What to do with natural material. Natural (natural) stone materials

2. NATURAL STONE MATERIALS

Natural stone building materials are materials obtained from unprocessed rocks, or from rocks that have undergone mechanical processing such as splitting, sawing, hewing, grinding, polishing, crushing followed by sieving, etc., but without prior thermal or chemical treatment .

Rocks are natural accumulations of mineral masses consisting of one (monomineral rocks) or several (polymineral) minerals. Mineral (from Latin minera - ore) is a natural body, approximately homogeneous in chemical composition and physical properties, formed as a result of various physical and chemical processes occurring in earth's crust. Each mineral has a specific chemical composition and characteristic physical and mechanical properties.

Based on their origin, rocks are divided into three groups: igneous or igneous (primary), sedimentary (secondary) and metamorphic (from the Greek metaforfo - to transform).

Igneous rocks were formed as a result of the cooling of a fiery liquid mass - magma, which tore apart the earth's crust and spilled onto its surface. Depending on the cooling conditions of the magma, igneous rocks are divided into deep (intrusive) and eruptive (effusive).

Deep rocks(granites, syenites, diorites, etc.) were formed as a result of the slow cooling of magma in the thickness of the earth’s crust under significant pressure upper layers. Under such conditions, rocks acquired a uniform crystalline structure as a result of the fact that large grains of various minerals firmly fused together.

Erupted rocks(basalts, andesites, diabases, etc.) were formed during the rapid cooling of magma on the surface of the earth. Under such conditions, complete crystallization of the cooling magma did not occur. Depending on the conditions of formation, the erupted rocks have a fine-grained, cryptocrystalline or amorphous structure. If gaseous products were slowly released from the viscous magma, a porous or pumice-like structure was formed. In addition, igneous rocks include clastic rocks, which were formed from tiny particles of crushed lava thrown to the surface of the earth during volcanic eruptions. These deposits remained in a loose state (volcanic ash, pumice) or, in the presence of natural cementing substances and under the pressure of the overlying layers, turned into dense cemented rocks (volcanic tuff).

Sedimentary rocks formed as a result of destruction (weathering) of igneous (primary) and other rocks under the influence of external conditions or as a result of the deposition of substances from any environment. Based on the nature of formation and composition, sedimentary rocks are divided into clastic rocks (mechanical sediments), clayey rocks, as well as chemo- and organogenic rocks.

Clastic rocks(mechanical sediments) - coarse products of mechanical destruction of igneous and other rocks under the influence of sudden changes in temperature, exposure to water and wind (breccias, conglomerates, sands, etc.). They are a loose mixture consisting of individual grains of destroyed primary rock; in a number of cases, loose mixtures were subjected to cementation with various natural substances, thereby forming solid rocks.

Clay rocks– dispersed products of deep chemical transformation of silicate and aluminosilicate minerals of parent rocks, transformed into new mineral species.

Chemical precipitation– chemogenic rocks formed during precipitation of mineral substances from aqueous solutions with their subsequent compaction and cementation (dolomite, magnesite, etc.).

Organogenic rocks formed as a result of the deposition of the remains of living (zoogenic) and plant (phytogenic) organisms, the skeletons and shells of which contained minerals. Such deposits, as a rule, were subjected to compaction and cementation (limestone, chalk, etc.).

Metamorphic, or modified, rocks formed in the thickness of the earth's crust as a result of significant modification of sedimentary or igneous rocks under the influence of high temperature, high pressure and other factors. Under these conditions, minerals recrystallized without melting, which contributed to an increase in the density of the resulting rocks compared to the original ones. As a rule, metamorphic rocks have a schistose structure, but sometimes they can retain the structure of primary rocks.

For natural stone materials, their petrographic characteristics, which makes it possible not only to establish the type of rock and make preliminary judgments about its quality, but also supplements the results of laboratory tests with such important data as color, degree of homogeneity and weathering of the rock, structure, composition, pattern characteristics, nature of splitting, surface properties and etc.

To compile a petrographic characteristic, they usually use a hammer, a steel needle, a magnifying glass, a hardness scale, a ruler with millimeter divisions and a 10% solution of hydrochloric acid. In this case, a large piece of rock is selected from the average sample, which most fully reflects all the characteristic features of this breed. Mainly pay attention to the following characteristics.

