Современные проблемы промышленного и гражданского строительства на занятиях английского языка. Кузьмина Е.В. - 24 стр.

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UNIT 4

TEXT A. MORTARS

Mortars are composed of a cementitious material, fine aggregate, sand,

and water. They are used for bedding unit masonry, for plasters and stuccoes,

and with the addition of coarse aggregate, for concrete. Here consideration is

given primarily to those mortars used for unit masonry and plasters. Properties

of mortars vary greatly, being dependent on the properties of the cementitious

material used, ratio of cementitious material to sand, characteristics and grading

of the sand, and ratio of water to solids.

Mortar is the matrix used in the beds and side joints of brickwork and for

plastering walls and floors. Its functions are as follows:

1) to distribute the pressure throughout the brickwork,

2) to adhere and bind together the bricks,

3) to act as a non-conductor and prevent the transmission of heat, sound, and

moisture from one side of wall to the other. The factors governing the choice of

mortars for various purposes are:

a) strength as being a main factor determining the strength of the wall

b) porosity and capillary characteristics as affecting the rain-excluding

properties and durability of the wall,

c) content of soluble safts which determines the possibility to destruction

of the masonry or brickwork.

Mortar consists of an inert aggregate bound by a cementing material. The

cementing material is most important in determining the characteristics of the

mortar. The usual cementing materials used for constructional work are

hydraulic limes or Portland cement.

Clean, sharp pit sand is the best aggregate. Old bricks, burnt ballast or

stories ground in a mortar mill may be used as substitutes for sand.

Mortars may be classified as follows:

1. Cement mortars

2. Cement-lime mortars

3. Lime mortars