The true density of the material depends on. Physical properties of building materials

Most building materials - These are porous bodies. Pores occupy only part of the body volume, the rest falls on the solid phase.
Density and porosity varies widely and thereby have a significant impact on the properties. The strength of the material increases with increasing density. On the other hand, the smaller the density, the easier it becomes the design. The air, which is in the pores, has low thermal conductivity, and the higher the porosity of the material, the better its heat insulating properties. Therefore, they seek to obtain thermal insulation materials with the lowest values \u200b\u200bof the RT (no more than 600kg / m3).
The properties of the material depend not only on the total volume of the pores. Of great importance is the character of porosity. Distinguish open and closed pores. Open pores communicate with each other and go to the surface of the material. Therefore, the material with open pores is easily saturated with water. In a humidified state, it begins to spend well heat, since the air in the pores is replaced by water, the thermal conductivity of which is 25 times more. Building materials possessing predominantly open porosity, poorly resist physical and chemical corrosion influences.
In some cases, the open porosity is formed in the structure of the material intentionally. This applies, for example, to sound-absorbing products, drainage pipes from ceramics or ceramzite concrete.
The pore sizes are also different: from a few millimeters to the micrometer and less. In thermal insulation materials, they are trying to form pores of the minimum size. In this case, heat transfer through the thickness of the material is reduced due to the decrease in convection and radiating. In the hydraulic concrete subjected to pressure impact of water, it must also contain preferably small pores, since at a diameter of pores less than 1 μm does not filter water through the body of concrete.
Closed pores that are not saturated with water, and semi-jammed, into which water penetrates only under pressure, increase the stability of the material.
In the physical meaning, the concept of emptiness and porosity are similar. In the manufacture of concrete and construction solution They strive to use bulk aggregates - sand, crushed stone or gravel with minimal voidness. In this case, to fill emptiness, less cement and concrete will need cheaper.
The activity of thin powders, such as cement, depends on the size of the particles: the smaller the particle, the more active the cement. The generalized characteristic of the physical state of powders includes a specific surface, which represents the ratio of the total area of \u200b\u200bthe surface of all particles to the mass of particles or the volume occupied by them.
Thus, the thinner particles, the greater the specific surface of the powder. Increasing it, get special species Portland cement, for example, rapidly hardening.
Very often in the course of operation, building structures are moisturized and the properties of the material are changed. In order to obtain the numerical characteristics of the properties of a material being exposed to moisture use the following concepts. Water absorption characterizes the ability of porous material to absorb and keep in the pores of drip-liquid moisture. This property reflects the maximum amount of moisture that can absorb the material, so it is sometimes called maximum moisture intensity. Numerical characteristics include water absorption and water absorption in volume. Water absorption by mass is equal to the ratio of the mass of water, fully saturated, to the mass of dry material.
Water absorption by weight is easy to determine the experimental way. To do this, weigh the sample of dry material T, then completely saturated with water and determine the mass in a water-saturated state of TN. The difference is TN is equal to the mass of the absorbed water of Tъ. The water absorption of various materials, which depends on the nature of porosity, can vary in wide limits. WM values \u200b\u200bare for granite 0.02 ... 0.7%, heavy concrete - 2 ... 4, brick - 8 ... 20, lungs thermal insulation materials With open porosity - 100% or more. Water absorption in volume never exceeds porosity, since the volume of water supplied water can not be greater than the amount of pores.
The values \u200b\u200bof WM and W0 characterize an extreme case in which the material is no longer able to absorb moisture. In real structures, the material may contain a certain amount of moisture obtained with a short-term moistening of drip-liquid water or as a result of condensation in the pores of water vapor from the air. In this case, the condition of the material is characterized by humidity.
Moisturization leads to a change in many properties of the material. The weight of the construction structure increases, thermal conductivity increases. IN real material There are always many structural defects, among which the most dangerous microcracks. Water has a propagating effect and, falling into microcracks, increases their length. As a result, the proportion of defects in the structure increases, which affects the strength of the material.
In the most waterproof materials - granite, heavy concrete - the values \u200b\u200bof the rank are approaching a unit, from non-desarmed - construction cardboard, unreleased clay - they are close to zero.
Under the influence of moisture porous materials swell. When drying, the reverse process takes place - shrinkage. Both of these processes that occur in the volume of structures unevenly cause significant structural stresses in the material. As a result, during swelling, the product or design can be sworn, and when shrinking in the material - there are cracks. Relative deformations of the shrinkage of the building mortar reach 0.5 ... 1 mm / m, concrete - 0.3 ... 0.7 mm / m. To reduce shrinking deformations, natural materials are impregnated with special substances, in composite artificial materials, such as concrete, regulate the composition.
