Building materials

Main building materials such as rocks and artificial stones, timber and metals.

Binding materials such as lime, gypsum and cement.

Secondary or auxiliary materials which are used for the interior parts of the buildings.

We use many building materials for bearing structures. Binding materials are used for making artificial stone and for joining different planes. For the interior finish of the buildings we use secondary materials.

Natural building materials are stone, sand, lime and timber. Cement, clay products and concrete are examples of artificial building materials.

Timber is the most ancient structural material. In comparison with steel timber is lighter, cheaper, easier to work and its mechanical properties are good. On the other hand, timber has certain disadvantages. First, it burns and is therefore unsuitable for fireproof buildings. Second, it decays.

At present an enormous amount of timber is employed for a vast number of purposes. In building timber is used too.

Timber is a name applied to the cut material derived from trees. Timber used for building purposes is divided into two groups: softwoods and hardwoods. Hardwoods are chiefly used for decorative purposes, as for paneling, veneering in furniture and some of them are selected for structural use because of their high strength and durability. In modern construction timber is often used for window and door frames, flooring, fences and gates, wall plates, for temporary buildings and unpainted internal woodwork.

+Timber cannot be used for either carpenters’ or joiners’ work immediately it has been felled because of the large amount of sap which it contains. Elimination of this moisture increases the strength, durability and resilience of timber.

Stone has been used as a structural material since the earliest days.

Almost all famous buildings of classic times, of the medieval and

Renaissance periods and of the 18^th and early 19^th centuries were erected of stone masonry. In some places stone was used because of the scarcity of timber but in other places stone was preferred because of its durability.

The stones which are usually used for masonry work are as follows:

1. 
   Granite is very hard, strong and durable. It is used particularly for basements, base courses, columns and steps and for the entire facades. Its colour may be grey, yellow, pink or deep red.
   
2. 
   Sandstone is composed of grains of sand or quarts cemented together. Sandstones form one of the most valuable materials. The durability of sandstones depends very largely upon the cementing material. Thus, there are different kinds of sandstones. Many sandstones are exceptionally hard and are selected for steps, sills, etc. It is an excellent material for concrete aggregate.
   
3. 
   Marble is a crystalline stone chiefly used for decorative purposes. White and black marbles are used for ornamental decoration where the beauty of the marble is shown to its best advantage.
   

All metals are divided into ferrous metals and non-ferrous metals. Ferrous metals include iron, steel and its alloys. Non-ferrous metals are metals and alloys the main component of which is not iron but some other good element. Metals, in general, and especially ferrous metals are of good importance in variations.

Metals possess the following properties:

1. 
   All metals have specific metallic lustre.
   
2. 
   They can be forged.
   
3. 
   Metals can be pulled.
   
4. 
   All metals except mercury are hard substances.
   
5. 
   They can be melted.
   
6. 
   In general, metals are good conductors of electricity.
   

These characteristics are possessed by all metals but the metals themselves differ from one another. Steel and cast iron are referred to the group of ferrous metals. Cast iron is the cheapest of the ferrous metals. It is chiefly used in building for compressed members of construction, as the supporting members. When an engineer designs a steelwork he must carefully consider that the steel frame and every part of it should safely carry all the loads imposed upon it. The steel framework must be carefully hidden in walls, floors and partitions. It is steel and metal that is employed as reinforcement in modern ferroconcrete structures. In the curriculum of the Institute there is a special course on metal structures.