Size and shape of pieces very diverse. The selected piece of rock is measured in three linear dimensions and thus its shape is determined - it can be regular or irregular, cuboid, plate-shaped, parallelepiped, rhombic, spherical, etc.

The shapes of rock samples help determine the possibility of obtaining a particular type of stone material.

Color The composition of rocks depends on their mineralogical composition, impurities and degree of weathering. Typically, rocks are divided by color into six groups: white (almost colorless), yellow to red, green, blue to violet, dark gray to black, multicolored (variegated).

Limestones and gypsums usually have a white color; the presence of clay and impurities in them gives the rock yellow and brown shades. Granites and syenites are usually characterized by a gray or red color; darker shades of these colors indicate the presence of mica-biotite in the rock. When describing color, the presence of colored spots, veins, etc. is noted.

Shine The individual minerals that make up a rock are characterized by the freshness of the rock and its pattern. Conventionally, a distinction is made between bright (glassy), pearlescent (rainbow-colored), greasy, dull (shimmering) and matte (no shine). A glassy luster is usually characteristic of quartz, a pearlescent luster is characteristic of mica, and a greasy luster is characteristic of talc. The faded, dull appearance of minerals with rusty tones indicates great weathering of the rock.

The color of the rock, its uniformity and luster make it possible to determine the types of minerals that make up the rock.

Mineralogical composition rocks are determined by the external characteristics of the main minerals that make up the rock, by the size of their inclusions and uniformity of distribution, as well as by the type of cementing substance and its location.

Structure rocks are determined by examining a fresh fracture; it can be crystalline dense and granular, with different crystal sizes (fine-, medium-, coarse- and coarse-grained) - granite, syenite, fluorite, etc.; porphyried - for porphyries; glassy - in obsidians; oolitic - in limestones, granular - in sandstones.

Texture (addition) The rock and its homogeneity are also determined by a fresh fracture of the rock. It can be dense - slatey, scaly and fibrous in composition or porous - cellular, perforated and earthy in composition, with small or large pores. At the same time, the presence of fracturing, the size and direction of the cracks, as well as the presence of various inclusions in the rock are determined.

Cleavage- this property characterizes the ability of some crystalline minerals to split along certain smooth planes upon impact, the latter are called cleavage planes.

Different minerals have different cleavages: very perfect cleavage - minerals that are easily split (for example, mica exfoliates into thin sheets in one direction); perfect cleavage - minerals split along certain planes, forming smooth and shiny surfaces (for example, calcite has cleavage in three directions, and feldspars in two); imperfect cleavage is very weakly expressed (for example, apatite); there is no cleavage - the mineral splits in uncertain directions and produces uneven fracture surfaces (for example, quartz). Amorphous materials do not have cleavage.

Cleavage reduces the strength of the rock and makes it difficult to machine natural stone materials.

When splitting a piece of rock with a hammer, pay attention to the sound produced by the impact; a clear, dull or rattling sound gives an idea of ​​the density of the rock and the presence of hidden fracturing.

Cleaved surface can be smooth, uneven, wavy, torn, angular, conchoidal, spherical. In addition, it is necessary to indicate the nature of the split - smooth, fibrous, rough, earthy, etc.

Individual ribs are divided into blunt, sharp, cutting, etc. The roughness of the splitting plane and the nature of the ribs are significant indicators of the properties of rock products, determining the complexity of its processing and its adhesion to cement stone.

Presence of carbonates in a rock sample is determined by exposing it to a 10% solution of hydrochloric acid, which causes “boiling” on the surface of the rock sample containing carbonates.

Hardness- the ability of a material to resist the penetration of another harder body into it. This property is important in the mechanical processing of stone materials.

The hardness of homogeneous stone materials is determined by a hardness scale, in which ten specially selected minerals are arranged in such a sequence that the next mineral in order leaves a line (scratch) on the previous one, but is not drawn by it itself (Table 1).

Table 1

Material hardness scale

For example, if the test material is scratched by apatite, and leaves a mark (scrat) on fluorspar, then its hardness corresponds to 4.5.

To have reliable data on the hardness of a stone, it is necessary to test at least three separate samples, making three determinations for each sample, as indicated above. According to the petrographic characteristics of the rock sample and the data in Table. 2, you can determine the mineralogical composition of the rock under study, and then, based on the content of minerals, their color, structure and cleavage, you can determine the type of rock and from Table. 3 - its properties.