Frost resistance is called the ability of a saturated material of the material to withstand multiple alternate freezing and thawing. Mark for frost resistance F denotes the largest number of freezing cycles - thawing, which withstand material samples without reducing compression strength of more than 15% (for some materials 25%); Mass loss should not exceed 5%.
In external structures, exposed to water and variable temperatures, frost resistance is a determining factor in durability. The design brand of materials on frost resistance is set to the type and conditions of operation of the structure, as well as climate. For example, a lightweight concrete and ceramic brick brands in frost resistance F15, F25 and F35 are used to build outdoor walls. Road concrete, working in more difficult conditions, manufactures f50 ... F200 brands, and hydraulic - to F500.
Method of evaluating frost resistance stone Materials By repeated freezing and thawing the samples proposed by the professor of the St. Petersburg Institute of Engineers of the Communications N.A. Belelyubsky was adopted in 1886 at the International Conference on Test Materials. This method is used and now in all countries.
For testing for frost resistance, standard samples of materials or whole small products (for example, brick) are initially saturated with water. After that, they are frozen at temperatures from -15 to -20 C. The samples are then removed from the freezer and thawed in water room temperature. Such freezing and thawing is one test cycle. With an increase in the number of cycles in the material structure, irreversible changes occur, which lead to a drop in strength.
Building structures during operation are subjected to a permanent or variable thermal effect. To characterize the properties of the material in this case, the concepts of thermal conductivity, heat capacity, thermal expansion, refractory and fire resistance are used.
Thermal conductivity is the property of the material to transmit heat when the temperature drops on opposite design surfaces. The amount of heat q passing through the enclosing surface, for example, through a wall depends on the surface area, temperature drop, wall thickness, passage duration heat flux, as well as from some coefficient x, characterizing the specific properties of the material.
Construction materials - heavy concrete, metals - differ significantly greater thermal conductivity.
The heat capacity is called the properties of the material to absorb heat when heated or give up when cooled. It is characterized specific heatequal to the amount of heat (CJ) required for heating 1 kg of material for one degree. Specific heat Inorganic building materials are ranging from 0.4 to 1 kJ (kg to), dry wood - 1.7 ... 2 kJ. In the water, the greatest heat capacity is 4.2 kJ, therefore, with moisturizing materials, their heat capacity increases. The numerical characteristics of heat capacity are used when calculating the heat-resistance of the enclosing structures. In addition, the values \u200b\u200bC need to know to calculate the cost of fuel and energy on the heating of materials and structures during winter work.
The thermal extension characterizes the property of the material to change the dimensions - when heated. For few exceptions, building materials are expanding. For the numerical characteristics of such a phenomenon, the temperature coefficient of linear expansion is used equal to the relative elongation of the material when it is heated by one degree.
Due to the thermal expansion of the deformation of the material in the design, they achieve significant values, therefore, in the structures of a large length, deformation seams provide for the avoidance of cracking.
Fireproof - the property of the material to withstand a long exposure to high temperatures, not softening and not deforming. Fireproofs consider materials withsting temperatures over 1580 ° C. Materials operating in the temperature range of 1350 ... 1580 ° C are called refractory, and at a temperature of less than 1350 ° C - low-melting. Fire resistance - the property of the material to resist the action of fire in a fire. Basic characteristic building structures In a fire, a degree of fire resistance, which depends on the material moistening and the limit of fire resistance.
Compurability is the ability of the material to ignite and burn. Materials are non-aggravated, challenged and combed.
Non-aggravated materials under the action of fire or high temperatures Do not ignite, do not smash and are not charred. These include such inorganic materials, such as concrete and steel.
Empty-refined materials are ignited, smoldering or charred only in the presence of ignition source. After removal of fire, burning or termination stops. This group includes, in particular, asphalt concrete, self-fighting foam, wood impregnated with special substances - antipyrenes.
The combined materials continue to burn or smoke even after removing the ignition source, i.e. Capable to independent burning in the atmosphere of normal composition. These include organic materials: wood, construction plastics, bituminous roofing and waterproofing materials, etc.
The fire resistance limit is a period of time (minutes or hours) from the start of fire before the emergence of the limit state. Loss consider the limit carrier ability. construct collapse; The occurrence of through-cracks in it, through which combustion and flames can penetrate on the opposite surface; Inappropriate heating by the opposite action of the fire of the surface, which can cause spontaneous ignition of other parts of the structure.
It is mistaken to believe that for the manufacture of fire-resistant design it is enough to apply a non-burnable material. This condition is necessary, but it is not enough. Some non-aggravated materials (granite, asbestos cement) are cracking in a fire, metal structures are strongly deformed. They have to protect more fire-resistant materials.

