The functional properties and reliability of building materials are determined mainly by their physical and chemical properties, which include density, bulk density, porosity, attitude to low temperatures, water absorption, frost resistance, resistance to aggressive environments, etc. Definition of these indicators and methods for their calculation are set out in the theoretical foundations of commodity science. Here we give a description of the properties specific to building materials and their indicators.
Frost resistance is the ability of a material in a water-saturated state to withstand repeated alternating freezing and thawing without visible signs of destruction and without a significant decrease in strength. Some building materials (walling, roofing) that come into contact with water and outside air gradually deteriorate during operation due to the fact that the material is saturated with water, which, when frozen, increases its volume (by approximately 9%), which leads to the destruction of pores.
Frost resistance of materials depends on strength and density. Dense materials with low water absorption are frost-resistant. Frost resistance tests are carried out in refrigeration chambers at temperatures below - 17°C. The number of cycles can reach from 10 to 200. Frost-resistant materials are those in which, after the specified number of cycles, there are no cracks, delamination, a decrease in strength of no more than 15%, and a weight loss of no more than 5%. Based on the number of freezing cycles they can withstand, building materials are divided into MRZ (F) grades: 10, 15, 25, 35, 50, 100, 150, 200.
Thermal conductivity is the property of a material to transfer heat. Thermal conductivity depends on the type of material, the nature of the pores, the amount of porosity, and humidity.
In porous materials, heat passes through pores filled with air, the thermal conductivity of which is very low. Therefore, the thermal conductivity of the material is judged by the porosity value - the greater the porosity, the lower the thermal conductivity.
The ability of a material to withstand high temperatures without destruction is called fire resistance. Based on fire resistance, materials are divided into three groups: fireproof (brick, asbestos-cement materials), difficult to burn (felt impregnated with clay mortar) and combustible (wood, roofing felt).
The ability of a material to withstand prolonged exposure to high temperatures without deformation is called fire resistance. This indicator is important for materials used in the manufacture of stoves and pipes.
Strength is the property of a material to resist destruction under the influence of stresses arising from loads and other factors. Most often, building materials experience compressive or tensile stress. Natural stones and bricks resist compression well, but are less resistant to tension (10-15 times). Wood and steel work well in both compression and tension.
Strength is usually characterized by the failure stress index and is calculated by dividing the load by the cross-sectional area of the sample. The breaking stress in compression for cement, asbestos-cement products, and bricks is conventionally called “grade.” Ordinary clay brick can be grades from 75 to 300, Portland cement from 300 to 800. The grades are standardized by GOSTs.
For many building materials, an important indicator is resistance to aggressive environments. This indicator is also called chemical (or corrosion) resistance. This property is especially important for materials of foundations, basements, sewer pipes, and sanitary equipment. The most resistant are ceramic materials, glass, and special bricks. Sand-lime brick, for example, is unstable to the action of carbonic acid dissolved in water, so it is not used for foundations.
For materials of organic origin (primarily wood), an important property is biostability - the ability to withstand the destructive effects of plant and animal organisms (fungi, mosses, lichens). They increase biostability by treating with antiseptics.
A comprehensive indicator of the quality of building materials is durability, characterized by service life.
Service life is the time during which a material or product, during operation, retains its properties at a level that ensures its functions. The service life is determined by strength, frost resistance, wear resistance, resistance to aggressive environments, and biostability. The service life is affected by the aging of the material occurring under the influence of the atmosphere and other factors. This is especially important for polymer materials, cements, etc.
Harmlessness is characterized by the ability of a material not to release substances into the environment in quantities harmful to human health. In this regard, polymer materials (linoleum, facing tiles, etc.) are subjected to thorough sanitary-chemical and toxicological testing. These groups of properties include electrification, also characteristic mainly of polymer materials. Electrification has a harmful effect on the human body and increases pollution. To remove electrification, antistatic agents are used.
Aesthetic properties are often decisive when choosing finishing materials, especially for interior decoration, such as wallpaper, tiles, linoleum, etc. These properties are determined by color, pattern, texture, shine, shape, texture. Wood, glass, ceramics, and polymer materials have high aesthetic properties.
Among the factors that determine the consumer properties of building materials, the following are of primary importance:
Feedstock, its composition and structure;
Production method (increasing porosity, reducing the volumetric mass of bricks during firing);
Application of protective and decorative coatings (affect protective properties - mechanical strength, wear resistance, chemical and water resistance, hardness, increasing aesthetic properties (glazing of ceramic tiles).
An important aspect is not only the production of high quality building materials, but also the preservation of quality during storage and transportation. It is especially important to comply with the rules of packaging and transportation for fragile building materials (glass, ceramics). For mineral binders, in addition to these rules, it is important to follow the correct storage regime. When humidity increases or moisture enters, these materials can completely lose their consumer properties.
Basic concepts, characteristics of classifications, classification by purpose All building materials and building structures can be classified into groups according to various criteria: type of product (pieces, rolls, mastic, etc.) basic raw materials used (ceramic, polymer, etc.) production methods (pressed, roll-calender, extrusion, etc.) purpose (structural, structural-finishing, decorative-finishing.) specific areas of application: roofing, heat-insulating, etc.) (wall,
origin natural (natural) and artificial. chemical composition (organic, inorganic) according to the degree of readiness for use (raw materials - lime, cement, gypsum, untreated wood, etc., semi-finished materials - fiberboard and chipboard, plywood, beams, metal profiles - materials ready for use - glass blocks, bricks, ceramic facing tiles, etc.) The division of SM into groups can be made not only by general characteristics (isotropic but also by individual anisotropic ones; particular characteristics are especially heavy, lightweight, light, especially light, by density, by fire resistance , according to frost resistance.)
The PRODUCTS group includes carpentry (window and door units, parquet), hardware (locks, handles, etc.), electromechanical (lighting fixtures, sockets, switches, etc.), sanitary, pipes and fittings. PRODUCTS also include SC parts: concrete and reinforced concrete wall and foundation blocks; beams, columns, floor slabs and other products of reinforced concrete plants and construction industry enterprises; More complex structural elements (trusses, frames, arches, shells, flights of stairs) often belong to the STRUCTURE group.
