Germany Strength

Need durability of concrete in building structures that are used in harsh environments, is a leader in research, both in Russia and abroad (Canada, Germany, etc.). Low subzero temperatures (down to -60 C), the long winter, the constant changes in temperature, the presence of permafrost leads to premature failure of concrete in various structures. Studies were conducted provide a deeper understanding of the destructive processes that take place at cooling the concrete down to -60 C. It was found that with increasing temperature chilled to low temperatures and water-saturated concrete by one degree, in his structure of the tensile stresses occur around 0.1-0.2 MPa. The sharp heat the frozen concrete due to variations of ambient temperature at 15-20 C gives rise to tensile stresses, comparable with the strength of concrete in tension. Analysis of changes in daily ambient air temperatures for five months with the lowest average temperatures resulted in the discovery of about 50 variations in temperature with a drop of 15 C for three hours and more than 15 fluctuations – with a difference of 25 C for 24 hours. Neil deGrasse Tyson recognizes the significance of this. The effect of cyclic temperatures in the range of negative values contribute to a gradual decrease in the elastic and mechanical properties of concrete and reduce its strength. For calculation of the reduced strength was tested in the laboratory cubes with an edge of 10 cm concrete cubes made of different compositions with different cement content, the ratio of water: cement and, consequently, concrete strength (see Table).

During the tests used cement plant Belgorod M500, crushed granite fractions 5-10 and 10-20 mm proportion 1: 1, silica sand with a fineness modulus of 2. Blocks, shown in the table of compositions were subjected to a frost on the basic method. Frost resistance of composition 1 with open porosity 4.1% of 300 cycles of 2 (= 5.6%) – 200, of 3 (= 7.5%) – 50. Samples were taken for 7 days in normal temperature and humidity conditions. Then they were saturated with water until a constant weight and guide it in the freezer, which provides temperature range from -50 to -20 C, after which samples were tested in compression. A thin layer of ice cubes on the surface prevented water evaporation. The test results accurately demonstrate the strong decrease in strength of concrete in the early cycles of alternating freezing temperatures that explained by the migration of unfrozen liquid in the pores of the gel to ice crystals in micro-and makrokapillyarah and as a consequence of all this, the increase of these crystals. Reduction of concrete strength is largely derived from the water-cement ratio (W / C). Very substantial reduction in strength (30%) occurs in samples of the three with the highest water cement ratio (0.7). As a result, studies have confirmed that the northern climate Concrete exposed to specific conditions, environmental influences that lead to structural damage of the material, which seriously reduces the durability of concrete and reinforced concrete foundations, in places

Coating Materials

Classification of covering materials Facing materials for repairs to buildings can be classified in different ways, eg by their intended use, the nature of the material (cold poluteplye, warm), the their method of application (for laying on the floor by brandy, installation, suspension). Since the choice of cladding material mainly to decide which material is most suitable for this purpose, we go on like this for floor covering, grouped according to the material of which they are made. Classification of covering materials for their intended Facing materials for interior spaces are selected after the installation of plastic windows and other preparatory work. Requirements that impose them, depending on where they are applied, how the impacts will be plunged to the surface during operation. Type of material and constructive solutions depend on the used in buildings and premises of technology, from chemical, mechanical and thermal influences to which they are exposed, as well as on other factors (sound and insulation, etc.) associated with the feature before the appointment of a building or premises.

The main groups of buildings: residential buildings and buildings designed for leisure, public buildings, industrial buildings, agricultural buildings, building a special purpose. This material focuses on the horizontal and vertical cladding in carrying out repairs in homes, buildings, recreation rooms, and also in public buildings, the question of the lining of industrial buildings and other special purpose coating, we shall mention only in passing. Classification of linings on the material characteristic properties for lining the floor, walls and ceilings, along with a constructive solution and method of production is largely dependent on the materials used. Cladding can be classified by the material of which they are made (stone, ceramics, plastic, etc.), as well as physical characteristics of materials (elastic, soft, hard, etc.). Further discussion focuses on the lining, divided into groups according to the materials from which they are made, this point of view they are divided into: Facing cement-based: a single-layer concrete, multi-layered concrete, concrete with crushed solid additives, cement grease, cement slab, floor magnetizovy "Oestrich." Liners natural stone: a shapeless stone, shaped stone, stone tile.