Concrete

CONCRETE - this is one of the most common and important building materials, which is produced by curing a mixture of binder, water, fillers and additives. Concrete is widely used in civil and industrial construction. In the case of erecting buildings of concrete, its types and grades are determined at the stage of a project. For various building elements used different types and grades of concrete. Necessary to determine which particular element of design (foundation, bearing walls, interior walls, floors) is selected grade of concrete. The main characteristic of concrete is the compressive strength, which determines the grade of concrete. By type of binder concretes are: - cement - silica - polymer, etc. According to the bulk mass of concrete can be divided into: - heavy - volume weight above 1800 kg / m 3, are used in industrial construction - light - weight not exceeding 1800 kg / m3. The price of concrete depends on: - the type of concrete (heavy concrete less porous) - the brand of concrete (the higher figure in the concrete mark, the higher the price). You should not: - use heavy concrete for the construction of interior partitions or superstructure of the building - to use cellular concrete when constructing underground structures (cellars, basements, etc.). It is optimal to purchase the concrete directly from the manufacturer, which will save considerable money. Preparation of concrete mix in individual housing for the preparation of concrete mix as a binder most commonly used Portland cement 400. Must be borne in mind that the cement is very hygroscopic, ie, rapidly absorbs moisture from the air and hardens. Therefore you should not buy the cement in advance, and if it was bought, then it should be kept in a sealed container (eg, tightly wrapped in polyethylene). Used the sand must be clean (no clay, silt and organic inclusions) and large. To separate the foreign inclusions sifting sand is recommended. The purer the sand, the higher the strength of concrete obtained. The use of insufficiently purified sand will cause an increase in cement consumption by 10-20 per cent of the recommended. Crushed stone is better to use small (5-20 mm fraction). Optimum results are obtained by the use of rubble from the natural rocks, shallow river or crushed gravel. Perhaps the use of artificial gravel, slag, limestone, however, remember that concrete structure using such fillers will be less durable. Approximate number of constituents for the preparation of 100 liters of concrete: Cement - 30 kg (3 buckets); Sand - 70 kg (5 bins); Rubble - 100 kg (8 bins), Water for mixing shall be clean and free of foreign inclusions. The amount of water is difficult to establish in advance, because it depends on the initial moisture content of sand and gravel and cement from vlagopotrebnosti. Typically, the amount of water is determined during the mixture preparation. First, dry ingredients (cement, sand, gravel) are mixed together, and then small portions of water is added until, until the mixture acquires the consistency of "thick cream". Mixture should not flow, so you can prepare by hand using shovels soviet or bayonet on a metal or wooden shield, a concrete floor. It should be remembered that the work on preparation of concrete mix should be held at a positive temperature environment. Reinforced concrete Reinforced concrete structures are divided into teams and monolithic. Precast concrete (eg, home) gather at the construction site of the individual elements (blocks, panels, etc.) made in factories. Monolithic concrete structure set in concrete at the construction site and allow you to create a modern home as an open-plan with large areas of many buildings and heat-insulating exterior walls. For this type of construction using rigid metal frame and solid construction of floors and walls. Note The binder is often used in reinforced concrete straining cement, which has the property to increase in volume during curing. As a result, receives reinforcement tensile stress, concrete - Compression and concrete structure becomes samonapryazhennoy. Coupled with a metal frame concrete provides unlimited possibilities for use in so-called span structures, such as indoor and 100 sq ft, with "overflow" of a functional space to another, a large indoor pool, etc. without any additional intermediate supports, while maintaining the small thickness of the walls and high thermal insulation properties of building envelopes. Three-layer construction of the outer walls of two layers of reinforced concrete thickness of 5 cm with an effective thermal insulation (polystyrene) in the middle. This design is light, with a high degree of insulating properties and is much cheaper than any other with bricks. In addition, the concrete based on cement bend practically watertight, allowing their use during construction at no additional waterproofing. Advantages of high fracture toughness, high strength, high water resistance, high corrosion resistance, durability Disadvantages of metal fittings lead to the creation of electric fields inside the concrete, which have an adverse impact on human health.