The names of structural buildings also determine the names of the SM and SI classification groups: wall, roof, heat-, sound-proof, acoustic. Construction materials and products: 1. Structural: Structural for enclosing structures, heat and sound insulating roofing, hydro- and vapor barrier, sealing for translucent fences for engineering and technical equipment for special purposes (heat-resistant, fire-resistant)
Structural and finishing: for the front layers of sandwich-type enclosing structures. for fencing of balconies and loggias for floors and stairs for partitions for suspended (acoustic) ceilings for stationary equipment and furniture for road surfaces Finishing: for exterior decoration of buildings and structures for interior decoration for special decorative protective coatings (anti-corrosion, fire retardant)
Architectural and construction requirements for SM The main products of the architectural and construction industry SM and SI requirements for building materials are conditionally classified into 3 groups: functional: (general construction, operational, sanitary and hygienic) aesthetic economic
The first subgroup of functional architectural and general construction requirements is determined by the type and purpose of M or SI, ease of transportation and storage, manufacturability of use, regardless of the operating mode of the structure in which it will be used. The second subgroup of functional requirements relates to the qualitative characteristics of materials and SI, almost exclusively for the operational requirements of individual industrial premises. defined buildings, structures, subgroups of structures will be laid out, where “in this case”. are called
Recently, especially in connection with the widespread introduction of synthetic and polymeric SM and SI into construction, sanitary and hygienic requirements have acquired particular importance. Aesthetic requirements for shape, color, pattern and surface texture of SM and SI are allocated to a special group. In addition to objective factors, these requirements are not free from the general artistic concept of the project and even from the subjective opinion of the author-architect. No less important is the group of economic requirements that determine the technical and economic efficiency and feasibility of the development, production and use of one or another SM and SI. Mandatory parameters of the customer’s economic requirements are a limit price (according to the estimate) and durability.
Operational and technical properties of SM Physical structural (density, porosity, volumetric mass) properties of SM negative moisture transfer, in relation to the action of temperature water permeability, water and (water absorption, humidity, water resistance, frost resistance) properties characterizing the relationship of SM to the action of heat (fire resistance, thermal conductivity, fire resistance) Mechanical strength, hardness, abrasion Chemical Corrosion resistance
Most modern SMs are capillary-porous bodies. Therefore, the most important indicator that influences many properties of SM is porosity - the degree to which the volume of the material is filled with pores - spaces, cavities between structural elements. The pores may contain gas (air) or liquid. There are micropores (0.001 -0.01 mm) and macropores (0.1 -1.2 mm), open or closed. Porosity is determined by the formula P = Vpore/Vo * 100% Based on porosity, SMs are divided into low porosity - P 50% (foam plastics - P = 99%.
The true density of a material is the ratio of the mass of a material in an absolutely dense state to the volume in an absolutely dense state (density of a substance). The average density of a material or simply density is the ratio of the mass of a material in its natural state (with voids, pores, cavities) to the volume in its natural state. SM densities: Concrete = 1800 -2600 kg/m 3 Steel = 7850 kg/m 3 Brick = 1400 -1900 kg/m 3 Glass = 2400 -2600 kg/m 3
The hygroscopicity of SM is its ability to absorb water and water vapor from the air. The water absorption of SM by volume is determined by the formula *100%, where is the mass of the samples in a dry state - the mass of the sample in a moistened state, V is the volume of the sample. Water absorption of SM by weight is determined by the formula *100%,
For some highly porous CMs, water absorption by mass can be more than 100%. Volumetric water absorption is always less than 100%. =150% wood, 12% brick, 3% heavy concrete, 0.5% granite, steel and glass do not absorb water. Moisture release is the ability of a material to release water in the presence of appropriate environmental conditions (low humidity, heating, air movement). Moisture loss is expressed by the drying rate of the SM as a percentage of the mass (or volume of the sample) lost per day at a relative air humidity of 60% and a temperature of 20 C 0.
Humidity W - moisture content in the material, related to the mass of the CM in a wet state in % (significantly less than its total water absorption) Water permeability - the ability of the CM to pass water under pressure. The value of water permeability is characterized by the amount of water passing through 1 cm 2 of pressure area within an hour; the value being tested is closely related to the corresponding material, especially according to GOST. from which the degree of dense character at constant is determined by the water permeability of the structure of the material. waterproof (steel,
Water resistance - characterized by the ratio of the ultimate compressive strength of a material saturated with water to the ultimate compressive strength of SM in a dry state by the coefficient Kr. Kp = 1 for metals and glass. If Kr
Thermal conductivity is the ability of a material to transmit through its thickness the heat flow that occurs when there is a temperature difference on the surfaces. This property of the heat passing through a wall made of the tested CM with a thickness of 1 m (a) and an area of 1 m 2 (A) over a period of 1 hour (t) is assessed at a temperature difference of C 0. Fire resistance is the ability of a CM to retain physical properties when exposed to fire and high temperatures developing in fire conditions
In relation to the effects of high temperatures, SM: non-combustible - do not ignite, do not smolder, do not char (concrete, brick, metal, stones). difficult to burn - they char, smolder, ignite with difficulty, and when the source of fire is removed, their combustion and smoldering stop (asphalt concrete, fiberboard). combustible - burn or smolder after removing the source of fire (wood, roofing felt, etc.). Fire resistance is the property of SM to withstand, without deformation, prolonged exposure to high temperatures. Cold resistance, viscosity and – other negative t. With 0. SM property, maintain operational ductility, characteristics when
Acoustic properties - sound insulation ability characterizes the reduction in the level of impacts of sound waves when they pass through the building envelope, sound absorption capacity. Optical properties - light transmittance - the ability to transmit direct and diffuse light, transparency (for windows and other light barriers) - the ability to transmit direct and diffuse light without changing the direction of its propagation.
Mechanical properties Associated with the ability of the SM to resist various force influences. Strength is the ability of a material to resist destruction or irreversible change in shape under the influence of internal stresses caused by external forces or other factors. The strength of the SM is assessed by the tensile strength R, (N/m 2) - the stress corresponding to the load at which the onset of destruction is recorded. The most common loads are: - compression - tension - bending and impact.
Ultimate compressive (tensile) strength R= P/A, where P is the load at which the first signs of failure are recorded, A is the cross-sectional area of the sample. Ultimate bending strength R=M/W, where M is the bending moment at which the first signs of failure are recorded. W is the moment of resistance of the sample section. The strength of the total SM work under several impacts is often estimated by dropping the load on the SM sample, spent on its destruction (before the appearance of the first crack) and referred to unit V of the material.
Hardness is the ability of a medium to resist internal stresses that arise when another, harder body penetrates it. Depending on the type of SM, various methods for assessing hardness are used. For metals, polymer-based materials, wood - pressing balls, cones or pyramids into the sample. For natural stone SMs - scratch with minerals included in the Mohs hardness scale (the hardest are diamond T 10, quartz T 7, talc T 1). The hardness of SM depends on its density. This property is not always directly dependent on strength (steel has different hardness). strength can have the same
Abrasion is the ability of SM to decrease in volume and weight due to the destruction of the surface of the layer under the pressure of abrasive forces. where A is the area of the material to which abrasive influences are applied, m and m 1 are the mass before and after abrasion. Abrasion largely depends on the density of the SM. This characteristic is very important for SM used for floors, sidewalks and roads. Very resistant to abrasion PCM - basalt, granite, etc.
