3. Concrete (a bit of history)

The ancient Romans discovered a mineral on the slopes of Mount \fesuvius. The mineral when mixed with limestone and burned, produced cement, that hardened underwater as well as in the air. This cement was harder and stronger than the ordinary lime mortar they had been using. As time passed, the new material not only became the preferred type for use in all their building projects but changed the character of Roman con­struction. Masonry of stone or brick was used to construct only the surfac­es of masonry piers and walls but the interiors were filled with large amounts of the new type of mortar.

Wfe now know that mortar continued the main ingredient of modern Portland cement. Thus, one can say that the Romans were the inventors of concrete constructions.

With the fall of the Roman Empire, knowledge of concrete construc­tion was lost. But in the eighteenth century English inventors began ex­perimenting with both natural and artificially produced cements. In 1824 an artificial cement, named Portland cement, was patented. This type of cement soon became very popular and the name Portland is in common use in the present day.

4. Climatic and weather conditions

Orientation and construction of buildings should receive special at­tention in places where environmental and climatic factors have a signifi­cant effect. Structural design, style and materials should be compatible with local climatic and weather conditions. For example, flat roofs should be avoided in areas with frequent rainfalls. Snow and wind are variable loads that should be taken into account while designing a structure and its roof. Tall buildings are not recommended in places where strong winds, humidity or fog are likely and bring damage.

Solar radiation can be also unpleasant, but if it is controlled, it can bring many advantages. Among these advantages there may be water heat­ing through solar panels.

Local industries and their disposition should be also taken into ac­count and controlled as atmospheric and noise pollution may be highly injurious and bring much harm.

Location and coordination of all services must also be preplanned and located on a site plan, worked out in accordance with the local cli­matic conditions. Sanitary accommodation is of primary importance. All conveniences must have ventilation, a cover, partitions and doors with suit­able fasterings.

Pair work. Put these questions to your groupmatc.

1. Why should flat roofs be avoided in areas with frequent rainfalls?

2. Which variable loads should be taken into account?

3. For what reasons are tall buildings not recommended in areas where

winds and fogs are frequent?

4. What advantages can solar radiation bring?

5. For what reasons should local industries be controlled?

5. Cladding

Cladding is a material used as the exterior wall enclosure of a build­ing. The cladding of a building is its most visible part. Its major purpose is to separate the indoor environment of a building from the outdoors.

Cladding must prevent the entry of water, snow and ice into a build­ing. Water on the face of a building is known to be driven by wind not only in a downward direction, but in every other direction, even upward.

Witer problems, that is keeping water out, are especially great on very tall buildings. These buildings rise to height where wind velocities are extremely high.

They are much higher than at ground level. It should be taken into account that on tall buildings water tends to penetrate the smallest crack or hole and enter the building.

Construct the questions in writing and answer them.

Unit Fourteen 112

WINDOW 112

Unit Fifteen 128

FLOOR 128

Control Yourself 132

REVIEW OF UNITS 13-15 132

Unit Two 30

EXCAVATION 30

Unit Three 42

FOUNDATION 42

Unit Five 40

WOOD 40

^^HrT -- ^i] T-- ^! ' J * 87

Control Yourself 89

REVIEW OF UNITS 4 7 89

Unit Nine 125

Control Yourself 138

REVIEW OF UNITS 8 9 138

Unit Eleven 92

Unit Twelve 116

CEILING 116

6. On what buildings, water, does, tend, the smallest crack or hole, to

penetrate ?

CLADDING (icontinued) A. Preventing Air Leakage

The function of a cladding is to prevent the passage of air between indoors and outdoors of a building. For this purpose it is necessary to reg­ulate air velocities within the building. Even small air leaks are extremely harmful. Why is it so?

It is because air leaks carry water though the wall, allow vapor to con­densate inside the walls, and allow noises to penetrate the walls of the build­ing from outside.

B. Controlling Light

The function of the cladding of a building is also to control the pas­sage of light. Especially important is controlling the passage of sunlight.

It is a well-known fact that sunlight is heat that may be harmful or harmless. It can be useful for illumination but harmful if it produces glare within a building. Besides, sunlight includes ultraviolet wavelengths that can be harmful for human skin. They may also cause harm to interior materials.

Answer the following questions.

1. What is the function of a cladding?

2. Why are small leaks harmful?

3. Why is controlling the passage of sunlight so important?

4. What kind of wavelengths does sunlight include? Why are they harmful?