General information about materials, their structure and properties. Thermal insulation materials and products made from them. Density is the ratio of the mass of a homogeneous material to a unit of its volume. This property is important when using materials in aviation and missile applications.

Works: All Selected To help the teacher Competition “Educational Project” Academic year: All 2015 / 2016 2014 / 2015 2013 / 2014 2012 / 2013 2011 / 2012 2010 / 2011 2009 / 2010 2008 / 2009 2007 / 2008 2006 / 2007 2005 / 6 Sorting: Alphabetically Newest

  • Study of the mechanical properties of spider silk

    In the work, the author examines the properties of spider silk and answers the question: is the thread of the spider web really so strong that you can hang a tank on it? The work provides arguments for and against, the author examines the mechanical properties and draws appropriate conclusions.

  • Study of free mechanical vibrations using the example of mathematical and spring pendulums

    The work identifies factors influencing the period and frequency of free mechanical oscillations of mathematical and spring pendulums. The dependence of the damping coefficient and logarithmic damping decrement on the type of substance during oscillations of mathematical and spring pendulums has been studied. The use of experiments allows us to consider the issue of free mechanical vibrations more clearly.

  • This work studies the properties of images obtained using a converging lens. It has been experimentally determined that, depending on the distance of the object from the lens, its image can be virtual or real, upright or inverted, enlarged or reduced, located either on the same side of the lens as the object, or on the other side of the lens relative to the object.

  • Study of the properties of materials used in local construction

    The work compares the thermal conductivity of materials used in local construction. A conclusion is drawn about the most popular building material and its advantages. A review of typical dwellings of different times and peoples and the materials used for their construction is made.

  • Study of the physical properties of dishwashing detergents

    The paper presents the results of a study of the density, viscosity, and surface tension coefficient of dishwashing liquids from some manufacturers.

  • Illustrated dictionary of physics. 8th grade

    Designed in the form of a presentation, the dictionary consists of four sections: thermal, electrical, electromagnetic phenomena and changes in the aggregate states of matter and includes 58 concepts. The words are located in two catalogs: alphabetical and thematic and combined into a single hypertext. The dictionary slides contain a definition, a brief description, an illustration, a calculation formula for a term, and buttons for going to catalogs. Some hyperlinked concepts can be explained in more detail by clicking on the appropriate slide.

  • Interactive presentation "Physic Scientists" using Visual Basic for Applications (VBA)

    The interactive presentation was developed using the BASIC visual programming language for Microsoft Office applications. Can be used both in physics lessons and in extracurricular activities.

  • Interactive electronic game "Test yourself"

    Learning is a very important process. But during training, fatigue accumulates, since you have to memorize many formulas, definitions, designations of various quantities, etc. The game element will help solve the problem of fatigue when memorizing program material. This paper proposes a game model to test students' knowledge. The principle of the game is described, a fundamental principle is proposed electrical diagram, a list of parts is given, and teaching materials are attached.

  • Information-illustrated problem book

    The problem book is dedicated to the integration of two subjects - physics and biology. It includes 10 problems that can be used in physics lessons on the topic “Mechanical Motion” in the 7th grade. Educational material about living nature is provided. Biophysical problems will contribute to the development of interest in physics. Information is presented in the form of text and illustrations.

  • Use of ground-based agricultural machinery in agricultural production

    One of the most common methods of treating agricultural plants to protect them from diseases and pests is pollination or spraying with pesticides. It is difficult to achieve good results using ground methods. For Russian agriculture, the situation in many regions is further complicated by the fact that farms simply do not have the appropriate equipment or it is faulty. Cultivation of fields in such farms becomes a big problem. But very often small aircraft come to the rescue. Airborne processing is an expensive undertaking compared to ground-based processing methods, but it has many advantages.

  • Using solar power plants at home

    Living without electricity is very difficult, but it costs a lot of money. Based on this, I wondered whether it was possible to produce electricity without significant costs. I learned that it is possible to use solar energy and conducted research in this direction. I collected information about which installations work using solar energy, studied them. After that, I calculated the amount of electricity consumed in my apartment and found out whether it was possible to use solar panels in it.

  • Study of the shock-absorbing properties of various substances

    The work was carried out comparative analysis shock-absorbing properties of various materials. Considering that the degree of pain upon impact depends on the time of impact, to evaluate the latter, voltage measurements were taken between the capacitor plates. Objects of study: various types road and floor coverings.

  • Study of the influence of different types of water on the growth and development of plants

    The work examines the influence of “living”, “dead” and holy water on the growth and development of agricultural plants.

  • Study of the diffusion properties of a substance in structured water

    IN recent years Interest in the unusual property of water - its memory - is growing; it has become the object of study by many prominent scientists. The effect of structured water on the diffusion of substances has also been little studied. This work describes our own method for producing structured water in a school laboratory and conducted experiments to study its effect on the diffusion properties of the substance.

  • Study of the dependence of relative indoor air humidity on various parameters

  • Study of the dependence of the burner efficiency of a household gas stove on the combustion mode

    The purpose of this school research project– find out how the burner efficiency of a household stove depends on gas consumption and the ratio of the sizes of the burner and cookware. Experiments are carried out with three burners various sizes using dishes of two diameters. In a series of experiments, water is heated on each burner with different gas flow rates (controlled by a gas meter). For each experiment, the fuel efficiency is calculated using spreadsheets and the results are presented in the form of graphs.

  • Research and diagnostics of nanoscale objects

    Introduction to physical methods for studying micro- and nanoscale objects. Carrying out qualitative elemental analysis of the surface of an unknown crystal structure using Auger electron spectroscopy with subsequent identification.

  • Research and identification of an unknown substance

    The work carried out a qualitative crystallographic analysis of an unknown structure using Raman spectroscopy with subsequent identification.

  • Study of the model properties of various paper airplane models

    My passion for aircraft construction began with paper models. We made them as a class in labor class. At the end of the lesson, the guys launched their airplanes, and I noticed that they flew differently. Some stick to a straight path, others turn to the side. I had a question: “What makes the same model fly differently?” And I decided to study the flying properties of various models of paper airplanes. The paper describes a study of aircraft with different masses, with different launch methods, in different conditions(indoors, street).

  • Study of the formation of a cumulative jet

    When physicists talk about cumulation, they usually mean short-term processes, such as explosions, and by cumulation they mean an increase in a certain place or direction of action of these processes. But cumulative jets of liquid can appear not only during explosions. Therefore, I decided to study the features of the interaction of “bodies of arbitrary shape with liquid” based on the nature of the “bursts”. The work examines the conditions for the formation of a cumulative jet and the factors on which its formation depends. The object of study was the types of splashes formed when a drop of liquid falls into a liquid; when a solid ball falls into a liquid; depending on the density of the liquid and balls, their radius and height of fall, on the height of the fall of a drop of liquid into a liquid, on the time between the separation of drops; the appearance of a splash when a test tube falls.

  • Study of the density of a walrus tooth (tusk)

    The project carried out a study of the density of a walrus tooth (tusk), and also compiled problems about walruses.

  • Study of food preparation for control of radionuclide content (strontium and cesium)

    The paper presents a study of the preparation of food products for control for the content of strontium and cesium radionuclides using fish samples as an example. The purpose of this work is to get acquainted with the laboratory, study methods for analyzing raw materials, intermediate products and finished products, study the instruments and scales located in the laboratory, and the radiochemical method for analyzing food samples.

General information about building materials.

During the construction, operation and repair of buildings and structures, building products and structures from which they are erected are subject to various physical, mechanical, physical and technological influences. A hydraulic engineer is required to competently select the right material, product or structure that has sufficient strength, reliability and durability for specific conditions.


LECTURE No. 1

General information about building materials and their basic properties.

Construction materials and products used in the construction, reconstruction and repair of various buildings and structures are divided into natural and artificial, which in turn are divided into two main categories: the first category includes: brick, concrete, cement, timber, etc. They are used during the construction of various building elements (walls, ceilings, coverings, floors). The second category is for special purposes: waterproofing, thermal insulation, acoustic, etc.

The main types of building materials and products are: natural stone building materials; inorganic and organic binding materials; forest materials and products made from them; hardware. Depending on the purpose, conditions of construction and operation of buildings and structures, appropriate building materials are selected that have certain qualities and protective properties from exposure to various external environments. Taking these features into account, any building material must have certain construction and technical properties. For example, the material for the external walls of buildings must have the lowest thermal conductivity with sufficient strength to protect the room from the external cold; material for drainage and drainage structures – waterproof and resistant to alternating wetting and drying; the material for covering the road (asphalt, concrete) must have sufficient strength and low abrasion to withstand the loads from transport.

When classifying materials and products, it is necessary to remember that they must have good properties And qualities.

Property- a characteristic of a material that manifests itself during its processing, application or operation.

Quality– a set of properties of a material that determine its ability to satisfy certain requirements in accordance with its purpose.

The properties of building materials and products are classified into three main groups: physical, mechanical, chemical, technological etc. .

TO chemical refer to the ability of materials to resist the action of a chemically aggressive environment, causing exchange reactions in them leading to the destruction of materials, a change in their original properties: solubility, corrosion resistance, resistance to rotting, hardening.

Physical properties: average, bulk, true and relative density; porosity, humidity, moisture transfer, thermal conductivity.

Mechanical properties: strength limits in compression, tension, bending, shear, elasticity, plasticity, rigidity, hardness.

Technological properties: workability, heat resistance, melting, speed of hardening and drying.

Physical and chemical properties of materials.

Average density ρ 0 mass m unit volume V 1 absolutely dry material in its natural state; it is expressed in g/cm3, kg/l, kg/m3.

Bulk density of bulk materials ρ n mass m unit volume V n dried, loosely poured material; it is expressed in g/cm3, kg/l, kg/m3.

True Density ρ mass m unit volume V material in an absolutely dense state; it is expressed in g/cm3, kg/l, kg/m3.

Relative density ρ(%) – degree of filling of the volume of material with solid matter; it is characterized by the ratio of the total volume of solid matter V in the material to the entire volume of the material V 1 or the ratio of the average density of the material ρ 0 to its true density ρ: , or.

Porosity P - degree of filling of the material volume with pores, voids, gas-air inclusions:

for solid materials: , for bulk materials:

Hygroscopicity- the ability of a material to absorb moisture from the environment and thicken it in the mass of the material.

HumidityW (%) – ratio of the mass of water in the material mV= m 1 - m to its mass in a completely dry state m:

Water absorption IN – characterizes the ability of a material, when in contact with water, to absorb and retain it in its mass. There are mass In m and volumetric V o water absorption.

Mass water absorption (%) – ratio of the mass of water absorbed by the material mV to the mass of the material in a completely dry state m:

Volumetric water absorption (%) – ratio of the volume of water absorbed by the material mV/ ρ V to its volume in a water-saturated state V 2 :

Moisture release– the ability of the material to release moisture.

Mechanical properties of materials.

Compressive strengthR – breaking load ratio P(N) to the cross-sectional area of ​​the sample F(cm 2). It depends on the size of the sample, the speed of application of the load, the shape of the sample, and humidity.

Tensile strengthR r - breaking load ratio R to the original cross-sectional area of ​​the sample F.

Bending strengthR And – determined on specially made beams.

Rigidity– the property of a material to produce small elastic deformations.