Deformative properties Elasticity is the ability of a material to deform under the influence of a load and spontaneously restore its original shape and size after the cessation of exposure to the external environment. Plasticity is the ability of a material to change shape and size under the influence of external forces without collapsing. After the cessation of force, the SM cannot spontaneously restore its shape and size. Permanent deformation is called plastic. Mechanical ability of significant fragility. a solid material exposed to plastic without collapsing under any deformation is called
Corrosion resistance Destruction of SM under the influence of aggressive substances is called corrosion. There are chemical, physical (without changing the chemical composition), physico-chemical and electrochemical corrosion (due to the occurrence of electric current at the SM phase boundary). Corrosion resistance is the ability of SM to resist the destructive effects of aggressive substances. When assessing the difference in the corrosion mass of aggressive medium samples and resistance before and SM after, the corresponding strength and elastic characteristics. determine the impacts of change
The degree of destruction of SM is determined by water absorption under vacuum. The progress of the destruction of the SM structure is judged on the basis of changes in the volume of water absorbed by the material. Based on the difference in the mass of dry and saturated samples, the increase V of internal pores accessible to the influence of an aggressive environment is calculated. This value is taken as a criterion for the corrosion resistance of SM. Complex properties of SM – durability – reliability – compatibility
Durability is the ability of SM and SI to maintain the required properties up to the limiting state specified by operating conditions. The durability of a material depends on the composition, structure and quality of the material, as well as on the combination of operational factors affecting it during the period: mode and level of loads, temperature, humidity, environmental aggressiveness. Durability is quantitatively measured by the time (in years) from the start of operation in a given mode until the limit state is reached. Reliability is one of the main complex properties of a SM, which determines its ability to perform its functions for a given time and under given operating conditions, while maintaining the established characteristics within certain limits.
Depends on: production conditions, transportation conditions, storage conditions, application conditions, operating conditions. The main significance of reliability is the exclusion of “failures” of sudden deterioration of the properties of M below the level of the rejection indicator. Compatibility - the ability of dissimilar materials or components to form a composite material, a durable and reliable SI, SC permanent connection and stably perform the necessary functions for a given time
Aesthetic properties of SM The aesthetic properties of SM include shape, color, texture, pattern (natural pattern - texture). The shape of the materials is perceived directly by the interior and visually affects the building. In the surface process, the originality of modern operation, facade architecture or the form of facing materials is laconic. This is usually a square or rectangle. Color is a visual sensation that arises as a result of the impact on the retina of the eye of electromagnetic vibrations reflected from the facial surface of the eye as a result of the action of light. The main characteristics of color are hue, lightness and saturation.
Color tonality - shows which part of the visible spectrum the color of the material belongs to; color tones are quantitatively measured by wavelengths. Lightness – characterized by the relative brightness of the reflection surface, SM, which, determined by the coefficient, represents, respectively, the ratio of the reflected light flux to the incident one. Color saturation is the degree of difference between a chromatic color and an achromatic color of the same lightness. Texture is the visible structure of the front surface of the SM, characterized by the degree of relief and gloss. Drawing – lines, stripes, spots and other elements on the front surface of the material that are different in shape, size, location, color.
Assessing the quality of building materials The likelihood of making an effective, high-quality decision when choosing the most appropriate SM in the process of designing an object increases as the number of options under consideration increases and the assessment of not only the individual properties of SM and SI, but the entire set of these properties that determine the quality of the product. Numerous methods for assessing the quality of construction projects (SC, SM, etc.) can be classified: - according to the degree of universality - according to the completeness of taking into account properties: a) complete, all properties are taken into account with the highest possible accuracy b) simplified, only basic properties are taken into account.
- according to the tasks being solved: a) methods that allow ranking by quality and at the same time assessing how many times one material is better than another; b) methods that allow only ranking. - by the nature of the assessment: a) expert (with the involvement of experts) b) non-expert (with sufficient information on all objects and all their properties). A comprehensive quantitative assessment of quality is considered as a two-step process: 1) assessment of simple properties 2) assessment of complex properties. CM
Currently, quantitative assessment and certification of the quality of SM is, as a rule, limited to the assessment of individual properties. All GOSTs and technical specifications regulate the number of indicators of some of the most important properties. Standardization and unification of management systems Standardization is the process of establishing and applying standards - a set of regulatory and technical requirements, norms and rules for products of mass use, approved as mandatory for enterprises and organizations of manufacturers and consumers of these products. GOSTs contain requirements for the properties of SM, their testing methods, rules for acceptance, transportation and storage. GOSTs are mandatory for use throughout
Specifications or temporary specifications - VTU - contain a set of requirements for quality indicators, test methods, acceptance rules for certain types of materials that are not standardized or have limited application. TUs operate within the department or ministry. In addition to GOSTs and TUs, SNi applies in construction. Py. On July 1, 2003, the law on technical regulation came into force in Russia. According to this law, GOSTs can be abolished, and the state will only ensure the safety of the technical environment of products through regulations. adoption of standards is proposed by the enterprises themselves. consumption and quality systems will be
Standardization methods include unification and typification. By unification we mean bringing various types of SM, SI, SK to a technically and economically rational minimum of standard sizes, grades, shapes, properties, etc. involves the development of standard SM, SI, SK Typification based on general technical characteristics. Typification requirements determine the release of SM, the dimensions of which are linked to the module - M (EMS). The accepted module size in Russia is 100 mm. Larger modules (3 M, 6 M, 12 M, 15 M, 30 M, 60 M) and fractional (1/2 M, 1/5 M, 1/10 M, 1/20 M, 1/50 M, 1/100 M). The module is used to coordinate the dimensions of SM, SI, SK, parts of buildings and buildings as a whole.
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South Ural State University
"Correspondence Faculty of Engineering and Economics"
ControlJob№1
in the discipline "Building materials"
Option-7
Completed:
student of group ZIEF-342
Checked:
Abyzav Viktor Alexandrovich
Chelyabinsk 2014
1. Which properties are main indicators quality construction materials? Give their defined no And illustrate examples
The main building materials in industrial and civil construction are cement, concrete, brick, stone, wood, lime, sand, ferrous metals, glass, roofing materials, plastic and others. All building materials have a number of common properties, but the quality indicators of these properties are different.