The specific value in the national economy of our country of building materials and products in terms of production and value is large; consumption of them every year increases in all areas of construction; They constitute a significant part of the value of buildings and structures. Economic spending and technically proper use of materials and products in the design and construction of buildings and structures is one of the main means of reducing the cost of construction. Our industry of building materials and products has achieved great success in the field of cement production, ceramic products, cellular concrete and, especially, precast concrete products. For the production of precast concrete, Russia occupies a leading place in the world. This contributed to the achievements of science as in learning properties natural materialsand in the creation of new artificial highly efficient materials.

Among the new artificial materials are the most promising are building materials and parts made on the basis of plastic masses.

Physical properties

Building materials used in the construction of buildings and structures are characterized by a variety of properties that determine the quality of the materials and the field of their application. For a number of signs, the basic properties of building materials can be divided into physical, mechanical chemical, the physical properties of the material characterize its structure or attitude to physical environmental processes. The physical properties include a mass, true and average density, porosity water absorption, waterproof, humidity, hygroscopicity, water permeability, frost resistance, air, steam, gas permeability, thermal conductivity and heat capacity, fire resistance and refractory.

Mass - - a set of material particles (atoms, molecules, ions) contained in this body. Mass has a certain volume, i.e. it takes part of the space. It is constant for this substance and does not depend on the speed of its movement and position in space. The bodies of the same volume consisting of various substances have an unequal mass. To characterize differences in mass of substances having the same volume, the concept of density is introduced, the latter is divided into true and average.

True density - - the ratio of the mass to the volume of the material in an absolutely dense state, so on. without pores and emptiness. To determine the true density p (kg / m3, g / cm3), we need a mass of material (sample) T (kg, d) to divide into absolute volume VA (M3, cm3) "occupied by the material itself (without pores):

Often the true density of the material belongs to the true density of water at 4 ° C, which is equal to 1 g / cm3, then defined true density It becomes like a dimensionless value.

Table 1. True and average density of some building materials

Material

Density, kg / m3

true

Limestone (dense)

Ceramic brick

Concrete heavy

Popoplasts

The average density is - a physical value determined by the ratio of the mass of the material to the entire volume occupied by them, including the pores and emptiness available in it. The average density M (kg / m3, g / cm3) is calculated by the formula:

where m is the mass of the material in natural condition, kg or g;

V-- material volume in natural state, m3 or cm3.

The average density is not a permanent value and varies depending on the porosity of the material. Artificial materials It can be obtained with the necessary average density, for example, changing the porosity, the concrete is severe with an average density of 1800-- 2500 kg / m3 or light with an average density of 500-- 1800 kg / m3.

