Floors in warehouses. Smooth concrete floors for a warehouse: preparation, laying, grouting

This technological redistribution is organizationally the most difficult stage in the installation of concrete floor coverings. Interruptions in the delivery of concrete even for 30-40 minutes (especially in summer), heterogeneous composition of concrete, different plasticity of the mixture lead to an irreversible deterioration in the quality of concrete floors - first of all, its evenness and durability.

The floor manufacturer in this case is completely dependent on the commitment and efficiency of the ready-mixed concrete supplier, so the choice of a concrete mixing unit is the most important stage in planning the entire work on flooring.

The concrete mixture is distributed over the grippers and compacted using vibrating screeds and internal vibrators. Special attention it is necessary to pay attention to the quality of concrete compaction along the rails, walls and around the columns. When installing "super-flat" floors, special high-quality vibrating screeds are used, and their geometry (deflection) must be checked and, if necessary, adjusted after each work shift.

The plasticity of the supplied concrete should also be checked. The manufacturer must measure the slump concrete mix from each mixer truck (“mixer”) and require the supplier to adjust the recipe. A slump change of more than 4 cm in a batch of concrete delivered in one shift can lead to difficulties in the performance of work and reduce the quality of the finished floor.

Leveling compacted concrete with hand screeds.

At traditional technology installation of concrete floors (use of guides and vibrating screeds) the evenness of the floors is largely determined by the professionalism of concrete layers. The use of high-quality guides, adjustable vibrating screeds is not a guarantee for the installation of coatings with a given evenness.

Unfortunately, without a lot of manual labor, it is not possible to obtain high-quality and even floors. In the manufacture of "super-flat" floors for narrow aisle stackers, 20 - 30% of all labor costs are for manual leveling of the concrete floor.

The use of concrete-laying complexes makes it possible to reduce the share of labor costs for the distribution and compaction of the concrete mixture, but also does not allow one to abandon manual labor for leveling freshly laid concrete.

Alignment is carried out using aluminum and wooden slats rectangular section, special smoothing profiles on telescopic handles with swivel joints.

Exposure of freshly laid concrete.

The exposure time depends on the temperature of the base, humidity and ambient temperature, the activity of the cement used in the preparation of the concrete mixture. As a rule, concrete is cured for 3 to 5 hours before subsequent processing operations. The frequently used concrete mixture vacuuming technology reduces the holding time to 1 - 2 hours, which simplifies the technology.

As recommended by the American Concrete Institute (ACI) and most hardener manufacturers further processing concrete can be started only after the depth of the footprint on the concrete is less than 4 - 5 mm. Such an unformalized recommendation indicates that the technology of concrete floors, and as a result, their quality, largely depends on the accumulated experience and professionalism of the installers.

If the concrete mixture is delivered to the construction site of non-uniform quality, the holding time of different sections of the laid concrete will be different in time, therefore, at this stage, it is necessary to carefully monitor the setting time of the concrete.

Application of 2/3 of the total amount of hardening composition to fresh concrete

The dry hardening mixture is applied to hardening concrete manually or with the help of special distribution carts. The latter method is the most preferred, as it allows to achieve a controlled and uniform distribution of the hardening mixture.

For the manufacture of reinforced concrete, dry mixes are used, which differ in the type of wear-resistant filler. The most common are fractionated quartz, corundum, silicon carbide and metal. In addition to the filler, the composition of the hardening mixtures includes Portland cement, water-retaining, plasticizing and other polymeric additives.

The type of reinforcing composition depends on the intensity of wear to which the floor is subjected. In warehouses where loaders and stackers with monolithic polyurethane wheels are used, hardening of floors on quartz and corundum filler is used. In rooms where the movement of trolleys on metal wheels is possible, only metal-filled mixtures are used. For "super-flat" floors, some firms produce reinforcing compounds that are characterized by increased plasticity and increased pot life and workability.

The total consumption of quartz and corundum hardener is 4 - 7 kg per sq.m., metal-filled - 8 - 12 kg. per sq.m.

Colored hardening compounds are produced and widely used, however, the color of the finished coating is never uniform due to the heterogeneity of the composition of the concrete mix, its thickness, and the application of the hardening composition. Alignment of the color of the floor occurs within 1 - 3 months, depending on the thickness of the concrete and the conditions of its hardening. The same applies to the “spotting” of the “natural concrete” hardener.

Hardener grout.

The dry hardener applied to the concrete is smoothed out using hand rails, which are aluminum profile section 50 x 100 or 50 x 150 mm, to which is attached a handle on a swivel joint. The use of a manual slat makes it possible to more evenly distribute the hardening mixture over the surface of the concrete and control its saturation with moisture coming from the concrete.