Physical and mechanicalAndmechanicalpropertiesconstructionmaterials: This group of properties consists, firstly, of the parameters of the physical state of materials and, secondly, of properties that determine the relationship of materials to various physical processes. The first includes the density and porosity of the material, the degree of powder grinding, the second includes hydrophysical properties (water absorption, humidity, water permeability, water resistance, frost resistance), thermophysical properties (thermal conductivity, heat capacity, thermal expansion) and some others.
Truedensity, pu is the mass per unit volume of a material taken in a dense state. To determine specific gravity, it is necessary to divide the weight of the dry material by the volume occupied by its substance, not counting the pores. It is calculated by the formula:
where m is the mass of the material, Va is the volume of the material in a dense state.
The true density of every material is a constant physical characteristic that cannot be changed without changing its chemical composition or molecular structure.
The true density of granite is 2.9 g/cm3, steel - 7.85 g/cm3, wood - on average 1.6 g/cm3.
Since most building materials are porous, true density is of auxiliary importance for their assessment. Another characteristic is used more often - average density.
Averagedensity, pc is the mass of a unit volume of material in its natural state, i.e., together with the pores and moisture contained in them. The average density of a porous material is, as a rule, less than the true one. Individual materials, such as steel, glass, bitumen, as well as liquid ones, have almost the same true and average density. The average density is calculated using the formula: pc=m/Ve
where m is the mass of the material, Ve is the volume of the material.
The average density of bulk materials - crushed stone, gravel, sand, cement, etc. - is called bulk density. The volume includes pores directly in the material and voids between grains.
This characteristic must be known when calculating the strength of structures taking into account their own weight, as well as for choosing vehicles when transporting building materials.
Relativedensity, d is the ratio of the average density of the material to the density of the standard substance. Water at a temperature of 4°C and having a density of 1000 kg/m3 is taken as the standard substance.
Porosity, P is the ratio of pore volume to the total volume of the material. Porosity is calculated using the formula: P=(1 - pc/pu)*100
where pc, pu are the average and true densities of the material.
The porosity of building materials varies widely, ranging from 0 (steel, glass) to 95% (foam concrete).
Water absorptionmaterial is called its ability to absorb and retain water in its pores. It is defined as the difference between the weights of a material sample in the water-saturated and dry states and is expressed as a percentage of the weight of the dry material (water absorption by mass) or the volume of the sample (water absorption by volume).
Water absorption is determined using the following formulas:
WM=(mв- mc)/mc and Wo=(mв- mc)/V
where mв is the mass of the sample saturated with water, mc is the mass of the sample dried to constant weight, V is the volume of the sample.
There is the following relationship between water absorption by mass and volume:
Water absorption is always less than porosity, since the pores are not completely filled with water.
As a result of saturation of the material with water, its properties change significantly: strength decreases, thermal conductivity, average density, etc. increase.
Humiditymaterial W is determined by the water content of the material at a given moment, so the percentage of moisture is lower than the total water absorption. It is determined by the ratio of the water contained in the material at the time the test sample is taken to the mass of dry material. Humidity is calculated using the formula:
W=(mvl- mc)/mc*100
where, mvl, mc is the mass of wet and dry material.
Water permeability is the ability of a material to pass water under pressure. The water permeability of a material depends on its porosity and the nature of the pores. Water permeability is encountered during the construction of hydraulic structures and water tanks.
The inverse characteristic of water permeability is water resistance - the ability of a material not to allow water to pass under pressure. Very dense materials (steel, bitumen, glass) are waterproof.
Frost resistance is the ability of a material in a water-saturated state to withstand repeated alternating freezing and thawing without signs of destruction and without a significant decrease in strength. Destruction occurs due to the fact that the volume of water when turning into ice increases by 9%. The pressure of ice on the pore walls causes tensile forces in the material. The frost resistance of materials depends on their density and the degree of filling with water.
Samples of the tested material, depending on their purpose, must withstand from 15 to 50 or more freezing and thawing cycles. In this case, the test is considered passed if there are no visible damages on the samples, the loss in weight does not exceed 5%, and the decrease in strength does not exceed 25%. Frost resistance is of great importance for wall materials that are alternately exposed to positive and negative temperatures, and is measured in freeze-thaw cycles.
Thermal conductivity called the ability of a material to conduct heat. Heat transfer occurs as a result of temperature differences between the surfaces bounding the material. The greater the porosity and the lower the average density, the lower the thermal conductivity coefficient. This material has greater thermal resistance, which is very important for external enclosing structures (walls and coverings). Materials with a low thermal conductivity coefficient are called thermal insulation materials (mineral wool, polystyrene, foam concrete, polystyrene concrete, etc.) They are used to insulate walls and coatings. The most thermally conductive materials are metals.
Fire resistance is the ability of materials to maintain their strength under high temperatures. Ignition resistance is determined by the degree of flammability. Based on the degree of flammability, building materials are divided into non-combustible, non-combustible and combustible. Fireproof materials do not ignite, smolder or char. These include stone materials (concrete, brick, granite) and metals.
Refractory materials ignite with great difficulty, smolder or char only in the presence of a fire source, for example, fiberboard boards, gypsum products with organic filling in the form of reeds or sawdust, felt soaked in a clay solution, etc. When the fire source is removed, these processes stop.
Combustible materials are capable of igniting and burning or smoldering after the fire is removed. All unprotected organic materials (timber, reeds, bitumen materials, felt and others) have such properties.
Fire resistance call the property of a material to withstand prolonged exposure to high temperatures without melting or softening. According to the degree of fire resistance, materials are divided into the following groups: fire-resistant, refractory and low-melting. Fireproof ones can withstand temperatures of 1580°C and above, refractory ones - 1350 - 1580°C, low-melting ones - less than 1350°C. Refractory materials are used in the construction of industrial furnaces, for lining boilers and thermal pipelines (refractory bricks, heat-resistant concrete, etc.).
Mechanicalpropertiesconstructionmaterials: The main mechanical properties of materials include strength, elasticity, plasticity, relaxation, fragility, hardness, abrasion, etc.
Durability is the property of a material to resist destruction and deformation from internal stresses under the influence of external forces or other factors (uneven settlement, heating, etc.). The strength of a material is characterized by its tensile strength or stress at failure of the sample. During compression, this stress is determined by dividing the breaking force by the original area of the sample.
There are different strength limits of materials in compression, tension, bending, shearing, etc. They are determined by testing standard samples on testing machines. The most important property of concrete is strength. It resists compression best of all. Therefore, structures are designed in such a way that concrete can withstand compressive loads. And only in certain designs is tensile or bending strength taken into account.
Abrasion-- the ability of materials to collapse under the influence of abrasive forces. This characteristic is taken into account when assigning materials for floors, stair steps and road surfaces.
