Stone has been one of the most sought-after building materials since ancient times. Despite the complexity of processing, it provides the highest technical and operational performance in the construction of various structures and structures. Today, this niche is also in demand, but in an optimized form. According to the technical documentation, there is a wide category of wall stones that are used in the construction industry. At the same time, there is no need to talk about the homogeneity of this class, since within it there are many classifications and differences in the performance characteristics of stones of different types. All of them, one way or another, are used in the construction industry, but they perform slightly different tasks.
Representation of material in normative documents
Technologies for manufacturing, testing, storage and transportation rules in relation to stones,intended for wall masonry, are regulated by the standards of GOST 6133-99. The wall stone in accordance with this document is a product made by pressing, vibrocompression, molding techniques based on a fine-grained or heavy mixture. However, there is also a category of solid minerals from rocks, which are also used in masonry. As for the requirements for transportation and storage, the main ones include the following:
- A document is attached to the batch with stones, which indicates the main characteristics of the material, volume, number of pieces and date of issue.
- In the passport, the stone must be accompanied by a document indicating the strength properties, average density, water absorption coefficient, etc.
- Storage of stones is organized separately: by purpose, type, dimensional characteristics.
- Space must be provided on pallets between batches for air circulation.
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 the intensive development of foam block and brick products with modified qualities. But mountain wall stones have some unique advantages:
- Originality of texture and texture. This is especially true for granite, onyx, marble and shell rock.
- Eco-friendly. In the manufacture of artificial stones, in any case, there will beuse synthetic additives as filling or binder elements. Natural stone, on the other hand, does not contain toxic components and is completely safe for domestic use.
- Mechanical reliability. Although modern technologies allow achieving high wear resistance and durability of concrete stones, rocks in the best samples demonstrate an unsurpassed combination of performance characteristics of strength, rigidity and density, which together make it easy to cope with dynamic and static loads.
Speaking about the specific indicators of mountain wall stones, we can note only one density, which on average reaches 2100 kg/m3. For comparison, for a foam block, the normative maximum does not exceed 1200 kg / m3. Another thing is that in modern construction, the responsibility of load-bearing structures is assigned not only to stones, but also to intermediate elements in the form of retention belts, metal bandages and corners. In such a configuration, high density and, accordingly, a large mass will become a burden and an additional risk factor.
Concrete wall stones
Actually, the main group of materials for laying 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 concrete derivative in an optimized release format. Expanded clay replaces sand or crushed stone filler. ATessence, it is foamed and later fired clay with cells in a sintered shell.
Today, there are dozens of modifications of this technology for the manufacture of artificial wall stone, but all of them are 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 quite cope with power structural tasks due to reinforcing inclusions. By itself, the modular design makes housing more resistant to dynamic impact processes. In optimized projects, combinations of a concrete structure and wood-shaving inclusions are used at all: for example, arbolite mixture on softwood sawdust.
The composition of the stone
Considering the entire range of components that are used in the process of making masonry stones, several types of materials can be distinguished:
- Binders. For the structural connection of elements and fillers, cement, lime, gypsum and slag binders are introduced into the composition of the wall stone.
- Fillers. This group is represented by crushed rocks in the format of sand, gravel and crushed stone. Also, crushed stone can be made from blast-furnace slag, and small aggregates can be made from ash and slag masses.
- Chemical additives. Used to improvematerial characteristics. These can be plasticizers and modifiers, which increase the performance of wall stones. The concrete structure becomes stronger, more resistant to frost and temperature extremes in principle, and also acquires moisture and bio-resistant 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 the construction site.
- Hollow stone is a block in the structure of which there are vertical voids, which are formed in accordance with the design of the structure during the production process. The specific design of hollow wall stone is determined by the desire of engineers to achieve certain performance properties, including weight reduction and more efficient thermal insulation (due to the air void buffer).
- Ordinary stone is a typical model of a masonry wall block, which is used in the construction of capital buildings with finishing.