For mechanized grouting, self-propelled and manual trowels are used. Grouting begins with discs (diameter 60, 90 or 120 cm) dressed on machines at minimum speed. Grouting is stopped after one or two passes over the surface.

Application of the remaining 1/3 of the hardener and final grouting.

After applying the remaining part of the hardening composition to the concrete surface, grouting is continued with the help of disks, and as the concrete hardens, the disks are removed from the trowels and continue to process the surface with blades. At the same time, the angle of inclination of the blades and the speed of rotation of the rotors are gradually increased.

Floors in warehouses are constantly subjected to huge mechanical loads from the movement of warehouse equipment, enormous pressure from racks, harsh abrasive and impact effects, and temperature changes. Their poor performance can cause significant financial losses associated with repairs and downtime.

Requirements for floors in warehouses

The bearing layer of the floor in warehouses in most cases is a reinforced concrete slab, made on a crushed stone, soil or sand base. The class of concrete for the structure, the thickness of the slab, the reinforcement zones, the diameter of the reinforcing bars, the dimensions of the cells of the reinforcing mesh are determined at the design stage of the floor, depending on the intensity and magnitude of the expected loads, the type of foundation, etc.

Depending on the type of warehouse (production, customs, transit) and its purpose (storage of pharmaceutical products, explosive materials, consumer goods, etc.), the corresponding requirements are also imposed on the floor.

Floors in warehouses should be:

resistant to abrasive wear - one of the most important factors in the destruction of concrete floors in warehouses. Abrasive wear occurs due to the movement of people and vehicles around the warehouse;
resistant to mechanical stress. Warehouse floors are subject to traffic, so they must be improved to withstand the resulting shear stresses;
impact resistant. Quite often in warehouses, various heavy objects fall on the floors, so the coating must be strong enough to withstand impact from falling objects and at the same time maintain its solidity;
resistant to various aggressive chemicals. Due to the use of various mechanisms and machines, floors in warehouses are contaminated with fuels and lubricants and products of engine operation. Floors in warehouses chemical industry may experience negative impact from various liquids, salts, alkalis, etc.;
insensitive to temperature changes. This is especially true for warehouses with access to the street, refrigerators and freezers;
impervious to liquids. The floor must be moisture resistant so that it is not adversely affected by frequent wet cleaning;
non-slip both dry and wet to ensure the safety of pedestrians and vehicles;
fireproof.

Features of flooring in warehouses

The key to the quality of concrete floors is compliance with all the rules of laying technology and the experience of contractors. When arranging a warehouse floor, it is necessary to plan in advance the location of racks, driveways, and decide on the equipment that will be used to load and transport stored goods.

When designing the floor, care should be taken to ensure that shrinkage joints do not end up at joints in areas of increased stress or along passage lines. All drain holes and technological grooves should not be mounted near rack supports or on the routes of movement of loading equipment.

More recently, storage in warehouses was carried out directly on the floors or on racks in 2-3 tiers. Warehouses with a storage height of more than 8 m were rare. In modern warehouses, the height of cargo storage reaches 14, 16 and even more meters. At the same time, the passages between the racks have become smaller, as well as the dimensions of warehouse equipment. Using modern technology and the “growth” of warehouses upwards, the requirements for evenness of the floors have also changed.

Warehouse floors should not have any slopes. This is primarily due to the stability of storage racks. There should also be no local irregularities on the floor, since lifting equipment often has low ground clearance and can simply “sit down” on a protruding hillock.

Moreover, even minor bumps floors lead to rather strong deviations of the mast of the loader and swaying of the lifted load. The most stringent requirements are imposed on the floors of those warehouses that use three-sided stackers, and the width of the aisles between them is 1.6-1.9 m.

Floors in warehouses with three-way stackers must comply with the following conditions:

with a warehouse height of up to 3 m, the difference in a segment of 2 m should be no more than 5 mm;
with a warehouse height of up to 6 m - no more than 3 mm;
with a warehouse height of more than 6 m - no more than 1.5 mm.

The labor and cost of making such "super-flat" floors is about 15-25% higher than flooring for one- or two-tier warehouses. That's why necessary requirements to the evenness of the floor must be determined by the customer at the stage of drawing up the technical specifications.

Protection of concrete warehouse floors

Concrete floors are often criticized for their poor resistance to moisture and chemicals. To date, there are two methods for solving this problem: the initial choice of concrete High Quality and subsequent strengthening of its upper layer.

The following compounds can be used to protect concrete floors in warehouses:

dedusting, hardening impregnations;
dry hardening mixes (topping);
polymer paint coatings;
polymeric high-filled self-leveling floors.

