Stone since ancient times takes the place of one of the most popular building materials. Despite the complexity of processing, it provides the highest technical and operational performance in the construction of various structures and structures. To date, this niche is also in demand, but in an optimized form. According to technical documentation, there is a wide category of wall stones that are used in the construction industry. At the same time, one does not have to talk about the homogeneity of this class, since inside it there are many classifications and differences in the operational characteristics of stones of various types. All of them, one way or another, are used in the construction industry, but they perform slightly different tasks.
Presentation of material in regulatory documents
Manufacturing, testing, storage technologies and transportation rules for stones intended for wall masonry are governed by the standards of GOST 6133-99. The wall stone in accordance with this document is a product made by pressing, vibropressing, molding on the basis of a fine-grained or heavy mixture. However, there is also a category of whole minerals from rocks, which are also used in masonry. As for the requirements for transportation and storage, the following can be attributed to the main ones:
- A document with the main characteristics of the material, volume, number of pieces and date of issue is attached to the batch with stones.
- In the passport, a stone must be accompanied by a document indicating strength properties, average density, water absorption coefficient, etc.
- Storage of stones is organized separately: according to purpose, type, size characteristics.
- Between lots on pallets there must be space for circulation of air flows.
Mountain stones
The traditional source of building stone is directly natural rock, which is processed to the desired format. This is not the most practical technology for obtaining building materials, especially against the background of intensive development of foam block and brick products with modified qualities. But mountain wall stones have several unique advantages:
- Originality of texture and texture. This is especially true of granite, onyx, marble and shell rock.
- Ecological cleanliness. In the manufacture of artificial stones, in any case, synthetic additives will be used as elements of the filling or binder. Natural stone is basically free of toxic components and is completely safe for domestic use.
- Mechanical reliability. Although modern technologies make it possible to achieve high wear resistance and durability of concrete stones, the rocks in the best samples demonstrate an unsurpassed combination of operational qualities of strength, rigidity and density, which together make it easy to cope with dynamic and static loads.
Speaking about specific indicators of mountain wall stones, one can note only one density, which on average reaches 2100 kg / m3. For comparison, in the foam block, the normative maximum does not exceed 1200 kg / m3. Another thing is that in modern construction the responsibility of load-bearing structures lies not only with stones, but also with intermediate elements in the form of holding belts, metal ties and corners. In this configuration, a high density and, accordingly, a large mass will become an encumbrance and an additional risk factor.
Concrete wall stones
Actually, the main group of materials for masonry walls in modern buildings, which consists of a large array of various stone modifications. According to traditional technology, expanded clay and water with cement are used as the basis for the production of such products. In other words, a derivative of concrete in an optimized output format. Expanded clay replaces sand or crushed stone filler. In essence, this is foamed and subsequently burnt clay with cells in a sintered shell.
Today, there are dozens of modifications of this technology for the manufacture of artificial wall stone, but they are all maintained in the same principles of forming the structure of the material. It should be light, granular (porous-cellular) and heat insulating. These qualities are directly dictated by the requirements for modern housing - inexpensive, warm, environmentally friendly, prefabricated and practical. But what about reliability? Foam and aerated concrete are quite able to cope with power structural tasks due to reinforcing inclusions. The modular design itself makes housing more resistant to dynamic processes. In optimized projects, combinations of concrete structure and wood-particle inclusions are used at all: for example, arbolite mix on sawdust from coniferous species.
Stone composition
Considering the entire range of components that are used in the processes of manufacturing stones for masonry walls, several types of materials can be distinguished:
- Astringents. For the structural connection of elements and fillers, cement, lime, gypsum and slag binders are introduced into the composition of the wall stone.
- Placeholders. This group is represented by crushed rocks in the format of sand, gravel and crushed stone. Crushed stone can also be made from blast furnace slag, and small aggregates from ash and slag masses.
- Chemical additives. Used to improve material performance. It can be plasticizers and modifiers, due to which the operational performance of wall stones increases. The concrete structure becomes stronger, more resistant to frost and temperature changes in principle, and also acquires moisture and biostable qualities. A specific set of additional properties is determined by the types of additives used.
Types of wall stones
The basic classification distinguishes the following varieties of this building material:
- Solid stone is a traditional cement-based block without internal voids or with the presence of technological grooves and niches designed to capture the product when lifting on a construction site.
- Hollow stone is a block in the structure of which there are vertical voids that are formed in accordance with the design project during the production process. The specific design of a hollow wall stone is determined by the desire of engineers to achieve certain operational properties, including light weight and more effective thermal insulation (due to the air buffer of voids).
- Ordinary stone - a typical model of a masonry wall block, which is used in the construction of capital buildings with decoration.
main parameters
Stones are designed and manufactured to specific standards. There are both unified general characteristics and arbitrary ranges that receive the corresponding marking. In terms of basic parameters, concrete wall stones are evaluated according to the following set of indicators:
- The shape is a rectangular box.