By magnitude middle density The humidity of the material is affected: the higher the humidity, the greater the average density. The average density of materials needs to be known to calculate their porosity, thermal conductivity, heat capacity, structural strength (taking into account their own mass) and calculating the cost of transportation of materials.

The porosity of the material is called the degree of filling its pores. The porosity P complements the density to 1 or up to 100% and is determined by the formulas:

The porosity of various building materials varies in large limits and is for bricks 25--35%, heavy concrete 5--10, aerated concrete 55-- 85 foam 95%, the porosity of glass and metal is zero. Not only the magnitude of porosity, but also the size, and the nature of pores, are small (up to 0, 1 mm) or large (from 0, 1 to 2 mm), closed or communicating are largely influenced on the properties of the material. Small closed pores that are evenly distributed throughout the volume of the material, give the material thermal insulation properties.

The density and porosity largely determine such properties of materials such as water absorption, water permeability, frost resistance, strength, thermal conductivity, etc.

Water absorption - - the ability of the material to absorb water and hold it. The value of water absorption is determined by the difference in the mass of the sample in a saturated water and absolutely dry states. The volumetric water absorption of WV is distinguished when the specified difference is related to the sample volume, and the mass absorption WM, when this difference is assigned to the mass of the dry sample. The feed-absorption in volume and by mass is expressed as a percentage and calculated by formulas:

where T1, - -Ass of a sample, saturated with water, g; T - the mass of dry sample, r; V is the volume of the sample in the natural state, cm3.

The saturation of materials by water adversely affects their basic properties: increases average density and thermal conductivity, reduces strength.

The degree of reduction of the strength of the material under its limit pressure, i.e., the state of complete saturation of the material with water is called water resistance and is characterized by the value of the softening coefficient

where RNAS is the tensile strength in the compression of the material in saturated water, MPa; Rice - the same, dry material.

The moisture content of the material is determined by the moisture content referred to the mass of the material in a dry state. The material moisture depends on both the properties of the material (porosity, hygroscopicity) and the surrounding medium (air humidity, the presence of contact with water).

Moisture product - - the property of the material to give moisture to the surrounding air, characterized by the amount of water (as a percentage by weight or volume of the standard sample), lost by the material per day at the relative humidity of the ambient air of 60% and temperature 20 "s.

The magnitude of moisture studies is of great importance for many materials and products, such as wall panels and blocks, wet plaster The walls that in the construction process usually have increased humidity, and under normal conditions, due to moisture, it dry out: water evaporates until the equilibrium is established between the humidity of the wall material and the humidity of the ambient air, i.e., so far the material does not reach the air dry status.

A hygroscopicity is called the property of porous materials to absorb a certain amount of water while increasing the humidity of the surrounding air. Wood and some thermal insulation materials due to hygroscopicity can absorb a large amount of water, while their mass increases, the strength is reduced, dimensions change. In such cases, protective coatings have to be used for wooden and rows of other structures.

Power Permeability - - The property of the material to pass water under pressure. The magnitude of the water permeability is characterized by the amount of water over 1 h through 1 cm2 of the area of \u200b\u200bthe test material at constant pressure. Waterproof materials include especially dense materials (steel, glass, bitumen) and dense materials with closed pores (for example, concrete of a specially selected composition).

Frost resistance - - the property of a saturated material of the material to withstand multiple alternate freezing and thawing without signs of destruction and a significant reduction in strength.

The freezing of water, filling the pores of the material, is accompanied by an increase in its volume by about 9%. As a result, the pressure on the pore walls occurs, leading to the destruction of the material. However, in many porous materials, water cannot fill over 90% of the volume of available pores, so the ice formed when the water freezing has free space for expansion. The destruction of the material occurs only after multiple alternate freezing and thawing.

Paro- and gas permeability - - the property of the material to pass through its thickness under the pressure of water vapor or gase (air). All porous materials in the presence of unclosed pores are able to skip or gas.

The vapor and gas permeability of the material is characterized by a coefficient of vapor-or gas permeability, which is determined by the amount of steam or gas in L, passing through a layer of material with a thickness of 1 m and an area of \u200b\u200b1 m2 for 1 hour with a difference in partial pressures on opposite walls 133, 3 Pa.