Hardness– the ability of a material (metal, concrete, wood) to resist penetration into it under the constant load of a steel ball.

LECTURE No. 2

Natural stone materials.

Classification and main types of rocks.

Rocks that have the necessary construction properties are used as natural stone materials in construction.

According to geological classification, rocks are divided into three types:

1) igneous (primary), 2) sedimentary (secondary) and 3) metamorphic (modified).

1) Igneous (primary) rocks formed during the cooling of molten magma rising from the depths of the earth. The structures and properties of igneous rocks largely depend on the cooling conditions of the magma, and therefore these rocks are divided into deep And poured out.

Deep rocks formed during the slow cooling of magma deep in the earth's crust at high pressures in the overlying layers of the earth, which contributed to the formation of rocks with a dense granular-crystalline structure, high and medium density, and high compressive strength. These rocks have low water absorption and high frost resistance. These rocks include granite, syenite, diorite, gabbro, etc.

Erupted rocks formed during the process of magma reaching the earth's surface with relatively rapid and uneven cooling. The most common eruptive rocks are porphyry, diabase, basalt, and volcanic loose rocks.

2) Sedimentary (secondary) rocks formed from primary (igneous) rocks under the influence of temperature changes, solar radiation, the action of water, atmospheric gases, etc. In this regard, sedimentary rocks are divided into clastic (loose), chemical And organogenic.

To the clastic Loose rocks include gravel, crushed stone, sand, and clay.

Chemical sedimentary rocks : limestone, dolomite, gypsum.

Organogenic rocks: limestone-shell rock, diatomite, chalk.

3) Metamorphic (modified) rocks formed from igneous and sedimentary rocks under the influence high temperatures and pressures during the rise and fall of the earth's crust. These include shale, marble, and quartzite.

Classification and main types of natural stone materials.

Natural stone materials and products are obtained by processing rocks.

By method of receipt stone materials are divided into torn stone (rubble) - mined by explosive means; rough stone - obtained by splitting without processing; crushed – obtained by crushing (crushed stone, artificial sand); sorted stone (cobblestone, gravel).

Stone materials are divided into stones according to their shape irregular shape(crushed stone, gravel) and piece products having the correct shape (slabs, blocks).

Crushed stone– acute-angled pieces of rock ranging in size from 5 to 70 mm, obtained by mechanical or natural crushing of rubble (torn stone) or natural stones. It is used as a coarse aggregate for the preparation of concrete mixtures and foundations.

Gravel– rounded pieces of rock ranging in size from 5 to 120 mm, also used for preparing artificial gravel-crushed stone mixtures.

– a loose mixture of rock grains ranging in size from 0.14 to 5 mm. It is usually formed as a result of weathering of rocks, but can also be obtained artificially - by crushing gravel, crushed stone, and pieces of rock.

LECTURE No. 3

Hydrotational (inorganic) binders.

1. Air binders.

2. Hydraulic binders.

Hydrotational (inorganic) binders are finely ground materials (powders) that, when mixed with water, form a plastic dough that is capable of hardening through chemical interaction with it, gaining strength, while binding the aggregates introduced into it into a single monolith, usually stone materials (sand, gravel, crushed stone) , thereby forming an artificial stone such as sandstone, conglomerate.

Hydration binders are divided into air(hardening and gaining strength only in air) and hydraulic(hardening in a humid, airy environment and under water).

Construction air limeCaO – a product of moderate firing of natural carbonate rocks at 900-1300°C CaCO3 containing up to 8% clay impurities (limestone, dolomite, chalk, etc.). Firing is carried out in shafts and rotary kilns. Most widespread received shaft furnaces. When calcining limestone in a shaft kiln, the material moving in the shaft from top to bottom passes through three zones in succession: a heating zone (drying of raw materials and the release of volatile substances), a firing zone (decomposition of substances) and a cooling zone. In the heating zone limestone is heated to 900°C due to the heat coming from the burning zone from gaseous combustion products. In the firing zone fuel combustion and limestone decomposition occurs CaCO3 on lime CaO and carbon dioxide CO2 at 1000-1200°C. In the cooling zone burnt limestone is cooled to 80-100°C by cold air moving from bottom to top.

As a result of firing, carbon dioxide is completely lost and lumpy, quicklime is obtained in the form of white or gray pieces. Lump quicklime is a product from which different types of building aerial lime are obtained: ground powdered quicklime, lime paste.

Construction aerated lime of various types is used in the preparation of masonry and plaster mortars, low-grade concrete (working in air-dry conditions), the production of dense silicate products (bricks, large blocks, panels), and the production of mixed cements.

Hydraulic and drainage structures and structures operate under conditions of constant exposure to water. These severe operating conditions of structures and structures require the use of binders that have not only the necessary strength properties, but also water resistance, frost resistance and corrosion resistance. Hydraulic binders have these properties.

Hydraulic lime obtained by moderate firing of natural marls and marly limestones at 900-1100°C. Marl and marly limestone used for the production of hydraulic lime contain from 6 to 25% clay and sand impurities. Its hydraulic properties are characterized by the hydraulic (or main) module ( m), representing the percentage ratio of the content of calcium oxides to the content of the sum of oxides of silicon, aluminum and iron:

Hydraulic lime is a slow-setting and slow-hardening substance. It is used for the preparation of mortars, low-quality concrete, lightweight concrete, and for the production of mixed concrete.

Portland cement– a hydraulic binder obtained by jointly finely grinding clinker and gypsum dihydrate. Clinker– a product of firing before sintering (at t>1480°C) of a homogeneous, specific composition of a natural or raw material mixture of limestone or gypsum. The raw material is fired in rotary kilns.

Portland cement is used as a binder in the preparation of cement mortars and concrete.

Slag Portland cement- contains a hydraulic additive in the form of granulated, blast furnace or electrothermophosphorus slag, cooled according to a special regime. It is obtained by joint grinding of Portland cement clinker (up to 3.5%), slag (20...80%), and gypsum stone (up to 3.5%). Portland slag cement has a slow increase in strength in the initial stages of hardening, but subsequently the rate of increase in strength increases. It is sensitive to ambient temperature, resistant to exposure to soft sulfate waters, and has reduced frost resistance.

Carbonate Portland cement obtained by co-grinding cement clinker with 30% limestone. It has reduced heat generation during hardening and increased durability.

LECTURE No. 4

Construction solutions.

General information.


Mortars They are carefully dosed fine-grained mixtures consisting of an inorganic binder (cement, lime, gypsum, clay), fine aggregate (sand, crushed slag), water and, if necessary, additives (inorganic or organic). When freshly prepared, they can be laid on the base in a thin layer, filling all its unevenness. They do not delaminate, set, harden and gain strength, turning into a stone-like material. Mortars are used for masonry, finishing, repair and other work. They are classified according to average density: heavy with medium ρ =1500kg/m3, light to medium ρ <1500кг/м 3 . По назначению: гидроизоляционные, талтопогенные, инъекционные, кладочные, отделочные и др.

Solutions prepared using one type of binder are called simple; solutions made from several binders are mixed (cement-lime). Construction mortars prepared with air binders are called air mortars (clay, lime, gypsum). The composition of solutions is expressed by two (simple 1:4) or three (mixed 1:0.5:4) numbers, showing the volumetric ratio of the amount of binder and fine aggregate. In mixed solutions, the first number expresses the volume fraction of the main binder, the second - the volume fraction of the additional binder relative to the main one. Depending on the amount of binder and fine aggregate, mortar mixtures are divided into fatty– containing a large amount of binder. Normal– with normal binder content. Skinny– containing a relatively small amount of binder (low plasticity).

To prepare mortars, it is better to use sand with grains that have a rough surface. Sand protects the solution from cracking during hardening and reduces its cost.

Waterproofing solutions (waterproof)– cement mortars of composition 1:1 – 1:3.5 (usually fatty), to which ceresite, sodium amominate, calcium nitrate, ferric chloride, and bitumen emulsion are added.

Ceresit– is a white or yellow mass obtained from aniline acid, lime, and ammonia. Ceresite fills small pores, increases the density of the solution, making it waterproof.

For the manufacture of waterproofing solutions, Portland cement and sulfate-resistant Portland cement are used. Sand is used as a fine aggregate in waterproofing solutions.

Masonry mortars– used for laying stone walls and underground structures. They are cement-lime, cement-clay, lime and cement.

Finishing (plaster) solutions- divided according to purpose into external and internal, according to location in the plaster into preparatory and finishing.

Acoustic solutions– lightweight solutions with good sound insulation. These solutions are prepared from Portland cement, Portland slag cement, lime, gypsum and other binders using lightweight porous materials (pumice, perlite, expanded clay, slag) as filler.

LECTURE No. 5

Ordinary concrete with hydration binders.

1. Materials for ordinary (warm) concrete.

2. Design of concrete mixture composition.

Concrete- an artificial stone material obtained as a result of hardening of a concrete mixture, consisting of hydration binders (cementing agents), small (sand) and large (crushed stone, gravel) fillers, water and, if necessary, additives dosed in a certain ratio.

Cement. When preparing a concrete mixture, the type of cement used and its grade depend on the operating conditions of the future concrete structure or structure, their purpose, and methods of performing the work.

Water. To prepare the concrete mixture, use ordinary drinking water that does not contain harmful impurities that prevent the hardening of the cement stone. It is prohibited to use sewage, industrial or domestic water, or swamp water for preparing concrete mixtures.

Fine aggregate. Natural or artificial sand is used as fine aggregate. Grain size from 0.14 to 5 mm, true density more ρ >1800kg/m3. Artificial sand is produced by crushing dense, heavy rocks. When assessing the quality of sand, its true density, average bulk density, intergranular voids, moisture content, grain composition and fineness modulus are determined. In addition, additional research should be conducted quality indicators sand - the shape of the grains (acute angle, roundness...), roughness, etc. Cereal or the granulometric composition of the sand must meet the requirements of GOST 8736-77. It is determined by sifting dried sand through a set of sieves with holes of size 5.0; 2.5; 1.25; 0.63; 0.315 and 0.14 mm. As a result of sifting a sample of sand through this set of sieves, a residue remains on each of them, called privatea i. It is found as the ratio of the mass of the residue on a given sieve m i to the mass of the entire sample of sand m:

In addition to partial residues, complete residues are found A, which are defined as the sum of all partial residues in % on the overlying sieves + the partial residue on this sieve:

Based on the results of sand sifting, its fineness modulus is determined:

Where A– total residues on the sieves, %.

According to the particle size modulus, coarse sand is distinguished ( M k >2.5), average ( M k =2.5…2.0), small ( M k =2.0…1.5), very small ( M k =1.5…1.0) .

By plotting the sand sifting curve on the graph of the permissible grain composition, the suitability of the sand for the manufacture of concrete mixture is determined.


1 - laboratory sieving curve for sand and coarse aggregate, respectively.

Of great importance in the selection of sand for a concrete mixture is its intergranular voidness. Vn(%) , which is determined by the formula:


ρ n.p.– bulk density of sand, g/cm3;

ρ – true density of sand, g/cm3;

In good sands, intergranular voids are 30...38%, in mixed-grained sands - 40...42%.

Coarse aggregate. Natural or artificial crushed stone or gravel with a grain size from 5 to 70 mm is used as a coarse aggregate for the concrete mixture.

