โ Analysis of the main principles of building materials, the main theoretical trends 1.Classification of building materials a. b. c. d. e. f. g. h. i. j. k. l. 1.Building materials may further be classified as inorganic and organic building materials. Inorganic materials consists of mud, cement, lime, gypsum, steel Organic materials such as wood and biomass. 2.Another classification based on technology for building materials spanning from production to application is Binders based on cement, lime, pozzolanic and polymeric materials Building components such as natural building stones, mud bricks, stabilized soil bricks, burnt clay bricks and blocks, concrete and pozzolanic blocks, organic fibres and various roofing and structural materials Water proofing compounds and sealants Paints, painting materials and coatings 3.A classification that appears to be more suited to the stage of industrialization in developing countries is Building materials for basic construction Special purpose materials Protective and decorative materials 4.Based on the improvements made on traditional materials for improved performance, a group of traditional material with innovations has emerged. These are called-innovations in traditional material. The introduction of a number of materials as new alternatives is called as new alternatives building materials.Therefore, based on the stage of developments brought into building material generation, building materials are classified as Conventional/traditional materials Innovations in traditional materials New and alternative materia 2. What is the difference between true and average . material density? True density: The masAn average density is defined as the total mass per unit of volume of a Average density: Mixture of 2 or more substances. In the case of the formula above, this is for a mixture with different quantities of each compound.s of a particle divided by its volume, excluding open and closed pores. 3. What is frost resistance and what are the methods for determining it? Frost resistance is the ability of a water-saturated material to endure repeated freezing and thawing with out visible signs of failure or considerable decrease of mechanical strength. The disintegrate being the result of water increase contained inside their pores increases in volume by up to 9% in the process of freezing. Frost resistance of materials is determined by freezing water-saturated specimens at the temperature between – 15 – 17°C and subsequently thawing them out. ๐พ๐๐ = ๐ ๐๐ ๐ ๐ค๐ where Rfr – compressive strength of material after the frost resistance test, Pa; Rws – compressive strength of water – saturated material before the test, Pa 4. What is the physical meaning of thermal conductivity, why does it depend and what is its dimension? Heat conductivity of a material is its ability to conduct heat. All materials conduct heat to a different degree. The heat conductivity of material is quantitatively evaluated by a coefficient which is equal to the quantity of heat flowing in 1 hour through a specimen of 1๐2 area 1 m thick when the temperature difference between its opposite and parallel flat surfaces is 1°K. 5. What is fire resistance and refractoriness? Fire-resistance is the ability of materials to resist the action of fire without substantial deformation or loss of strength. According to their fire-resistance building materials may be subdivided into noncombustible, fire-resistive and combustible. Noncombustible materials neither smoulder nor char under the action of fire. Natural (rock) and non-organic mineral materials (ceramic) belong to this category. However, some of these materials (glass, metal) suffer considerable deformation and melt. That is why they cannot be referred to noncombustible materials. Fire-resistive materials are ones which char, smoulder and ignite with difficulty when exposed to the action of flame but continue to burn or smoulder only in the presence of flame. Combustible materials burn and smoulder under the action of fire and go on burning after the starting flame is removed. All organic materials, not treated with fire-proof compounds, fall into this category. โกLocation of the raw material base of Uzbekistan in the production of building materials 1. What are ceramic materials and products? Ceramic materials are manufactured from clay compositions by moulding and subsequent burning, an intermediate drying of freshly moulded items being a frequent practice. 2. What materials are used as raw materials for the manufacture of ceramic materials? Raw materials are quarried by the open pit method with the aid of power shovels. Preparation of raw materials involves disintegration of clay’s natural structure, removal or grinding of large inclusions, mixing the clay with admixtures and water until a readily mould able mass is obtained. Depending on the properties of raw materials and on the kind of items produced, ceramic mass is prepared by the stiff-mud, soft-mud and slip casting methods. 3. Give a classification of ceramic materials and products Universality of properties, a wide range of products, high strength, durability and reasonable cost of ceramic items underlie their wide use in the most various subassemblies of buildings and installations, such as walls, heating units, wall and floor facing materials, sewer pipes, lining materials for chemical industry apparatus and light porous aggregates for prefabricated reinforced concrete items (pic. 13-17). 4. Briefly describe the general technological scheme for the production of ceramic products. In the stiff-mud method, clay is first crushed and dried, then ground and molded at a moisture content, from 8 to 12%. In the stiff-mud method, the clay is moulded in hydraulic or mechanical presses at pressures of 15 MPa and over. The soft-mud moulding method involves crushing of clay, then processing it in a mixer, where it is mixed with lean admixtures and simultaneously humidified until a homogeneous plastic mass of moisture content from 20 to 25% is obtained. In the soft-mud method, ceramic items (brick for wall, pipes, and tills for facing walls) are manufactured mainly in auger machines. 5. What indicators characterize the quality of ceramic bricks and where is it used in construction? In the slip casting method, the starting materials are ground and mixed with a large amount of water (up to 60%) until a homogeneous paste (clip) is obtainted. The mass is directly cast into moulds. Using this method, small-size ceceramic tiles for façade decoration and sanitary ceramica items are manufactured. โขEnergy, resource-saving and environmentally friendly technologies of building materials 1. What materials are called thermal insulation?
