4. Translate the following groups of words into Russian:

Act – active – action – activity; to compress – compressive – compression; easy – easily; to define – definition – definite – indefinite; to form – formal – formation; design – designer; sufficient (a) – sufficient (n) – sufficiency (n).

5. Do vocabulary test:

1) age	1) нагрузка
2) attain	2) загружать
3) carry	3) твердеть
4) deposit	4) мешалка
5) entire	5) возраст
6) harden	6) нести
7) loan	7) твердый
8) mixer	8) натяжение
9) solid	9) полный
10) tension	10) достигать
11) action	11) объем
12) allow	12) раствор
13) binder	13) определенный
14) certain	14) действие
15) design	15) сила
16) force	16) поддерживать
17) prevent	17) предотвращать
18) support	18) связующее вещество
19) uniform	19) равномерно

II. Reading Comprehension.

1. Read and translate the text.

MORTAR

Definition. Mortar is the adherent mass or product obtained by mixing with water intimate and properly proportioned mixtu­res of sand and cement, sand and lime, cement and lime, until the entire mass is plastic and homogeneous. The mixing mау be done by a skilled workman with a hoe and shovel; but it is pre­ferable to do the work with a mechanical mixer.

Mixing. Mortar should be mixed in a drum having a peripheral speed of 200 ft. per minute. Mortar may remain in the mixer for at least 2 min. after all the ingredients have been deposited in it, and after it has attained its peripheral speed.

Tensile Strength. The tensile strength of mortar comes into play in resisting forces due to eccentric loading, which throw one side of a wall into compression and the other side into tension. No masonry structure can be designed to eliminate all eccentric loading. Even in the best design, it is im-possible to use sufficient tension members to relieve the masonry of all tensile stress so a certain amount of tensile strength is necessary in the mortar.

The chief load a wall must support is that due to compres­sion, hence, the compressive strength of mortar is considered of paramount importance.

Lime Mortar. When ordinary quicklime is slaked, mixed with sand, and used as mortar, the mixture hardens very slowly and never attains much strength. The hardening is due to the fact that the slaked lime gradually absorbs carbon dioxide from the atmosphere and recarbonates, forming a sort of artificial limestone. So far as is known, there is no chemical ac­tion between the lime and the sand of the mortar. Though the statement is made occasionally that with increasing age a certain amount of chemical action does take place, resulting in the formation of a certain percentage of lime silicate. This, however, is more than doubtful. The sand is an inert material, added to prevent shrinkage and cracking.