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Basic types of reinforced concrete products
An industry of precast reinforced concrete provides the products for all branch of construction. It is possible to divide all complex products into linear, flat, block and spatial, depending on their geometrical features. Columns, slabs girders, beams, piles belongs to the linear products; roof slabs and ceilings, panels of building walls, walls of reservoirs and others - to flat products; wall and foundation blocks- to block products; rings of wells, elements of silos, lifts and others - to spatial products. Wall panels products (Fig. 14.8) are widely used in civil buildings. Large amount of panels for external walls can be made consisting of one layer of lightweight concrete with porous aggregates or cellular concrete. The most widely used is light claydite concrete wall panels for concrete structures with density 900-1100 kg/m3. As a rule, panels have a texture layer on the facade side measuring 20-30 mm thick. Panels are faced by ceramic, glass tiles, decorative concrete, silicon enamels and other materials. For reduction of the mass of external walls and improvement of their heat-insulation properties panels which consist of two reinforced concrete layers and layer of heat insulation material between them are manufactured. The thickness of walls from such “sandwich” panels goes down to 250-300 mm, mass diminishes by 50%. For floors of buildings, hollow and ribbed slabs with ordinary reinforced or prestressed concrete with ultimate compressive strength 20-30 MPa are used. The hollow slabs are produced with round or oval voids, length up to 6-12 m and width up to 1.5-2.4 m. The ribbed slabs have length up to 15 m and width of up to 3m. Columns and cross-bars are principal elements of building frames. Crane beams and girders are the main elements for industrial buildings.
Columns usually have a rectangular, square or t-shaped cross section. Mainly heavy-weight concrete with ultimate compressive strength 30-40 MPa is applied for columns construction. Considerable reduction in the cost of concrete and steel reinforcement is realized when used as framework elements with ultimate compressive strength of 50-80 MPa. Reinforced concrete products and structures are widely applied in the construction of irrigational systems, underground pipelines, pumping station buildings, elements of bridges etc. (Fig. 14.9). Water-towers, pools, aqueducts and pools, piers and other engineering buildings are economically erected as monolithic constructions. Reinforced concrete pipes (Fig. 14.10) are widely used in the construction of different piping systems. The service life of reinforced concrete pipelines can be as high as 80-100 years, whereas metallic pipes for same use usually last for not more than 30 years. Reinforced concrete pipes are used for various assignments in irrigational and drainage construction. As a result of their impermeability to water, they may be laid in the embankments of highways and railways; sewage and gully, through which economic domestic, industrial and waste waters are passed. The pipes can have different cross-sections and/or configurations: round, elliptic, rectangular, or various other difficult forms.
Reinforced concrete pipes are usually 3-8 m in length. The minimum diameter of pipes is 300 mm and as a rule, the maximal diameter does not exceed 2500mm. Concrete with ultimate compressive strength between 30-50 MPa, and water-pressure-resistance 0.4-1.2 MPa is suitable for pipes. Depending on the external environments, reinforced concrete pipes are divided into pressure (with hydrostatical pressure of 0.5-2 MPa), low pressure (0.3 MPa) and nonpressure.
Date: 2015-12-18; view: 1130
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