Use of the concrete-plate as the base of the building often becomes a forced measure in the absence of the opportunity to order specialized FBS or cast a monolith. In the conditions of tight construction time and complex logistics at remote sites, developers pay attention to the available facilities. PDN (road plates) or PDWhich are easier to find on sale. Operating load These products are initially designed for transport, not static pressure walls, which requires careful testing of the load-bearing capacity of the soil before starting work.
The use of road plates is justified for temporary structures, warehouses or households, where the requirements for thermal insulation and tightness are lower than that of a residential building. Structural strength The concrete in such products is high, however, geometric parameters and reinforcement may not meet the requirements for the capital structure. Before purchasing a batch, it is necessary to conduct a detailed calculation of loads to avoid distortions and cracks in the future.
Classification and labelling of productsIn the construction market under the general name "road plates" there are several types of products, each of which has its own characteristics. reinforcement and appointments. The main difference lies in the manufacturing technology: there are pre-stressed They have very low stress structures, which directly affects their ability to withstand bending moments. Marking PDN indicates the use of stress reinforcement, which makes such products more resistant to cracking under load.
In turn, products with labeling PD They are made using a conventional reinforcement frame. load-bearing capacity Such plates are lower, and they are more often used for laying temporary roads or as a base for light constructions. When choosing a material for the foundation, it is critically important not to confuse these brands, as the visual difference may not be obvious without studying the quality passport.
⚠️ Attention: The use of plates with unstressed reinforcement for two-storey buildings made of heavy materials (brick, aerated concrete) is strictly not recommended without additional reinforcement.
Advantages and disadvantages of technologyThe main argument in favor of the choice road-slab It is available and speed of installation. The finished product is delivered by a manipulator and laid by a crane in a matter of hours, which eliminates the long technological interruptions necessary to gain strength. monolithic. This allows you to significantly reduce the time of construction of the box of the building and start work on the construction of walls almost immediately after leveling the base.
However, the technology has significant disadvantages associated with geometry and thermal properties. Standard. road-slab It is 6 meters long, which creates many docking seams that are difficult to seal perfectly. Heat loss through such seams can be significant, requiring high-quality insulation of the basement and underground space.
To minimize heat loss of the joint plates must be sealed with cement-sand solution with the addition of liquid glass or special waterproofing mastics.
In addition, the weight of one plate can reach 2-2.5 tons, which requires the use of heavy equipment for unloading and installation. This increases the cost estimate and limits the use of the method in areas with difficult entrance or weak soil, where equipment can get stuck.
Load calculation and soil preparationA fundamental mistake many developers make is to ignore the preparation. foundation under prefabricated stoves. Road products are designed for distributed load from the wheels of transport, but the point pressure of the walls of the house can lead to local pressing of the soil. Before laying, it is necessary to remove the fertile layer of soil and perform a sand and gravel cushion with a thickness of at least 30-40 cm.
Every layer pillows It must be carefully tampered with a vibrating rink or rink. The density of the base is checked by the fingerprint method: the footprint on the surface should not be deeper than 2-3 cm. If the soil is hollow or weak, a drainage device or replacement of the soil with a non-fluffy material may be required.
☑️ Verification of the readiness of the basis
Installation and alignment technologyThe laying process begins with the marking of the axes of the building and installation lighthouse. The plates are stacked tightly together, but it is rarely possible to achieve the perfect fit of the faces. The gaps between the elements are filled with concrete solution, and on top of the entire base is often arranged. tie-up 5-10 cm thick, which works as a load distributor.
A level or laser level is used to ensure horizontality. The height difference on the entire area of the foundation should not exceed 2 cm by 10 meters of length, otherwise there will be problems with the construction of the walls of the first floor. In the joints, the plate rebar can be connected to each other to create a single lantern.
⚠️ Warning: Do not attempt to break off the protruding reinforcement with a Bulgarian without need - this reduces the bearing capacity of the structure. It is better to provide its location when designing.
Waterproofing and insulationPrefabricated foundation from road-slab It has many seams, which are bridges of cold and ways of penetration of moisture. Waterproofing is performed in two stages: first, the coating insulation is applied to the upper plane of the plates, then the rolled material is lined (for example, the coating is applied to the upper plane of the plates). Technonicol or analogues) with overlap at the joints.
Insulation is usually performed with extruded polystyrene foam (EPPS) which is placed on top of the waterproofing. This material has a high compressive strength and does not absorb moisture, which is critical to protect the foundation from the pressure of the water. frostburden. The thickness of the insulation is calculated based on the climatic zone of the construction region.
| Type of material | Thermal conductivity (W/m·K) | Compressive strength (kPa) | Water absorption (%) |
|---|---|---|---|
| Styrofoam (PPS) | 0.035 - 0.040 | 100 - 150 | 2 - 4 |
| Extruded PPP | 0.028 - 0.032 | 200 - 400 | 0.2 - 0.5 |
| Mineral wool | 0.035 - 0.045 | 10 - 50 | 1 - 5 |
| ceramzit | 0.10 - 0.15 | 50 - 100 | 8 - 20 |
How to properly dock the sheets of insulation?
spoiler: The EPPS sheets are stacked in staggered order if two layers are used. The joints of the first layer should not coincide with the joints of the second. All seams between the sheets of one layer must be glued with foil tape or filled with mounting foam with a low expansion coefficient.
Common mistakes in constructionOne of the most common mistakes is saving money. geodetic. Laying plates "by eye" without reference to the horizon leads to a distortion of the entire building, which is especially critical for frame houses and buildings made of aerated concrete. Cracks in the walls can appear after a year of operation.
Another mistake is the absence pavement Or its wrong device. Water running off the roof should be diverted from the foundation as far as possible. If water penetrates the plates, in winter the soil will swell unevenly, which will cause deformation of the base.
⚠️ Warning: Do not leave the foundation open for winter without loading. Frost bloating can push light plates up, breaking their flatness.
The quality of the foundation of road plates 80% depends on the preparation of the base and proper waterproofing, and not only on the brand of concrete of the plates themselves.
FAQ: Frequently Asked Questions
Can I use old used slabs with cracks?
The use of plates with through cracks or a visible violation of the integrity of the reinforcement frame is prohibited for load-bearing structures. Cracks indicate a loss of bearing capacity. It is allowed to use products with small surface chips after their repair with special compositions, but only for light buildings.
Do I need to build armopods on top of the road plates?
Yes, the device of a monolithic armoposse on top of a prefabricated foundation is extremely desirable. It binds the disparate plates into a single platform, levels the surface and evenly distributes the load from the walls, preventing local squeezing.
What is the minimum grade of concrete allowed?
For foundations, it is recommended to use slabs of concrete of a class not lower B22.5 (M300). The use of lower grades is possible only for temporary structures or subject to additional calculations of strength and structural reinforcement.
How long does that foundation last?
If the installation technology, high-quality waterproofing and the absence of aggressive groundwater, the life of the foundation from road plates can be 50 years or more. However, it is inferior to the monolithic plate in tightness and heat efficiency.