Polymer coatings for warehouse floors

The choice of polymer coating depends on the operating conditions of the floor in a particular warehouse. Most often, polyurethane compounds are used to protect floors in warehouses, which have excellent wear resistance. Polyurethane impregnation penetrates concrete to a depth of 2-6 mm, thus forming a concrete polymer in the upper layer of the base. Due to this, the density of the floor increases, and it is also sealed. Polyurethane self-leveling floor is characterized by high tensile and compressive strength. It has high impact resistance and withstands very high mechanical loads. In modern warehouses, self-leveling floors made with the help of a two-component polyurethane material Polymerstone-2 have proven themselves well.

Bulk polymer floors are recommended for use in warehouses Food Industry as they provide additional safety and hygiene for food storage. Such floors are also indispensable in warehouses for chemical products, as they are distinguished by increased safety.

An epoxy or polyurethane-based impregnation can be used instead of a self-leveling floor. If a more budget option is preferred, then the floor can be painted with polyurethane enamel, for example, Polymerstone-1. It will give the flooring elasticity, as well as resistance to abrasion and various deformations. The undeniable advantage of concrete floor paints is their low cost.

Concrete paints primarily perform protective functions. They prevent the penetration of water into the pores of concrete, reduce abrasion, reduce crumbling of the floor under the influence of physical activity. Floors in warehouses do not need spectacular decoration. For them, the main thing is not beauty, but protection. Although they are sometimes dyed bright colors to allocate work areas or places for finished products.

Concrete paints can in some cases be applied directly to floors, but they must be dry and free of dust and dirt. However, paints will adhere and retain their properties much better if applied to prepared surfaces (sanded and primed). For these purposes, special polymeric primers and impregnations are used.

The time of non-repair operation of any polymer coating depends to a large extent on the preparation of the surface of the concrete base. The adhesion of the polymer and concrete depends on the degree of roughness of this surface. Reliable adhesion of the polymer coating to the concrete base can be ensured by shot-blasting concrete or grinding with an abrasive tool.

Shot blasting or grinding of concrete allows you to achieve a uniform surface roughness. With the help of these operations, the area of adhesion of concrete and polymer increases many times, the layer of cement laitance is removed and the grains of the filler are exposed.

The technology of applying highly filled coatings consists of the following operations:

processing of the concrete base by grinding or shot-blasting (ensuring the necessary roughness, removing cement laitance);
jointing of cracks and their filling with sealant;
applying a low-viscosity primer in order to create the necessary degree of adhesion of the polymer coating to the concrete base;
application of the main highly filled coating layer over the uncured primer;
processing the cured coating layer with a mosaic grinder;
cleaning the floor surface from dust with a construction vacuum cleaner;
applying a colored protective and decorative coating;
cutting expansion joints and filling them with polyurethane sealant.

Such a coating can be used 2-3 days after installation is completed. Pedestrian traffic is allowed every other day.

For more information about the technology of installing concrete floors in a warehouse, see the article Technology for installing warehouse concrete floors.

How much does a warehouse floor cost?

The cost of a floor for a warehouse includes two components: the cost of installation and the cost of operation. In the event that the floor is not designed correctly, various defects will occur, the elimination of which will require additional costs. Therefore, it is more profitable to create high-quality floors, and especially in modern warehouses, where the quality of structures is of paramount importance.

Warehouse floors cost:

Warehouse floors are one of the most important elements warehouse complex. They experience enormous loads, harsh abrasive, mechanical, impact, constantly influenced by chemical elements and temperature extremes.

Warehouse floor requirements

Warehouse floors are subject to increased requirements. Such coatings must be:

Resistant to abrasion - one of the main factors in the destruction of warehouse floors.
Resistant to mechanical stress. Warehouses often move traffic, so the flooring must have improved characteristics to withstand shear stresses. The floors in garages should also have the same property.
Impact resistant. Heavy objects may fall on the floors. In this case, the monolithicity of the coating should not be violated.
With chemical resistance. Warehouse floors in the chemical industry are exposed to aggressive liquids: solvents, paints, acids, etc.
insensitive to temperature changes. Industrial floors in industries where elevated temperatures are used with frequent changes are often violated prematurely. Particularly relevant additional strengthening of the base is for warehouses with access to the street, freezing and cold rooms;
impervious to liquids. So that frequent wet cleaning does not have a detrimental effect on the floors in warehouses, and substances harmful to the environment do not get into the soil through them, the coating should not let liquid through.
Non-slip, both dry and wet, to ensure the safety of vehicles and pedestrians.

Fireproof and durable to ensure the safety of the goods or raw materials stored in the warehouse. That is why, when installing industrial floors for a warehouse, it is necessary to take into account operational requirements, load distribution parameters and other factors. Do not miss any of these nuances and pick up the best option arrangement of warehouse floors will be helped by the specialists of Prom-Flor.

Selection of floor coverings in stock

The choice of coverage is carried out taking into account the above requirements.

Among the most reliable modern coatings are self-leveling floors for a warehouse made of polymeric materials.