To ensure optimal grain composition, coarse aggregate is divided into fractions depending on the largest grain size D max.; At D naib=20mm coarse aggregate has two fractions: from 5 to 10 mm and from 10 to 20 mm;

At D naib=40mm – three fractions: from 5 to 10 mm; from 10 to 20 mm and from 20 to 40 mm;

At D naib=70mm – four fractions: from 5 to 10 mm; from 10 to 20 mm; from 20 to 40 mm; from 40 to 70 mm. The intergranular void ratio of the coarse aggregate has a great influence on cement consumption when preparing a concrete mixture. Vp.kr(%), which is determined with an accuracy of 0.01% using the formula:

ρ n.kr– average bulk density of coarse aggregate.

ρ k.kus– average density of coarse aggregate in a piece.

The intergranular voids indicator should be minimal. Its lower value can be obtained by selecting the optimal grain composition of coarse aggregate.

The grain composition of coarse aggregate is determined by sifting dried coarse aggregate with a set of sieves with holes size 70; 40; 20; 10; 5 mm taking into account its maximum D naib and minimum D name size.

Crushed stone- usually an artificial loose material with unrounded rough grains, obtained by crushing rocks, coarse natural gravel or artificial stones. To determine the suitability of crushed stone, it is necessary to know: the true density of the rock, the average density of crushed stone, the average bulk density of crushed stone, the relative intergranular voids and moisture content of crushed stone

Gravel– loose natural material with rounded, smooth grains, formed during the process of physical weathering of rocks. The same requirements apply to gravel as to crushed stone.

Supplements. Introduction of additives into cement, mortar or concrete mixture is simple and in a convenient way improving the quality of cement, mortar stone and concrete. Allowing to significantly improve not only their properties but also technical and operational performance. Additives are used in the production of binders, preparation of mortars and concrete mixtures. They allow you to change the quality of the concrete mixture and the concrete itself; affecting workability, mechanical strength, frost resistance, crack resistance, water resistance, water resistance, thermal conductivity, resistance to the environment.


The main properties of a concrete mixture include cohesion (the ability to maintain its homogeneity without separating during transportation, unloading), homogeneity, water-holding capacity (plays a significant role in the formation of the structure of concrete, its acquisition of strength, water resistance and frost resistance), workability (the ability to quickly minimum cost energy to acquire the required configuration and density, ensuring the production of high-density concrete).

Freshly prepared concrete mixture must be well mixed (homogeneous), suitable for transportation to the place of installation, taking into account weather conditions, while resisting water separation and delamination.


The task of designing and selecting the composition of a concrete mixture includes choosing necessary materials(binder and other components) and establishing their optimal quantitative ratio. Based on this, a concrete mixture with specified technological properties is obtained, as well as the most economical and durable concrete that meets design and operational requirements with the minimum possible cement consumption. Consequently, a concrete mixture of the designed composition must have non-delamination, the necessary workability, cohesion, and concrete made from this mixture must have the required properties: density, strength, frost resistance, water resistance.

The simplest way to design the composition of a concrete mixture is to calculate by absolute volumes, which is based on the assumption that the prepared, laid and compacted concrete mixture should not have voids.

The design of the composition is carried out using current recommendations and regulatory documents in the following sequence:

1. Assigned for a given grade of concrete Rb rational brand of cement Rts.

2. Determine the water-cement ratio V/C, for ordinary concrete with V/C ≥0,4: V/C=ARts/(Rb+0.5ARts) ; Where Rts – brand of cement; Rb– brand of concrete; A– coefficient taking into account the quality of the components used.

3. Assign an approximate water consumption per 1 m 3 of concrete mixture. The water consumption required to obtain a concrete mixture of a given mobility depends not only on the type and largest size of the aggregate, but also on the shape and roughness of the grains.

4. Calculate cement consumption (kg per 1 m 3 of concrete) using the found ratio V/C and the accepted approximate water consumption: ;

5. The consumption of aggregates is calculated based on the condition that the sum of the absolute volumes of all constituent materials of concrete is equal to 1 m 3 of laid and compacted concrete mixture:

C, V, P, Kr– consumption of cement, water, sand, coarse aggregate per 1m3 of mixture, kg.

ρ c, ρ in, ρ p, ρ cr– density of these materials, kg/m3;

- their absolute volumes, m3.

Formulas for determining the consumption of aggregates (kg per 1 m 3 of concrete):

coarse aggregate:

r– coefficient separation of grains of coarse aggregate, taken approximately (tabular data)

P cr– voidness of coarse aggregate.

Ρ n.kr– bulk density of coarse aggregate.

fine aggregate (sand):

6. Calculate the estimated average density of the concrete mixture:

and concrete yield coefficient:

Concrete yield ratio β should be within 0.55...0.75.

The designed composition of the concrete mixture is specified in trial batches. They also check the mobility of the concrete mixture. If the mobility of the concrete mixture turns out to be greater than required, then water and cement are added to the mix in small portions, while maintaining a constant ratio V/C until the mobility of the concrete mixture becomes equal to the specified value. If the mobility turns out to be greater than the specified value, then sand and coarse aggregate are added to it (in portions of 5% of the original amount), maintaining the selected ratio V/C. Based on the results of test batches, adjustments are made to the designed composition of the concrete mixture, taking into account that in production conditions the sand and coarse aggregate used are in a wet state, and the coarse aggregate has some water absorption and consumption ( l) the required water for preparing 1 m 3 of concrete mixture is specified using the formula:

IN– consumption of found (calculated) water, l/m 3

P, Kr– consumption of sand and coarse aggregate, kg/m3

Wn, Wcr – moisture content of sand and coarse aggregate, %.

In kr– water absorption of coarse aggregate, %.

LECTURE No. 6

1. Preparation, transportation and laying of concrete mixture. Care of freshly laid concrete and quality control.

2. Hydraulic concrete.

3. Special types of concrete.


Concrete mixtures are prepared in stationary concrete plants or in mobile concrete mixing plants. The quality of the concrete mixture (homogeneity) is influenced by the quality of its mixing during the preparation process. The mixing time is several minutes. It is allowed to re-mix the concrete mixture within 3...5 hours from the moment of its preparation. The most important condition for preparing a concrete mixture is careful dosing of the constituent materials. Deviation in dosage is allowed no more than ±1% by weight for cement and water, and no more than ±2% for aggregates. The prepared concrete mixture is delivered to the laying site using special vehicles. The duration of transportation of the finished concrete mixture to the laying site should not exceed 1 hour. Currently, the concrete mixture is laid mechanically using concrete pavers and concrete distributors. Compaction of the concrete mixture during laying ensures high-quality filling of all gaps with the mixture. The most common method of compacting a concrete mixture is vibration. When a concrete mixture vibrates, the friction between its components decreases, fluidity increases, the mixture becomes a heavy viscous liquid and becomes compacted under the influence of its own weight. During the compaction process, air is removed from the concrete mixture and the concrete acquires good density. To improve the structure-forming properties of concrete, increase its strength, frost resistance, and water resistance, repeated vibration of the concrete mixture is used after 1.5-2 hours. from the moment of the first vibration.

To obtain high-quality concrete, proper care of freshly placed concrete is necessary. Failure to maintain freshly placed concrete can result in low-quality concrete. The main measures for caring for concrete are covering with well-moistened burlap, sand, sawdust, and coating with a film-forming compound. Covering should be done no later than 30 minutes after compacting the concrete mixture.

IN winter time There are the following methods of care: unheated and with artificial heating. Non-heating methods include thermos methods with antifreeze additives. Artificial heating of concrete is carried out by electric heating, steam heating, and air heating.


Concrete used in the construction of hydraulic engineering and drainage structures, constantly or periodically washed with water, is called hydraulic engineering. Hydraulic concrete must have not only strength and frost resistance, but also water resistance and water resistance, which will ensure its long-term service in the aquatic environment.

Depending on the location in relation to the water level, hydraulic concrete in buildings or structures is divided into underwater– constantly in the water; variable level zones– subject to periodic washing with water; surface– located above the variable level zone. Based on the surface area of ​​structures, hydraulic concrete is divided into massive and non-massive, and based on its location in the structure - external and internal zones.

Basic construction and technical properties of hydraulic concrete– water resistance, frost resistance, water absorption, strength, resistance to the aggressive effects of water, heat dissipation, durability, mobility and rigidity of the concrete mixture.

Portland cement is used as a binding material for hydraulic concrete. To improve the quality of hydraulic concrete, it is recommended to introduce additives into it that can reduce volumetric expansion, shrinkage, and water demand. Sand for hydraulic concrete is used coarse, medium-sized and fine natural or artificial, from hard and dense rocks. Gravel and crushed rock are used as coarse aggregates for hydraulic concrete.


Extra heavy concrete– used for special protective structures (for protection against radioactive influences). It has an average density of more than 2500 kg/m3. Magnetite, limonite, hydrogenite, hematite, barite are used as fillers, which determines the name of the concrete - magnetite, limonite, barite, ... The binders in this concrete are Portland cement, Portland slag cement and aluminous cement.

Road concrete– used in the construction of highways, airfields, and city streets. High-quality materials are used to prepare the road concrete mixture. Plasticized Portland cement is used as a binder.

Dry concrete– this is a dry concrete mixture, dosed at the factory from dry components (cement, sand, coarse aggregate...). At the laying site, the concrete mixture is mixed with water in concrete mixers or directly in concrete mixer trucks.

LECTURE No. 7

Concrete and reinforced concrete products in irrigation and drainage construction.

General information.

Reinforced concrete- This is an artificial material representing concrete, inside of which there is steel reinforcement. Steel reinforcement absorbs well not only compressive, but also tensile forces that arise in a structure during eccentric compression, tension, and bending. Reinforced concrete structures can be monolithic, when concreting is carried out directly at the construction site, and prefabricated, when the structures are manufactured in factories.

Prefabricated concrete and reinforced concrete products are classified according to the type of concrete: cement, silicate; internal structure: solid and hollow; by purpose: for residential, public, industrial, water management and other buildings and structures.

Reinforced concrete structures, structures and products are made from ordinary concrete of a grade not lower than 200, lightweight concrete of a grade not lower than 50 and dense silicate concrete of a grade not lower than 100. Concrete of grade 200 is used for the manufacture of lightly loaded concrete and reinforced concrete products that work mainly in compression. Concrete grades 300, 400, 500, 600 are used in the manufacture of reinforced concrete products with high load-bearing capacity.

Concrete used for the preparation of concrete and reinforced concrete products, structures and structures for irrigation and drainage purposes must ensure their reliability and durability.

To form conventional (non-stressed) reinforced concrete monolithic structures, as well as prefabricated products and structures, welded meshes and frames, rolled meshes made of hot-rolled steel reinforcement are used. In the manufacture of non-stressed structures and products, high-strength wire and reinforcing ropes are used. The reinforcement is pre-stretched (stressed). The reinforcement is tensioned before concreting using various anchors and clamps. After laying, hardening of the concrete mixture and the concrete acquiring strength, the ends of the reinforcement are released (cut off) and it, trying to return to its original state, strains (compresses) the concrete. When installing stressed structures, the reinforcement is placed in special channels, and then stretched in such a way that during the stretching process, these elements are compressed into the structure. After achieving the required compression of the structure and stretching of the reinforcement, its ends are anchored, and the channels through which the reinforcement passes are sealed with high-strength cement mortar. When the solution acquires the necessary strength, the ends of the reinforcement are cut off, as a result of which the structure acquires tension, which allows it to increase its load-bearing capacity.