To know the thermal conductivity of the material is necessary with the heat engineering calculation of the thickness of the walls and overlaps of heated buildings, as well as when determining the required thickness of the thermal insulation of hot surfaces, such as pipelines, factory oven, etc.

Heat capacity - the property of the material to absorb the determined amount of heat when heated and highlight it during cooling,

The heat capacity is the specific heat capacity, equal to quantity Warm (J) required for heating 1 kg of material for 1 ° C. Specific heat, KJ (kg - ° C), artificial stone materials 0, 75--0, 92, wood - - 2, 4--2, 7, steel - - 0, 48, water - 4.187.

The heat capacity of the materials is taken into account when calculating the heat resistance of the walls and overlaps of heated buildings, heating the components of concrete and the solution for winter work, as well as when calculating furnaces.

Fire resistance - - the malfunction of the material to withstand the action of high temperatures and water in a fire. According to the degree of fire resistance, building materials are divided into non-aggravated, difficult and burned.

Failed materials under the action of fire or high temperatures are not ignited, not smoldering and not charred. These materials include natural stone materials, brick, concrete, steel. It is difficult to combat materials under the action of fire with difficulty flammifying, smoldering or harboring, but after removing the source of fire, their burning and drainage stops. An example of such materials can serve a wood-cement material Fibrol and asphalt concrete. The combined materials under the influence of fire or high temperatures are flammable and continue to burn after removing the source of fire. To these materials, first of all include wood, felt, only referenced,

Refractory is called the property of the material to withstand a long exposure to high temperatures, not melted and not deformed. According to the degree of refractoriness, materials are divided into refractory, refractory and low-melting.

Refractory materials are able to withstand the long-term effects of the temperature above 1580 ° C. They are used for inner cladding industrial furnaces (chammed brick). The refractory materials are withstanding the temperature from 1350 to 1580 ° C (Gzhel brick for masonry furnaces). Lightweight materials softened at temperatures below 1350 ° C (ordinary clay brick).

Thermal conductivity - - the property of the material to transmit through the thickness of the heat in the presence of the temperature difference on the surfaces that limit the material. The thermal conductivity of the material is estimated by the amount of heat passing through the wall from the test material with a thickness of 1 m, with an area of \u200b\u200b1 m2 per 1 hour, with the difference in the temperatures of the opposite surfaces of the wall 1 ° C. The thermal conductivity is measured in W / (MK) or W / (MK).

The thermal conductivity of the material depends on many factors: the nature of the material, its structure, porosity, humidity, as well as from the average temperature at which heat is transmitted. The material of the crystalline structure is usually better than the material of the amorphous structure. If the material has a layered or fibrous structure, its thermal conductivity depends on the direction of heat flow with respect to the fibers, for example, the thermal conductivity of wood along the fiber is 2 times larger than the fibers across the fibers.

The thermal conductivity of the material is largely affected by the magnitude of the porosity, size and nature of pores. Small-sized materials are less thermal conductive than large-porous, even if their porosity is the same. Materials with closed pores have less thermal conductivity than materials with informative pores. The thermal conductivity of a homogeneous material depends on its average density. So, with a decrease in the density of the material, the thermal conductivity is reduced and vice versa. Thermal conductivity in air-dry state of heavy concrete 1, 3--1, 6, ceramic brick 0, 8--0, 9, mineral Wat 0, 06--0, 09 W / (MS).

Mechanical properties

Mechanical properties characterize the ability of the material to resist the destroying or deforming effects of external forces. TO mechanical properties Treative strength, elasticity, plasticity, fragility, resistance to impact, hardness, abrasibility, wear.

Strength - - the property of the material to resist the destruction under the action of internal stresses arising from external loads. Under the influence of various loads, materials in buildings and structures are experiencing various internal stresses (compression, stretching, bending, slice, etc.). Strength is the main property of the majority of building materials, the magnitude of the load is depends on its value, which can perceive this element at a given section.

