limit this process, expansion joints are cut into the concrete screed. There are three types:

• insulating - made in places where the floor comes into contact with all building structures: walls, columns, and prevent the transmission of vibrations;
• shrinkage - relieve stress during drying and shrinkage of concrete, which occurs unevenly;
• structural - made in those places where there is contact between concrete laid at different times.

Seams should be cut as soon as the concrete has acquired sufficient strength, but before any cracks appear. The location of the seams is marked with chalk, they are cut in the order in which the concrete was laid. The cutting depth is approximately 1/3 of the thickness of the concrete screed. To make it easier to care for the seams and strengthen their edges, seal them. The type of sealant is selected depending on the operating conditions and the expected load on the floor. Before sealing, the seam is thoroughly cleaned of dust and debris. After carefully completing all the steps, the screed is allowed to harden and dry.

Summary

Laying concrete floors is a procedure that can be performed not only by professionals, but also independently. In any case, close attention should be paid to compliance with all stages of the technological process, some of the nuances and subtleties of which were highlighted in the article. This approach will result in a strong, durable floor that can withstand heavy loads and cope with its task adequately.

→ Building quality control

Polyvinyl acetate-cement-concrete coatings

Polyvinyl acetate-cement-concrete coatings are made from a mixture of crushed stone, sand, cement, polyvinyl acetate emulsion and water, and, if appropriately indicated in the project, pigments and dyes. This type of flooring consists of several films of polyvinyl acetate mastic, each 1-1.5 mm thick, applied to a well-prepared base. Polyvinyl acetate coatings are highly durable, wear-resistant, fire-resistant, have good adhesion to any type of substrate and are a type of warm and elastic floors. The installation of polyvinyl acetate floors is not allowed in rooms with abundant or. long-term moisture, as they are slightly water-resistant. To increase water resistance, floors can be coated one or two times with high-strength varnishes No. 170, 52 or 4-c. The bases for polyvinyl acetate coatings must be rigid, so they are made of concrete, cement mortar or xylolite. Humidity. concrete base or cement screed before application. Mastic should not exceed 6%, xylolite - 15%; the strength of concrete and xylolite should be at least 50 kg/cm2, lightweight concrete panels - 150, gypsum concrete - 75 kg/cm2. Before applying polyvinyl acetate mastic, it is necessary to accept the bases prepared for the self-leveling coating. Polyvinyl acetate mastics are prepared from a mixture of polyvinyl acetate emulsion, dust filler, pigments and water. The use of a mushy emulsion with resinous grains exfoliated from water for the production of coatings is prohibited. The emulsion can be stored in a hermetically sealed container at temperatures from O to +40 ° C for no more than one year. This must be taken into account when accepting it during construction. Emulsions stored at sub-zero temperatures, regardless of shelf life, are rejected. As dust-like fillers, marshalite or finely ground stone materials of light colors with a compressive strength of at least 400 kg/cm2 (quartz sand, light granite, marble, etc.) and a grain size of no more than 0.15 mm are used. The dust filler must be uniform in color for a given amount of work, air-dry, with a moisture content of no more than 3%. without lumps, clay, organic and other impurities. Dust-like materials must be stored in a dry place. Pigments used for mastic must be finely ground, acid-resistant and light-resistant (ochre, red lead, mummy). Before use, they must be ground with the addition of a small amount of water, which ensures their uniform distribution in the mastic and completely prevents the formation of dry lumps. The color of the coating is selected visually according to standards and assessed at daylight based on hardened dry samples (cement-sand tiles measuring 20X30 cm). The color must be agreed upon with the customer and the designer's supervision. All sinking irregularities, cracks and potholes in the base are filled with polyvinyl acetate mastic with a composition of 1:3 (polyvinyl acetate emulsion, dust filler) without adding dye and water, and the tubercles are ground off with carborundum or an electric grinder. When preparing mastic, control its weight composition, the amount of added water, viscosity (90-100 s, measured with a 133-4 viscometer) and the duration of movement (at least 5 minutes). The prepared mastic is filtered through a sieve with a cell size of 0.5 mm. Then, after settling for 15-20 minutes, the floating foam is removed from the surface of the mastic, and the mastic is loaded into the tank of the spray apparatus. The tank has a conical bottom, and the mastic sampling tube must reach the cone so that no foam gets into the nozzle. Spraying is carried out using a nozzle nozzle or a gun. Spraying units have spare nozzles to replace clogged ones. The prepared mastic should be used within 5-6 hours at an air temperature of 10-15 °C and within 2-3 hours at 20-25 °C. Dilution of thickened mastic with water or polyvinyl acetate emulsion is prohibited. It is necessary to ensure that the tanks of the spraying units are washed with water before loading new, freshly prepared mastic. The hardening time of coatings made of polyvinyl acetate mastic is 4-5 hours for putty mixtures and 3-4 hours for the covering layer. It is recommended to apply the second layer 24 hours after applying the first and to thoroughly remove dust from its surface before doing so. Layers should be applied in strips 1-1.25 m wide in the direction of the exit door. Walking on unhardened mastic or laying walking boards and other devices on it is not allowed. When there is a break in work, the floor area is fenced off with slats or strips of plywood. When resuming work, the edge of the previously laid layer is covered with slats to protect it from fresh spray and the mastic is continued to be applied to the surface. neighboring plot floor. It is necessary to control that hardening of the applied layer occurs without moisture and dust getting on the floor; the room should be ventilated without creating drafts. In living rooms, mastic floors are usually rubbed with colorless wax parquet mastics. Washing polyvinyl acetate floors with water is not allowed. When accepting polyvinyl acetate floors into operation, they are subject to the same requirements as parquet floors.