Examples of descriptions of external features and petrographic characteristics of rock samples:

A. A sample of irregular shape, close to parallelepiped, measuring 120 x 180 x 270 mm. The color is light gray. A rock made from white orthoclase with a glassy sheen, muscovite, quartz. Quartz and muscovite are evenly distributed at approximately 20% each. The rock is dense, of medium crystalline structure. The split is close to regular, medium roughness, sharp ribs. According to petrographic external features, the rock under study is granite.

B. A cube-shaped sample measuring 160 x 170 x 190 mm, gray and uniform in color. The breed is homogeneous and dense. Hardness 5. The split is regular with a slightly rough surface, the ribs are sharp. No signs of weathering were found. A drop of hydrochloric acid solution caused a “boiling” on the surface of the sample. According to petrographic external features, the rock under study is limestone.

table 2

CHARACTERISTICS OF ROCK MINERALS

Table 3

MAIN INDICATORS OF ROCK PROPERTIES

Fence made of shell rock blocks

Natural stone materials are used for the construction of houses and building components. For the construction of house components, such as foundations, plinths, walls, stoves, various natural stone materials are used.

2. Igneous rocks.

3. The main types of building materials belonging to the group of sedimentary rocks.

4. The main types of building materials belonging to the group of metamorphic rocks.

5. Natural building stone materials and products.

Natural stone materials and products are obtained from various rocks, which are divided into igneous, sedimentary and metamorphic.

Igneous rocks

The most common representatives of metamorphic rocks are marble, hornfels and quartzites, as well as schists, gneisses, various mylonites and cataclasites. Marble is a recrystallized limestone, and marble can be ground and polished well. Physico-mechanical properties The composition of metamorphic rocks varies over a fairly wide range.

Marble is a holocrystalline metamorphic carbonate rock that was formed as a result of the recrystallization of dolomite or limestone. For construction needs, the following rocks are used as marble: dense dolomite, marbled limestone, carbonate breccias and carbonate conglomerates, and official stone.

Marble contains quite a large amount of impurities of other minerals, such as feldspar, hematite, chalcedony, limonite, quartz, pyrite and organic compounds that affect its quality. For example, the content of quartz impurities makes it difficult to saw and polish marble. Marble has the following physical properties:

density depending on the amount of impurities from 1900 to 2800 kg/m 3 ; fracture resistance 10-30 MPa; compression strength 100-250 MPa; porosity no more than 1%; water absorption within 0.15...0.50%; hardness 3-4. Fine-crystalline marble with a jagged connection of grains is the most durable and best polished. Marbles are distinguished by an exceptional variety of patterns and colors. The color of marble depends on the impurities.

Quartzites are a metamorphic rock composed mainly of quartz grains, macroscopically indistinguishable from each other, which merge into a continuous dense mass with a conchoidal or splintered fracture. The formation of quartzite is associated with the recrystallization of quartz sandstones during regional metamorphism.

Quartzites also include recrystallized rocks that were formed from siliceous gels of chemogenic origin. They make up the main part of the formations of ferruginous quartzites, which, even with strong metamorphism, retain high porosity, unlike quartzites of clastic origin and are easily destroyed. Quartzites of chemogenic origin are characterized by a high (up to 95-99%) SiO 2 content, high (up to 1710-1770°C) fire resistance and mechanical strength.

Quartzites with a high SiO 2 content (up to 98...99%) are used to produce metallic silicon and its alloys, for the manufacture of refractory silica products, and as a flux in metallurgy. Quartzites are widely used as a facing and decorative building material.

Natural stone materials and products

Wall made of rubble stone

Natural stone materials and products are obtained from rocks by crushing, splitting, sawing, trimming, grinding and polishing. They are mined in quarries and processed in special factories. They are supplied for construction in the form of rubble stone, crushed stone, sand or wall stones and blocks, slabs and profiled products.

Rubble stone is irregularly shaped pieces of rock, weighing 15-40 kg, consisting mainly of limestone and sandstone. They are used for laying foundations and walls of both underground and above-ground parts of the building. Wall stones and blocks are obtained by sawing from limestone and tuff. Stones are used for laying the walls of buildings, bridge supports and cladding.