Polymer floors can be applied as a thin-layer reinforcing impregnation, as a coloring coating or as full-fledged thick-layer polymer floors filled with reinforcing mixtures, such as quartz.

In the warehouse, a concrete floor reinforced with topping or impregnations can also be used. The main thing is that the floor covering meets all operational requirements.

Polymer floors for a warehouse

Polymer floors are increasingly being used in production and storage facilities. An ideal option is self-leveling floors for a warehouse. This is a thick-layer coating that is practically not subjected to abrasive influences, withstands significant loads, and does not allow excessive dust formation.

When the installation of self-leveling floors for a warehouse is impractical or a budget option is preferable, you can paint the floor with polyurethane enamel. It will not replace 100% self-leveling floors, but will give the flooring additional elasticity, resistance to deformation, abrasion and abrasive effects.

Instead of a self-leveling floor for warehouses, impregnation on a polyurethane or epoxy basis can be used. As you know, epoxy floors are one of the most resistant types of polymer coatings, so this impregnation provides compressive or tensile strength, impact resistance.

In addition, the use of polymer coatings is relevant where, according to operating conditions, only polymer floors can be used - in food production e.g. to provide additional hygiene and storage safety food products. Self-leveling floors in workshops and warehouses of the chemical industry will become indispensable, since they have increased fire safety.

Warehouse concrete floors

Concrete floors are most in demand for arranging warehouses, regardless of whether a self-leveling floor is being laid or the concrete layer will be the finish. Concrete is indispensable at the stage of preparing the base for any floor covering.

The optimal solution for a warehouse is concrete floors with quartz topping, and for rooms with heavy loads - using metallized topping. They are resistant to abrasion, shock, dynamic loads. Such floors are cheaper than polymeric ones. Besides, modern technologies allow you to give concrete floor coverings attractive appearance, if required by the purpose of the room.

As an underlying base, concrete floors for a warehouse must be arranged using reinforcement and fillers from expanded clay and crushed stone. Such a foundation will be reliable and durable.

Floors in warehouses, being one of the constituent parts complex, carry the heaviest loads. Modern high-shelf industrial and goods terminals must meet the requirements of users. In particular, floors must not only meet the specified strength parameters, but also withstand mechanical loads, resist wear, temperature fluctuations and have many other characteristics.

Warehouse floor requirements

Warehouse floors are exposed to high abrasion during operation. Abrasive particles of different fractions are found on the wheels of conventional and special equipment, shoe soles, and therefore the coating must not only be durable, but also guaranteed to meet many requirements:

abrasive wear. Abrasion leads to the appearance of potholes and depressions on the coating, which in turn violates performance. This increases the risk of collapse of racks, physical injury to employees.
. Industrial floors are subject to maximum wear and tear in places of passage, U-turns, work areas and others. It is here that it is necessary to apply a coating with high characteristics of strength and practicality. The greatest danger for warehouses is loaded with trolley structures of small diameter wheels of the "rokla" type, which, among other things, create shear stress in the surface layer of the floor layers.
Impact resistance – mandatory requirement for floors. The specifics of the work is such that heavy objects often fall on the coating, therefore protective layer must be especially strong so that any mechanical impact does not violate the solidity of the floors.
Chemical resistance and aggressive environments. current industrial production leads to the appearance in the warehouse of various oils, paints, organic and chemical solvents, and other liquids that tend to spill. The load on the coating increases many times, which means that the floors for warehouses must have a protective layer that protects the base from destruction, while the aesthetic appearance of the surface is important.
Thermal strength. Manufacturing processes allow work in both high and low temperature conditions. The mode difference is one of the main reasons for the destruction of the coating. When choosing a base, it is necessary not only to take into account the constant operating temperature, but also the possibility of local increases / decreases. For example, cleaning or opening external gates in the cold season, when the load on the floor increases many times over.
Water repellency coatings are the main requirement for floors in terminals. Impenetrability determines the indicators of opportunity wet cleaning, the impact of any liquids on the base, and so on.
crack resistance. This characteristic increases the life of the floor, and also improves the impact-resistant qualities of the coating.
Anti-slip. Warehouse floors that do not meet the specifications are unsuitable for premises. The requirement must be met both in the dry state of the base and in the wet state, otherwise the risk of injury to workers increases many times over.
fire safety and preventing the spread of fire are shown for all floors in warehouses, therefore, wooden bases or their elements are not allowed in warehouses. Increased requirements are imposed on floors in the evacuation zone, exit-entrance groups.
Noise absorption is mandatory in cases where warehouse work involves the transportation of goods by means of special equipment, during periods of repair or renovation of areas.

Additional requirements for floors in warehouses

In order for industrial floors to be not only durable, but also practical, it is necessary to comply with additional conditions required for certain types of structures.

