Материал: 1493

Задание 5. На основе информации, данной в переводе, и текста, представленного после таблицы, дайте развернутое толкование понятия.

Construction aggregate

Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined materials in the world. Aggregates are a component of composite materials such as concrete and asphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material. Due to the relatively high hydraulic conductivity value as compared to most soils, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and road side edge drains. Aggregates are also used as base material under foundations, roads, and railroads. In other words, aggregates are used as a stable foundation or road/rail base with predictable, uniform properties (e.g. to help prevent differential settling under the road or building), or as a low-cost extender that binds with more expensive cement or asphalt to form concrete.

The American Society for Testing and Materials publishes an exhaustive listing of specifications for various construction aggregate products, which, by their individual design, are suitable for specific construction purposes. These products include specific types of coarse and fine aggregate designed for such uses as additives to asphalt and concrete mixes, as well as other construction uses. State transportation departments further refine aggregate material specifications in order to tailor aggregate use to the needs and available supply in their particular locations.

Sources for these basic materials can be grouped into three main areas: Mining of mineral aggregate deposits, including sand, gravel, and stone; use of waste slag from the manufacture of iron and steel; and recycling of concrete, which is itself chiefly manufactured from mineral aggregates. In addition, there are some (minor) materials that are used as specialty lightweight aggregates: clay, pumice, perlite, and vermiculite.

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Malachite is a copper carbonate hydroxide mineral. This opaque, green banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures and spaces, deep underground, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare but do occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur. Typical malachite is laminated and whether or not microbes intervene in its formation is unknown.

Marble is a fine-grained metamorphic rock that is strong and weather-resistant; more often used in indoor than outdoor paving and walls because of its cost and its slickness when wet.

Задание 3. Обобщите материал схем 1, 2, 7, 9. Составьте учебный текст на английском языке о классификации строительных материалов по разным основаниям.

Задание 4. Изучите таблицу, выпишите транскрипцию терминов из словаря. Используйте полученную информацию при выполнении следующего задания.

Задание 5. Заполните пустые графы таблицы. Используйте следующие выражения:

путем смешения – by alligation (mixture)

в определенной пропорции – in the degree (rapport, ratio) просеянный гипс – siftage (sifted) plaster stone

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