The blocks are used to make slabs to specified dimensions with textured processing of the front surfaces. Profiled products - steps, window sills, cornice parts - are obtained by processing blocks and slabs on special machines.

Among the many different types of natural stone materials used today in the construction of private houses, shell limestone occupies a special place. Such houses made of shell limestone can often be found in southern countries CIS, in particular in Ukraine, Georgia and Armenia.

Natural stone material made of limestone is also used for laying walls. It is also called rubble stone and can be torn, slab or bedded. The stone used in the construction of walls must be clean, without cracks, delaminations or other defects.

Gravel is a product of the natural destruction of rocks, consisting of rounded pieces. Like sand, gravel can be gully, river or sea.

Gravel and pebbles are loose stone materials. They are small pebbles of different shapes and colors. Gravel occurs with pebbles ranging in size from five to eighty millimeters. If the size of the gravel is up to twenty millimeters, then it is classified as small gravel, if from twenty to forty millimeters, then it is classified as medium gravel, and from forty to eighty – as coarse gravel.

Crushed stone is produced by crushing larger stones in special stone crushers. It is produced in the same sizes as gravel and is used as a filler for concrete mixtures. The pieces of crushed stone have an acute angular shape. Before using, crushed stone and gravel are first washed with water. Natural stone materials are characterized by high performance, frost resistance and wear resistance

Rocks are natural formations, making up the various geological bodies from which the earth’s crust (lithosphere) is built. They are natural combinations or mechanical mixtures crystalline mineral grains of different composition, along with which amorphous matter and organic residues may be present; Rocks include mixtures of liquid mineral substances (inorganic and organic) found in the earth's crust.

Based on their origin, rocks are divided into three groups: igneous (effusive and intrusive), sedimentary and metamorphic. Igneous rocks are rocks formed directly from magma (a molten mass of predominantly silicate composition formed in the deep zones of the Earth), as a result of its entry into the upper horizons of the Earth, cooling and solidification. Depending on the solidification conditions, intrusive (deep) rocks are distinguished into effusive (outpoured) rocks.

Sedimentary rocks (SRP) are rocks that exist in thermodynamic conditions characteristic of the surface part of the earth's crust, and are formed as a result of redeposition of weathering products and destruction of various rocks, chemical and mechanical precipitation from water, the vital activity of organisms, or all three processes simultaneously .

Metamorphic rocks are rocks formed in the thickness of the earth's crust as a result of changes (metamorphism) of sedimentary and igneous rocks due to changes in physicochemical conditions. Due to the movements of the earth's crust, sedimentary rocks and igneous rocks are exposed to high temperatures, high pressures and various gas and water solutions, and they begin to change.

Natural stone is a natural building material. Natural stone refers to all rocks used in construction. For example: marble, granite, tuff, slate, sandstone, limestone and onyx.

Natural stone is one of the oldest materials used by people for building houses or cladding facades. Thanks to its beauty, strength and durability, natural stone is a decoration for palaces, temples, estates or ordinary houses. Most often, natural stones are used for cladding buildings, both inside and outside. For interior cladding, special marble or granite wallpaper is used. The combination of mosaic designs and patterned structures gives beauty and richness to the appearance. Facade cladding with natural stone is also very popular. Firstly, it has an attractive appearance, and secondly, it is a very environmentally friendly and at the same time very durable material. Natural stone is also wear-resistant, frost-resistant and almost does not absorb moisture. The disadvantage of this material is its relative high cost.

History of education

In later geological epochs When the earth's crust had already reached significant thickness, magma spilled onto the surface in small quantities, mainly during volcanic eruptions. During a volcanic eruption, magma was released into the air under high pressure and, as it cooled, was very quickly penetrated by expanding gases. Some of the magma spread over the surface of the earth in thin layers, quickly cooling and becoming saturated with gases. As a result, rocks of an amorphous structure with high porosity were obtained in the form of accumulations of loose particles or in the form of continuous massifs. Such rocks are called loose volcanic or volcanic cemented.