UV resistance. This is an indicator for warehouses with impressive glazing and structures without a roof;
Antistatic required when storing highly sensitive equipment;
Aesthetics . Often industrial warehouses are a customer service area and therefore comfort in such premises is also necessary;
Ease of cleaning is needed to maintain cleanliness.

Choice of base coat

In addition to quality requirements, floors in industrial warehouses must be different. long term and ease of commissioning. And this means that the basis is chosen taking into account the need for local renewal with the possibility of quickly putting the territory into operation. In addition, the factors of dynamic, static loads, temperature and humidity conditions of work, base thickness, cleaning mode should also be taken into account. And, of course, the price of floors matters, which affects the quick payback of all work.

Today, one of the most reliable is considered a self-leveling polymer floor. The compositions are applied in several ways:

As an impregnation to strengthen the base;
Paint coating (single-component enamel compositions);
Bulk polymers such as thin-, thick-layer coatings with quartz fillers.

The choice of method depends on the area of \u200b\u200bthe room, it is allowed to use one or all options. In particular, it is possible to make a self-leveling floor with local hardening in places of the greatest load and susceptibility to abrasion. The total price will remain affordable, the strength parameters will be observed. Polymer floors today remain one of the most practical, resistant to impact loads, abrasives, chemical attack.

Floor options and prices

Industrial floors can be painted with Polymerstone-1 one-component polyurethane enamel (price from $50). Forming a durable coating, the protective layer is easy to care for, while being resistant to abrasion and has a long service life. Enamel has elastic properties, which allows it to be applied to the coating in places with maximum load, the tendency of the base to deformation and mechanical shock.

Two-component polyurethane compounds, price from $60-75 differ even more the best performance. Self-leveling floor of this type withstands huge loads associated with compression / tensile, has high strength for mechanical, chemical, directional impact and is not subject to abrasive and temporary abrasion. The coating remains solid during periods of temperature fluctuations, does not crack or chip.

The most important quality that a self-leveling floor has is the ability to renew the coating at any time. It is enough to prepare and level the base in places where the load is especially high, purchase the composition and fill it according to the instructions. Fast drying, the possibility of prompt commissioning of the warehouse, available price category and carrying out a cycle of works on your own without the involvement of specialists - additional advantages of self-leveling floors for warehouses and terminals. The load withstood by such a base is many times stronger than the usual concrete floors.

The floors in modern warehouse complexes are in extremely harsh operating conditions - they are subject to static and dynamic loads from lifting equipment (weighing up to 10 tons), abrasive wear, and shock. Efficient functioning of the warehouse, among others important factors, depends on the quality of floor coverings and their durability.

Not the most expensive element of the building - floors can, if performed poorly, lead to significant financial losses associated with their repair and downtime separate zones warehouse.

As a rule, the customer imposes only three requirements on the floors of the warehouse: dustlessness, absence of cracks and evenness (much less often decorative and chemical resistance).

If any floor should be characterized by dustlessness, the absence of cracks and other defects, then evenness depends on the type of warehouse. The most stringent requirements for floor evenness are imposed in warehouse complexes where narrow-aisle stackers with a lifting height of more than 9.0 m are used. The numerical values of evenness in this case are determined by the suppliers of lifting mechanisms. The cost and labor costs for the implementation of such "super-flat" floors are significantly (15-25%) higher than coatings for one- or two-tier storage on, therefore, at the stage of drawing up the technical assignment, the customer must determine both the type of lifting mechanisms and the really necessary requirements for floor evenness.

The requirements of dustlessness and durability are met by two types of floors - concrete and polymer (with the necessary reservation - their competent arrangement).

Polymer coatings

Polymer coatings are installed dry (minimum 21 days after laying) concrete base. Concrete must have the required evenness - leveling a concrete base with a polymer is unreasonably expensive and technically difficult.

In the vast majority of cases, polymer coatings based on epoxy or polyurethane binders are used in warehouses.

According to the thickness and device technology, polymer coatings can be conditionally divided into thin-layer (painting) - 0.2-0.5 mm, self-leveling (liquid) - 1-4 mm and highly filled - 4-8 mm.

The term of maintenance-free operation of any polymer coatings to a large extent depends on the preparation of the surface of the concrete base. The adhesion of the polymer to the base is determined by the degree of surface roughness (adhesion area) and the absence of a layer of laitance or latex film on the surface (with which the coating may peel off from the concrete).

The only way to ensure reliable adhesion of the polymer coating to the base is its treatment with shot blasting machines. To remove individual irregularities, it is possible to process with diamond cutters, grinders or other mechanisms as an additional one, performed before shot blasting.

Shot blasting of concrete gives a uniform surface roughness, repeatedly increasing the adhesion area of the coating and concrete, removes the film of cement laitance and exposes the grains of the aggregate, thereby increasing adhesion.

