Fire danger building materials Characterized by the following properties:

1. Combustion;
2. Flammability;
3. The ability to spread the flame on the surface;
4. Smoke-forming ability;
5. Toxicity of combustion products.

By felingbuilding materials are divided into combustible (d) and non-combustible (NG).

Building materials refer to non-combustible with the following values \u200b\u200bof the flammability parameters defined by experimentally: the temperature increase is not more than 50 degrees Celsius, the weight loss of the sample is not more than 50 percent, the duration of stable fumeful burning is not more than 10 seconds.

Building materials that do not satisfy at least one of the following parameter values \u200b\u200bspecified in paragraph 4 of this article relate to combustible. Combustible building materials are divided into the following groups:

• Wematory (g1) having a flue gas temperature of not more than 135 degrees Celsius, the degree of damage to the length of the test sample is not more than 65 percent, the degree of damage to the mass of the test sample is not more than 20 percent, the duration of independent burning 0 seconds;
• Moderate-burning (g2) having flue gases no more than 235 degrees Celsius, the degree of damage to the length of the test sample is not more than 85 percent, the degree of damage to the mass of the test sample is not more than 50 percent, the duration of independent burning is not more than 30 seconds;
• Normal-burning (GZ) having flue gases no more than 450 degrees Celsius, degree of damage to the length of the test sample more than 85 percent, the degree of damage to the mass of the test sample is no more than 50 percent, the duration of independent burning is no more than 300 seconds;
• Silnogorous (G4), having a flue gas temperature of more than 450 degrees Celsius, the degree of damage to the length of the test sample is more than 85 percent, the degree of damage to the mass of the test sample is more than 50 percent, the duration of independent burning is more than 300 seconds.

For materials related to the combustible groups G1-GZ, the formation of burning melt drops during testing (for materials related to combustibility groups G1 and G2 is not allowed to form a melt drops). For non-combustible building materials Other indicators fire danger Do not define and are not normalized.

By flammabilitycombustible building materials (including floor carpets) depending on the size of the critical surface density of the heat flux are divided into the following groups:

• Faceless (B1), having the magnitude of the critical surface density of the heat flux of more than 35 kilowatts per square meter;
• Male-ignorant (B2) having the magnitude of the critical surface density of heat flux at least 20, but not more than 35 kilowatts per square meter;
• Flammable (PT) having the magnitude of the critical surface density of the heat flux of less than 20 kilowatt per square meter.

By flame spread speeds On the surface of combustible building materials (including floor carpets), depending on the magnitude of the critical surface density of the heat flux, are divided into the following groups:

• Non-expression (RP1) having the magnitude of the critical surface density of the heat flux of more than 11 kilowatt per square meter;
• Weak-rapid (RP2) having the magnitude of the critical surface density of heat flux at least 8, but not more than 11 kilowatts per square meter;
• Moderatically-stencil (RPZ) having the magnitude of the critical surface density of heat flux at least 5, but not more than 8 kilowatt per square meter;
• Strong-standing (RP4) having the magnitude of the critical surface density of the heat flux of less than 5 kilowatt per square meter.

By smoke-formingabilities combustible building materials depending on the value of the smoke coefficient are divided into the following groups:

• With low smoke-forming ability (D1), having a smoke formulation less than 50 square meters per kilogram;
• With moderate smoke-forming ability (d2) having a smoke coefficient of at least 50, but not more than 500 square meters per kilogram;
• With high smoke-forming ability (DZ) having a smoke-forming coefficient of more than 500 square meters per kilogram.

By toxicitycombustion products combustible building materials are divided into the following groups in accordance with table 2 of the annex to this federal law:

• Low hazard (T1);
• Moderate (T2);
• High-hazardous (TK);
• Extremely dangerous (T4).

Depending on the fire hazard groups, building materials are divided into the following Fire hazard classes:

Properties of fire hazard of building materials	Fire hazard class of building materials depending on groups
	Km 0.	Km1	Km2.	Km3	Km4.	Km5
Spray	NG	G1.	G1.	Г2.	Г2.	G4
Flammability	—	IN 1	IN 1	AT 2	AT 2	IN 3
Smoke-forming ability	—	D1	D3 +.	D3.	D3.	D3.
Toxicity of combustion products	—	T1.	T2.	T2.	T3.	T4.
Spreading flame on floors for floors	—	RP1	RP1	RP1	RP2.	RP4

When obtaining substances and materials, use, storage, transportation, processing and disposal.

To establish requirements fire safety To the design of buildings, structures and systems fire protection The classification of building materials for fire danger is used.

Indicators of fire hazard and fire hazard of substances and materials

The list of indicators necessary for evaluating the fire hazard and fire hazard of substances and materials depending on their aggregate state, is given in Table 1 of the annex to the Federal Law of FZ-123 (" Technical Regulations About fire safety ").

Methods for determining the indicators of fire hazard and fire hazard of substances and materials are set regulatory documents Fire safety.

Indicators of fire hazard and fire hazard of substances and materials are used to establish requirements for the use of substances and materials and calculating fire risk.