Precast concrete products.

Drainage pipes made of soil silicate concrete made from a mixture of local soil (sand, sandy loam, loam), ground slag and an alkaline component. Pipe length 333 mm, internal diameter 50; 70; 100; 150 mm, wall thickness 10; 15; 20 mm. They have great load-bearing capacity and frost resistance. They are used in the construction of closed drainage dryers.

Drainage pipes made of filter concrete produced by layer-by-layer pressing. Pipe lengths are 500, 600, 900 mm, internal diameters are 100, 150 and 200 mm, wall thickness is 25, 30, 40 mm. They are intended for the installation of closed drainage.

Foundation pillars, made from concrete grade 100, are used as columnar foundations log, panel and frame wooden buildings.

Reinforced concrete products and structures.

Foundation blocks for trays have brands F-12-6, F15-9, F18-9, F21-12, where the first digit indicates the length L, the second – width IN block. They are made from hydraulic concrete grades of at least 200.

Trays parabolic cross-section for irrigation systems have a socket on one side and a smooth end on the other side. They are produced in non-tensioned (LR) lengths L=6000 mm, and stressed (OSR) length L=8000 mm grades, respectively LR-4; LR-6; LR-8; LR-10 and LRN-4; OSR-6; OSR-8; LRN-10, where the number indicates the depth of the trays H in dm. The trays are made of hydraulic concrete grade 300.


Glass and glass products.

Glass– a supercooled melt of complex composition from a mixture of silicates and other substances. Molded glass products are subjected to a special heat treatment - firing.

Window glass They are produced in sheets ranging in size from 250x250 to 1600x2000mm in two grades. By thickness, glass is divided into single (2mm thick), one-and-a-half (2.5mm), double (3mm) and thickened (4...6mm).

Showcase glass They are produced polished and unpolished in the form of flat or bent sheets with a thickness of 6..12 mm. It is used for glazing shop windows and openings.

Highly reflective sheet glass– this is ordinary window glass, on the surface of which a thin translucent light-reflecting film made on the basis of titanium oxide is applied. Glass with film reflects up to 40% of the incoming light, light transmission is 50...50%. Glass reduces visibility from the outside and reduces the penetration of solar radiation into the room.

Radioprotective sheet glass- This is ordinary window glass, on the surface of which a thin transparent screening film is applied. The screening film is applied to the glass during the process of its formation on machines. Light transmission not lower than 70%

Wired glass– manufactured on production lines by continuous rolling with simultaneous rolling inside the sheet metal mesh. This glass has a smooth, patterned surface and can be clear or colored.

Heat-absorbing glass has the ability to absorb infrared rays of the solar spectrum. It is intended for glazing window openings in order to reduce the penetration of solar radiation into rooms. This glass allows rays to pass through visible light no less than 65%, infrared rays no more than 35%.

Glass pipes made from ordinary transparent glass by vertical or horizontal drawing. Pipe length 1000...3000 mm, internal diameter 38-200mm. The pipes can withstand hydraulic pressure up to 2 MPa.

Sitalls obtained by introducing a special composition of crystallization catalysts into the molten glass mass. Products are formed from such a melt, then they are cooled, as a result of which the molten mass turns into glass. During the subsequent heat treatment of glass, its complete or partial crystallization occurs - sitole is formed. They have great strength, low average density, and high wear resistance. They are used for cladding external or interior walls, production of pipes, floor slabs.

Stemalit represents sheet glass of various textures, covered on one side with dull ceramic crystals of different colors. It is made from unpolished display or rolled glass with a thickness of 6...12mm. It is used for external and internal cladding of buildings, manufacturing wall panels.

LECTURE No. 8

Non-firing artificial stone materials and products based on hydration binders.


Non-firing artificial stone materials and products are made from a mixture of binders, water and aggregates through its formation and appropriate processing. By type of binder They are divided into silicate, lime-slag, gas silicate, aerated concrete, gypsum, gypsum concrete, asbestos-cement, etc.

According to hardening conditions– they are divided into products that harden during autoclave and heat treatment, and into products that harden in an air-humid environment.

Autoclave hardening materials and products.

For the production of autoclave-hardening products, local materials are widely used: lime, quartz sand, industrial waste.

Durable and waterproof autoclave materials and products are obtained as a result of the chemical interaction of finely ground lime and siliceous components during their hydrothermal treatment in a steam environment at 175°C in autoclaves under a pressure of 0.8...1.4 MPa. As a result of a chemical reaction, a durable and water-resistant substance (calcium silicate) is created, which cements the sand particles, forming an artificial stone. Autoclave materials and products can have either a dense or cellular structure.

Autoclaved silicate concrete– a mixture of calcareous-siliceous binder, sand and water. Lime-pozzolanic, lime-slag and lime-ash cements are used as binders. Products made from silicate autoclaved concrete have sufficient frost resistance, water resistance and chemical resistance to some aggressive environments. Large, dense, silicate wall blocks are made from autoclaved silicate.

Autoclaved cellular concrete prepared from a homogeneous mixture of mineral binder, silica component, gypsum and water. The binding materials are Portland cement and ground lime. During exposure of the product before autoclave treatment, hydrogen is released from it, as a result of which tiny bubbles are formed in a homogeneous plastic-viscous binder medium. During the process of gas release, these bubbles increase in size, creating spheroidal cells throughout the entire mass of the cellular concrete mixture.

During autoclave treatment under pressure of 0.8..1.2 MPa in a high-humidity air-steam environment at 175...200°C, intensive interaction of the binder with silica components occurs with the formation of calcium silicate and other cementing new formations, thanks to which the structure of cellular highly porous concrete acquires strength .

Single-row cut panels, wall and large blocks, single-layer and double-layer wall curtain panels, single-layer slabs of interfloor and attic floors are made from cellular concrete.

Sand-lime brick molded on special presses from a carefully prepared homogeneous mixture of pure quartz sand (92...95%), airborne lime (5...8%) and water (7...8%). After pressing, the brick is steamed in autoclaves in an environment saturated with steam at 175°C and a pressure of 0.8 MPa. Making bricks single size 250x120x65mm and modular(one and a half) size 250x120x88mm; solid and hollow, front and ordinary. Brick grade: 75, 100, 125, 150, 200, 250.

Asbestos-cement products.

For the manufacture of asbestos-cement products, an asbestos-cement mixture is used, consisting of fine-fiber asbestos (8...10%), Portland cement for asbestos-cement products and water. After the mixture hardens, an artificial asbestos-cement stone material is formed, representing cement stone. For the production of asbestos-cement products, grade III-IV asbestos, Portland cement for asbestos-cement products of grades 300, 400, 500 or sand cement consisting of Portland cement and finely ground quartz sand and water with a temperature of 20 ... 25 ° C, which does not contain clay impurities, organic substances and mineral salts.

Pipes non-pressure and pressure water pipes, for laying telephone cables and gas pipes have the correct cylindrical shape. They are smooth and have no cracks. Gravity pipes used when laying non-pressure internal and external pipelines transporting rubble and atmospheric waste water; during the construction of non-pressure tubular hydraulic structures and drainage collectors of drainage systems; when laying cables underground. Pressure pipes widely used in the construction of underground water pipelines, modern automated irrigation systems, and heating networks.

Flat slabs Pressed facings are produced unpainted or painted. They are used for cladding walls and panel partitions. Their length is 600...1600mm, width 300...1200, thickness 4...10mm.

Gypsum and gypsum concrete products.

Products based on gypsum binders have a relatively low density, sufficient strength, are fireproof, have high sound and heat insulating properties, and are easy to process (sawing, drilling). To increase the moisture and water resistance of gypsum products, gypsum-cement-pozzolam and gypsum-slag-cement-pozzolam are used in their manufacture. binders, cover them with waterproof, waterproof protective paints or pastes. Products based on gypsum binders are made from gypsum dough, gypsum mortar or gypsum concrete with mineral fillers (sand, expanded clay gravel...) and organic fillers (sawdust, shavings, reeds...). Gypsum and gypsum concrete products have significant fragility, therefore, during their manufacture, reinforcing materials are introduced into them in the form of wooden slats, reeds, metal reinforcement (mesh, wire...)

Gypsum cladding sheets made from gypsum sheet lined with cardboard on both sides. Gypsum sheet is prepared from a mixture building gypsum with mineral or organic additives. They are used for internal cladding of walls, partitions, and ceilings of buildings.

Gypsum boards for partitions made from a mixture of building gypsum with mineral or organic fillers. The slabs are produced solid and hollow with a thickness of 80...100mm. Gypsum and gypsum concrete partition slabs are used to construct partitions inside a building.

Gypsum concrete panels for subfloors made of gypsum concrete with a compressive strength of at least 7 MPa. They have a wooden slatted frame. The dimensions of the panels are determined by the size of the premises. The panels are designed for linoleum and tile floors in rooms with normal humidity.

Gypsum ventilation blocks made from building gypsum with a compressive strength of 12...13 MPa or from a mixture of gypsum-cement-pozzolanic binder with additives. Blocks are designed for the device ventilation ducts in residential, public and industrial buildings.

LECTURE No. 9

Artificial firing materials

General information.

Artificial firing materials and products (ceramics) are obtained by firing a molded and dried clay mass at 900...1300°C. As a result of firing, the clay mass is transformed into an artificial stone that has good strength, high density, water resistance, water resistance, frost resistance and durability. The raw material for the production of ceramics is clay with in some cases, thinning additives introduced into it. These additives reduce the shrinkage of products during drying and firing, increase porosity, and reduce the average density and thermal conductivity of the material. Sand, crushed ceramics, slag, ash, coal, and sawdust are used as additives. The firing temperature depends on the temperature at which the clay begins to melt. Ceramic building materials are divided into porous and dense. Porous materials have a relative density of up to 95% and water absorption of no more than 5%; their compressive strength does not exceed 35 MPa (brick, drainage pipes). Dense materials have a relative density of more than 95%, water absorption of less than 5%, compressive strength of up to 100 MPa; they are wear-resistant (floor tiles).

Ceramic materials and products made from low-melting clays.

1) Ordinary clay bricks of plastic pressing are made from clays with or without thinning additives. The brick is a parallelepiped. Brick brands: 300, 250, 200, 150, 125, 100, 75.

2) Ceramic hollow brick (stone) of plastic pressing is produced for masonry load-bearing walls one-story and multi-storey buildings, interior spaces, walls and partitions, cladding brick walls. Brick grade: 150, 125, 100 and 75.


3) Lightweight building bricks are made by molding and firing a mass of clay with burnable additives, as well as from mixtures of sand and clay with burnable additives. Brick size: 250x120x88mm, grades 100, 75, 50, 35.

Ordinary clay brick is used for laying internal and external walls, pillars and other parts of buildings and structures. Clay and ceramic hollow bricks are used for laying internal and external walls of buildings and structures above the waterproofing layer. Light brick is used for laying external and internal walls of buildings with normal indoor humidity.