Thin-layer coatings, as a rule, are not used in the manufacture of new floors, but serve to protect old concrete coatings that have begun to dust and collapse. The durability of painting systems does not exceed one or two years, after which it is required for several days (sometimes up to 10 days) to close the repaired warehouse area for repainting.

Self-leveling (self-leveling) coatings were used in the 80s and 90s of the last century. Currently, they are practically not used in the construction of warehouses due to their high cost, low resistance to abrasion and a tendency to peel. It is possible to use them for leveling the passages of narrow-aisle stackers with a lifting height of more than 6-8 m on poor-quality concrete bases.

The technology of self-leveling coatings is relatively simple and includes the preparation of a concrete base, the application of a primer (primer) and the main self-leveling layer. Productivity when laying such coatings reaches 600-700 sq.m. in shift.

Highly filled coatings are characterized by high wear and impact resistance. Most often they are used to repair old concrete coatings, or in the construction of warehouses with increased requirements for decorativeness, chemical resistance and dustlessness.

The technology of highly filled coatings includes the following operations:

processing of the concrete base (removing the layer of cement laitance and providing the necessary surface roughness) using a shot blasting machine;
jointing cracks and filling them with sealant, followed by reinforcing the crack with fiberglass and applying a second layer of sealant;
applying a low-viscosity primer that provides the required amount of adhesion of the entire coating to the base;
application of the main colored highly filled coating layer using spatulas (near walls and columns) and a special paddle stacker (Power Trowel) over the uncured primer layer;
processing of the hardened layer using mosaic grinders, followed by dust removal;
applying a layer of colored protective and decorative coating;
cutting expansion joints on the cured coating and filling them with polyurethane sealant.

The beginning of operation of a covering - in 2-3 days after laying completion (pedestrian traffic in 1 day).

Due to the high labor intensity, the productivity when laying such coatings is no more than 1500 sq.m. in Week.

concrete floors

Concrete coatings are most widely used due to their relatively low cost, since the manufacture of a wear-resistant coating is combined in one technological cycle with the installation of a monolithic bearing slab.

The design of a concrete slab depends on many factors - the characteristics of the base, the loads on the floor, the location of the racks, the type of reinforcement, etc.

During the construction of new warehouses, compacted sand, less often reinforced concrete, serves as the basis for the floor. monolithic slab. When renovating buildings, the base is often the old floors of concrete tiles, monolithic concrete and etc.

At the stage of designing the floor, it is necessary to know the basic characteristics of the base, so its specialized examination is mandatory. In new construction, when compacted sand serves as the basis for the concrete floor, the customer must control the degree of its compaction, not relying on the contractor's data, but involving an independent specialized laboratory, which will prevent further subsidence of the floor and the formation of cracks.

In its pure form, concrete coatings for the manufacture of warehouse floors are practically not used because of their low wear resistance and significant dusting. To give the concrete floor high performance characteristics are used technological methods surface (1-3 mm) hardening with the help of liquid or dry compositions at the stage of concrete flooring.

Special high-strength cement-polymer compounds with a layer thickness of 5-12 mm are also used, which are laid on unhardened or "old" concrete.

The most widely used technology for hardening concrete floors with dry mixes.

Technological operations when constructing a concrete pavement with an upper hardened layer:

Leveling the base surface.
The survey determines the highest elevation of the base, after which the thickness of the concrete slab is specified, which should not be less than the design one.
In accordance with the recommendations of ACI302.IR-89 of the American Concrete Institute, the minimum thickness of a concrete slab placed on a cast-in-situ concrete base is 100 mm. If the concrete pavement is laid on compacted soil, its thickness is usually 150-250 mm, depending on the loads on the floor and the reinforcement used. It should be noted that the installation of a concrete floor with a thickness of 50-100 mm, despite the cost savings due to the reduction of concrete consumption, is unjustified, since in the vast majority of cases it leads to significant cracking and further destruction of the coating.

Breakdown of the floor area into maps (captures)

If racks will be installed in the warehouse, the edges of the grips should, if possible, be located between the racks.

This is especially important for high-bay storage, as there are increased requirements for evenness of floors, and experience with concrete pavement shows that the largest number unevenness occurs along the edges of the grips. The width of the grips for "extra-flat" floors should not exceed 4 m (in rare cases, 6 m). The length of the cuts is determined according to the daily paving output in order to avoid unnecessary so-called. "cold" or "construction" joints arising from breaks in concreting.

Installing guides

As guides, special concrete products or metal forms are used, less often a square metal hollow profile or channel. The evenness of the floors directly depends on the quality of the guides, therefore, for "super-flat" floors, only special forms with increased rigidity and evenness of the upper edge should be used. To install guides, it is preferable to use optical levels, and use laser levels for selective control of the correct installation.