The list of indicators necessary to assess the fire hazard of substances and materials depending on their aggregate state

Fire hazard indicator	Substances and materials in various aggregate state			Dust
	gaseous	liquid	solid
Safe experimental maximum gap, millimeter	+	+	-	+
Selection of toxic combustion products from a unit of combustion mass, kilogram per kilogram	-	+	+	-
Group of flammability	-	-	+	-
A combustion group	+	+	+	+
Flame distribution group	-	-	+	-
Smoke formation coefficient, square meter per kilogram	-	+	+	-
Radiant flame ability	+	+	+	+
Fire index, Pascal for meter per second	-	-	-	+
Flame spread index	-	-	+	-
Oxygen index, surround interest	-	-	+	-
Concentration limits of flame distribution (ignition) in gases and pairs, surround interest, dusty, kilogram on cubic meter	+	+	-	+
Concentration limit diffusion burning gas mixtures in the air, volumetric interest	+	+	-	-
Critical surface density of thermal flux, Watt per square meter	-	+	+	-
Linear flame propagation rate, meter per second	-	-	+	-
The maximum rate of flame propagation along the surface of the combustible fluid, meter per second	-	+	-	-
Maximum explosion pressure, Pascal	+	+	-	+
The minimum phlegmatizing concentration of the gaseous phlegmatizer, Volumetric interest	+	+	-	+
Minimum ignition energy Joule	+	+	-	+
Minimal explosive oxygen content, Volumetric interest	+	+	-	+
Lower working heat combustion kilodzhoule per kilogram	+	+	+	-
Normal flame propagation rate, meter per second	+	+	-	-
The toxicity of combustion products, gram on cubic meter	+	+	+	+
Oxygen consumption per unit of combustible mass kilogram per kilogram	-	+	+	-
The limiting speed of the disruption of the diffusion torch, meter per second	+	+	-	-
Explosion rate of explosion Megapascal per second	+	+	-	+
Ability to burn when interacting with water, air oxygen and other substances	+	+	+	+
Inflammation ability for adiabatic compression	+	+	-	-
Self-burning ability	-	-	+	+
Ability to exothermic decomposition	+	+	+	+
Inflammation temperature Degree Celsius	-	+	+	+
Flash temperature, degree Celsius	-	+	-	-
Self-ignition temperature, degree Celsius	+	+	+	+
Temperatures degree Celsius	-	-	+	+
Temperature limits of flame distribution (ignition), degree Celsius	-	+	-	-
Specific bulk speed, kilogram per second per square meter	-	+	+	-
Specific heat combustion, Joule per kilogram	+	+	+	+

Classification of substances and materials ( with the exception of building, textile and leather materials) by fire danger

The classification of substances and materials on fire danger is based on their properties and ability to form hazardous factors of fire or explosion.

The combustible substances and materials are divided into the following groups:
1) non-combustible - Substances and materials unable to burn in the air. Non-combustible substances can be fire-free (for example, oxidizing agents or substances separating combustible products when interacting with water, air oxygen or each other);
2) harmony - substances and materials capable of burning in the air when exposed to an ignition source, but unable to burn independently after removing it;
3) gorry - Substances and materials capable of self-turn, as well as ignite under the influence of the ignition source and on their own after it is removed.

Methods for combustibility tests of substances and materials are established by regulatory documents on fire safety.

Classification of construction, textile and leather materials for fire danger

The classification of construction, textile and leather materials for fire danger is based on their properties and the ability to form dangerous fire factors.

The fire danger of construction, textile and leather materials is characterized by the following properties:
1) spray;
2) flammability;
3) the ability to spread flame on the surface;
4) smoke-forming ability;
5) toxicity of combustion products.

Flame distribution speed over surface

By the rate of flame propagation on the surface of combustible building materials (including floor carpets), depending on the size of the critical surface density of the heat flux, are divided into the following groups:

1) unprinted (RP1)having the magnitude of the critical surface density of the heat flux of more than 11 kilowatt per square meter;

2) weatherproof (RP2)having the magnitude of the critical surface density of the heat flux of at least 8, but not more than 11 kilowatts per square meter;

3) moderatically-stencil (RP3)having the magnitude of the critical surface density of the heat flux at least 5, but not more than 8 kilowatts per square meter;

4) strong-Straightening (RP4)having the magnitude of the critical surface density of the heat flux less than 5 kilowatt per square meter ..

Smoke-forming ability

According to the smoke-forming ability, combustible building materials, depending on the value of the smoke formation, are divided into the following groups:

1) with low smoke-forming ability (D1)having a smoking coefficient of less than 50 square meters per kilogram;

2) with moderate smoke-forming ability (d2)having a smoking coefficient of at least 50, but not more than 500 square meters per kilogram;

3) with high smoke-forming ability (D3)having a smoking coefficient of more than 500 square meters per kilogram ..

Toxicity

On the toxicity of combustion products, combustible building materials are divided into the following groups in accordance with table 2. Annexes to federal law No. 123-FZ:

1) low hazard (T1);
2) moderate (T2);
3) highness (T3);
4) extremely dangerous (T4).

Classification of combustible building materials according to the value of the combustion product toxicity

Hazard Class	The toxicity of combustion products depending on the exposure time
	5 minutes	15 minutes	30 minutes	60 minutes
Low hazard	more than 210.	more than 150.	more than 120.	more than 90.
Moderate	more than 70, but not more than 210	more than 50, but not more than 150	more than 40, but not more than 120	more than 30, but not more than 90
Highlyland	more than 25, but not more than 70	more than 17, but not more than 50	more than 13, but not more than 40	more than 10, but not more than 30
Extremely dangerous	not more than 25.	no more than 17.	not more than 13.	not more than 10.

Classification of individual species of substances and materials

For floor carpets, the combustibility group is not determined.

Textile and leather materials on flammability are divided into flammable and hard-flameable. The cloth ( non-woven cloth) Classified as flammable material if the following conditions are performed during tests:

1) the time of the flame burning of any of the samples tested during ignition from the surface is more than 5 seconds;

2) any of the samples tested during the ignition from the surface, roasts to one of its edges;

3) Cotton cotton wool lights up under any of the test samples;

4) the surface flash of any of the samples extends more than 100 millimeters from the ignition point from the surface or edge;

5) The average length of the charred area of \u200b\u200bany of the samples tested when exposed to a flame from the surface or edge is more than 150 millimeters.

To classify building, textile and leather materials, the value of the flame propagation index (I) is a conditional dimensionless indicator, which characterizes the ability of materials or substances to ignite, spread the flame on the surface and highlight heat. For the spread of flames, materials are divided into the following groups:

1) non-flames on the surface having a flame distribution index 0;

2) slowly spreading the flame on the surface having a flame distribution index no more than 20;

3) Fast-spreading flames on the surface, having a flame distribution index of more than 20.