All primary or igneous rocks of deep, eruptive and volcanic origin, exposed to atmospheric phenomena (temperature changes, humidity, wind, etc.), undergo a process of weathering (destruction). The destruction process also affected many minerals that form igneous rocks. The organic world (plant and animal) and chemical processes also took part in the destruction of primary rocks. As a result of weathering of igneous rocks, new rocks called secondary or sedimentary rocks were formed. Most of The upper layers of the earth's crust in our time consists of sedimentary rocks and they play a greater role than igneous rocks. The formation of sedimentary rocks followed different paths. Some of them are the same igneous rocks, but disintegrated into parts and sorted by water according to the size of the particles or their weight. Such rocks are called: clastic or mechanical deposits.

Types of natural stone materials

All stone materials used in construction can be divided into two main groups: 1) materials used in their original form (without processing), 2) materials suitable for construction purposes only after appropriate processing

Marble. The name “marble” comes from the Greek “marmaros”, which means brilliant. This granular crystalline rock resulted from the recrystallization of limestone and dolomite under the influence of high temperature and pressure. But in construction, the word “marble” refers not only to this stone, but also to other rocks similar to it. For example, marble-like limestones and dolomites. The vast majority of marble lends itself well to processing with any tools, which allows you to expand the already rich range of its colors. For example, polishing enhances the pattern and color of marble, polishing reduces its brightness and clarity, and the texture of chipping completely hides the pattern, but significantly brightens the overall background.

Based on decorative properties, processing capabilities and breadth of application, marble is divided into white, gray and colored. White marble contains practically no impurities, so it is often homogeneous and has a fine- and medium-grained structure. This marble is easy to process. The most valuable is considered to be fine-grained white marble, which is famous for its warm tone and the fact that it is translucent. This stone is also called statue stone, as it is widely used in sculpture. White marble is considered a very capricious home stone, which is due to its special structure: it is poorly protected from staining and yellowing. This applies primarily to inexpensive varieties. Such marble should be used with caution when cladding facades. Of course, his specifications allow you to survive both severe frosts and mechanical damage, but after some time it may lose its beauty and shine, fade and become covered with yellow spots.

Gray marble is most often heterogeneous and has layered colors. The characteristic pattern of gray marble is “cloudy” and “snowy landscape”. This type of marble is easy to process and polish. It, like white marble, is used for external and internal cladding. Among colored marbles, blue-blue varieties are considered rare. All of them lend themselves well to polishing. The heat-resistant qualities of marble make it possible to use this stone for external cladding of fireplaces or rooms associated with high temperatures. The water absorption coefficient of marble, like that of granite, is quite low, so it can be used in the construction of pools, bathtubs and fountains.

Granites. Granite (from the Latin “granum” - grain) is the most common rock. It has a pronounced granular-crystalline structure and consists mainly of feldspars, quartz, mica and other minerals. Based on the size of the grains, granites are divided into fine-grained, medium-grained, and coarse-grained. The color palette of granite is extremely rich. Most often, gray granite is found in different shades - from light to dark. There are also pink, orange, red, bluish-gray and sometimes bluish-green granite. Granites with blue quartz are extremely rare. The following varieties of granites are considered the most decoratively valuable: fine-grained light gray with a blue tint, deep dark red and greenish-blue.

Granite is well polished, maintaining a mirror-like surface shine for a long time, and is easy to carve, which allows you to create various textures. To create decorative effects, some types of granites are subjected to heat treatment. Light gray granites then acquire a delicate sugar-white hue. Due to its high mechanical properties and performance properties, granite is widely used in the construction of basement structures, cladding embankments, building facades, and floors. Fine-grained granite is used in sculpture (since its structure allows impact processing), and coarse-grained granite is used for the construction of monumental structures. Very often, granites include syenites, which differ from granites in less pronounced grain size and the absence of quartz (due to this they are better processed). Syenites are darker than granites: they usually have gray, dark gray, gray-blue, dark pink colors. They are used in construction in the same way as granites.

Tuff- light, cemented, porous rock. Having high decorative properties, it is a valuable finishing building material. According to the method of geological formation, the main types of tuffs are distinguished: volcanic, calcareous and siliceous. Calcareous and siliceous tuffs form, in contrast to volcanic tuffs, a group of rocks united by genesis - the deposition of calcium carbonate or siliceous substance from solution in places where mineral springs reach the earth's surface. As a result of the weathering of rocks, water dissolves chemical compounds, forming a solution, from which secondary precipitation and the formation of new rocks occur. When deposits occur as a result of inorganic chemical processes, "scale" and tuffs are formed. At exit points earth's surface water sources, the pressure drops and carbon dioxide is removed from the solution, as a result of which the compounds dissolved in the water disintegrate and a precipitate falls in the form of calcareous or siliceous tuffs.