In the United States and European countries for the past two decades, the technology of laying concrete floors with the help of automatic concrete paving complexes, which are mobile units with a telescopic mechanism on which a leveling device equipped with vibrators is fixed (for example, Somero, USA). Concrete-laying complexes provide automatic control of the level of the laid concrete mix - for this, a stationary laser emitter is used, installed in the line-of-sight zone and receivers mounted on the mechanism itself. An actuating hydraulic mechanism adjusts the height of the screed several times per second, which makes it possible to obtain an acceptable evenness of the concrete pavement in warehouses where reach trucks are used.

Productivity at laying by such mechanisms reaches 5000 sq.m. in shift. Therefore, guides for such laying are rarely installed and do not significantly affect the evenness of the floors.

Flatness measurements of floors made using this technology show that only in rare cases the evenness values meet the requirements for the operation of narrow aisle stackers.

Reinforcement (installation of reinforcement)

For reinforcing floors, meshes of AIII reinforcement are used, or dispersed reinforcement with steel fibers. Quite often, combined reinforcement is used - in addition to reinforcing cages (mesh), steel fibers are added to concrete to reduce cracking of the concrete floor.

The choice of the type of reinforcement is determined by the designer, depending on the loads on the floor and the characteristics of the base.

When using traditional reinforcement using reinforcing meshes, it is very important to control their location relative to the base and the given floor level. As the experience of domestic and foreign construction shows, the crack resistance and, consequently, the durability of the floor depend on the correct installation of the reinforcement.

This is especially important in the case of making a concrete coating of small thickness, reinforced with a single mesh - an incorrectly laid mesh (for example, laid directly on the base) not only does not prevent cracking, but is often its source. Therefore, with such a floor design, it is desirable to use combined reinforcement (in addition to installing a reinforcing mesh, introduce metal fiber into the concrete).

Dispersed reinforcement of concrete with metal fiber (consumption of 25-40 kg per cubic meter of concrete) sometimes makes it possible to abandon the installation of traditional reinforcing meshes, drastically reduce labor costs, use high-performance concrete-laying complexes, however, it imposes extremely stringent requirements on the quality of soil compaction and selection composition of the concrete mixture. Unfortunately, at present, domestic normative base the use of metal fibers for flooring is not developed, there are no standardized practical advice for the preparation of concrete mixtures.

The device of sedimentary seams

Sedimentary seams separate the columns and walls of the building from the floor covering. They are arranged by installing 3 mm thick polyethylene foam tape around the columns and along the outer and internal walls building.

This operation prevents the formation of cracks in concrete floor due to the settlement of walls and columns, caused both by subsidence of the soil base, and by changes in seasonal loads on the building structure.

Delivery of the concrete mixture to the construction site and its distribution over the grips and compaction with the help of internal vibrators and vibrating screeds.

The concrete mixture is distributed over the grippers and compacted using vibrating screeds and internal vibrators. Particular attention must be paid to the quality of concrete compaction along the rails, walls and around columns. When installing "super-flat" floors, special high-quality vibrating screeds are used, and their geometry (deflection) must be checked and, if necessary, adjusted after each work shift.

The plasticity of the supplied concrete should also be checked. The manufacturer must measure the slump of the concrete mixture from each mixer truck ("mixer") and require the supplier to adjust the recipe. A slump change of more than 4 cm in a batch of concrete delivered in one shift can lead to difficulties in the performance of work and reduce the quality of the finished floor.

With the traditional technology of concrete flooring (the use of guides and vibrating screeds), the evenness of the floors is largely determined by the professionalism of the concrete layers. The use of high-quality guides, adjustable vibrating screeds is not a guarantee for the installation of coatings with a given evenness.

Unfortunately, without a lot of manual labor, it is not possible to get high-quality and even floors. In the manufacture of "super-flat" floors for narrow aisle stackers, 20-30% of all labor costs are for manual leveling of the concrete floor.

Alignment is carried out with the help of aluminum and wooden slats of rectangular section, special smoothing profiles on telescopic handles with swivel joints.

Curing fresh concrete

The exposure time depends on the temperature of the base, humidity and ambient temperature, the activity of the cement used in the preparation of the concrete mixture. As a rule, concrete is cured for 3-5 hours before subsequent processing operations. The frequently used concrete mixture vacuuming technology reduces the holding time to 1-2 hours, which simplifies the technology.

In accordance with the recommendations of the American Concrete Institute (ACI) and most firms producing hardening compounds, further processing of concrete can only be started after the depth of the footprint on the concrete is less than 4-5 mm. Such an unformalized recommendation indicates that the technology of concrete floors, and as a result, their quality, largely depends on the accumulated experience and professionalism of the installers.