Main parameters
Stones are designed and manufactured to certain standards. There are both unified general characteristics and arbitrary ranges that receive the appropriate marking. In terms of basic parameters, concrete wall stones are evaluatedfor the following set of indicators:
- The shape is a rectangular box.
- Color texture - set by the manufacturer, but usually neutral grays, browns and light yellows.
- Ends - usually flat, but grooves, tongues and tongues are also allowed. At least one end face must still remain flat.
- Internal filling: as already noted, stones can be produced full-bodied and hollow. In both cases, the weight should fit into 31 kg. The voids can be through, but they must be placed perpendicular to the support surface. The thickness of walls formed by stones with internal cavities must be at least 20 mm.
- The supporting surface is flat or with longitudinal grooves, the indentation of which from the sidewall can be at least 20 mm.
- Corners - straight or rounded.
Decorative stone
Also called facing and is used as a protective or decorative design for wall masonry. Has one or two outer edges. The peculiarity of this product is that it is used as a finishing material. If the standard wall models of stones directly form the load-bearing structure, then the facial modifications decorate it.
The function of a decorative stone also determines its design 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 durable plank with a natural texture. Although in this category, wall stone can benatural and artificial. Moreover, the assortment of the second group is more extensive, as it gives more structural and texture possibilities in manufacturing. As for the natural facial stone, most often these are solid cuts, characterized by a natural noble texture, for which they are highly valued. For example, a facade stone costs 80-100 rubles per piece. Thin large-format veneer is available on the market for several thousand rubles, which is explained by the complexity of its production and high decorative properties. By comparison, the cost of expanded clay concrete is 40-60 rubles / piece. And this despite the fact that standard concrete blocks perform a more important task of the frame element of the building.
Performance properties of stone
The combination of physical and mechanical performance properties 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 are:
- Compressive strength - from 7 to 20 MPa. Not the strongest side of concrete products, but, as already noted, this disadvantage is compensated by weight reduction.
- Frost resistance. Without obvious signs of deformation (stratification, peeling, chipping), the material is able to withstand from 15 to 50 defrosting-freezing cycles at extreme temperatures. Moreover, an important condition for verification is the preliminarysaturation of the structure with water, which expands in the frozen state and exerts a load on the structure of the stone shell.
- Humidity - coefficient no more than 12-15% depending on the type of product.
- Activity of radionuclides (natural) – about 350-400 Bq/kg.
- Thermal conductivity is an average of 0.3 W/(m °C), which is typical for expanded clay concrete and most porous cement-based blocks.
For each of the above properties, there are special test methods that are used in the factory before labeling. In most cases, reference samples, laboratory or field conditions are used for testing.
Material advantages
Much in the overall assessment of this stone depends on its type, manufacturing technology and specific conditions of use. 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:
- Affordability 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.
- Eco-friendly. Despite the need to use synthetic binders, and sometimes plasticizers with other chemical additives, regulations set stringent environmental safety requirements with limits allowed for use in residential construction.
- 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.
- Easy blocks. In practice, during operation, this advantage is imperceptible, however, during the construction process, it facilitates both the workflow and the transportation of material. In addition, it is worth adding the pliable structure of concrete stones, which allows you to easily adjust the shape of the blocks when installing non-standard structures.
If we talk about shortcomings, then almost all of them are the reverse side of positive qualities. Indeed, these are not the most durable products, and in some modifications they can even support combustion, but these nuances should be taken into account even at the design stages of a house. In accordance with them, designers are considering compensatory measures to reduce possible negative factors in the operation of an object made of a concrete wall block.
Conclusion
In different variations, the concept of concrete-block stones has been used by builders for a long time, but in recent years this direction is experiencing a new round of evolutionary development. Moreover, the spread of modular construction technology has become the engine of the new trend, into which blocks of foam and expanded clay concrete also organically fit. The cost of materials, averaging 50 rubles per piece, also corresponds to the principles of optimized housing. But does this mean that we are talking about low quality buildings? The question is ambiguous, since at home,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 gaining in price.