Slates– these are rocks with an oriented arrangement of constituent minerals and well-defined foliation, i.e. ability to split into thin plates. This is a stone very different in appearance and properties. Rather, we can talk about a whole group of finishing stones, united under the general name - slate. For example, hardness. For slate it ranges from 2 to 6 on the Mohs scale. This roughly corresponds to the hardness of gypsum (2) and orthoclase (6). There is also a wide variation in the water absorption coefficient - from 0.01 to 3%. All types of slate have one thing in common - the durable layered (slate) structure of this material, which creates a unique, expressive surface texture. Therefore, this stone allows you not to create the same type of interiors.

Sandstone is a sedimentary rock that is formed as a result of exposure to moisture, wind, and temperature changes that have a destructive effect. Sand can be fine or coarse. Under the influence of time, the reverse process is also possible, when such a material hardens, this requires the presence of a fastening agent and pressure. Sandstone comes in the following varieties (based on mineral composition): oligomict and polymict. When the basis of this raw material is quartz (90% of the mass or more), then it belongs to the oligomict group; there are also half-spar-quartz, mica-quartz and other varieties of this material (the mass fraction of quartz in them is from 60% to 90%) . It can also be either homogeneous or layered. In the case when this material is dominated by feldspar over quartz or, for example, more complex mixtures where cement from fine-grained clastic material is also present, this variety belongs to the polymictic species.

In construction, this type of raw material is widely used both as rubble stone and in facing work. It is resistant to various types of environments, temperature changes, moisture, and frost-resistant. It is an environmentally friendly product and has a bactericidal effect. When cut, it has a bizarre, always individual pattern. In decoration, as an element of the interior or exterior, it is used for finishing fireplaces, cladding plinths, floors, sidewalks, walkways, and stairs. At the same time, there are several ways to process sandstone: tumbling - when it is given the shape of a stone with rounded edges, or carrying out a single or double chip on the front side. The use of natural materials in decorative works always guarantees the uniqueness and originality of the object.

Limestone- sedimentary rock of organic, less often chemogenic origin, consisting mainly of CaCO 3 (calcium carbonate) in the form of calcite crystals of various sizes. It consists mainly of shells of marine animals and their fragments, called shell rock. Calcium carbonate, which is part of limestone, can dissolve in water and also slowly decompose into carbon dioxide and the corresponding bases; the first process is the most important factor in the formation of karst, the second, occurring at great depths under the influence of the deep heat of the earth, provides a source of gas for mineral waters. During metamorphism, limestones recrystallize and form marbles. Limestone was widely used as a building material, and fine-grained varieties were used to create sculptures. Firing limestone produces quicklime, an ancient binding material still used in construction. One of the main building materials obtained from limestone is limestone crushed stone, which is widely used in road construction and in the production of concrete.

Onyx- a mineral, a chalcedony (fibrous) variety of quartz, in which minor impurities create plane-parallel colored layers. The banded variety of marble is often called Mexican onyx or Algerian onyx. Color - brown with white and black patterns, red-brown, brown-yellow, honey, white with yellowish or pinkish layers. Onyx is especially characterized by plane-parallel layers of different colors. Agate and carnelian onyx (“sardonyx”, “sard”) have been used by people since prehistoric times to make small carved artistic objects (glyptics), as well as carved cylinder seals. This is one of the most valuable ornamental stones. Calcite (marble, etc.) types of onyx are widespread and are among the most accessible and inexpensive decorative and ornamental materials. Both before and now, they are widely used in serial household and large products: all kinds of small and medium plastic, onyx vases, boxes, candlesticks, tabletops. It is also used in mosaics and cladding. Relatively inexpensive ornamental stone.

K category: Stone cladding

Natural stone materials

Materials and products mined and manufactured from rocks using mechanical processing methods are called natural stone materials. Examples of such materials are facing slabs made of grayite, marble, limestone, as well as crushed stone.

Rocks- these are significant accumulations of minerals in the earth's crust, having a more or less constant composition.

Minerals are products of natural reactions that have a certain chemical composition and characteristic physical properties.

