Английский язык для студентов строительных специальностей

UNIT 5. BUILDING MATERIALS | 109

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Building material is any material which is used for a construction purpose. Many naturally occurring substances, such as clay, sand, wood and rocks have been used to construct buildings. Apart from naturally occurring materials, many man-made products are in use, some more and some less synthetic. The use of building materials is typically segmented into specific trades, such as carpentry, plumbing, roofing and insulation work.

Building materials can be categorized into two sources, natural and synthetic. Natural building materials are those that are unprocessed or minimally processed by industry (lumber or glass). Synthetic materials are made in industrial settings after human manipulations (plastics and paints).

Rock is the longest lasting building material available. It is a very dense material so it gives a lot of protection too. Dry-stone walls have been built for as long as humans have put one stone on top of another. Eventually different forms of mortar were used to hold the stones together, cement being the most commonplace now. Wood is a product of trees and sometimes other fibrous plants used for construction purposes when cut or pressed into lumber and timber, such as boards or planks. Wood can be very flexible under loads, keeping strength while bending, and is incredibly strong when compressed vertically.

A brick is a block made of kiln-fired material, usually clay or shale. Clay bricks are formed in a mould, or in commercial

manufacture more frequently by extruding clay through a die and then wire-cutting them to the proper size. Bricks have been used as a building material since the 1700s. This was probably due to the fact that it was much more flame retardant than wood, and cheap to produce. Cinder blocks replaced clay bricks in the late 20th century. They are made mostly with concrete.

Concrete is a composite building material made from the combination of aggregate and a binder. After mixing, the cement hydrates and eventually hardens into a stone-like material. This is the material referred to by the term concrete. For a concrete construction of any size, as concrete has a low tensile strength, it is strengthened using steel rods or bars. This strengthened concrete is called reinforced concrete. Concrete has been the predominant building material in this modern age due to its longevity, formability, and ease of transport.

Metal is used as structural framework for larger buildings such as skyscrapers, or as an external surface covering. There are many types of metals used for building. Steel is a metal alloy whose major component is iron, and is the usual choice for metal structural building materials. It is strong, flexible, and if treated well lasts a

long time.

Clear windows have been used since the invention of glass to cover small openings in a building. They provided humans with the ability to both let light into rooms while at the same time keeping inclement weather outside. Glass which is very brittle is generally made from mixtures of sand and silicates in a very hot fire stove called a kiln. Additives are very often added to the mixture when making to produce glass with different colours or characteristics.

The term plastics covers a range of synthetic or semi-synthetic organic polymerization products. Plastics vary immensely in heat tolerance, hardness, and resiliency. Combined with this adaptability, the general uniformity of composition and lightness of plastics ensures their use in almost all industrial applications today.

More recently synthetic polystyrene or polyurethane foam has been used on a limited scale. It is light weight, easily shaped and