Test methods to determine the classification indicators of fire danger of construction, textile and leather materials are established by regulatory documents on fire safety

Introduction

The nomenclature of building materials contains hundreds of names. Each material is somewhat different from others. external species, chemical composition, structure, properties, field of application in construction and behavior in fire conditions. However, between materials not only there are differences, but also many general signs.

Know the fire properties of building materials, evaluate the behavior of structures in a fire, to offer effective methods Fireproofs of structural elements, carry out calculations of the strength and stability of buildings under fire exposure is obliged to engineer-designer, construction engineer, engineer Operational. But first of all it is the responsibility of a fire safety engineer.

Under the behavior of building materials in a fire, a complex of physicochemical transformations is understood that lead to a change in the state and properties of materials under the influence of intensive high-temperature heating.

External and internal factors that determine the behavior of building materials in conditions of fire

building Material Heating Metal Fireproof

In order to understand what changes occur in the structure of the material, how its properties change, i.e. As the internal factors affect the behavior of the material in the conditions of a fire, it is necessary to know the material itself: its origin, the essence of manufacturing technology, composition, initial structure and properties.

During the operation of the material in conventional conditions External factors affect it:

scope (for cladding floor, ceiling, walls; indoors with a normal medium, with an aggressive medium, outside the room, etc.);

air humidity (than it is higher, the higher the humidity of the porous material);

various loads (than they are higher, the hardest material resist them effectively);

natural impacts ( solar radiation, air temperature, wind, atmospheric precipitation, etc.).

The listed external factors affect the durability of the material (deterioration of its properties during the time of normal operation). What they are aggressively (more intense) affect the material, the faster its properties change, the structure is destroyed.

With a fire, in addition to those listed, significantly more aggressive factors affect the material, such as:

heat ambient;

the time of finding the material under the influence of high temperature;

impact fire extinguishes;

the impact of the aggressive environment.

As a result of material impact external factors Fire in the material may flow certain negative processes (depending on the type of material, its structure, states during operation). The progressive development of negative processes in the material leads to negative consequences.

Basic propertiescharacterizing the behavior of building materials in a fire

Properties call the ability of materials to react to the impact of external and internal factors: power, humidity, temperature, etc.

All properties of materials are interconnected. They depend on the form, composition, structure of the material. A number of them have a more substantial, others - a less significant impact on the fire hazard and behavior of materials in a fire.

In relation to the study and explanation of the nature of the behavior of building materials in conditions of fire, it is proposed as the main one to consider the following properties:

Physical properties: bulk mass, density, porosity, hygroscopicity, water absorption, water permeability, vapor and gas-permeability.

Mechanical properties: strength, deformability.

Thermophysical properties: thermal conductivity, heat capacity, temperature, thermal expansion, heat capacity.

Properties characterizing fire hazard materials: flammability, heat dissipation, smoke formation, isolating toxic products.

The properties of materials are usually characterized by the corresponding numerical indicators, which are determined using experimental methods and means.

Properties characterizing fire hazard building materials

Under fire danger, it is customary to understand the likelihood of the emergence and development of a fire concluded in the substance, state or process.

The fire hazard of building materials is determined by the following fire and technical characteristics: flammability, flammability, flame proliferation over the surface, smoke-forming ability and toxicity.

Flavoring is a property that characterizes the ability of the material to burn. Building materials are divided into two categories: non-combustible (NG) and combustible (g).

Combustible building materials are divided into four groups:

G1 (weaklyor);

G2 (moderate horizon);

G3 (normal-burning);

G4 (strong-burning).

Flammability - the ability of the material to ignite from the ignition source, or when heated to self-ignition temperature. Felous construction materials on flammability are divided into three groups:

B1 (hard-flameable);

B2 (moderately relocated);

B3 (flammable).

The spread of the flame is the ability of the material sample to spread the flame on the surface in the process of its combustion. Flavored building materials on the spread of flame on the surface are divided into four groups:

RP1 (non-prolonged);

RP2 (weak-string);

RP3 (moderately distribution);

RP4 (strongly aspiration).

Smoking - the ability of the material to allocate smoke with combustion, is characterized by a smoke-forming coefficient.

Smoke formation coefficient is a value that characterizes the optical density of the smoke formed during the combustion of the material sample in the experimental installation. Flawing construction materials for smoke-forming abilities are divided into three groups:

D1 (with low smoke-forming ability);

D2 (with moderate smoke-forming ability);

DZ (with high smoke-forming ability).

Indicator of the toxicity of products of combustion of materials - the ratio of the amount of material to the unit volume of the experimental installation chamber, during the combustion of which the released products cause 50% of experimental animals. Flavored building materials for the toxicity of combustion products are divided into four groups:

T1 (low hazard);

T2 (moderate);

TK (highly hazardous);

T4 (extremely dangerous).

Metals, their behavior in conditions of fire and ways to increase resistance to its effects

Black (cast iron, steel);

Colored (aluminum, bronze).

Aluminum alloys

Metal behavior in fire

When the metal is heated, the mobility of atoms increases, the distances between atoms and the relationship between them weaken are increasing. Thermal expansion of heated bodies is a sign of an increase in interatomic distances. Big influence On deterioration mechanical properties Metal has defects, the number of which increases with increasing temperature. At melting point, the number of defects, an increase in the interatomic distances and the weakening of relations reaches such an extent that the initial crystal cell collapsed. Metal goes into a liquid state.