2. Describe the most important igneous deep mountain breeds Specify their compound, properties And region applications V construction
Magma is a high-temperature silicate melt, which, depending on the cooling regime, can form:
Dense crystalline rocks, if the cooling of magma occurred slowly and under high pressure deep in the earth's crust (deep igneous rocks);
Amorphous (glassy) or weakly crystallized, and in the presence of gas in the magma
Porous rocks (extruded igneous rocks).
The mineral composition of rocks depends on the chemical composition of the magma. There are acidic magmas (Si02 content > 65%), intermediate (Si02 content = 50...65%) and basic (Si02 content< 50 %). В горных породах, образовавшихся из кислой магмы, обязательно присутствует кварц.
If the rock was formed from mafic magma, it is dominated by dark-colored ferromagnesian aluminosilicates.
In almost all igneous crystalline rocks, the bulk of the volume is feldspar.
The main representatives of igneous rocks:
Granite-- granular-crystalline rock, composed of three minerals: quartz (20...40%), feldspars (40...70%) and mica (5...20%); sometimes mica is replaced by hornblende. The construction properties of granites (on average) are as follows: density - 2600...2700 kg/m; compressive strength is 100...250 MPa, and tensile strength, like other stone materials, is 20...30 times lower; due to low porosity and low water absorption (< 1 %) граниты очень морозостойки (F >1000); their chemical resistance is also high; granites are hard rocks (hardness more than 6). The color of granites is determined by the color of the feldspar and is most often gray, pink and dark red. Granites are well polished, acquiring a decorative appearance. Granites are widely used for cladding buildings and engineering structures (embankments, bridges, etc.), flooring of public buildings and monumental sculpture.
Syenites-- analogues of granite, but without quartz (formed from medium magmas); properties and applications are the same as granite.
Diorites are a dark gray, finely crystalline rock consisting mainly of feldspars (about 75%) and dark-colored minerals. Density -- 2800...3000 kg/m3. It has increased impact strength. Used for cladding and in road construction (paving stones, etc.).
Gabbro-- coarse-crystalline rock formed from basic magma; consists of feldspars (about 50%) and dark-colored minerals (augite, hornblende, etc.). Density -- 2900…3300 kg/m3; ultimate compressive strength - 200...350 MPa. Like granite, gabbro is characterized by high frost resistance and resistance to weathering. Color - dark gray, dark green to black. Gabbro is highly polished and has a beautiful texture. One of the varieties of gabbro - labradorite - is very decorative due to the iridescent feldspar it contains. The erupted dense rocks have a weakly crystallized or glassy structure. A number of erupted rocks are characterized by a porphyry structure (Fig. 4.2, b), when crystals of some mineral are embedded in the general amorphous mass. Thus, the erupted analogue of granite - quartz porphyry - has inclusions of quartz crystals, the analogue of diorite - porphyrite - has inclusions of feldspars. Some types of porphyry are very decorative.
Basalt- analogue of gabbro - the most common erupted rock; depending on the conditions of formation, it has a glassy or cryptocrystalline structure. The color of basalt is dark gray to black. In terms of physical and mechanical properties, basalt is similar to gabbro, and even surpasses it in strength (Lszh reaches 500 MPa). Basalts are very hard, but brittle rocks, which makes them difficult to process. Dense extruded rocks are less decorative and less resistant to weathering than their deep-seated counterparts. They are used mainly as crushed stone for concrete, filling railway tracks, etc. Basalt is also used as a raw material for stone casting and for the production of high-quality mineral wool. The erupted porous rocks were formed directly during volcanic eruptions. The primary products of the eruption are volcanic ash, sand and pumice; over time they could cement, forming tuffs
VolcanicashAndsand-- powdery particles that have a glassy structure, due to which they are capable of hardening with the addition of lime or cement, and sometimes on their own. They are used as an active additive to binders (they were first used in Ancient Rome - the ashes of Vesuvius - to make lime water-resistant).
Pumice is a very porous light rock in the form of pieces measuring 5...100 mm. The density of pumice in a piece is 500... 1000 kg/m. High porosity (up to 80%) causes low thermal conductivity (0.14...0.23 W/(m * K)). The compressive strength of pumice is not high - 2...4 MPa, but this is enough to produce lightweight concrete based on pumice. In addition, pumice is used in ground form as an additive to cements and as an abrasive powder.
Volcanictuffs- a rock formed from volcanic ash, which was monolithized as a result of sintering of a mass that retained a high temperature, or as a result of natural cementation. Volcanic tuffs are porous rock (P = 30...60%) with a low density of 800...1800 kg/m3. The pores of tuff are mostly closed, which determines its high frost resistance. Compressive strength depends on porosity and is 2...20 MPa. The thermal conductivity of tuff is 1.5...2 times lower than that of brick. The color of the tuffs is varied, but not bright, but dull; main shades: red-orange to brownish-lilac. The largest deposits of tuff, resulting from the activity of the now extinct Ararat volcano, are found in Armenia. Tuffs are used as a facing material, and in areas of large deposits - as an effective material for laying walls. Due to the low hardness of tuff, wall stones are cut from it using a mechanized method directly in the quarry (Fig. 4.3). In finely ground form, tuff is used as an additive to cement. building material glass cement
3. What is yourself construction glass. What are basics his production, properties And region applications?
BUILDING GLASS -- glass products used in construction.
Building glass is used for glazing light openings, constructing transparent and translucent partitions, cladding and finishing walls, stairs and other parts of buildings. Building glass also includes heat and sound insulating materials made of glass (foam glass and glass wool), glass pipes for hidden electrical wiring, water supply, sewerage and other purposes, architectural details, elements of glass-reinforced concrete floors, etc. Most of the range of building glass is used for glazing light openings: sheet window glass, mirrored, corrugated, reinforced, patterned, double-layer, hollow blocks, etc. The same range of glass can be used for constructing transparent and translucent partitions.
Leafywindowglass, most widely used in construction, is produced from molten glass mass, mainly by vertical or horizontal continuous stretching of a strip, from which, as it cools and hardens, sheets of the required sizes are cut from one end. A significant disadvantage of sheet window glass is the presence of some waviness, which distorts objects viewed through it (especially at an acute angle).
Mirrorglass It is processed by grinding and polishing on both sides, due to which it has minimal optical distortion. The modern most common method of producing mirror glass consists of horizontal continuous rolling of glass melt between two shafts, annealing of the molded strip in a tunnel furnace, grinding and polishing on mechanized and automated conveyor units. Mirror glass is made with a thickness of 4 mm and higher (in special cases - up to 40 mm), high-quality materials are used for melting it, so it also has higher light transmittance than ordinary window glass; used mainly for glazing windows and doors in public buildings, shop windows and for making mirrors; mechanical properties differ little from the mechanical properties of window glass.