4) Roof tiles made from fatty clay by firing at 1000...1100°C. Good-quality tiles, when lightly struck with a hammer, produce a clear, non-rattling sound. It is strong, very durable and fire resistant. Disadvantages - high average density, which weighs down the load-bearing structure of the roof, fragility, the need to install roofs with a large slope to ensure rapid water drainage.

5) Drainage ceramic pipes made from clays with or without thinning additives, internal diameter 25...250 mm, length 333, 500, 1000 mm and wall thickness 8...24 mm. They are made in brick or special factories. Drainage ceramic pipes are used in the construction of drainage, humidification and irrigation systems, collector and drainage water pipelines.

Ceramic materials and products from refractory clays.

1) Stone for underground collectors is made of a trapezoidal shape with side grooves. It is used when laying underground sewers with a diameter of 1.5 and 2 m, when constructing sewerage and other structures.

2) Ceramic facade tiles are used for cladding buildings and structures, panels, blocks.

3) Ceramic sewer pipes made from refractory and refractory clays with thinning additives. They have a cylindrical shape and length of 800, 1000 and 1200 mm, internal diameter 150...600 m.

4) Floor tiles are divided into smooth, rough and embossed according to the type of front surface; by color - single-color and multi-color; in shape - square, rectangular, triangular, hexagonal, tetrahedral. The thickness of the tiles is 10 and 13 mm. It is used for installing floors in industrial and water management buildings with wet conditions.

LECTURE No. 10

Coagulation (organic) binders.

Mortars and concretes based on them.

Organic binding materials used in the construction of waterproofing, in the manufacture of waterproofing materials and products, as well as waterproofing and asphalt solutions, asphalt concrete, are divided into bitumen, tar, and bitumen-tar. They dissolve well in organic solvents (gasoline, kerosene), are waterproof, can, when heated, transform from a solid to a plastic and then a liquid state, have high adhesion and good adhesion to building materials (concrete, brick, wood).

Bituminous materials.

Bitumen is divided into natural and artificial. In nature, pure bitumen is rare. Typically, bitumen is extracted from porous sedimentary rocks impregnated with it as a result of the rise of oil from underlying layers. Artificial bitumens are obtained during oil refining, as a result of distilling gases (propane, ethylene), gasoline, kerosene, and diesel fuel from its composition.

Natural bitumen– a solid or viscous liquid consisting of a mixture of hydrocarbons.

Asphalt rocks– rocks impregnated with bitumen (limestones, dolomites, sandstones, sands and clays). Bitumen is extracted from them by heating, or these rocks are used in ground form (asphalt powder).

Asphaltites– rocks consisting of solid natural bitumen and other organic substances insoluble in carbon disulfide.


Tar materials.

Tar obtained by dry distillation (heating at high temperatures without air access) of hard or brown coal, peat, and wood. Depending on the source material, tar is divided into coal tar, lignite tar, peat tar, and wood tar.

Coal tar– a viscous dark brown or black liquid consisting of hydrocarbons.

Coal Pitch- a black solid substance obtained after distilling almost all oil fractions from tar.

Coal tar, pitch, when heated or dissolved, forms toxic fumes, so care must be taken when working with them.

Asphalt solutions.

Asphalt solutions are used in the construction of waterproofing plasters and coatings, sidewalks, and floors. They can be hot (cast) or cold. The composition of asphalt solutions is selected depending on the operating conditions in buildings.

Cold asphalt solution made from a mixture of petroleum bitumen (5...10%) with the addition of a solvent (benzene), powder mineral filler(limestone, dolomite) and clean dry sand, mixed in special mortar mixers heated to 110...120°C. Hardening of cold asphalt mortar occurs due to the evaporation of the solvent.

Hot asphalt solution made from a mixture of bitumen (or tar, pitch), powdered mineral filler and sand. The mixture of components of the hot asphalt solution is mixed in special mixers and heated to 120...180°C. The asphalt solution is laid in layers while hot, rolling each layer with rollers.


Asphalt concrete.

Asphalt concrete is prepared in specialized asphalt plants or installations. Depending on their purpose, they are divided into road, for flooring; depending on the composition - bitumen and tar; depending on the styling temperature - cold and hot.

Cold asphalt concrete laid in layers on dry or slightly damp surfaces with light rolling with rollers. It is made from a mixture of liquid bitumen, solvents, powdered mineral filler (limestone, sand), pure crushed stone and sand by mixing and heating.


LECTURE No. 11

Polymer materials.

General information.

Polymer materials are natural or synthetic high-molecular organic compounds consisting of a huge number of atoms. The structure of polymer molecules can have linear or volumetric character. Polymers, whose molecules have linear structure, have thermoplasticity - softening when heated, they harden again when cooled. Softening and hardening can be carried out repeatedly. Repeated heating followed by cooling does not significantly change the properties of the material (polyethylene, polystyrene). Polymers having volumetric structure molecules are thermoresponsive - they cannot repeatedly melt and harden reversibly. When first heated, they become plastic and take on a given shape, turning into an infusible and insoluble state (phenoplasts).

According to elastic properties Polymers are divided into plastics (hard) and elastics (elastic).

Polymer materials contain three groups of substances: binders, plasticizers and fillers. Binders Synthetic resins are used. As plasticizers introducing glycerin, camphor and other substances that increase the elasticity and plasticity of polymers, facilitating their processing. Fillers(powder, fibrous) give polymer products greater mechanical strength and prevent shrinkage. In addition, pigments, stabilizers, hardening accelerators and other substances are added to the composition.

In the manufacture of polymer building materials, products and structures, the greatest use is made of polyethylene (films, pipes), polystyrene (boards, varnishes), polyvinyl chloride (linoleum), polymethyl methacrylate ( organic glass).

Due to their good mechanical properties, elasticity, electrical insulating qualities, and the ability to take any shape during processing, polymer materials have found wide application in all areas of construction and in our everyday life.


Initial polymer materials.

Depending on the production method, polymers are divided into polymerization and polycondensation. Polymerization polymers are produced by polymerization. These include polyethylene and polystyrene. Polycondensation polymers are produced by the polycondensation method. These include polyester, acrylic, organosilicon and other resins, polyesters, and polyurethane rubbers.

Polyethylene obtained by polymerization of ethylene from associated and natural gas. It ages under the influence of solar radiation, air, and water. Its density is 0.945 g/cm 3, frost resistance is -70°C, and heat resistance is only 60...80°C. According to the production method, a distinction is made between high pressure polyethylene (HDPE), low pressure polyethylene (LDPE) and chromium oxide catalyst (P). When heated to 80°C, polyethylene dissolves in benzene and carbon tetrachloride. It is used for the production of films of finishing materials.

Polyisobutylene– rubber-like or liquid elastic material obtained by polymerization of isobutylene. It is lighter than polyethylene, less durable, has very low moisture and gas permeability, and almost does not age. It is used for the manufacture of waterproofing fabrics, protective coatings, films, as additives in asphalt concrete, a binder for adhesives, etc.

Polystyrene– thermoplastic resin, a product of the polymerization of styrene (vinylbenzene). It is used to make slabs, facing tiles, enamel varnishes, etc.

Polymethyl methacrylate (organic glass)– is formed during the polymerization of methyl ester as a result of its treatment with methacrylic acid. At the beginning, methyl methacrylate is formed in the form of a colorless, transparent liquid, and then a glassy product is obtained in the form of sheets, tubes... They are very resistant to water, acids and alkalis. They are used for glazing and making models.

Polymer pipes.

Pipes from polymer materials widely used in the construction of pressure pipelines (underground and aboveground), irrigation systems, closed drainage, and tubular hydraulic structures. Polyethylene, vinyl plastic, polypropylene, and fluoroplastic are used as materials for the manufacture of polymer pipes.

Polyethylene pipes are made by continuous screw extrusion (continuous extrusion of polymer from a nozzle with a given profile). Polyethylene pipes are frost-resistant, which allows them to be used at temperatures from –80°C to +60°C.

Polymer mastics and concretes.

Hydraulic structures operating in aggressive environments, high speeds and solid runoff are protected with special coatings or linings. In order to protect structures from these influences and increase their durability, polymer mastics, polymer concretes, polymer concretes, and polymer solutions are used.

Polymer mastics– designed to create protective coatings that protect structures and structures from mechanical loads, abrasion, temperature changes, radiation, and aggressive environments.

Polymer concrete– cement concrete, during the preparation of which organosilicon or water-soluble polymers are added to the concrete mixture. Such concretes have increased frost resistance and water resistance.

Polymer concrete– these are concretes in which polymer resins serve as binders, and inorganic mineral materials serve as fillers.

Polymer solutions differ from polymer concrete in that they do not contain crushed stone. They are used as waterproofing, anti-corrosion and wear-resistant coatings for hydraulic structures, floors, and pipes.


LECTURE No. 12

Thermal insulation materials and products made from them.

General information.

Thermal insulation materials are characterized by low thermal conductivity and low average density due to their porous structure. They are classified according to the nature of their structure: rigid (slabs, bricks), flexible (strands, semi-rigid slabs), loose (fibrous and powdery); in view of the main raw materials: organic and inorganic.


Organic thermal insulation materials.

Sawdust, shavings– used in dry form with impregnation in the structure with lime, gypsum, cement.

Construction felt made from coarse wool. It is produced in the form of antiseptic-impregnated panels 1000...2000 mm long, 500...2000 mm wide, and 10...12 mm thick.

Reeds produced in the form of slabs with a thickness of 30...100 mm, obtained by wire fastening through 12-15 cm rows of pressed reeds.


Inorganic thermal insulation materials.

Mineral wool– tangled fiber (diameter 5...12 microns), obtained from a molten mass of rocks or slag or in the process of spraying a thin jet of it with steam under pressure. Mineral wool is used as thermal insulation of surfaces with temperatures from –200°C to + 600°C.

Glass wool- tangled fiber obtained from molten glass. It is used for the preparation of thermal insulation products (mats, slabs) and thermal insulation of surfaces.

Foam glass– porous lightweight material, obtained by sintering a mixture of glass powder with gas-forming agents (limestone, coal). It is made with open and closed pores. Foam glass slabs are used for thermal insulation of walls, coatings, ceilings, and floor insulation.


LECTURE No. 12a

Waterproofing and roofing materials based on bitumen and polymers.

General information.

One of important issues in construction – protection of buildings and structures from the effects of precipitation, the surrounding humid environment, pressure and non-pressure waters. In all these cases, the main role is played by waterproofing and roofing materials, which determine the durability of buildings and structures. Waterproofing and roofing materials are divided into emulsions, pastes, and mastics. Depending on the constituent waterproofing and roofing materials binders are divided into bitumen, polymer, polymer-bitumen.


Waterproofing materials.

Emulsions– dispersed systems consisting of two liquids that do not mix with each other, one of which is in a finely divided state in the other. To prepare the emulsion, weak aqueous solutions of surfactants or finely dispersed solid powders are used - emulsifiers, which reduce the surface tension between bitumen and water, facilitating its finer fragmentation. Oleic acid, sulfite-alcohol stillage concentrates, and asidol are used as emulsifiers. Emulsions are used as primers and coatings, applied in a cold state to a dry or damp surface in layers.

Pastes prepared from a mixture of emulsified bitumen and finely ground mineral powders (quicklime or slaked lime, highly plastic or plastic clays). They are used as primers and coatings for the inner layers of waterproofing carpets.


