Aluminium building materials

1. AP-325
Building Material & Science-V
By: Ar. Ashwani Singh
Aluminium As A Building Material

2. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Contents:
• Manufacturing of Aluminium & Its Environmental Impact
• Properties of Aluminium
• Types of Aluminium Sections & Sheets & Usage in Buildings

3. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium is being the 3rd most plentiful element
Light-weight, Corrosion Resistance, Strength at Low Temp, Ductility,
Non-toxic etc characteristics makes it as suitable Building Material
Aluminium being the abundant in nature, it is never found free
The most common compounds are:
1. Alum (Potassium Aluminium Sulphate - KAl(SO4)2·12H2O)
2. Alumina (Aluminium Oxide- Al2O3)
Aluminium-Introduction

4. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Souces of Aluminium:
Bauxite
Bauxite is a rock formed from a reddish clay material called laterite soil and is most
commonly found in tropical or subtropical regions. Bauxite is primarily comprised of
aluminum oxide compounds (alumina), silica, iron oxides and titanium dioxide
Bauxite ore is the world’s primary source. The ore first chemically processed to produce
alumina(Aluminium Oxide)
Alumina is then smelted using an electrolysis process to produce pure aluminum metal.
The ore is acquired through environmentally responsible strip-mining operations.
Bauxite reserves are most plentiful in Africa, Oceania and South America.

5. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Manufacturing of Aluminium:
Aluminum is manufactured in two phases:
• The Bayer Process-
Refining of bauxite ore to obtain aluminum oxide,
• Hall-Heroult Process
Smelting of aluminum oxide to release pure aluminum.

6. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
The Bayer process
• Ore is mechanically crushed & mixed with caustic soda, Grinded in a mill to produce a
slurry (a watery suspension) containing very fine particles of ore
• Slurry is pumped into a digester-a pressure cooker like tank.
• Slurry is heated to 230-520°F (110-270°C) under pressure of 50 lb/in 2 till aluminum
containing compounds are dissolved
• The hot slurry, which is now a sodium aluminate solution, passes through a series of
flash tanks that reduce the pressure and recover heat that can be reused in the
refining process
• The slurry is pumped into a settling tank. As the slurry rests in this tank, impurities
that will not dissolve in the caustic soda settle to the bottom of the vessel
• Aluminum in the settling tank remains dissolved in the caustic soda hence the residue
(called "red mud") accumulates in the bottom that consists of fine sand, iron oxide,
and oxides of trace elements like titanium
• Remaining liquid, which is like coffee, pumped through a series of cloth filters. Any
fine particles of impurities that remain in the solution are trapped by the filters.

7. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
The Bayer process
• This material is washed to recover alumina and caustic soda that can be reused.
• The filtered liquid is pumped through a series of six-story-tall precipitation tanks. Seed
crystals of alumina hydrate (alumina bonded to water molecules) are added through
the top of each tank. The seed crystals grow as they settle through the liquid and
dissolved alumina attaches to them.
• The crystals precipitate (settle to the bottom of the tank) and are removed. After
washing, they are transferred to a kiln for calcining (heating to release the water
molecules that are chemically bonded to the alumina molecules). A screw conveyor
moves a continuous stream of crystals into a rotating, cylindrical kiln that is tilted to
allow gravity to move the material through it. A temperature of 2,000° F (1,100° C)
drives off the water molecules, leaving anhydrous (waterless) alumina crystals. After
leaving the kiln, the crystals pass through a cooler.

8. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Manufacturing of Aluminium:

9. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Manufacturing of Aluminium:
The Hall-Heroult process
• Smelting of alumina into metallic aluminum takes place in a steel vat called a
reduction pot. The bottom of the pot is lined with carbon, which acts as one electrode
(conductor of electric current) of the system. The opposite electrodes consist of a set
of carbon rods suspended above the pot; they are lowered into an electrolyte solution
and held about 1.5 in (3.8 cm) above the surface of the molten aluminum that
accumulates on the floor of the pot. Reduction pots are arranged in rows (potlines)
consisting of 50-200 pots that are connected in series to form an electric circuit. Each
potline can produce 66,000-110,000 tons (60,000-100,000 metric tons) of aluminum
per year. A typical smelting plant consists of two or three potlines.
• Within the reduction pot, alumina crystals are dissolved in molten cryolite at a
temperature of 1,760-1,780° F (960-970° C) to form an electrolyte solution that will
conduct electricity from the carbon rods to the carbon-lined bed of the pot. A direct
current (4-6 volts and 100,000-230,000 amperes) is passed through the solution.

10. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Manufacturing of Aluminium:
The Hall-Heroult process
• The resulting reaction breaks the bonds between the aluminum and oxygen atoms in
the alumina molecules. The oxygen that is released is attracted to the carbon rods,
where it forms carbon dioxide. The freed aluminum atoms settle to the bottom of the
pot as molten metal. The smelting process is a continuous one, with more alumina
being added to the cryolite solution to replace the decomposed compound. A
constant electric current is maintained. Heat generated by the flow of electricity at the
bottom electrode keeps the contents of the pot in a liquid state, but a crust tends to
form a top the molten electrolyte. Periodically, the crust is broken to allow more
alumina to be added for processing. The pure molten aluminum accumulates at the
bottom of the pot and is siphoned off. The pots are operated 24 hours a day, seven
days a week.
• A crucible is moved down the potline, collecting 9,000 lb (4,000 kg) of molten
aluminum, which is 99.8% pure. The metal is transferred to a holding furnace and then
cast (poured into molds) as ingots.

11. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Manufacturing of Aluminium:
The Hall-Heroult process
One common technique is to pour
the molten aluminum into a long,
horizontal mold.
As the metal moves through the
mold, the exterior is cooled with
water, causing the aluminum to
solidify. The solid shaft emerges
from the far end of the mold, where
it is sawed at appropriate intervals
to form ingots of the desired length.
Like the smelting process itself,
this casting process is also
continuous.

12. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium-Properties

13. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
• Being Recyclable and good scrap value makes it best suited for building
construction
• Smooth and Bright finish
• Air-tightness when used with rubber gaskets makes it best for use against
Dust, Rainwater and in air conditioned space
• Corrosion resistance
Aluminium reacts with the oxygen in the air to form an extremely thin layer of oxide.
Layer is dense and provides excellent corrosion protection.
Layer is self-repairing if damaged. Anodising increases the thickness of the oxide layer
and thus improves the strength of the natural corrosion protection. Ductility &
malleability is essential for extrusion. With the metal either hot or cold, this property is also
exploited in the rolling of strips and foils, as well as in bending and other forming operations.
Aluminium-Importance

14. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Casting Based
Casting is the original and most widely used method of forming aluminum into
products. Technical advances have been made, but the principle remains the same:
Molten aluminum is poured into a mold to duplicate a desired pattern. The three most
important methods are die casting, permanent mold casting and sand casting.
Casting Based Products:
• Hardware & Fitting
• Baluster Heads
• Grills
• Engines and Parts
• Utensils etc
Aluminium-Products

15. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Extrusion Based
Extrusion is a technique where heated materials such as aluminium are forced through
an opening to form a shaped profile. Once the aluminium has been pushed through
the container by the ram within the press, it will form the extruded profile which will
be the same shape as the opening in the die
Casting Based Products:
• Door Frames
• Window Frames
• Facades
• Channels
• Tubes etc
Aluminium-Products

16. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Foil & Powder Based Aluminum Products
Foil made from aluminum is thin, light, easy-to-use and highly hygienic. It is widely
found in everything from packaging for pharmaceuticals, foodstuff and other
commodities, to electrolytic capacitors, lithium ion batteries and construction
materials.
Foil Based Products:
• Aluminiun Foils
• Packaging
• Electrical equipm
• Industrial Comp etc
Aluminium-Products

17. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Foil & Powder Based Aluminum Products
In form of powders, Aluminum is used for several applications such as manufacture of
slurry, explosive and detonators, hermit process used for manufacture of Ferro alloys
and for specialized welding applications such as rails, pyrotechnic to manufacture
crackers, sparkles and other pyrotechnic products
Powder Based Products:
• Crackers
• Welding essentials
• AAC Block
• Paints etc
Aluminium-Products

18. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Sheet Based Aluminum Products
Aluminum sheet is any aluminum sheet metal thicker than foil but thinner than 6mm,
it comes in many forms including diamond plate, expanded, perforated and
painted aluminum sheet.
Aluminum plate is any aluminum sheet metal that is thicker than 6mm.
Powder Based Products:
• Chequered Plates
• Corrugated Sheets
• Shuttering etc
Aluminium-Products

19. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium Doors & Windows
• Aluminium doors and window frames are made from extruded aluminium
sections.
• The channels and box sections have flanges and grooves for double glazing
and weather-stripping.
• The glazed doors are commonly advertised as ‘patio doors’.
• Aluminium is a conductive material heat transmission can be reduced by
separating the ALU profile in 2 parts using an insulating material to reduce
the thermal transmission.

20. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium Hinged Doors

21. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium Hinged Doors

22. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium Casement Hinged Doors with
Top Fixed

23. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium Window-Fixed

24. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium Window-Two Track Sliding
Windows Single Glazed with Wire-mesh Fixed

25. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium –Colors

26. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Environment Impact of Manufacturing of Aluminium

27. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Aluminium-Environmental Impact
Aluminum is an abundant element within Earth’s surface— but getting it out of the ground is an
arduous process, requiring heavy machinery to plow up acres and acres of land. Fortunately, the
environmental impact of that process can be somewhat balanced out by post-mining
rehabilitation, efficient recycling, and generally reducing our consumption.

28. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
There are environmental impacts associated with each stage of aluminum production, from
extraction to processing. The major environmental impact of refining and smelting is
greenhouse gas emissions.
Green House Gases Emission
Refining & Smelting
These gases result from both the electrical consumption of smelters and the byproducts of
processing. The greenhouse gases resulting from primary production include perfluorocarbons
(PFC), polycyclic aromatic hydrocarbon (PAH), fluoride, sulfur dioxide (S02), and carbon dioxide
(CO2). Of these gases, PFC’s resulting from the smelting process are the most potent. Primary
aluminum production is the leading source of perfluorocarbon emissions
PAH emissions result from the manufacture of anodes for smelters and during the electrolytic
process. Sulfur dioxide and sodium fluoride are emitted from smelters and electrical plants. SO2
is one of the primary precursors of acid rain. CO2 emissions occur during smelting and result
from the consumption of carbon anodes and from PFC emissions.
Aluminium-Environmental Impact

29. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
The atmospheric pollutants from primary aluminum production also produce acid rain when
they mix with water vapor. Aluminum poses no danger of environmental toxicity when soil pH
remains at or above 5.0, however acid rain lowers the pH of soil and forces aluminum into
solution. This causes it to leach into the water supply where it can damage root systems and
create acidified lakes. Due to its natural abundance, the amount of aluminum that enters the
environment due to regular weather processes far exceeds anthropogenic contributions.
A life cycle analysis of aluminum shows distinct advantages to recycling the material. The
primary benefit of recycling aluminum is reduced energy consumption. Aluminum recovery from
scrap requires only 5 percent of the energy required to extract it. Therefore, secondary
aluminum production from recycling scrap has the potential to significantly reduce greenhouse
gas emissions. The most common source of aluminum scrap is aluminum cans, but automobiles,
building materials, and appliances are also viable sources. Repeated recycling of aluminum does
not affect its quality.
Aluminium-Environmental Impact

30. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Environmental properties
Pros Cons
Plentiful resource Very high energy use
Use of hydro-electricity can dramatically
reduce fossil fuel energy
Open-cast mining of bauxite can seriously damage
local eco systems and communities
High durability Smelting uses large amounts of water
Low maintenance Emissions to air and water from processing, some
of which are hazardo
European production highly regulated for
pollution
Bauxite residue storage and management which
demands land use and can sometimes fail (eg Ajka
alumina sludge spill, Hungary, 2010)
Recycling uses a fraction of the energy used in
primary production
Long transportation routes in between extraction,
processing and fabrication adds to embodied
energy
Aluminium-Environmental Impact

31. Building Material & Science-V
B.Arch 5th Semester
Aluminium As A Building Material
Environmental properties
Pros Cons
Very high levels of recovery in construction
and recycling
Environmental regulations governing production
can vary greatly throughout the world
Due to economics, the EU is currently a net
exporter of aluminium scrap – which compromises
the recycling industry in Europe
Aluminium-Environmental Impact
So, is aluminium a ‘sustainable’ material?
There isn't a straightforward answer. There's no doubting the wide range of uses of aluminium.
It has the advantage of light weight combined with high strength and durability, which, in many
situations could be considered indispensible. But the hard reality of its soaring embodied carbon
along with a currently disappointing recycling rate still make it a difficult material to use without
some degree of consideration. Certainly the building designer should be able to justify
aluminium's function/application where specified.