(Binding Materials, Concrete and Structural Steel)
There are many building materials nowadays. We must consider many factors in choosing them: availability, cost, physical properties and others.
Timber, steel and concrete all vary. Even steel, uniform as it appears to be, varies considerably in its microstructure. Concrete is even less uniform than many other materials.
Lime, gypsum and cement are the tree materials most widely used in building construction for the purpose of binding together masonry units, such as stone, brick and as constituents of wall plaster. Cement is the most important component of concrete.
Another important class of cement is high alumina cement. High alumina cement is a material containing alumina. It has an extremely high rate of strength increase which is, owing to the violence of chemical reaction, accompanied by a considerable evolution of heat. It is very resistant to chemical attack.
Portland cement like other materials can to some extent be modified to suit a particular application. The scope for such purpose-made cements has led to the development of an increasing variety such as alumina cement, blast-furnace slag and pozzuolanas. Portland blast-furnace cement has greater resistance to some forms of chemicals.
The most important building materials may now be considered to be structural steel and concrete. Concrete may be considered an artificial conglomerate of crushed stone, gravel or similar inert material with a mortar. A mixture of sand, screenings or similar inert particles with cement and water has the capacity of hardening into a rock line mass is called mortar. The fundamental object in proportioning concrete or mortar mixes is the production of a durable material of requisite strength, water tightness and other essential properties at minimum cost. To attain this end careful attention must be given to the selection of cement, aggregate and water.
The most accurate method of measuring proportions is to weigh the required quantities of each material. It is widely used in large building construction, but in small building construction the less accurate method of measuring proportions by volumes is frequently used. The chief inaccuracies in volumetric measurement arise from the wide variation in the bulk of the fine aggregate due to small changes in its moisture content and faulty methods of filling measuring devices.
Workability and strength tests are chief control tests made on concrete. To be able to undergo high compressive loads is a specific characteristic of this material.
Wordlist
| availability uniform concrete lime cement (alumina cement) slag structural steel mortar water tightness aggregate moisture content high compressive loads | наличие, ассортимент одинаковый бетон известняк цемент (цемент с содержанием глинозема) шлак строительная сталь цементный раствор водонепроницаемость заполнитель содержание влаги высокие нагрузки на сжатие |
Контрольная работа № 3
Проработайте по учебнику следующие разделы: 1. причастие I и II; 2. страдательный залог; 3.сложные существительные; 4. придаточные предложения, 5.возвратные местоимения.
Вариант № 1.
I. Перепишите сложные существительные, подчеркните в них основное слово; переведите их на русский язык.
a dining room, a rock line, a countryside, a farmhouse, a bathroom, a staircase.
II. Образуйте от глаголов причастие I, переведите словосочетания на русский язык
A (to build) house – a building house, a scenery (to change), (to bind) materials, a (to increase) variety, a (to measure proportions) method, people (to move)