The minerals involved in the formation of a rock are called rock-forming minerals for that rock. Depending on the conditions of formation, rocks are divided into igneous (primary), sedimentary (secondary) and metamorphic (modified).

The complexity of processing natural stone and the quality of products obtained from it depend on the mineralogical composition, structure (structure, texture, porosity, fracturing, workability, abrasiveness, anisotropy) and physical and mechanical properties of the rock.

The structure of a rock is characterized by structural features determined by the size, shape and ratio of the minerals that form it. The structures are holocrystalline, semi-crystalline, semi-crystalline and glassy. The structure largely determines the decorative qualities of the rock.
Rock texture refers to the relative arrangement and distribution of rock-forming minerals. Textures can be massive, linear-parallel, banded, layered, porous.

The porosity of a rock is determined by the ratio of the volume of voids to the volume of the rock mass. Igneous rocks have the least porosity. Thus, the porosity of granites is 1.2%, diabases and gabbros - 1%, quartzites - 0.8%. The porosity of sedimentary rocks reaches 20-25%.

Fracture is the presence of cracks in a rock. This is a characteristic property of all rocks without exception. Fractures can be open, closed, closed and hidden. When processing stone, the type of fracturing and false layering of the stone are taken into account, i.e. the ability of the rock to split along parallel planes.

Machinability- this is the ability of a rock to take a given shape and texture of the front surface when exposed to various tools.

The abrasiveness of rock is characterized by the wear of stone-processing tools during friction. It depends on the content of natural abrasive minerals in the rock (quartz, feldspars, flint, corundum, garnet). Coarse-grained rocks with sharp-angled grains have higher abrasiveness than fine-grained rocks with rounded grains.

Anisotropy- this is the ability of rocks (especially granites) to split more easily in certain directions. Anisotropy is manifested to a large extent in micas contained in granites.

The anisotropy of the rock is taken into account when determining the distance between the sockets for wedges when splitting blocks.

Natural stone materials. They are obtained from rocks. They have high weather resistance, durability and beautiful coloring.

Rocks are divided into three main groups: primary, secondary and metamorphic.

Primary (igneous) rocks were formed by the cooling of molten magma. These include granite, syenite, diorite, labradorite, gabbro, basalt, diabase. These materials have a dense structure, heavy weight, high mechanical strength and thermal conductivity. A porous type of igneous rock - volcanic tuff - with a low density (1000-1500 kg/m3) has significant mechanical strength and good thermal insulation properties. The listed stone materials are used for preparing crushed stone, laying foundations of buildings, cladding walls and floors, and making stair steps.

Secondary rocks were formed from the impact of water, ice, variable temperature, gases (clastic and loose rocks) on primary rocks, as well as as a result of the deposition of shells and shells of simple organisms at the bottom of reservoirs (sedimentary rocks).

When primary rocks are destroyed, gravel and sand are formed, which serve as raw materials for the production of concrete and mortars. Sedimentary rocks include gypsum, dolomite, and calcareous tuffs.

Limestones are used as raw materials for the production of binders, and also as walling and facing materials.

Metamorphic rocks - marble, gneisses, quartzites - were formed as a result of the influence of various external factors on them. For example, marble is limestone that has acquired a crystalline, dense structure due to pressure and high temperature. Metamorphic rocks are used for cladding walls of buildings and flooring in sales areas of large retail enterprises.

Facing slabs and stones are made by sawing or splitting blocks of natural stone, followed by mechanical processing. Rocks used for the manufacture of facing slabs must have a compressive strength of at least 5 MPa, frost resistance of at least MP3 15. Slabs for flooring and wall cladding have a rectangular shape with a side size of 200... 1000 mm. Large slabs (up to 3 m2) are made from stronger rocks, and smaller slabs (up to 1 m2) are made from less durable ones. The facing slabs are given a variety of textures on the front surface - mirrored, polished, sawn, dotted, grooved, corrugated. The high durability of facing made of stone slabs requires 5...8 times less operating costs than finishing with colored solutions or silicate and lime paints. It is especially cost-effective to use granite, marble, limestone, and tuff in areas where these rocks are mined.

Mineral binders. They are produced by firing in kilns from natural stone materials (gypsum, anhydride, dolomite, magnesite, limestone). The pieces obtained after firing are turned into powder by grinding. The smaller the grain size after grinding (grind fineness), the higher the activity of the binder. When mixed with water, the powder turns into a liquid (dough-like) state, then gradually hardens, turning into a stone-like substance. The process of hardening of binders is called setting. The setting time is counted from the moment the binder is mixed with water.

