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

5. Riveting and Welding

6. 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.

7. 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..
Composition of steel
Iron, Carbon, Manganese, Aluminum, Chromium, Columbium, Copper, Molybdenum, Nickel, Silicon, Vanadium

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

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

15. 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

16. Ferrous Metals
applying metal coatings – galvanizing, electro plating, tin plating
add a thin layer of another metal to an item made of steel, in order to prevent rusting - galvanising

17. 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.

18. 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

19. 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

20. 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)

21. 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

22. 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

23. 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