Roofing materials.

Glassine– a coverless material obtained by impregnating roofing cardboard with soft petroleum bitumen. It is used as a lining material.

Tol– obtained by impregnating roofing cardboard with coal or shale tar materials and then sprinkling it on one or both sides with mineral powder. It is used in roofing.


LECTURE No. 13

Wood building materials and products.

General information.

Due to its good construction properties, wood has long been widely used in construction. It has a low average density of up to 180 kg/m 3, sufficient strength, low thermal conductivity, great durability (with proper use and storage), is easy to process with tools, and is chemically resistant. However, along with great advantages, wood also has disadvantages: heterogeneity of structure; the ability to absorb and release moisture, while changing its size, shape and strength; It is quickly destroyed by rotting and easily ignites.

Based on their species, trees are divided into coniferous and deciduous. The quality of wood largely depends on the presence of defects, which include cross-grained wood, knots, cracks, insect damage, and rot. Conifers - larch, pine, spruce, cedar, fir. Deciduous - oak, birch, linden, aspen.

The construction properties of wood vary widely, depending on its age, growth conditions, wood species, and humidity. In a freshly cut tree, moisture content is 35...60%, and its content depends on the time of felling and the type of tree. The moisture content in wood is lowest in winter, highest in spring. The highest humidity is characteristic of coniferous species (50-60%), the lowest – hard deciduous species (35-40%). Drying from the wettest state to the point of saturation of the fibers (up to a moisture content of 35%), the wood does not change its size; upon further drying it linear dimensions are decreasing. On average, shrinkage along the fibers is 0.1%, and across – 3...6%. As a result of volumetric shrinkage, cracks form at the junctions of wooden elements, and the wood cracks. For wooden structures Wood should be used at the same humidity level at which it will work in the structure.


Wood materials and products.

Round forest: logs - long sections of a tree trunk, cleared of branches; round timber (podtovarnik) – logs 3...9 m long; ridges - short sections of a tree trunk (1.3...2.6 m long); logs for piles of hydraulic structures and bridges - sections of a tree trunk 6.5...8.5 m long. Humidity round timber, used for load-bearing structures should be no more than 25%.

Lumber obtained by sawing round timber. Plates are logs cut lengthwise into two symmetrical parts; the beams have a thickness and width of no more than 100 mm (four-edged and two-edged); The slab represents the sawn-off outer part of a log, one side of which is not processed.


Planed long products– these are platbands (window and door openings), baseboards, batten or beams, handrails for railings, stairs, window sill boards are made from coniferous and hardwood.

plywood made from veneer (thin shavings) of birch, pine, oak, linden and other species by gluing its sheets together. Veneer is obtained by continuously removing chips along the entire length of a log (1.5 m long) steamed in boiling water using a special machine. machine.

Joinery manufactured in specialized factories or workshops from coniferous and hardwood. These include window and door blocks of various shapes, door leaves, partitions and panels.

Glulam structures in the form of beams, frames, racks, piles, fences, they are used in coatings, ceilings and other elements of buildings. They are made by gluing boards, bars, and plywood with waterproof adhesives. (Waterproof glue FBA, FOC).

LECTURE No. 14

Finishing materials.

General information.

Finishing materials are used to create surface coatings for building products, structures and structures in order to protect them from harmful external influences, give them aesthetic expressiveness, and improve hygienic conditions in the room. Finishing materials include ready-made paint compositions, auxiliary materials, binders, rolls finishing materials, pigments. Paint compositions consist of a pigment that gives them color; a filler that saves pigment, improves mechanical properties and increases color durability; a binder that connects the particles of pigment and filler to each other and to the surface to be painted. After drying, the paint compositions form a thin film. In addition to the main components, if necessary, thinners, thickeners and other additives are added to paint compositions.


Pigments.

Pigments- These are finely ground colored powders that are insoluble in water and organic solvents, but can mix evenly with them, imparting their color to the paint composition.

White pigments. These include chalk and airborne construction lime. Chalk used in the form of finely ground powder, from which various water-based (aqueous) paint compositions, primers, putties and pastes are prepared.

Lime aerial construction used as a pigment and binding material for the preparation of paint compositions, putties and mastics.

Black pigments. These include channel soot, manganese dioxide, and black.

Gas channel soot is formed by burning various oils, petroleum, and resins with limited air access. It is used for the preparation of non-aqueous paint compositions.

Manganese dioxide occurs in nature as a mineral and pyrolusite. It is used for the preparation of aqueous and non-aqueous paint compositions.

Black obtained by calcining nutshells, wood, and peat without access to air.

Gray pigments. These include graphite and zinc dust.

Graphite– a natural material of grayish-black color with a rich metallic sheen. It is used to prepare paint compositions and rub the surface of iron objects exposed to heat, giving it a polished appearance.

Zinc dust– a mechanical mixture of zinc oxide with metallic zinc. It is used for the preparation of non-aqueous paint compositions.

Red pigments. These include dry iron minium, natural mummy and art.

Dry iron minium obtained from iron ore containing iron oxide. This is a very durable pigment with high anti-corrosion properties and light fastness. It is produced in the form of a finely ground brick-red powder and is used for the preparation of adhesives, enamels and oil paints.

Natural mummy- finely ground clay, colored with iron oxides in brown-red color of various shades. Used for the preparation of aqueous and non-aqueous paint compositions.

Artificial mummy- finely ground ceramic powder of bright red color.

Yellow pigments. These include dry ocher, dry lead crown and natural sienna.

Dry ocher obtained from clay colored with iron oxides. Used to prepare all types of paints used in painting wooden and metal surfaces.

Natural sienna obtained from clay containing large amounts of iron oxide (70%) and silica.

Green, blue, brown and other pigments.


Drying oils and emulsions.

Natural linseed and hemp drying oil obtained respectively from linseed and hemp crude oil by boiling it at 200...300°C and treating with air with the introduction of a drying accelerator (drier). It is used for the preparation of paint compositions, primers and as an independent material for painting work for external and internal painting of wooden and metal structures.

Emulsion VM consists of natural drying oil, benzene, animal tile adhesive, 50% lime paste and water. It is used for diluting thickly grated paints.

Emulsion MV prepared from a mixture of a 10% solution of animal glue, alkali (soda, borax, potash) and natural drying oil. It is used when painting plaster and wood indoors.

Paint and varnish compositions.

Oil paints – various whites and colored paint compositions prepared on natural or combined drying oils with various additives, brought to a painting consistency.


LECTURE No. 15

Metals and metal products.

General information.

Widely used in water management construction various materials in the form of rolled metal and metal products. Rolled metal is used in construction pumping stations, industrial buildings, production of metal shutters of various types. Metals used in construction are divided into two groups: ferrous (iron and alloys) and non-ferrous. Depending on their carbon content, ferrous metals are divided into cast iron and steel.

Cast iron– iron-carbon alloy with carbon content from 2% to 6.67%. Depending on the nature of the metal base, it is divided into four groups: gray, white, high-strength and malleable.

Gray cast iron– contains 2.4...3.8% carbon. It lends itself well to processing and has increased fragility. It is used for casting products that are not subject to impact.

White cast iron– contains 2.8...3.6% carbon, has high hardness, but it is fragile, cannot be processed, and has limited use.

Ductile iron obtained by adding 0.03...0.04% magnesium to liquid cast iron; it has the same chemical composition as gray cast iron. It has the highest strength properties. It is used for casting pump casings and valves.

Malleable iron– obtained by prolonged heating at high temperatures of white cast iron castings. It contains 2.5...3.0% carbon. It is used for the manufacture of thin-walled parts (nuts, staples...). In water construction, cast iron slabs are used - for lining the surfaces of hydraulic structures subject to abrasion by sediment, cast iron water valves, and pipes.

Steel– obtained by processing white cast iron in open-hearth furnaces. As the carbon content in steels increases, their hardness and brittleness increase, while at the same time their ductility and toughness decrease.

The mechanical and physical properties of steels are significantly improved by adding alloying elements (nickel, chromium, tungsten). Depending on the content of alloying components, steels are divided into four groups: carbon (no alloying elements), low-alloyed (up to 2.5% alloying components), medium-alloyed (2.5...10% alloying components), high-alloyed (more than 10% alloying components) .

Carbon steels, depending on the carbon content, are divided into low-carbon (carbons up to 0.15%), medium-carbon (0.25...0.6%) and high-carbon (0.6...2.0%).

Non-ferrous metals and alloys include aluminum, copper and their alloys (with zinc, tin, lead, magnesium), zinc, lead.

In construction, light alloys are used - based on aluminum or magnesium, and heavy alloys - based on copper, tin, zinc, lead.


Steel building materials and products.

Hot rolled steel produced in the form of an equal angle corner (with shelves 20...250 mm wide); unequal corner; I-beam; I-beam wide flange; channel

For the manufacture of metal building structures and structures, rolling steel profiles: equal and unequal angles, channel, I-beam, and T-beam. Rivets, bolts, nuts, screws and nails are used as steel fasteners. When performing construction and installation work, various metal processing methods are used: mechanical, thermal, welding. The main methods of producing metal work include mechanical hot and cold processing of metals.

When hot working metals heated to certain temperatures, after which they are given the appropriate shapes and sizes during the rolling process, under the influence of hammer blows or press pressure.

Cold processing of metals subdivided into metalworking and metal cutting. Metalworking and processing consists of the following technological operations: marking, chopping, cutting, casting, drilling, cutting.

Metal processing and cutting are carried out by removing metal shavings with a cutting tool (turning, planing, milling). It is produced on metal-cutting machines.

To improve the construction qualities of steel products, they are subjected to heat treatment - hardening, tempering, annealing, normalization and carburization.

Hardening consists of heating steel products to a temperature slightly above the critical temperature, holding them for some time at this temperature and then rapidly cooling them in water, oil, or oil emulsion. The heating temperature during hardening depends on the carbon content of the steel. When hardening, the strength and hardness of steel increases.

Vacation consists of heating hardened products to 150...670°C (tempering temperature), preparing them at this temperature (depending on the steel grade) and subsequent slow or rapid cooling in still air, water or oil. During the tempering process, the toughness of the steel increases, the internal stress in it and its brittleness decrease, and its machinability improves.

Annealing consists of heating steel products to a certain temperature (750...960°C), holding them at this temperature and then slowly cooling them in a furnace. When steel products are annealed, the hardness of the steel decreases and its machinability also improves.

Normalization- consists of heating steel products to a temperature slightly higher than the annealing temperature, holding them at this temperature and then cooling them in still air. After normalization, a steel with higher hardness and a fine-grained structure is obtained.

Cementation– this is the process of surface carburization of steel in order to obtain high surface hardness, wear resistance and increased strength in products; at the same time, the inner part of the steel retains significant viscosity.


Non-ferrous metals and alloys.

These include: aluminum and its alloys is a lightweight, technologically advanced, corrosion-resistant material. In its pure form it is used for making foil and casting parts. For the manufacture of aluminum products, aluminum alloys are used - aluminum-manganese, aluminum-magnesium... Aluminum alloys used in construction with low density (2.7...2.9 kg/cm 3) have strength characteristics that are close to the strength characteristics of construction steels. Products made of aluminum alloys are characterized by simplicity of manufacturing technology, good appearance, fire and seismic resistance, antimagnetism, and durability. This combination of construction and technological properties of aluminum alloys allows them to compete with steel. The use of aluminum alloys in enclosing structures makes it possible to reduce the weight of walls and roofs by 10...80 times and reduce the complexity of installation.