Rentalpatternedglass has a patterned surface obtained by rolling between two rollers, one of which is corrugated; both colorless and colored are produced; used in cases where diffused light is required.
PatternedglassWithmatteor"frosty"pattern used for internal partitions, door panels and glazing of staircases; made by treating the surface of window or mirror glass. The matte pattern is obtained by treating the surface with a jet of sand under the template. A pattern reminiscent of a frosty pattern on glass is obtained by applying a layer of animal glue to the surface, which, during the drying process, comes off along with the top layers of glass.
Reinforcedglass contains wire mesh in its thickness; it is more durable than usual; when broken by blows or cracked during a fire, its fragments scatter, being bound by reinforcement; Therefore, reinforced glass is used for glazing lanterns in industrial and public buildings, lift cabins, staircases, and fire wall openings. It is produced by the method of continuous rolling between rolls with rolling of wire mesh, wound from a separate drum. Corrugated reinforced glass, shaped like corrugated asbestos-cement sheets, is used to construct partitions, lanterns, and cover glass galleries and passages.
Twin(batch)glassWithairorlight-scatteringlayer(for example, made of glass fiber) have good thermal insulation properties; are made by gluing 2 window panes with an interlining frame. The thickness of double glass with an air gap is 12-15 mm.
Hollowglassblocks are manufactured by pressing and subsequent welding of two glass half-boxes; used to fill light openings, mainly in industrial buildings; provide good illumination of workplaces and have high thermal insulation properties. The blocks are laid in the openings using mortar in the form of panels bound with metal. bindings.
Facingglass(marblit) is an opaque colored sheet glass. It is produced by periodically rolling glass melt on a casting table, followed by annealing in tunnel furnaces. It is used for finishing facades and interiors of residential and public buildings. Cladding glass also includes colored metallized glass.
4. Which exist modern representation O products hydration And hardening Portland cement?
Portland cement is a hydraulic binder obtained by finely grinding Portland cement clinker with gypsum, and sometimes with special additives.
Clinker is produced by firing a finely dispersed homogeneous raw material mixture consisting of limestone and clay or some other materials (marl, blast furnace slag, etc.) until sintering.
To regulate the setting time of cement, gypsum stone is added to the clinker during grinding in an amount of no less than 1.5 and no more than 3.5% of the clinker mass in terms of sulfuric acid anhydride SO3.
The quality of clinker depends on its chemical and mineralogical composition.
Limestone used for the production of Portland cement consists of two main oxides (CaO and CO2), and clay is made of various minerals containing the oxides SiO2, Al2O3, Fe2O3. During the firing of the raw material mixture, CO2 is removed, and the remaining oxides CaO, SiO2,
Al2O3 and Fe2O3 form clinker minerals. The chemical composition of Portland cement clinker is characterized by the following content of basic oxides, %:
calcium oxide CaO 63 - 67;
silica SiO2 21 - 24;
alumina Al2O3 4 - 7;
iron oxide Fe2 O3 2 - 4.
In addition to the main oxides, Portland cement clinker may also contain other oxides: magnesium oxide MgO, alkali oxides K2O and Na2O, which reduce the quality of cement.
Magnesium oxide, fired at a temperature of about 1500 °C, extinguishes very slowly when interacting with water and causes cracks to appear in already hardened mortar or concrete.
The presence of more than 1% alkali oxides in cement can cause the destruction of hardened concrete on such cement.
The listed oxides are not present in the clinker in free form, but form silicates, aluminates and calcium aluminoferrites in the form of minerals with a crystalline structure, and some of them are included in the compounds of the glassy phase. The main minerals of Portland cement are:
tricalcium silicate 3CaO SiO2 ------C3S;
dicalcium silicate 2CaO SiO2 ------C2S;
tricalcium aluminate 3CaO Al2O3 ----C3A;
tetracalcium aluminum ferrite 4CaO Al2O3 Fe2O3 ----C4AF.
The mineralogical composition of clinker has a direct connection with the basic physical and mechanical properties of cement, making it possible to predetermine the properties of Portland cement and design its composition for concrete for specific operating conditions.
The technological process for the production of Portland cement consists of the following main operations: extraction of limestone and clay, preparation (crushing, grinding) of raw materials and corrective additives, preparation of a homogeneous mixture of a given composition, firing of the mixture, grinding clinker into a fine powder together with gypsum, and sometimes with additives.
Depending on the method of preparing the raw material mixture, there are two main methods of producing Portland cement: wet and dry. In the wet process, raw materials are crushed and mixed in the presence of water, and the mixture is fired as a liquid slurry in rotary kilns; when dry - the materials are crushed, mixed and fired dry.
When Portland cement is mixed with water, a plastic cement paste is formed, which gradually thickens and turns into stone.
Typical reactions characteristic of the hardening of Portland cement and other binders are hydration reactions that occur with the addition of water. They can occur without the decomposition of the main substance or be accompanied by its decomposition (hydrolysis reactions).
The hardening process of Portland cement mainly depends on the hydration of calcium silicates, aluminates and aluminoferrites.
HYDRATIONANDHARDENINGPORTLAND CEMENT
Setting and hardening of Portland cement is a complex physical and chemical process. The silicates, aluminates and ferrites contained in cement, when mixed with water, undergo processes of hydration (addition of water) and hydrolysis with the formation of high-strength crystals. The hydration reaction is characterized by the addition of water without decomposition of the aspen substance.
The monograph examines modern ideas about the nature of hardening of binders, including issues of the composition of cement slurries, the stoichiometry of Portland cement hydration products, and the physicochemical basis of the processes of formation of dispersed structures of binders. A special place is occupied by studies of the mechanism of structure formation processes in dispersions of mineral binders - tricalcium silicate, tricalcium aluminate, tricalcium aluminate in the presence of gypsum and filler, cement dispersions.
When pozzolanic Portland cement hardens, due to the slower course of this process, less heat is released than when hardening Portland cement. However, the reduction in heat generation is not proportional to the content of the additive, which is explained by the acceleration of hydration of Portland cement grains.
5. Compound, properties And region applications acid-resistant cements?
Compound: This is a powdery material obtained by joint grinding of pure quartz sand and sodium silicofluoride (it is possible to mix separately crushed components). Quartz sand can be replaced in acid-resistant cement with beshtaunite or andesite powder. Acid-resistant cement is mixed with an aqueous solution of liquid glass, which is the binder; The powder itself does not have astringent properties.
Properties: The compressive strength of acid-resistant concrete reaches 50-60 MPa. Being resistant to acids (except hydrofluoric, hydrofluorosilicic and phosphoric), acid-resistant concrete loses strength in water and is destroyed in caustic alkalis.