In the temperature range from absolute zero To the melting point of changes in the volume of all typical metals is approximately equally - 6-7.5%. Judging by this, it can be considered that an increase in the mobility of atoms and distances between them, and, accordingly, the weakening of the interatomic bonds, characteristic of all metals in almost the same degree, if they are heated to one and the same homologous temperature. Homological temperature is a relative temperature, expressed in the fraction of melting temperature (TPL) by absolute scale Kelvin. For example, iron and aluminum at 0.3tpl have the same strength of interatomic bonds, and therefore, the same mechanical strength. According to the graduate scale, it will be: for iron 331 OS, for aluminum 38 OS, i.e. ?in iron at 331 ° C is equal ?in aluminum at 38 ° C.

An increase in temperature leads to a decrease in strength, elasticity and an increase in plasticity of metals. The lower the melting point of metal or alloy, with lower temperatures there is a reduction in strength, for example, in aluminum alloys - at lower temperatures than the steels.

At high temperatures, the creep deformations also occur, which are a consequence of an increase in plasticity of metals.

The higher the loading value of the samples, the more low temperatures begins the development of creep deformation and the sample is rupture, and with smaller values \u200b\u200bof relative deformation.

With increasing temperature, the thermophysical properties of metals and alloys are changed. The nature of these complex and is difficult to explain.

Along with general patterns, characteristic of the behavior of metals when heated, the behavior of steels in a fire has features that depend on a number of factors. So, the nature of the behavior is influenced primarily chemical composition Steel: carbon or low-alloyed, then method of manufacturing or hardening reinforcement profiles: hot rolling, thermal hardening, cold broach, etc. When heating samples of hot-rolled fittings from carbon steel, it decreases its strength and an increase in plasticity, which leads to a decrease in strength limits, fluidity, increase relative elongation and narrowing. When cooled such steel, its initial properties are restored.

A somewhat different nature of behavior when heated low-alloyed steels. When heated to 300 OS, there is some increase in the strength of a number of low-alloy steels (25G2C, 30HG2C, etc.), which is preserved and after cooling. Consequently, low-alloyed steel at low temperatures even increase strength and less intensively lose it with increasing temperature due to alloying additives. Features of the behavior of thermally hardened fittings in the conditions of fire is an irreversible hardening loss, which is caused by the release of steel. When heated to 400 OK, some improvement in the mechanical properties of thermally hardened steel, expressed in increasing the conditional yield strength while maintaining the strength limit. At temperatures above 400, an irreversible decrease in both the yield strength and strength (time resistance) occurs.

The reinforcing wire, strengthened by slap, and heated also irreversibly loses hardening. The higher the degree of hardening (stagnation), the Tea at a lower temperature begins its loss. The reason for this is the thermodynamically unstable state of the crystal lattice, hardened with slab steel. When the temperature increases to 300-350, the recrystallization process begins, during which the crystal lattice deformed as a result of the lattice is rebuilt towards normalization.

The main feature Aluminum alloys is low, compared with steel, heating resistance. An important feature of some aluminum alloys is the ability to restore strength after heating and cooling if the heating temperature did not exceed 400 OS.

Low-alloy steel has the greatest resistance to the action of high temperatures. Considerable steel behave somewhat worse without additional hardening. Even worse - steel strengthened in thermal way. The lowest resistance to the action of high temperatures has steel harboring, and even lower - aluminum alloys.

Methods for increasing the resistance of metals to the effects of fire

Ensure the renewal of the preservation of the properties of metals under fire conditions in the following ways:

the choice of products from metals, more resistant to fire;

special manufacture metal products more resistant to heat;

fireproof metal products (structures) by applying external thermal insulation layers.

Stone materials and their behavior in a fire

Classification of rocks by origin:

Overhead (magmatic, primary) breeds

Sediment (secondary) breeds

Metamorphic (modified) breed

Overhead (magmatic, primary) breeds:

Massive:

deep (granites, shenietites, diorites, gabbro);

poland (porphyra, diabases, basalts, etc.).

Cholly:

loose (volcanic ashes, pumice);

sampled (volcanic tuffs).

Sediment (secondary) breeds:

Chemical (Gypsum, Anhydrite, Magnesites, Dolomites, Mergeli, Lime Tuffs, etc.).

Organogenic (limestone, chalk, shells, diatomites, trees).

Mechanical sediments:

loose (clay, sand, gravel);

sampled (sandstones, conglomerates, breccia).

Metamorphic (modified) breeds:

Overhead (Gneisis).

Sediment (quartzites, marbles, clay shale).

Classification of inorganic binders:

Air (air lime, plaster).

Hydraulic (portland cement, clay cement).

Acid-resistant ( liquid glass).

Stone artificial materials:

Burnt building materials based on inorganic binders:

concrete and reinforced concrete;

solutions;

asbestos cement;

gypsum and gypsum concrete products;

silicate products.

Frying building materials:

ceramics;

stone melts.

Silicate materials:

Facing plates

Cellic products (Penosilikat, Gasilicat).

The behavior of stone materials in a fire

The study of the behavior of stone materials in the conditions of fire was engaged in several decades, many researchers of our country.

The nature of the behavior of stone materials in a fire in principle is the same for all materials, only quantitative indicators are distinguished. Specific features are due to the action of only internal factors inherent in the analyzed material (when analyzing the behavior of materials in identical conditions of external factors).

Features of the behavior of natural stone materials in a fire

Monomineral rocks (gypsum, limestone, marble, etc.) when heated behave more calmly than polymineral. They undergo at the beginning of a free thermal expansion, freeing from physically related moisture in the pores of the material. It does not lead to a reduction in strength and even its growth may even be observed with a calm distance of free moisture. Then as a result of action chemical processes dehydration (if the material contains chemically associated moisture) and dissociation The material undergoes gradual destruction (reduction of strength to almost zero).

Polymineral rock breeds behave mainly similarly to monomineral, except that, when heated, significant stresses arise, due to various magnitudes of thermal expansion coefficients in components that are part of the rock. This leads to the destruction (reduction in strength) of the material.