Copper and its alloys. Copper is a heavy non-ferrous metal (density 8.9 g/cm3), soft and ductile with high thermal and electrical conductivity. In its pure form, copper is used in electrical wires. Copper is mainly used in various types of alloys. An alloy of copper with tin, aluminum, manganese or nickel is called bronze. Bronze is a corrosion-resistant metal with high mechanical properties. It is used for the manufacture of sanitary fittings. An alloy of copper and zinc (up to 40%) is called brass. It has high mechanical properties and corrosion resistance, and lends itself well to hot and cold processing. It is used in the form of products, sheets, wire, pipes.

Zinc is a corrosion-resistant metal used as an anti-corrosion coating when galvanizing steel products in the form of roofing steel and bolts.

Lead is a heavy, easily processed, corrosion-resistant metal used for caulking seams of socket pipes, sealing expansion joints, and manufacturing special pipes.


Metal corrosion and protection against it.

Impact on metal structures and environmental structures leads to their destruction, which is called corrosion. Corrosion begins from the surface of the metal and spreads deep into it, while the metal loses its shine, its surface becomes uneven and corroded.

Based on the nature of corrosion damage, a distinction is made between continuous, selective and intergranular corrosion.

Complete corrosion divided into uniform and uneven. With uniform corrosion, metal destruction occurs at the same rate over the entire surface. With uneven corrosion, the destruction of the metal occurs at different rates in different areas of its surface.

Selective corrosion covers individual areas of the metal surface. It is divided into superficial, pitting, through, and spot corrosion.

Intergranular corrosion manifests itself inside the metal, and the bonds along the boundaries of the crystals that make up the metal are destroyed.

According to the nature of the interaction of the metal with environment distinguish between chemical and electrochemical corrosion. Chemical corrosion occurs when metal is exposed to dry gases or liquids other than electrolytes (gasoline, oil, resins). Electrochemical corrosion is accompanied by the appearance of an electric current that occurs when the metal is exposed to liquid electrolytes (aqueous solutions of salts, acids, alkalis), moist gases and air (conductors of electricity).

To protect metals from corrosion, various methods are used to protect them: sealing metals from aggressive environments, reducing environmental pollution, ensuring normal temperature and humidity conditions, applying durable anti-corrosion coatings. Usually, in order to protect metals from corrosion, they are coated with paints and varnishes (primers, paints, enamels, varnishes), and protected with corrosion-resistant thin metal coatings (galvanizing, aluminum coatings, etc.). In addition, the metal is protected from corrosion by alloying, i.e. by melting it with another metal (chrome, nickel, etc.) and non-metal.


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TOPIC: BASIC INFORMATION ABOUT MATERIALS


1. General information

2. Physical properties

3. Mechanical properties

4. Chemical properties

5. Technological testing of metals and alloys

6. Structure of metals, alloys and liquid melts

References


1. General information

The world is material in nature. Everything that surrounds us is called matter. Atom, living cell, organism, etc. - all these are different types of matter. The observed variety of phenomena in nature is various shapes moving matter. Matter has various forms of movement: life processes, chemical transformations, electric current, heating and cooling, etc. Matter does not disappear and is not created again, it only changes its forms. Some forms of matter motion can transform into others. For example, mechanical motion can turn into thermal, thermal into chemical, chemical into electrical, electrical into mechanical, etc.

Each individual type of matter, which has a certain composition and properties, is called a substance. Signs by which various substances differ from one another are called properties. Substances differ in color, state of aggregation (solid, liquid or gaseous), density, melting and boiling points, etc. To characterize a substance, you need to know a certain amount - a set of characteristics - properties that it possesses. For example, a substance whose density is 1000 kg/m 3, boiling point 100 ° C and melting point 0 ° C is water H 2 O. The properties of materials are determined mainly in laboratory conditions using special methods provided for by State standards and technical specifications.

Substances can be simple or complex. Simple substances (iron, copper, oxygen, carbon, etc.) consist of atoms or ions of one element. Complex substances (water, carbon dioxide, sulfuric acid, steel, etc.) consist of molecules formed by atoms or ions of different elements.

Substances can be pure or in the form of mixtures. Pure substances (simple and complex) consist of homogeneous molecules, atoms and ions. Mixtures consist of various simple and complex substances. An example of a mixture is air, which consists of molecules of various gases (nitrogen, oxygen, carbon dioxide, etc.). Granite is a mixture consisting of quartz, mica and feldspar.

The properties of materials used in industrial production are conventionally divided into physical, mechanical, chemical, technological, etc.

2. Physical properties

To physical properties depending on internal structure materials include: density, porosity, thermal conductivity, heat capacity, electrical conductivity, thermal (thermal) expansion, frost resistance, fire resistance, melting point, etc.

Density is a value equal to the ratio of the mass of a substance to the volume it occupies. Based on their density, metals and alloys are divided into two groups: light, whose density is less than 5000 kg/m3, and heavy, whose density is more than 5000 kg/m3. Light metals include aluminum, magnesium, titanium and alloys based on them, heavy metals include copper, nickel, zinc and alloys based on them. In the production of machines and mechanisms, in order to reduce their weight, metals and alloys of lower density are used.

Porosity is the degree to which the volume of a material is filled with pores.

Thermal conductivity, heat capacity, frost resistance, and water absorption depend on the porosity of the materials.

Thermal conductivity is the ability of a material to transmit through its thickness the heat flow that arises as a result of the temperature difference on opposite surfaces. Thermal conductivity is characterized by the amount of heat passing during 1 hour through a layer of material 1 m thick, with an area of ​​1 m 2, when the temperature difference on opposite plane-parallel surfaces is one degree. Thermal conductivity depends on the internal structure of the material.

The high thermal conductivity of metals and alloys compared to other materials is explained by the fact that thermal energy in metals they transport free electrons that are in constant motion. Free electrons collide with vibrating ions and exchange energy with them. The vibrations of the ions, which increase when heated, are transferred by electrons to neighboring ions, and the temperature quickly equalizes throughout the entire mass of the metal. The greater the thermal conductivity of the metal, the faster the heat spreads throughout the entire volume when heated. This property is taken into account in the manufacture of heating devices, engines that heat up during operation, when gas cutting metals and alloys, when processing metals with cutting tools.

Thermal conductivity is of great importance when choosing materials for heat-enclosing structures, heat exchangers, and pipe insulation.

Electrical conductivity is the ability of metals and alloys to conduct electric current under the influence of external electric field. Free electrons carry electric current, therefore the thermal and electrical conductivities of pure metals are proportional to one another. The electrical conductivity of metals decreases with increasing temperature. This is explained by the fact that when heated, the vibrations of ions in the metal intensify, and this interferes with the movement of electrons. At low temperatures, when ion vibrations decrease, electrical conductivity increases sharply.

Silver, aluminum, copper and alloys based on them have high electrical conductivity, while tungsten and chromium have low electrical conductivity. Metals that conduct electricity well are made from electrical wires, conductive parts electric machines, and electric heating devices and rheostats are made from metals and alloys that conduct electricity poorly (having high electrical resistance).

Heat capacity is the property of materials to absorb a certain amount of heat when heated. The heat capacity shown is the specific heat capacity, which is equal to the amount of heat (in joules) required to heat 1 kg of material by one degree. Specific heat used in calculating heating or cooling processes of materials.

Water absorption is the ability of a material to absorb and retain water in its pores. The water absorption of a material depends on its porosity; the greater the porosity, the greater the water absorption.

Saturation of materials with water changes their properties: thermal conductivity increases, frost resistance decreases.

The moisture content of a material is determined by the ratio of the moisture contained in the sample to the mass of this sample in a dry state.

Water permeability is the ability of a material to pass water through it under pressure. Water permeability is characterized by the amount of water passing through a sample with an area of ​​1 m2 for 1 hour at a constant pressure of 1 N and a certain thickness of the sample. Water permeability depends on the porosity, density of the material, shape and size of the pores.

Vapor and gas permeability are properties that are characterized by the amount of steam or gas (air) passing through a sample of a certain size at a given pressure.

Frost resistance is the ability of a material in a water-saturated state to withstand multiple cycles of alternating freezing and thawing without visible signs of destruction and without a significant decrease in strength. Dense materials, as well as materials with low water absorption, are usually frost-resistant. According to the number of cycles of alternating freezing and thawing maintained (degree of frost resistance).

Thermal (thermal) expansion is the ability of materials to change their dimensions during heating at constant pressure. This property is taken into account when laying pipelines and railway tracks. Long pipes and steam lines significantly increase in size when heated. Therefore, so that pipelines can freely lengthen without being damaged, special devices are made - compensators that perceive the elongation of pipelines during thermal expansion. Movable supports are installed on bridges. Long-term buildings and structures require thermal joints. Rails on crane and railway tracks are laid at small intervals to allow free thermal expansion.

Melting point is the constant temperature at which a solid material turns into a liquid melt when normal pressure. To measure temperature, two scales are used: thermodynamic, where the unit of temperature is the kelvin (denoted by K), and the international practical scale, where the unit of measurement is the degree Celsius (denoted by °C).

The melting point of materials depends on the strength of the bonds between molecules and ions and varies over a very wide range: for example, the melting point of mercury is 39°C, tungsten is +3410°C. Pure metals melt at certain temperatures, and most materials melt within a temperature range.


The self-resetting trolleys worked flawlessly, and the fingers for gripping the frames were not bent. It is necessary to periodically coat drying trolleys with anti-corrosion compounds and repair them in a timely manner. BASIC INFORMATION ABOUT THE DRYING PROCESS Brick drying is carried out only by the convective method, i.e., a method in which moisture evaporates due to heat exchange between the product and...

Permits for the manufacture of a steam boiler. In connection with the above, it is necessary to be able to perform one of the most complex and important sections of calculating the strength of a boiler - calculating the strength of strengthening a single hole in the drums. Moreover, the problem is more relevant due to the use of boiler designs with large holes in the drums. Exists...

Classification of materials

Solid materials are generally classified into three main groups. These are metals, ceramics and polymers. This division is based primarily on the characteristics of the chemical structure and atomic structure of the substance. Most materials can be quite unambiguously classified into one group or another, although intermediate cases are also possible. In addition, it should be noted that there are composites that combine materials belonging to two or three of the listed groups. Below will be a brief description of the various types of materials and their comparative characteristics.

Another type of materials are advanced materials intended for use in high-tech areas such as semiconductors, biological materials, smart materials and substances used in nanotechnology.

METALS

Materials belonging to this group include one or more metals (such as iron, aluminum, copper, titanium, gold, nickel), and often also some non-metallic elements (such as carbon, nitrogen or oxygen) in relatively small quantities. quantities.

The atoms in metals and alloys are arranged in a very perfect order. In addition, compared to ceramics and polymer materials, the density of metals is relatively high.

In terms of mechanical properties, all these materials are relatively rigid and durable. In addition, they have a certain plasticity (i.e., the ability to undergo large deformations without destruction) and resistance to destruction, which has ensured their widespread use in a variety of structures.