- Color texture - set by the manufacturer, but usually it is a neutral gray, brown and light yellow shades.
- The ends are usually flat, but grooves, ridges and dowels are also allowed. At least one end face must still remain flat.
- Internal filling: as already noted, stones can be produced corpulent and hollow. In both cases, the weight should be 31 kg. The voids can be through, but they must be placed perpendicular to the surface of the support. The thickness of the walls formed by stones with internal cavities should be at least 20 mm.
- The supporting surface is flat or with longitudinal grooves, the indent of which from the sidewall can be at least 20 mm.
- Corners - straight or rounded.
Decorative rock
It is also called facial and is used as a protective or decorative decoration of wall masonry. It has one or two outer faces. The peculiarity of this product is that it is used as a finishing material. If standard wall models of stones directly form a power supporting structure, then facial modifications decorate it.
The function of decorative stone determines its structural features. The main distinguishing feature of such products can be called a small thickness - an average of 15 to 30 mm. In fact, it is a solid bar with a natural texture. Although in this category, wall stone can be both natural and artificial. Moreover, the assortment of the second group is vast, as it provides more structural and textural capabilities in the manufacture. As for the natural face stone, most often these are whole cuts, characterized by a natural noble texture, for which they are highly appreciated. For example, a facade stone costs 80-100 rubles / pc. Thin large-format veneer is available on the market for several thousand rubles, due to the complexity of its production and high decorative properties. In comparison, the cost of expanded clay concrete is 40-60 rubles / pc. And this despite the fact that standard concrete blocks perform a more responsible task of the frame element of the building.
The operational properties of the stone
The combination of physical and mechanical operational properties has determined the wide scope of this building material. Far from all of them, this stone can compete with alternative materials for masonry and wall decoration, but the combination of “working” qualities makes it a very attractive solution. So, among the most significant properties of wall stones can be identified:
- Compressive strength - from 7 to 20 MPa. Not the strongest side of concrete products, but, as already noted, this drawback is made up for by reducing weight.
- Frost resistance. Without obvious signs of deformation (delamination, peeling, chipping), the material is able to withstand from 15 to 50 defrost-freeze cycles at extreme temperatures. Moreover, an important condition for verification is the preliminary saturation of the structure with water, which expands in the frozen state and puts a strain on the structure of the stone shell.
- Humidity - coefficient of not more than 12-15%, depending on the type of product.
- The activity of radionuclides (natural) is about 350-400 Bq / kg.
- Thermal conductivity is on average 0.3 W / (m · ° C), which is typical for expanded clay concrete and most porous blocks based on cement.
For each of the above properties, there are special verification methods that are used in the factory before labeling. In most cases, reference samples, laboratory or field conditions are used for testing.
Material benefits
Much in the overall assessment of this stone depends on its type, manufacturing technology and specific application conditions. Nevertheless, it should be borne in mind that the same qualities are revealed differently under different operating conditions. One way or another, the following factors can be attributed to the advantages of concrete-based wall stone:
- Price availability of technology implementation. Inexpensive raw materials and equipment for the manufacture of blocks makes it possible to organize the production process even in a private workshop.
- Ecological cleanliness. Despite the need to use synthetic binders, and sometimes plasticizers with other chemical additives, the standards establish stringent environmental safety requirements with limits that are acceptable for use in the construction of residential buildings.
- High insulating properties. Houses made of the same foam or aerated concrete are characterized by silence and thermal comfort - largely due to the porous structure.
- Lightness of blocks. In practice, during operation, this advantage is imperceptible, but during the construction process it facilitates both the work process and the transportation of material. To this, it is worth adding the pliable structure of concrete stones, which allows you to easily adjust the shape of the blocks when installing custom designs.
If we talk about the shortcomings, then almost all of them are the flip side of the positive qualities. Indeed, these are not the most durable products and in some modifications can even support combustion, but these nuances should be taken into account at the design stages of the house. In accordance with them, designers are considering compensatory measures to reduce the possible negative factors of operation of an object from a concrete wall block.
Conclusion
In various variations, the concept of concrete block stones has been used by builders for a long time, but in recent years this direction has been experiencing a new round of evolutionary development. Moreover, the engine of a new trend was the spread of modular construction technology, into which blocks of foam and expanded clay concrete fit in organically. The cost of materials, an average of 50 rubles / piece, also complies with the principles of optimized housing. But does this mean that we are talking about low quality buildings? The question is ambiguous, since houses that are optimized for specific operating conditions, in principle, should not have high technical and physical qualities in terms of parameters that are not needed. On the other hand, if we draw analogies with traditional brick houses with full-size masonry, then block-modular houses from the same expanded clay will really lose in a number of characteristics, while significantly winning in price.