We illustrate the peculiarities of the behavior of monomineral and polymineral rocks during heating on the example of two materials: limestone and granite.

Limestone - monomineral rockconsisting of Calcite Calcite mineral. The heating of calcite up to 600 OS does not cause significant changes in the mineral, and is accompanied only by its uniform expansion. Above 600 OS (theoretically, the temperature 910 OS) begins the calcite dissociation by the SAS3 \u003d Cao + CO2 reaction, as a result of which carbon dioxide is formed (up to 44% by weight from the source material) and loose low-term calcium oxide, which causes an irreversible reduction in limestone strength. When testing the material during heating, as well as after heating and cooling unloaded state, it was found that when the limestone heats up to 600, its strength is increased by 78% due to the removal of physically bound (free) moisture from the micropore material. Then the strength decreases: at 800 ° C, it reaches the initial, and at 1000, the strength is only 20% of the initial.

It should be borne in mind that in the process of cooling the majority of materials after high-temperature heating, the change continues (more often - reduction) of strength. The reduction in limestone strength to the initial occurs after heating to 700 OS, followed by cooling (in a hot condition up to 800 ° C).

Since the dissociation process of the SASO3 proceeds with significant heat absorption (178.5 kJ / kg), and forms the porous calcium oxide has a low thermal conductivity, the SAO layer creates a heat-shield barrier on the surface of the material, a slightly slowing delayed lamp.

Upon contact with water when steaming a fire (or moisture out of the air after cooling the material), the hydration reaction was reacting formed during the high-temperature heating of the negro lime SAO. Moreover, this reaction proceeds with cooled lime.

Saa + H2O \u003d sa (it) 2 + 65.1 kJ.

The calcium hydroxide formed at the same time increases in volume and is a very loose and fragile material that is easily destroyed.

Consider the behavior of granite when heated. Since granite is a polymineral rock, consisting of a field spat, quartz and mica, his behavior in a fire will be largely determined by the behavior of these components.

After heating the granite up to 200 OS and the subsequent cooling, an increase in strength by 60% is observed, associated with the removal of internal stresses arising during the formation of granite as a result of uneven cooling of the molten magma, and the difference in the magnitude of the temperature expansion coefficients of minerals constituting granite. In addition, an increase in strength to some extent, apparently, is also due to the removal of free moisture from the micropores of granite.

At temperatures above 200 OS, a gradual decrease in strength begins, which is explained by the emergence of new internal stresses associated with the difference in thermal expansion coefficients of minerals.

A significant reduction in granite strength occurs above 575 OS due to changes in the volume of quartz, undergoing a modification transformation ( ?-quartz B. ?-quartz). At the same time, the formation of cracks can be detected in the abnormal eye. However, the total strength of granite in the considered temperature temperature range remains high: at 630 OS, the tensile strength of granite is equal to the initial value.

In the temperature range of 750 ... 800 OS and above, the reduction of granite strength due to the dehydration of minerals of the field split and mica, as well as the modification transformation of quartz from ?-quartz B. ?-tridimitis at 870 OS. At the same time, deeper cracks are formed in granite. The tensile strength of Graniteapri 800 OS is only 35% of the initial value. It has been established that the heating rate affects the change in the change in granite strength. So, with quick (one-hour) heating, its strength begins to decline after 200 OS, while after a slow (eight-hour) - only with 350 OS.

Thus, it can be concluded that limestone is more resistant to heating with material than granite. Limestone almost completely retains its strength after heating to 700 ° C, grant - up to 630 OS and subsequent cooling. In addition, limestone undergoes significantly less temperature expansion than granite. It is important to take into account when assessing the behavior of artificial stone materials in a fire, in which granite and limestone are included as aggregates, such as concrete. It should also be borne in mind that after heating to high temperatures and the subsequent cooling of natural stone materials, their strength is not restored.

Features of the behavior of artificial stone materials when heated

Since concrete is a composite material, its behavior during heating depends on the behavior of cement stone, aggregate and their interaction. One of the features - chemical compound When heated to 200 OS calcium hydroxide with silica quartz sand (There are conditions similar to that in the fact that they are created in the autoclave for a quick hardening of concrete: high blood pressure, temperature, air humidity). As a result of such such a compound, an additional amount of calcium hydrosilicates is formed. In addition, under the same conditions there is an additional hydration of clinker minerals of the zemny stone. All this contributes to some increase in strength.

When the concrete is heated above 200, oppositely directed deformations undergoing a shrinkage of the binder and expanding aggregate arise, which reduces concrete strength along with destructive processes occurring in a binder and aggregate. Expanding moisture at temperatures from 20 to 100 OS presses on the pore walls and the phase transition of water in steam also increases the pressure in the pores of concrete, which leads to the occurrence of a stress state that reduces strength. As free water removed, the strength may increase. When warming up the samples of concrete, in advance dried in a drying closet at a temperature of 105 ... 110 OS to constant mass, physically related Water There is no, therefore, such a sharp reduction in strength at the beginning of heating is not observed.

When cooled concrete after heating, the strength, as a rule, practically corresponds to the strength of that maximum temperatureTo which the samples were heated. In certain types of concrete, it is somewhat reduced when cooled due to longer finding material in the heated state, which contributed to a deeper flow in it with negative processes.

Concrete deformativity as heated increases by increasing its plasticity.

The higher the relative load on the sample, the more with a smaller critical temperature it collapses. According to this dependence, researchers conclude that with increasing temperature, concrete strength falls when testing in a stressed state.

Moreover, building construction Of the heavy concrete (reinforced concrete), prone to explosive destruction during the fire. This phenomenon is observed in the designs, the material of which has moisture content above the critical value with an intensive rise in the temperature in a fire. The more dense concrete, the lower its vapor permeability, more micropores, the more inclined to the emergence of such a phenomenon, despite more high strength. Lightweight and cellular concrete with volumetric mass below 1200 kg / m3 are not prone to explosive destruction.