Application of 2/3 of the total amount of hardening composition to fresh concrete

The type of reinforcing composition depends on the intensity of wear to which the floor is subjected. In warehouses where loaders and stackers with monolithic polyurethane wheels are used, hardening of floors on a corundum filler, or based on silicon carbide, is used. In rooms where the movement of trolleys on metal wheels is possible - only metal-filled mixtures.

For "super-flat" floors, some firms produce reinforcing compounds that are characterized by increased plasticity and increased pot life and workability.

The total consumption of quartz and corundum hardener is 4-7 kg per sq.m., metal-filled - 8-12 kg per sq.m.

Colored hardening compounds are produced and widely used, however, the color of the finished coating is never uniform due to the heterogeneity of the composition of the concrete mix, its thickness, and the application of the hardening composition. Alignment of the color of the floor occurs within 1-3 months, depending on the thickness of the concrete and the conditions of its hardening. The same applies to the “spotting” of the “natural concrete” hardener.

Grout hardener

The dry hardener applied to the concrete is smoothed with the help of hand rails, which are an aluminum profile with a section of 50 x 100 or 50 x 150 mm, to which a handle is attached on a swivel hinge. The use of a manual slat makes it possible to more evenly distribute the hardening mixture over the surface of the concrete and control its saturation with moisture coming from the concrete.

For mechanized grouting, self-propelled and manual trowels are used. Grouting is started with discs dressed on machines (diameter 60.90 or 120 cm) at minimum speed. Grouting is stopped after one or two passes over the surface.

Application of the remaining 1/3 of the hardener and final grouting

Application of protective water-retaining varnish

Since the concrete used for floors is made from Portland cement, it is characterized by curing shrinkage. Shrinkage results in cracks - both surface and structural (over the entire depth of the concrete layer). Surface shrinkage cracks can subsequently open up and lead to surface flaking and floor failure. To prevent cracking, it is necessary to drastically reduce the evaporation of moisture from the concrete surface, especially in the early stages of curing. To do this, use special water-retaining varnishes - solutions of acrylic copolymers in organic solvents or water. With the recommended varnish consumption of 100-150 ml per sq.m. film thickness on concrete is 0.05-0.08 mm. This is quite enough to slow down the evaporation of moisture from the concrete slab and prevent cracking.

Critical in this operation is the time of application of water-retaining varnish - the interval between the completion of grouting and laying varnish should be minimal and be calculated in minutes.

The varnish is applied using rollers or pneumatic sprayers. Some varnishes with a low solids content require reapplication at intervals of 0.5-1 hour.

When the floors are used, the water-retaining varnish wears off.

Cutting is carried out using special machines with diamond or corundum discs to a depth of 1/3 of the thickness of the concrete coating, but not less than 2.5 cm.

Joint cutting is carried out no later than 6-8 hours after the final grouting of the hardened layer, which makes it possible to avoid the appearance of shrinkage cracks.

The step between the seams depends mainly on the thickness of the concrete. According to ACI recommendations, the spacing between joints should not exceed 30-40 concrete slab thicknesses. The location of the seams is determined depending on the location and spacing of the columns and the configuration of the warehouse.

Filling shrinkage and expansion joints

Since concrete shrinkage occurs over a fairly long period (intensive - the first three months), the joints must be filled with elastomeric sealants as late as possible. For concrete floors with a thickness of 100-150 mm, the filling of joints can be started no earlier than 1.5-2 months after their installation. For concrete floors with a thickness of 200-300 mm, this period should not be less than 3 months.

Such requirements complicate the organization of work, because seam sealing operations must be performed in the conditions of an existing warehouse. On the other hand, filling joints earlier than the specified period, as a rule, leads to a violation of adhesion between the sealant and the edges of the joint, which inevitably leads to the repair of joints in an existing warehouse.

As practice shows, the most effective is the use of rigid polyurethane or epoxy sealants with high hardness (more than 90 cu Shore A) and low elasticity (relative elongation up to 150%).

The most common method of filling joints - laying a polyethylene foam cord and filling with sealant to a depth of 5-7 mm does not always ensure the durability of the floor. Often, the edges of the seams under the influence of heavy traffic are chipped, which leads to further destruction of the damaged areas. In foreign literature, there are recommendations not to use a polyethylene foam cord at all, but to fill the seam with sealant to the full depth. Thanks to advances in technology, there are more new system additional filling of a floor -.

Thus, the task of obtaining a dust-free and durable floor requires both significant efforts on the organization of production and high professionalism of engineers and workers from the contractor. On the other hand, the quality of work is influenced by many factors that do not directly depend on the floor installer. This is a stable temperature in the room not lower than 10 degrees C, the absence of drafts, water leaks, adjacent construction organizations in the work area, the availability of effective site lighting.

The customer and the general contractor must be sympathetic to the requirements of the floor installer and plan in advance the time of his work.