Современные проблемы промышленного и гражданского строительства на занятиях английского языка. Кузьмина Е.В. - 35 стр.

UptoLike

Составители:

Рубрика:

A thermoplastic material is one having the property of softening when

heated and of hardening and becoming rigid again when cooled. Hence, such a

material is normally hard at room temperature but will soften and become

moldable, adhesive, and cohesive when heated to some higher temperature.

This property of thermoplasticity is well-recognized in such organic materials

as cellulose acetate, polyethylene, and vinyl polymers and in glasses at

temperatures around and somewhat above the softening points thereof. The

value of this property is apparent in the forming of articles through molding,

pressing, extrusion, rolling, etc., and in forming composite structures,

laminates, and the like.

Hydraulic cement is one that is capable of hardening under the influence

of water. Hence, such a material, when mixed with water and allowed to stand,

gradually sets up as a hard, massive solid structure. Portland cement is probably

the best known material commercially of this type.

Text C. New types of concrete

Not long ago a new building material was born. Called alkali-slag

concrete, most of its components come literally from under foot. Cement is

replaced by a mixture of granulated blast-furnace slags and sodium and

potassium compounds. The filler can be sand or sandy loams containing various

amounts of clay, which usually cannot be used with conventional cement.

The new material has been tested successfully and is now being used for

roads, pavements, irrigation systems and other structured. Specialists estimate

that the use of alkali-slag concrete will help save hundreds of millions of rubles

on the country's construction projects.

Chemically resistant concrete (кислотоупорный) may be sometimes used

in the construction of structures attacked by chemically active media (среда),

i.e. industrial, hydraulic and underground structures. It has been proposed to

prepare a chemically resistant concrete using a binder (вяжущее), a vitreous

sodium silicate (стекловидный силикат натрия). Then such a vitreous silicate

is dissolved in water, liquid (жидкий) glass is obtained. In order to assist in the

solidification (затвердение) of a liquid glass and increase its water resistance