Application: Acid-resistant cement is used for the production of acid-resistant mortars and concretes, putties. In this case, acid-resistant fillers are used: quartz sand, granite, andesite.
Acid-resistant concrete is used to make tanks, towers and other structures in chemical plants, and baths in pickling shops. Acid-resistant solutions are used when lining reinforced concrete, concrete and brick structures with acid-resistant tiles (ceramic, glass, diabase) at chemical industry enterprises.
6. Pycnometer It has mass 24.1 G., A With breakdown finely ground boiling lime - 34,3 G. Weight pycnometer With lime, filled kerosene before tags, amounted to 74,17 G., A weight pycnometer without lime was equal to 66,6 G. Define density substances lime-boilers at provided What pycnometer, filled water, weighs 74,2 G
Mass of lime = 74.17 - 66.6 = 7.57
P = 7.57/(7.57+74.2-74.17)*(74.17-0.0012)+0.0012 = 0.08865 g/cm 3
Answer: 0.08865 g/cm 3
7. On extinction 1,5 tons lime-boilers, containing 80% active CaO , spent 1000 l. water, 38% which evaporated at extinguishing. Define humidity received fluff lime
When interacting with water, calcium oxide is quenched, forming fluff - calcium hydroxide: CaO + H 2 0 = Ca (OH) 2 + 15.176 kcal
2) 120 *73/1000=8 ,76 %
Answer: 8.76%
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Wall materials are classified according to the type of product, purpose, type of raw materials used, manufacturing method, average density, thermal conductivity, compressive strength and other characteristics.
By type of product: single brick 250?120?65 mm and thickened brick 250?120?88 mm; full-size wall stones 390?190?188, 490?240?188, 380?190?288 mm; additional (three-quarters 292?190?188, 367?240?188, 292?190?298 mm); halves 195?190?188, 245?240?188, 195?190?288 mm; small blocks (weighing up to 40 kg); large blocks (weighing up to 3 tons and thickness 40...60 cm); panels (single-layer thickness 20...40 cm); multilayer (15…30 cm thick). panel length 6.3; 1.5; 0.75 m; the height is a multiple of 0.6 and is usually 1.2 and 1.8 m.
By purpose: external and internal walls, partitions.
By type of raw materials used: mineral (brick, aerated concrete products, etc.); organic (wall products made of wood concrete, wood and lignomineral stones).
By manufacturing method: obtained by casting, plastic molding; using the method of semi-dry pressing, vibrating, sawing out of rocks, assembling wall structures.
By hardening method: non-firing, subdivided into materials that harden under normal conditions, at elevated temperatures, at elevated temperatures and pressures (concrete with porous aggregates, cellular concrete? Sand-lime brick, etc.); firing: bricks and ceramic stones.
By average density: especially light - medium density value - up to 600; light - 600...1300; lightweight - 1300...1600 kg/m 3.
By thermal conductivity: low thermal conductivity with a thermal conductivity value of up to 0.06; average - up to 0.018; high - more than 0.21 W/(m 0 C).
By compressive strength (grade): stone wall materials of high, medium and low strength (Table 1).
By construction method: prefabricated, monolithic and precast-monolithic.
By design: single-layer and multi-layer.
According to the nature of the static load: load-bearing, self-supporting, non-supporting.
Fire resistance: fireproof (does not ignite, does not smolder, does not char); difficult to combust (they ignite, smolder, continue to burn in the presence of a flame); combustible (ignite, smolder and burn after the fire is removed).
Table 1. Brand of wall stone materials
External load-bearing walls are the most complex construction of the publication. They are exposed to numerous and varied force and natural influences.
Performing several basic functions: thermal insulation, sound insulation, load-bearing, the wall must meet the requirements for durability, fire resistance, provide a favorable temperature regime, have decorative qualities, and protect the premises from adverse external influences. At the same time, it must satisfy the general technical requirements for minimum material consumption, as well as economic conditions.
When assessing wall structures, special attention is paid to the issue of durability. The advantage of a single-layer wall is the certainty of its durability. The durability of a multilayer wall with effective insulation will be limited by the durability of the insulation, which is significantly less than that of the structural material. Increasing the operational reliability (durability) of the heat-insulating material in the wall structure is the key to increasing the durability of the multilayer multilayer structure as a whole.
For each type or group of wall materials, state standards (GOSTs) or technical conditions (TU) are approved, which reflect the requirements for materials and their testing methods.
Ceramic bricks and stones must meet the requirements of GOST 350-95 “Ceramic bricks and stones. THAT". The most common are: solid and perforated bricks with dimensions of 250×120×65 mm; thickened brick - 250?120?88 mm; ceramic stones - 250?120?138 mm.
Wall panels. According to the design solution, panels are distinguished:
Single-layer lightweight concrete;
Three-layer, made of heavy or light concrete with an internal heat-insulating layer;
Multilayer with insulation and a protective decorative screen.
Construction and operational properties of wall materials and products.
Average density ? m, kg/m3, is a physical quantity determined by the ratio of the mass of the material to the entire volume it occupies, including the pores and voids present in it:
where m e, V - mass and volume of the material in a dry state.
The value of average density varies depending on the porosity and humidity of the material and is used to calculate its porosity, thermal conductivity, heat capacity, strength, as well as for calculations of warehouses, lifting and transport operations. For wall products, the lowest average density with the required strength is desirable. The average density indicator is: for wall ceramic products - 1400...1600; lightweight concrete with porous aggregates - 950…1400; porous ceramics and cellular concrete - 400..800; wood and lignomineral products - 1000...1400 kg/m 3.
For bulk materials (expanded perlite and vermiculite, ceramite, agloporite, fuel slag, etc.) used for thermal insulation backfill, the bulk density is 250...800 kg/m 3 .
Porosity P, %, is the degree of filling of the volume of material with pores:
P = (1 - ? m /?) 100,
Where?, ? m - true and average density, respectively, kg/m3 (t/m3).
The total porosity value for common wall materials is: sand-lime brick - 10...15, ceramic brick - 25...35, lightweight concrete - 55...85%. For wall materials, from the standpoint of ensuring thermal insulation properties, closed small pores are recommended, evenly distributed throughout the entire volume of the material. The frost resistance of products also depends on the nature of the pores; it is desirable to have pores with interconnected reserve micropores.
Emptiness P y, %, is the degree of filling of the volume of material with technological voids. Voids (air gaps) in the structure of wall products are created using both technological and design methods. The volume of voids in hollow ceramic bricks ranges from 13...33%, ceramic stones - 25...40%, sand-lime bricks - 20...40%, wall stones - 25...30%, large-porous concrete - 40...60%.