Building materials depending on the origin and structure in different ways confront various stresses. So, materials of mineral origin (natural stones, brick, concrete, etc.) are well resist compression, much worse cut and even worse stretching, so they are used mainly in compression designs. Other building materials (metal, wood) work well on compression, bending and stretching, so they are successfully used in various structures (beams, farms, etc.) operating on bending.

Table 2. Strength of some building materials

Materials

Strength, MPa, with

tensile

Heavy concrete

Ceramic brick

Wood (along the fibers)

Fiberglass

The strength of building materials is usually characterized by a brand, which corresponds to the largest limit of compressive strength obtained when testing

Fragility - - the property of the material instantly collapsed under the action of external forces without preliminary deformation. Fragile materials include natural stones, Ceramic materials, glass, cast iron, concrete, etc.

Resistance to impact is called the property of the material to resist the destruction under the action of shock loads. In the process of operation of buildings and structures, materials in some structures are subjected to dynamic (shock) loads, for example, in the foundations of blacksmith hammer, bunkers, road coatings. Fragile materials are badly resist. Hardness - - the property of the material to resist the penetration of another material, more solid. This property is of great importance for materials used in floors and road surfaces. In addition, the hardness of the material affects the complexity of its processing.

There are several ways to determine the hardness of materials. Wood hardness, concrete is determined, pressing a steel ball into samples. The magnitude of the hardness is judged by the depth of plowing the ball or the diameter of the received imprint. The hardness of natural stone materials is determined on a scale of hardness (method of combos), in which ten specially selected minerals are located in such a sequence, when the next mineral leaves the line (scratch), on the previous one, and it does not read it (Table 3). For example, if the test material is drawn by apatitis, and himself leaves the line (scratch) on the platform, its hardness corresponds to 4, 5.

Abrasability - - the property of the material to change in volume and mass under the influence of abrasive efforts. Abrasion depends on the possibility of using material for the device of floors, steps, stairs, 9r and roads. The abrasability of materials is determined in laboratories on special machines - - abrasion circles.

The wear is called the destruction of the material with the joint action of abrasion and impact. Elasticity - - the property of the material is deformed under load and take the initial shape and dimensions after removal of load. The greatest voltage at which the material still has elasticity is called the elasticity limit. Elasticity is a positive property of building materials. As an example of elastic materials, you can call rubber, steel, wood.

Plasticity - - the ability of the material to be changed under the load and dimensions without forming breaks and cracks and keep the changed shape and dimensions after removing the load. This property is opposite to elasticity. An example of a plastic material is lead, clay dough, heated bitumen.

Conclusion:

In modern conditions, when the market is saturated with goods, only those commercial structures are successfully operating, where the goods are able to capture trends in a change in demand, determine the causes of their occurrence and promptly apply measures to improve the structure of the range and conjugation of its individual positions in the consumer market.

Non-food products occupy a significant proportion in the total turnover of goods, which is determined, on the one hand, their wide range, and on the other, the need to use them in everyday life. Over the past decade, the range of goods has been significantly updated, both due to the receipt of imported products and due to modern products of Russian production.

Bibliography

300 modern construction and facing materials: - St. Petersburg, Onyx, 2008, 128 p.

Handbook of Building Materials: L. I. Dvorkin, O. L. Dvorkin - Moscow, Infra-Engineering, 2010, 472 p.

Handbook of building materials and products: V. N. Basin, L. V. Shulyakov, D. S. Dubiago - St. Petersburg, Phoenix, 2008- 448 p.

Physico-chemical bases of building materials science: - St. Petersburg, publishing house of the Association of Construction Universities, 2004, 192 p.

Each of the building materials has a number of properties that distinguish it from another material. These properties that distinguish materials from each other include: appearance, composition, structure, specific and volume weight, density, porosity, etc.
The properties inherent in individual materials are discussed below - in the characteristics of each material separately, the concepts of the general physico-mechanical properties of materials are given here.