Specific behavior of lungs and mesh concrete, unlike the behavior of heavy concrete in the fire, is more for a long time Warming up due to their low thermal conductivity.

Wood, its fire hazard, fire protection methods and evaluation of their effectiveness

Physical structure of wood:

Sapwood.

Core.

The dependence of the volumetric mass on the wood breed

Phone Wood Wood Moisture Building1.Hexuality, Pine, 650 Cedders, Fir, EL5002. Frameholders, Birch, Maple, Clene, Beech, Acacia, Vyaz7003. Large Larithic, Topol, Olha, Lipa500

Wood decomposition products:

35% - coal;

45% - liquid distillate;

20% - gaseous substances.

Wood behavior when heated in a fire conditions:

° C - the decomposition of wood begins, accompanied by the separation of volatile substances, which can be detected by the characteristic odor.

150 ° C - the non-combustible decomposition products occurs (water - H2O, carbon dioxide - CO2), which is accompanied by a change in wood flowers (it turns yellow).

200 ° C - Wood begins charring, purchasing brown color. Gases that allocate are combustible and consist mainly of carbon monoxide - co, hydrogen - H2 and vapors organic substances.

250-300 ° C - the ignition of wood decomposition products.

Ideal wood decomposition scheme:

The dependence of the mass velocity of the burnout of wooden bars from the cross-sectional area.

The dependence of the mass velocity of the fire burning from the volumetric mass 1. r. 0 \u003d 350 kg / m3; 2. r. 0 \u003d 540 kg / m3; 3. R. 0 \u003d 620 kg / m3.

Wood flame retardants

Thermally insulating clothes ( wet stucco; coating with non-combustible materials; coating with intimidating paints);

Fire retardant paints ( phosphate coatings; Paint IFC; SC-L paint);

Fire retardant coating (superphosphate coating; lime-clay saline coating (IGS));

Impregnating compositions (deep impregnation of wood: a solution of flames under pressure; in hot-cooled baths).

Conclusion

In order for the building to fulfill its purpose and was durable, it is necessary to choose the correct materials, both structural and finishing. It is necessary to know well the properties of materials, the stone is, a metal or tree, each of them has its own characteristics of behavior in a fire. Nowadays, we have enough good information about each material and it is necessary to approach very seriously and deliberately, in terms of security.

Bibliography

1.Gaidar L.E. Building materials [Text] / L.E. Gaidar. - M.: Appliances, 2007. - 367 p.

2.Gryzin A.A. Tasks, structures and their stability in the fire [Text] / A.A. Gryzin. - M.: Prospekt, 2008. - 241 p.

.Lakhtin Y.M. Materials Science [Text]: Tutorial for higher technical educational institutions / Yu.M. Lachtin - M.: Mechanical Engineering, 1999. - 528 p.

.Romanov A.L. Properties of building materials and assessment of their quality [Text] / A.L. Romanov. - M.: World of Book, 2009. - 201 p.

5. SNIP 21-01-97 *. Fire safety of buildings and structures, paragraph 5 fire and technical classification . Construction Materials.

Zenkov N.I. Construction materials and their behavior in a fire. - M.: VIPTSH MVD USSR, 1974. - 176 p.

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A combustion group - This is the classification characteristic of the ability of substances and materials to.

When determining the fire hazard of substances and materials (), distinguish :

• gases - These are substances, the pressure of saturated vapors of which at a temperature of 25 ° C and a pressure of 101.3 kPa exceeds 101.3 kPa;
• liquids - These are substances, the pressure of saturated vapors of which at a temperature of 25 ° C and a pressure of 101.3 kPa less than 101.3 kPa. Liquids also include solid melting substances, melting point or dripping of which are less than 50 ° C.
• solids and materials - These are individual substances and their mixture compositions with a melting point or dropping point greater than 50 ° C, as well as substances that do not have a melting point (for example, wood, fabrics, etc.).
• dust - These are dispersed solids and materials with particle size of less than 850 microns.

One of the indicators of fire hazardiness of substances and materials is a combustion group.

Substances and materials

According to GOST 12.1.044-89, the combustible substances and materials are divided into the following groups ( with the exception of building, textile and leather materials):

1. Non-combustible.
2. Harmony.
3. Combustible.

Non-combustible - These are substances and materials, unable to burn in the air. Non-combustible substances can be fire-free (for example, oxidizing agents or substances excreting combustible products when interacting with water, air oxygen or other).

Harmony - These are substances and materials capable of burning in the air when exposed to the ignition source, but unable to burn after it is removed.

Gorry - These are substances and materials capable of self-turn, as well as ignite when exposed to the source of ignition and burn yourself after removing it.

The essence of the experimental method of determining the combustibility is to create temperature conditions that contribute to the combustion and assessing the behavior of the studied substances and materials under these conditions.

Solid (including dust)

The material belongs to the non-combustible group, if the following conditions are met:

• the average temperature change in the furnace, on the surface and inside the sample does not exceed 50 ° C;
• the medium-briefing value of the mass loss for five samples does not exceed 50% of their average value of the initial mass after air conditioning;
• the average-parent value of the duration of stable burning of five samples does not exceed 10 s. The test results of five samples in which the duration of stable burning is less than 10 s, taken equal to zero.

By the value of the maximum temperature increment (Δt max) and the mass loss (Δm), materials are classified:

• difficult: ΔT Max< 60 °С и Δm < 60%;
• combustible: Δt max ≥ 60 ° C or Δm ≥ 60%.

Combustible materials are divided depending on the time (τ) achievement (T MAX) on:

• faceless: τ\u003e 4 min;
• average flammability: 0,5 ≤ τ ≤ 4 min;
• flammable: τ.< 0,5 мин.