The substance should set only after it has been placed in the mold. Binders can harden in air or water. Binders that harden in air are called air binders; those that harden in water are called hydraulic binders.

Air binders - air lime, building gypsum. The lime is supplied to the construction site unslaked. In this form it is called kshelka. When lime is slaked with water, it disintegrates into a fine white powder - fluff. When the fluff is mixed with water, lime paste is obtained, which is used to prepare masonry and plaster mortars. Construction gypsum is produced by firing natural gypsum and then grinding it into a fine powder. When gypsum is mixed with water, a gypsum dough is formed, which gradually thickens and turns into a stone-like state. When exposed to moisture, the strength of hardened gypsum is significantly reduced, so it is used for plastering interior walls, making partitions, and architectural details.

Hydraulic binders - Portland cement, aluminous, lime-pozzolanic and lime-slag cements - are used for the preparation of concrete and mortars. Portland cement is most often used in the construction of buildings. It is produced by firing a mixture of limestone and clay. After firing, the sintered mixture - clinker - is ground into a fine powder. The powder, mixed with water, turns into dough, sets and begins to harden. During the first seven days, hardness and strength increase rapidly, then slow down and reach the calculated values ​​on the 28th day. Normal hardening of cement paste occurs at a temperature of plus 15 ° C in a humid atmosphere. At temperatures of 0°C and below, the cement paste freezes and strength does not increase. In factories, when making concrete products, their hardening is artificially accelerated by heating (heat treatment) with steam or other methods. Within a day of heat treatment, 50...70% of the design strength of concrete is achieved. Such a product can be released from the factory and placed into a case. The plant guarantees the remaining 50 - 30% of strength within 28 days after manufacturing the product. The strength of cement is characterized by its grade. The grade is set according to the bending strength of special samples. The samples are made from cement mortar with a composition of 1: 3 (by weight) and are tested 28 days after production. The cement industry produces Portland cement grades 300, 400, 500 and 600.

Hardened Portland cement, which is under constant influence of water (for example, in the foundations of a building), turns out to be unstable and collapses, especially if the waters washing it contain dissolved salts and acids. In these cases, concrete is prepared from alumina cement, lime-pozzolanic Portland cement and Portland slag cement.

Cement is transported in special railway carriages and cement trucks equipped with devices for pneumatic loading and unloading, as well as in multi-layer paper or cellophane bags; stored in bunkers, silos or in closed rooms with a floor raised above the ground. It should be taken into account that when stored, even under the most favorable conditions, the activity of cement decreases after three months by 20%, and after a year to 40%.

Natural stone materials are materials and products obtained by mechanical processing (crushing, splitting, sawing) of rocks. In this way, facing slabs, stones and blocks for laying walls, and crushed stone are obtained. Some rocks (sand, clay, gravel) are used without treatment. All these types of building materials are called nonmetallic.

Thanks to its diverse properties, high strength, durability and unlimited reserves, stone has been a universal building material since ancient times. Monumental structures made of natural stone have survived to this day: Egyptian pyramids, Greek and Roman temples, arenas and aqueducts, cathedrals of Ancient Rus'.

With the advent of artificial stone materials (concrete, ceramics) and industrial methods of constructing buildings and structures, the role of natural stone in construction has changed significantly. Currently, natural stone is mainly used as a filler in concrete, as a raw material for the production of ceramics, binders, glass, etc., as well as for cladding buildings and engineering structures, as a local building material for masonry walls.

Natural stone materials are classified by density (heavy with a density of more than 1800 kg/m3 and light with a density of less than 1800 kg/m3); compressive strength (for grades from 4 to 1000, with light stone materials having grades up to 200, and heavy ones - from 100 and above) and frost resistance.

Technical requirements for natural stone materials and products are established by the relevant GOSTs and TUs, depending on the purpose of the material and the operating conditions of the structure or structure.

According to the degree of processing, a distinction is made between roughly processed stone materials (sand, gravel, crushed stone, rubble stone) and piece products (sawn piece stones and blocks for walls, slabs and profile products for external and internal cladding of buildings and structures).

Natural stone materials