Specific and bulk weight

Weight is the value of gravity, usually measured by grams, kilograms or tons. The specific weight is the weight of 1 cm3 of the material in grams taken in absolutely tight state.
Specific gravity water equal to unity (1 cm3 water weighs 1 g). The proportion of all other solid, bulk and liquid materials is compared with water weight. The share of materials is determined in laboratories.
The volume weight is called the weight of the unit of material in a natural state, i.e., together with the pores and voids. If 1 m3 serves as a unit of material volume of the material, then its weight is expressed in tons and, therefore, volumetric weight is determined in t / m3. When measuring the volume of material in cubic centimeters, the weight is expressed in grams, and bulk weight - in g / cm3.

Density and porosity

The density is called the degree of material filling in the substance. The body density is expressed as a percentage of its total volume.
Materials with a density of 100% are very small (steel, quartz, glass); The density of most materials is significantly less than 100%.
Porosity is called the degree of filling material of the material by pores. Porosity is also expressed as a percentage of the total volume of this material. Thus, the percentage expressing density and the percentage expressing the porosity of the material should in the amount to give 100%. Pores are closed or communicating cells in the material filled with air.
Density and porosity have a big impact on such important properties of materials, as durability, water absorption, thermal conductivity, frost resistance and, therefore, durability.

Water absorption, moisture production, water permeability

Water absorption is determined by the ability of the material to absorb water. The amount of water absorbed by the pores of the material taken as a percentage of the total material volume expresses water absorption. Water absorption due to this may not be more porosity.
Water absorption reduces the strength of the material, reduces its frost resistance, thermal conductivity and as a result of this is a harmful property for building materials.
Moistribution - the rate of drying materials - the property opposite to water absorption. As the material is drying, frost resistance, strength, thermal conductivity is restored.
The water permeability is called the ability of the material through its thickness of water.
The degree of water permeability depends on the porosity of the material and on the form of the pores: the pores are closed do not let the water. The larger in the material of the open pore and emptiness, the more its water permeability.

Frost resistance

Frost resistance is called the ability of the material to resist the frost to the destructive effect on it. Frost resistance is determined by alternating freezing and thawing the material saturated water.

Elasticity, plasticity, fragility

Elasticity is the ability of a material that has changed its shape under the influence of the load, to restore it after this load will be deleted. An example of an elastic material is a student gum: such a gum can be twice as well, but after it was released, it completely straightened.
Plasticity is a property opposite to elasticity and lies in the ability of the material to maintain a form-modified form after this load will be deleted. An example of a plastic material can serve as a window melting, which is easy to give any form.
The fragility is called the body's ability to easily change its shape under the influence of even a small load. The fragile material in contrast to the plastic, as a rule, cannot be given the desired shape, since such material is destroyed under load: it is crushed into parts or crumbles. An example of a fragile material can serve as glass.

Strength, hardness, abrasibility

The strength is the ability of materials to resist the destruction under the action of the load. The strength is manifested in the ability of the material to resist compression, stretching, bending, twisting, cutting, impact, etc. Strength affects the ability of the material to resist abrasion, weathelation, etc.
Hardness - the property of the material to resist the penetration of another body into it. The hardness of the materials depends on their abrasibility.
The abrasibility is called the property of the material to lose the smallest particles from its surface under the influence of friction about another body. Abrasability is of great importance for materials used for floors, stairs; In particular, the materials used for the color of the floors, stairs should have a small abrasion.

Air permeability, gas and vapor permeability

Air permeability, as well as gas and vapor permeability, call the ability of the material to pass air, gas and steam through its thickness.

Fire resistance

Materials that are not subject to significant destruction in the fire are called fire-resistant. Half-resistant materials are not burning, but significantly destroying in a fire, half-portable - burn, but, being a protected flame retardant environment, not burning open flame, and burnable - burning open flames and quickly destroying.
Materials withsting considerable heating up to 1580 ° are called refractory.
Materials withsting without destruction sharp fluctuations in temperature (transitions from large frosts to heat) are called temperature-resistant.

References: V. P. Ivanov. "Paint, luggage and glass work", M., 1958

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