Gaza

In the presence of concentration limits The spread of flame gas belongs to combustible ; In the absence of concentration limits of the spread of the flame and the presence of a temperature of self-ignition gas refer to difficult to work ; In the absence of concentration limits of the spread of flames and the temperature of self-ignition gas refer to negustic .

Liquids

In the presence of ignition temperature, the liquid belongs to combustible ; In the absence of ignition temperature and self-oscillating temperature, the liquid belongs to difficult to work . In the absence of flash temperatures, ignition, self-ignition, temperature and concentration limits of flame propagation, liquid belongs to the group negustic . Combustible fluids with an outbreak temperature of not more than 61 ° C in a closed crucible or 66 ° C in an open crucible, tipflemic mixtures that do not have a flash in the closed crucible belong to flammable . Particularly dangerous Called flammable liquids with a flash point of no more than 28 ° C.

Classification of building materials

Definition of a combustibility group

The fire danger of construction, textile and leather materials is characterized by the following properties:

1. The ability to spread flame on the surface.
2. Smoke-forming ability.
3. Toxicity of combustion products.

Building materials depending on the values \u200b\u200bof flammability parameters are divided into groups on non-combustible and combustible (For floor carpets, the combustion group is not determined).

NG (non-combustible)

Non-combustible building materials based on test results according to methods I and IV () are divided into 2 groups.

Building materials refer to non-combustible I group

• the increase in the temperature in the furnace is not more than 30 ° C;
• the duration of steady flame burning is 0 C;
• heat combustion no more than 2.0 mJ / kg.

Building materials refer to non-combustible group II With the following mid-industrial values \u200b\u200bof flammability parameters according to methods I and IV (GOST R 57270-2016):

• the increase in the temperature in the furnace is no more than 50 ° C;
• loss of mass samples no more than 50%;
• the duration of sustainable flame burning is not more than 20 s;
• heat combustion no more than 3.0 MJ / kg.

It is allowed to attribute without testing to non-combustible I group The following building materials without staining them external surface either with the outer surface staining with the compositions without the use of polymer and (or) organic components:

• concretes construction solutions, plasters, adhesives and putty, clay, ceramic, porcelain and silicate products (bricks, stones, blocks, plates, panels, etc.), fibrotennye products (sheets, panels, stoves, pipes, etc.) except in all cases of materials manufactured using polymer and (or) organic binder fillers and fibers;
• products from inorganic glass;
• products made of steel, copper and aluminum alloys.

Building materials that do not satisfy at least one of the above indicated values \u200b\u200bof the parameters I and II groups of non-combustible are related to the combustion group. and are subject to tests according to methods II and III (GOST R 57270-2016). For non-combustible building materials, other indicators of fire danger are not determined and not normalized.

Combustible building materials depending on the values \u200b\u200bof the combustibility parameters determined by the method II, are divided into four combustible groups (M1, G2, G3, G4) In accordance with the table. Materials should be attributed to a specific combustion group, provided that all the average average parameter values \u200b\u200bset by the table for this group are configured.

G1 (weaklyor)

Wemologies - These are materials having a flue gas temperature of not more than 135 ° C, the degree of damage along the length of the test sample is not more than 65%, the degree of damage to the mass of the test sample is not more than 20%, the duration of independent burning is 0 seconds.

Г2 (moderate ignorance)

Modearegorean - These are materials having a flue gas temperature of not more than 235 ° C, the degree of damage along the length of the test sample is not more than 85%, the degree of damage to the mass of the test sample is no more than 50%, the duration of independent burning is not more than 30 seconds.

G3 (NormalGorgiy)

NormalGorgiy - These are materials having a flue gas temperature of not more than 450 ° C, the degree of damage along the length of the test sample is more than 85%, the degree of damage to the mass of the test sample is no more than 50%, the duration of self-burning is no more than 300 seconds.

G4 (strong-horror)

Silnogorchy - These are materials having a flue gas temperature of more than 450 ° C, the degree of damage along the length of the test sample is more than 85%, the degree of damage to the mass of the test sample is more than 50%, the duration of independent burning is more than 300 seconds.

Table

Group of flammability materials	Greencondition parameters
	Temperature of flue gases T., ° C.	Degree of damage S. L,%	Degree of damage by weight S. M,%	Duration of independent burning T c.g, with
G1.	Up to 135 inclusive	Up to 65 inclusive	Up to 20.	0
Г2.	Up to 235 inclusive	Up to 85 inclusive	Up to 50	Up to 30 inclusive
G3	Up to 450 inclusive	Over 85.	Up to 50	Up to 300 inclusive
G4	Over 450.	Over 85.	Over 50.	Over 300.
Note. For materials related to the combustibility groups G1-G3, the formation of burning droplets of melt and (or) burning fragments during the test is not allowed. For materials related to combustion groups G1-G2, the formation of melt and (or) melt drops during the test is not allowed.

Video what is a combustibility group

Sources: ; Baratov A.N. Gore - Fire - Blast - Security. -M.: 2003; GOST 12.1.044-89 (ISO 4589-84) System of labor safety standards. Firelessness of substances and materials. Nomenclature of indicators and methods for their definition; GOST R 57270-2016 Construction materials. Test methods for combustibility.

Purpose of classification substances and materials on fire hazard and fire hazard (Chapter 3 of Art. 10-13 ФЗ №123):

1. The classification of substances and materials on fire hazard and fire hazard is used to establish fire safety requirements when producing substances and materials, use, storage, transportation, processing and disposal.

2. To establish fire safety requirements to the design of buildings, structures and fire protection systems, the classification of building materials for fire danger is used.

Classification of building materials for fire hazard (Article 13 of the Federal Law No. 123).

1. The classification of building materials for fire danger is based on their properties and ability to form dangerous fire factors given in table 1 Annexes to Federal Law No. 123.

2. Fire danger construction Materials are characterized by the following properties :
1) flammable;
2) flammability;
3) the ability to spread the flame on the surface;
4) smoke-forming ability;
5) Toxicity of combustion products.

