1. Building Materials
Metals

2. Metals Useful building material
Exist in nature as compounds like oxides, carbonates, sulphides and phosphates
Ores → Remove the impurities → metals
Ferrous metals – iron is the main constituent eg. Cast iron, wrought iron, steel
Non Ferrous metals – iron is not the main constituent eg. Aluminium, zinc, lead, tin

3. Ferrous Metals
Iron
Available abundantly but not freely. It is found in ores
Eg. Magnetite – Fe3O % iron
Haematite – Fe2O3 – 70% iron
Limonite – 2 Fe3O4.3H2O – 60% iron
Iron pyrite – FeS3 – 47% iron
Haematite

4. Ferrous Metals Pig Iron Crush the iron ore to 50cm cubes
Knock off the impurities (توقف عن التدخين الشوائب)
Calcine (حول إلى كلس) the ore cubes
Smelt (صهر) in a blast furnace using carbon– reduction takes place and a bit of sulphur is removed
Add flux (تدفق) (limestone) - to remove the sulphur
Molten metal is tapped and casted into pigs

5. Ferrous Metals Pig Iron Contains carbon – 4 - 5%
Silicon, phosphorous, manganese and sulphur – %
Properties of pig iron
Hard and brittle
Melts easily
Hardened but not tempered or magnetized
weak in tension
Uses of pig iron
Base plate, door brackets, etc

6. Ferrous Metals Cast Iron
Pig iron is remelted with limestone and coke and refined in cupola furnace
Pored into moulds – cast iron
2-4%carbon
Fair degree of plasticity and hardness to be casted
Casting – sand casting, hollow casting

7. Ferrous Metals Properties of cast iron Hard and brittle
Cannot be riveted or welded
Strong in compression but weak in tension
Mp °C
Cannot be magnetised

8. Riveting and Welding

9. Ferrous Metals Wrought iron Pure iron
Removing the impurities of cast iron
Impurities – 0.5% where carbon – 0.15%
Molten iron is first refined by blasting air in the furnace.
The metal is cooled and poured into moulds.
The metal becomes brittle.
Melted again in reverboratory furnace where iron melts due to the burning of gas
Process repeated several times

10. Ferrous Metals Wrought iron Is ductile, malleable, tough and elastic
Can be welded
Resists corrosion
Uses
Roof coverings
Rivets, chains, ornamental gates, etc

11. Ferrous Metals Steel and iron
Iron is an element while steel is an alloy of iron and carbon.
Iron has less carbon than steel.
Steel is used in construction because it is stronger than iron and has a superior tensile strength.
Iron was known to the humans from the beginning of civilization while steel was discovered much later.

12. Ferrous Metals
Steel
The most suitable among metallic building material
Because of wide range of physical and mechanical properties
By controlling the carbon content, alloying elements and heat treatment, a desired combination of hardness, strength and ductility can be obtained in steel

13. Ferrous Metals Manufacture of Steel Bessemer process
Open Hearth process
Electric process
Blast of hot air is pressurized to oxidise the carbon
Carbon and Manganese are added and hot air is blasted again
Then the molten materials is pored into moulds to form ingots

14. Ferrous Metals Properties and uses
Mild steel – low carbon or soft steel
Rolled section, reinforcing bars, roof coverings, railway tracks
High carbon steel – %carbon - hard steel – RCC and pre-stressed concrete members
High tensile steel – % carbon – prestressed concrete construction

15. Ferrous Metals Rolled steel sections
Structural steel can be rolled into various shapes and sizes
I-section
T- section
Channel section
Angle section – 40x6mm
Tube section
Bars
Flats
Plates
Sheets
Strip

16. Ferrous Metals Bars Rolled steel sections
Structural steel can be rolled into various shapes and sizes
I-section
T- section
Channel section
Angle section
Tube section
Bars
Flats
Plates
Sheets
Strip
Plates
2000x1000x8mm
Flats
30x10mm

17. Ferrous Metals Rolled steel sections
Structural steel can be rolled into various shapes and sizes
I-section
T- section
Channel section
Angle section
Tube section
Bars
Flats
Plates
Sheets
Strip
Sheets
strips
Sheets
2000x600x4mm

18. Ferrous Metals Reinforcing steel bars
Concrete being weak in tension requires reinforcement which is invariably steel
Available in the form of bars of different diameters and of
different chemical composition – mild steel, high tensile steel and
surface characteristics – plain or deformed

19. Ferrous Metals Rusting and Corrosion
When steel is exposed to atmosphere, the humid air causes rusting and along with rain produces oxidation and corrosion

20. Ferrous Metals
The glass powder melts, flows, and then hardens to a smooth, durable vitreous coating on metal - enameling
To safe guard from rusting and corrosion, some of the prevalent methods are
enameling;
applying metal coatings – galvanizing, electro plating, tin plating
Applying organic coatings – painting and coal tarring

21. Ferrous Metals
applying metal coatings – galvanizing, electro plating, tin plating
Galvanised steel is steel that has been coated with zinc in order to prevent rusting / corrosion. Sometimes the galvanising process is referred to as hot dip galvanising. The zinc forms a barrier against corrosion in that the steel underneath does not come into contact with water / moisture in the air.
add a thin layer of another metal to an item made of steel, in order to prevent rusting - galvanising

22. Ferrous Metals
applying metal coatings – galvanizing, electro plating, tin plating
In industry electroplating is often the process used to galvanise steel products as it is more efficient and more cost effective than the hot dipping process. The thickness of the coating can be determined with great accuracy.

23. Non Ferrous Metals
Production of non ferrous metals is small when compared to iron but they are used as building material despite their high cost
Aluminium, copper, tin, zinc, lead and manganese
Aluminium
zinc
copper
tin

24. Non Ferrous Metals Aluminium Ore – Bauxite (Al2O3.2H2O)
The ore is purified by Bayer’s process and then
Reduced to aluminium by Hall Hirout’s process
Bauxite is converted to alumina by
Roasting, grinding, heating with sodium hydrate and filtering

25. Non Ferrous Metals Aluminium
Then it is agitated for several hours to precipitate the hydrate, which is separated , washed and calcined at 1000°C
Aluminum is extracted by electrolysis of alumina in a molten bath of crystolite (fluoride of alumina and sodium)

26. Non Ferrous Metals Properties of Aluminium
Silver white in colour with a metallic lustre
Malleable, less ductile than copper
Very light, soft, strong and durable, low thermal conductivity, good conductor of electricity

27. Non Ferrous Metals Uses of aluminium
Pure aluminium is soft and is not suitable for structural purposes
But satisfactory properties are achieved by alloying copper, manganese, zinc, silicon, nickel with aluminium.
Make door and window frames
Railings
Corrugated sheets
Aluminium sheets are used over doors in bathrooms
Aluminium powder is used to make paint
Parts of engine, airplanes, utensils, etc
Aluminium alloys used in the manufacture of rolled sections – angles, channels, I-sections, round and rectangular pipes, rivets and bolts

28. Non Ferrous Metals Alloy Duralumin Contains copper (3-5%)
Magnesium (0.5-1%)
Manganese ( %)
Iron ( %)
silica ( %)
Strength is equal to mild steel
Used for construction