Humidity of a material is determined by the moisture content divided by the mass of the material in a dry state. The humidity of a material depends both on the material itself (porosity, hygroscopicity) and on the environment (air humidity, contact with water). For wall materials, the release humidity indicator is: for foam - aerated concrete - 15...35; wood concrete - 20.35; expanded clay concrete - 15…18; wood-mineral blocks - 7...8%.
Hygroscopicity - the property of porous materials to absorb a certain amount of water when the humidity of the surrounding air increases. Hygroscopic humidity is: for wood - 12...18, cellular concrete - up to 20%, wood concrete - 10...15, ceramic wall materials - 5...7%.
Capillary humidification - the ability of materials to absorb moisture as a result of its rise through capillaries. The possibility of humidification due to capillary suction must be taken into account when using wall products, especially in the basement of buildings. Capillary moisture is reduced or prevented by installing a waterproofing layer between the foundation and the wall structure, as well as by waterproofing the latter.
Moisture loss - the property of a material to release moisture to the surrounding air. It is characterized by the amount of water lost by the material per day at a relative ambient humidity of 60% and a temperature of 20 0 C.
Aerated concrete wall products actively absorb moisture and do not release moisture well, while wood concrete products dry quickly.
Water resistance - the ability of a material to maintain its strength properties under conditions of complete water saturation.
Frost resistance - the ability of a material saturated with water to withstand repeated alternating freezing and thawing without signs of destruction, a significant decrease in strength and weight loss.
In terms of frost resistance, wall materials are graded F15, F25, F35, F50. The minimum acceptable grade for ordinary wall materials is F15, for facing ones - F25. The number indicates the number of cycles of alternating freezing (4 hours) and thawing (4 hours). One cycle is equal to 8 hours.
Vapor and gas permeability - the property of a material to pass water vapor or gases (air) through its thickness when a pressure difference occurs on its opposite surfaces.
The gas permeability coefficient is: for cement-sand plaster - 0.02; ceramic brick - 0.35; highly porous materials - 10 kg/(m h Pa).
Thermal conductivity - the property of a wall material to transmit heat flow through its thickness in the presence of a temperature difference on the surfaces limiting the material. Thermal conductivity is determined experimentally (GOST 7076-87) by recording the heat flow passing through the material.
Determination of thermal conductivity on a large fragment of a wall. The thermal conductivity of products is determined on a fragment of the wall, the size of which, taking into account the mortar joints, must correspond in thickness based on the presence of one stud and one tread row of bricks or stones for products with horizontal voids.
Laying a wall fragment with a single-row chain ligation on a complex mortar of grade 50, average density 188 kg/m 3, composition 1:0.9:8 (cement: lime: sand) by volume, on Portland cement grade 400, with cone slump for solid products 12…13 cm, for hollow ones - 9 cm.
Laying a fragment from enlarged products with through voids larger than 20 mm in size. They are carried out by filling the voids with effective insulation (porous fillers, expanded polystyrene, foam concrete, etc.) or using a technology that excludes filling the voids with masonry mortar.
Determination of thermal conductivity on a small fragment of a wall. According to the methodology of the Research Institute of Building Physics, it is possible to determine the thermal conductivity of products on a small fragment of a wall consisting of 12 bricks or stones.
The thermal conductivity index is: for solid ceramic brick - 0.8; hollow - 0.55; silicate brick - 0.82; cellular concrete with an average density of 600 kg/m 3 - 0.25; lightweight concrete on porous aggregates with an average density of 1200 kg/m 3 - 0.44; wood and lignomineral stones - 0.4...0.5; wood - 0.2 W/(m 0 C).
The thermal conductivity of effective thermal insulation materials is 0.33...0.1 W/(m 0 C).
Heat capacity - the property of a material to absorb a certain amount of heat when heated and release it when cooled.
The heat capacity of the material is taken into account when calculating the thermal resistance of walls in heated buildings. For these purposes, it is desirable to use materials with a higher heat capacity.
Strength - the ability of a material to resist destruction under the action of external forces that cause internal stress in it. Tensile strength is measured in pascals (Pa) or mega pascals (MPa).
The strength limits of wall materials in compression and bending are determined according to GOST 8462-85. The compressive strength of some wall materials, by which their grade is determined, is: for ceramic and sand-lime bricks - 7.5...30; expanded clay concrete - 7.5…15; cellular concrete - 2.5…7.0; wood along the grain - 30...65; wood concrete - 2.5...3.5; wood and lignomineral stones - 2.5...7.5 MPa.
Durability - The service life of a building product until the loss of 50% of the indicators of its basic properties is determined by a set of characteristics such as chemical, biological, climatic resistance, immunity to ultraviolet irradiation, etc. Durability is determined by the period of time (years) of reliable operation of building structures.
Construction materials are an integral component of the processes of building construction, repair, reconstruction and modernization of various facilities. High demands are placed on their quality. The latter is confirmed by certificates, declarations and other accompanying documents. A manufacturer who wants to successfully sell products of this type, have high competitive indicators, and expand the sales market is obliged to check building materials for certification and state registration. It is aimed at identifying environmental and fire safety, efficiency, and compliance with the declared characteristics.
Common methods for assessing the quality of building materials
There are several ways to assess the quality of modern building materials. The choice of method depends directly on the type of product. Most often, such procedures are subjected to:
- Cement according to GOST R. A declaration is issued on its basis.
- Asphalt and other materials intended for road construction are certified according to the CU TR.
- Finishes and other products with fire-resistant characteristics are subject to fire certification. The procedure is being carried out within the framework of the Russian TR.
- Fresh wood materials undergo special phytosanitary control.
- Varnishes, paints, enamels, mounting foams and sealants, primers, plasters and other dry mixtures are subject to state registration according to a single standard.
Algorithm for certification of building materials
You can obtain a certificate of state registration of products confirming the quality of building materials from Rospotrebnadzor. This process is quite complex and lengthy. The task is especially difficult for those producers who have not previously encountered such events. To reduce time losses, avoid bureaucratic delays, and increase the chances of successfully passing control, you should seek professional help.
Companies that provide services for assessing building materials for compliance with standards and requirements solve a whole range of complex problems:
- draw up the necessary requests to regulatory authorities;
- collect, analyze and competently prepare the documentary base;
- organize laboratory examinations (select samples, select testing methods, etc.);
- evaluate, if necessary, the production conditions of products;
- facilitate the issuance of certificates and declarations.
The presence of such documents allows manufacturers to conduct legal trading activities not only in the Russian Federation, but also in other countries. Their validity period varies. When assessing products according to GOST, it ranges from 3 years, according to TR CU - up to 5 years. Certificates issued for one-time supplies have an unlimited validity period. The certificate of state registration is classified as unlimited.