3. Feling Construction Materials divided into: combustible (g) and non-combustible (NG).

Building materials are related to non-flammable With the following values \u200b\u200bof the flammability parameters, determined by experimentally: the temperature increase is not more than 50 degrees Celsius, the weight loss of the sample is not more than 50 percent, the duration of stable fumeful burning is not more than 10 seconds.

Construction materials that do not satisfy at least one of the above parameter values \u200b\u200binclude to flammable.

Combustible building materials are divided into the following groups:

1) wemologies (G1), having a flue gas temperature not more than 135 degrees Celsius, the degree of damage to the length of the test sample is not more than 65 percent, the degree of damage to the mass of the test specimen is not more than 20 percent, the duration of independent burning is 0 seconds;

2) modearegorean (G2), having flue gases no more than 235 degrees Celsius, the degree of damage to the length of the test sample is not more than 85 percent, the degree of damage to the mass of the test specimen is not more than 50 percent, the duration of independent burning is not more than 30 seconds;

3) normalGorgiy (GZ) , having flue gases no more than 450 degrees Celsius, the degree of damage to the length of the test sample is more than 85 percent, the degree of damage to the mass of the test sample is no more than 50 percent, the duration of independent burning is no more than 300 seconds;

4) silnogorchy (G4. ), having a flue gas temperature of more than 450 degrees Celsius, the degree of damage to the length of the test sample is more than 85 percent, the degree of damage to the mass of the test sample is more than 50 percent, the duration of independent burning is more than 300 seconds.

For materials related to the combustible groups G1-GZ, the formation of burning melt drops during testing (for materials related to combustibility groups G1 and G2 is not allowed to form a melt drops). For non-combustible building materials, other indicators of fire danger are not defined and are not normalized.

On flammability combustible building materials (including floor carpets), depending on the size of the critical surface density of the heat flux, are divided into the following groups:

1) claimed (IN 1 ), having the magnitude of the critical surface density of the heat flux of more than 35 kilowatts per square meter;

2) mOREESHNOGOVANEMENT (AT 2), having the magnitude of the critical surface density of heat flux at least 20, but not more than 35 kilowatts per square meter;

3) Flammable (Vz), Having the magnitude of the critical surface density of the heat flux of less than 20 kilowatt per square meter.

By speed of flame spread over the surface Combustible building materials (including floor carpets) depending on the size of the critical surface density of the heat flux are divided into the following groups:

1) non-prolonged ( RP1 ), having the magnitude of the critical surface density of the heat flux of more than 11 kilowatt per square meter;

2) weak-rapid (RP2. ) having the magnitude of the critical surface density of the heat flux at least 8, but not more than 11 kilowatts per square meter;

3) moderately prioritizing ( RPZ ) having the magnitude of the critical surface density of the heat flux at least 5, but not more than 8 kilowatts per square meter;

4) strongly prostrate (RP4. ), Having the magnitude of the critical surface density of the heat flux of less than 5 kilowatt per square meter.

For smoke-forming ability combustible building materials Depending on the value of the smoke coefficient, the following groups are divided into the following groups:

1) with low smoke-forming ability (D1 ), having a smoke-forming coefficient less than 50 square meters per kilogram;

2) with moderate smoke-forming ability (D 2 ), having a smoke coefficient of at least 50, but not more than 500 square meters per kilogram;
3) with high smoke-forming ability (DZ), Having a smoke formation coefficient of more than 500 square meters per kilogram.

To toxicity products combustion combustible building materials are divided into the following groups in accordance with Table 2 of Annexes to Federal Law No. 123:

1) Low hazard (T1);

2) moderate ( T2);

3) highly hazard ( TK);

4) extremely dangerous (T4).
Table 2. Classification of combustible building materials according to the value of the toxicity of combustion products (adj. To FZ No. 123)

Fire hazard classes of building materials depending on the fire hazard groups of building materials are given in Table. 3 applications to FZ №123.

Table 3. Fire hazard classes of building materials (ad. For FZ №123)

(Table in the editorial office entered from July 12, 2012 Federal law from July 10, 2012 N 117-FZ.

Note. The list of indicators of the fire hazard of building materials sufficient to assign the fire hazard classes of KM0-km5 is determined in accordance with the table 27 of the annex to the FZ No. 123.

Table 27. The list of indicators required to assess the fire hazard of building materials (Table in the editorial office of the Federal Law No. 123, entered into force from July 12, 2012 dated July 10, 2012 N 117-FZ)

Appointment of building materials	List of necessary indicators depending on the purpose of building materials
A combustion group	Flame-wound group	Group of ignorance	Smoke-forming ability	Group toxicity combustion products
Materials for wall decoration and ceilings, including coatings of paints, enamels, varnishes	+	-	+	+	+
Materials for floating floors, including carpets	-	+	+	+	+
Roofing materials	+	+	+	-	-
Waterproofing and vapor insulation materials with a thickness of more than 0.2 millimeters	+	-	+	-	-
Heat insulation materials	+	-	+	+	+

Notes:

1. The "+" sign indicates that the indicator must be applied.

2. The sign "-" denotes that the indicator does not apply.3. When applied waterproofing materials For the surface layer of the roof, their fire danger indicators should be determined by the "roofing materials" position.

For the classification of building materials should be applied the value of the flame spread index (I) - a conditional dimensionless indicator that characterizes the ability of materials or substances to ignite, spread the flame on the surface and highlight heat.

By spreading flames Materials are divided into the following groups:

1) non-flames on the surface having a flame distribution index 0;

2) slowly spreading the flame on the surface having a flame distribution index no more than 20;

3) Fast-spreading flames on the surface, having a flame distribution index of more than 20.

Test methods to determine the classification indicators of fire danger of construction, textile and leather materials are established by regulatory documents on fire safety.