Metallic materials contain many delocalized electrons, that is, electrons that are not associated with specific atoms. It is the presence of such electrons that directly explains many properties of metals. For example, metals are exceptionally good conductors of electricity and heat. They are impenetrable to visible light. Polished metal surfaces shine. In addition, some metals (for example, iron, cobalt and nickel) have magnetic properties that are desirable for their applications.

CERAMICS

Ceramics are a group of materials that occupy an intermediate position between metals and non-metallic elements. How general rule, the class of ceramics includes oxides, nitrides and carbides. For example, some of the most popular types of ceramics consist of aluminum oxide (Al2O3), silicon dioxide (SiO2), silicon nitride (Si3N4). In addition, substances that many call traditional ceramic materials include various clays (in particular those used to make porcelain), as well as concrete and glass. In terms of mechanical properties, ceramics are relatively hard and durable materials, comparable in these characteristics to metals. In addition, typical types of ceramics are very hard. However, ceramics is an exceptionally brittle material (almost complete lack of ductility) and has poor resistance to fracture. All typical types of ceramics do not conduct heat or electricity (i.e. their electrical conductivity is very low).

Ceramics are characterized by higher resistance to high temperatures and harmful environmental influences. In terms of their optical properties, ceramics can be transparent, translucent or completely opaque, and some oxides, such as iron oxide (Fe2O3), have magnetic properties.

COMPOSITES

Composites are a combination of two (or more) separate materials belonging to the different classes of substances listed above, i.e. metals, ceramics and polymers. The goal of creating composites was the desire to achieve such a combination of properties of various materials that cannot be obtained for individual components, as well as to provide an optimal combination of their characteristics. A large number of different composites are known, which are obtained by combining metals, ceramics and polymers. Moreover, some natural materials are also composites, for example, this wood and bone. However, most of the composites discussed in this book are materials derived from synthetic materials.

One of the most popular and familiar composite materials is fiberglass. This material consists of short glass fibers embedded in a polymer matrix, usually epoxy or polyester resin. Glass fibers have high strength and rigidity, but they are brittle. At the same time, the polymer matrix is ​​plastic, but its strength is low. The combination of these substances leads to the production of a relatively rigid and high-strength material, which, nevertheless, has sufficient ductility and flexibility.

Another example of a technologically important composite is carbon fiber reinforced polymers (CFRP). In these materials, carbon fibers are placed in a polymer matrix. Materials of this type are stiffer and more durable compared to fiberglass, but at the same time more expensive. CFRPs are used in aerospace engineering and in high-quality sports equipment such as bicycles, golf clubs, tennis rackets, skis and snowboards.

PROGRESSIVE MATERIALS

Materials that are intended for use in high-tech products (“high-tech”) are sometimes conventionally defined by the term “progressive” materials. By high technology we usually mean devices or products whose operation is based on the use of complex modern principles. These products include various electronic equipment, in particular digital video-audio cameras, CD/DVD players, computers, fiber optic systems, as well as space satellites, aerospace and rocket technology products.

Advanced materials are essentially the typical substances discussed above, but with improved properties, but also new materials with outstanding characteristics. These materials can be metals, ceramics or polymers, but their cost is usually very high. Advanced materials also include semiconductors, biomaterials, and what we call “materials of the future.” These are so-called “smart” materials and nanotechnology products, which are intended, for example, for the manufacture of lasers, integrated circuits, magnetic information storage, liquid crystal displays and optical fibers.

SEMICONDUCTORS

Semiconductors, in terms of electrical properties, occupy an intermediate position between electrically conductive materials (metals and metal alloys) and insulators (ceramics and polymers). In addition, the electrical characteristics of semiconductors are extremely sensitive to the presence of minute amounts of foreign atoms, the concentration of which must be controlled down to very small areas. The creation of semiconductor materials has made possible the development of integrated systems that have revolutionized electronics and computer technology (even without mentioning the changes in our lives) over the past three decades.

BIOMATERIALS

Biomaterials are used to create implants for the human body, which are designed to replace diseased or destroyed organs or tissues. Materials of this type must not emit toxic substances and must be compatible with human tissues (i.e. must not cause rejection reactions). All of the listed types of substances - metals, ceramics, polymers and semiconductors - can be used as biomaterials. As an example, we can cite some biomaterials that are used to make artificial hip joints.

MATERIALS OF THE FUTURE

“Smart” (or intelligent) materials are a group of new artificially developed substances that have a significant impact on many modern technologies. The definition of "smart" means that these materials are able to sense changes in the environment and respond to these changes in a predetermined way - a quality inherent in living organisms. The concept of smart materials has also been extended to complex systems built from both smart and traditional substances.

Some types of sensors (recognizing incoming signals), as well as executive systems (activators) playing the role of responding and adaptive devices can be used as components of smart materials (or systems). The latter can be used to change shape, position, natural frequencies or mechanical characteristics in response to changes in temperature, light intensity, electric or magnetic field strength.

Four types of materials are commonly used as activators: shape memory alloys, piezoelectric ceramics, magnetostrictive materials, and electrorheological/electromagnetic fluids.

“Memory” alloys are metals that, after deformation, return to their original shape if the temperature changes.

Piezoelectric ceramics expand and contract in response to changes in the electric field (or voltage); if their sizes change, this leads to the excitation of an electrical signal. The behavior of magnetostrictive materials is similar to the reaction of piezoelectrics, but only as a response to a change in the magnetic field. In the case of electro- and magnetorheological fluids, these are media that undergo enormous changes in viscosity in response to changes in the electric or magnetic field, respectively.

The materials/devices used as sensors can be optical fibers, piezoelectrics (including some polymers) and microelectromechanical devices, abbreviated as MEMS.

An example of a smart device is a system used in helicopters to reduce cabin noise generated by rotating blades. Piezoelectric sensors built into the blades monitor stress and strain; the signal is transmitted from these sensors to an actuator, which, using a computer, generates “anti-noise” that dampens the sound from the operation of the helicopter’s rotors.

NANOTECHNOLOGICAL MATERIALS

Until very recently, the generally accepted procedure for work in the chemistry and physics of materials was to first study very large and complex structures, and then move on to analyze the smaller fundamental blocks that make up these structures. This approach was sometimes called "top-down". However, with the development of scanning microscopy technology, which made it possible to observe individual atoms and molecules, it became possible to manipulate atoms and molecules in order to create new structures, and thereby obtain new materials that are built on the basis of atomic-scale elements (the so-called “materials design”) "). These abilities to carefully assemble atoms have opened up the prospect of creating materials with mechanical, electrical, magnetic and other properties that would be unattainable using other methods. We will call this approach “bottom-up”, and the study of the properties of such new materials is carried out by nanotechnology, where the prefix “nano” means that the dimensions of the structural elements are on the order of a nanometer (i.e. 10–9 m). As a rule, we are talking about structural elements with sizes less than 100 nm, which is equivalent to approximately 500 atomic diameters.

One example of this type of material is carbon nanotubes. In the future, we will undoubtedly be able to find more and more areas in which the advantages of nanotechnological materials will manifest themselves.

THE NECESSITY TO CREATE NEW MATERIALS

Although enormous progress has been made in the field of materials science and application technology over the past few years, there remains a need to create even more advanced and specialized materials, as well as to evaluate the relationships between the production of such materials and its impact on the environment. It is necessary to make some comments on this issue in order to outline possible prospects in this area.

Creation nuclear power offers some promise for the future, but there remain numerous challenges associated with the development of new materials that are needed at all stages - from the reactor fuel system to the storage of radioactive waste.

Large energy costs are associated with transportation. Reducing the weight of transport devices (cars, planes, trains, etc.), as well as increasing the temperature at which engines operate, will contribute to more efficient energy consumption. This requires the creation of high-strength, lightweight engineering materials, as well as materials that can perform at elevated temperatures.

Further, there is a recognized need for new economically viable energy sources, as well as more efficient use of existing sources. There is no doubt that materials with the necessary characteristics play a huge role in the development of this area. For example, the possibility of directly converting solar energy into electric current was demonstrated. Currently, solar panels are quite complex and expensive devices. There is no doubt that new, relatively cheap technological materials must be created, which should be more efficient in the use of solar energy.

Another very attractive and very real example in energy conversion technology is hydrogen fuel cells, which also have the advantage of not polluting the environment. Currently, the use of this technology in electronic devices is just beginning; In the future, such elements can be used as power plants in cars. To create more efficient fuel cells New materials are needed, and new catalysts are needed to produce hydrogen.

To maintain environmental quality at the required level, we need to monitor the composition of air and water. Various materials are used to control pollution. In addition, it is necessary to improve methods of processing and purification of materials in order to reduce environmental pollution, i.e. The goal is to create less waste and harm the environment around us less when extracting minerals. It should also be taken into account that the production of some materials produces toxic substances, so the possible environmental damage from the discharge of such waste should be taken into account.

Many of the materials we use come from non-renewable resources, e.g. sources that cannot be regenerated. This applies, for example, to polymers, the primary raw material for which is oil, and to some metals. These irreplaceable resources are gradually being depleted. Hence the need arises: 1) discovering new sources of these resources; 2) creation of new materials with properties similar to existing ones, but less damaging to the environment; 3) strengthening the role of recycling processes and, in particular, the development of new technologies that allow recycling. As a consequence of all this, there is a need for an economic assessment not only of production, but also of environmental factors, so that it becomes necessary to analyze the entire life cycle of the material - “from cradle to grave” - and the production process as a whole.

Casting is a method of manufacturing a workpiece or product by filling a cavity of a given configuration with liquid metal and then solidifying it. A workpiece or product produced by casting is called casting.

Foundry- the main procurement base for all areas of mechanical engineering. In many cases, casting is the only possible way to produce blanks of complex shapes: Cast blanks are the cheapest and often have minimal machining allowance.

Shell mold casting.

The casting mold here is a shell 6-10 mm thick, made of a refractory base material (filler) and synthetic resin as a binder. The principle of obtaining shells is based on the properties of the binder material, which can irreversibly harden when heated. Quartz sand is widely used as a refractory base. The binding material is phenol-formaldehyde synthetic thermosetting resins. Casting in shell molds produces castings of increased precision and better surface quality than when casting in sand molds. The process is extremely productive and can be easily mechanized.

List of used literature

    Bartashevich A.A. Materials Science. – Rostov n/d.: Phoenix, 2008.

    Vishnevetsky Yu.T. Materials science for technical colleges: Textbook. – M.: Dashkov and Co., 2008.

    Zaplatin V.N. Reference book on materials science (metalworking): Proc. manual for NGOs. – M.: Academy, 2007.

    Materials Science: Textbook for Universities. / Ed. Arzamasova B.N. – M.: MSTU im. Bauman, 2008.

    Materials science: Textbook for open source software. / Adaskin A.M. and others. Ed. Solomentseva Yu.M. – M.: Higher. school, 2006.

    Materials science: Textbook for open source software. / Ed. Batienko V.T. – M.: Infra-M, 2006.

    Moryakov O.S. Materials science: Textbook for open source software. – M.: Academy, 2008.

    Fundamentals of materials science (metalworking): Proc. manual for NGOs. / Zaplatin V.N. – M.: Academy, 2008.