civil engineering

2. plastic
POLYMER : The word polymer literally means “ many parts “.
that contains many chemically bonded parts which
themselves are bonded together to form a solid.
Two industrially important polymeric materials are:
1. Plastics
2. Elastomers
Plastic is a synthetic material made from a wide range of
organic polymers such as polyethylene, PVC, nylon, etc., that
can be moulded into shape while soft, and then set into a
rigid or slightly elastic form.

3. Classification of plastic
There are many ways of classifying plastics. They can be
classified considering various aspects, as according to their:
1. Behaviour with respect to heating,
2. Structure
3. Physical and mechanical properties.

4. Classification of plastic
Behaviour with
respect to heating Structure Physical and
mechanical properties
Thermo-plastics
Thermo-setting
Homogeneous
Heterogeneous
Rigid Plastics
Semi-rigid
Plastics
Soft Plastics
Elastomers

5. Themoplastic & thermosetting
Basic difference between Thermoplastics and Thermosetting plastics
THERMOPLASTICS THERMO-SETTING
PLASTICS
Thermoplastics variety
softens by heat and
hardens when cooled
down. It can be used by
remolding as many times
as required.
Thermosetting plastics
can not be reused .This
variety requires a great
pressure and momentary
heat during molding
which hardens on
cooling.

6. Thermo-plastics
 Allow plastic deformation when it is heated.
 They are brittle and glossy.
 They are soluble in certain solvents.
 Swell in the presence of certain solvents.
Polystyrene used for electrical insulation, handles of tools...
Polyamide used for making ropes, belts, etc...
PVC or polyvinyl chloride for the manufacture of insulation
materials, pipes, containers, etc...
PROPERTIES

7. Thermo-setting plastics
 These are soluble in alcohol and certain organic solvents, when they are
in thermo-plastic stage. This property is utilized for making paints and
varnishes from these plastics.
 These are durable, strong and hard.
They are mainly used in engineering application of plastics.
PROPERTIES
Polyesters (thermosetting, reinforced with glass fibers)
Properties: good mechanical, electrical, and chemical properties, good
resistance to heat and chemicals
Applications: boats, luggage, swimming pools, automotive bodies, chairs

8. Thermo-setting plastics
 Electronic chips
 Fibre-reinforced composites
 Polymeric coatings
 Spectacle lenses
 Dental fillings
General Uses

9. Homogeneous plastics
This variety of plastic contains carbon chain i.e. the
plastics of this group are composed only of carbon
atoms and they exhibit homogeneous structure.
Heterogeneous plastics
This variety of plastic is composed of the chain
containing carbon and oxygen, the nitrogen and other
elements and they exhibit heterogeneous structure.

10. Based on physical and chemical properties
Soft Plastics
Semi-rigid
Plastics
Elastomers
Rigid Plastics

11. Rigid plastics
These plastics have a high modulus of elasticity and they retain
their shape under exterior stresses applied at normal or
moderately increased temperatures.
Semi-Rigid plastics
These plastics have a medium modulus of elasticity and the
elongation under pressure completely disappears, when pressure
is removed.
The plastic keys on your keyboard are hard, while the plastic around the cables
of the same computer is soft.

12. soft plastics
 These plastics have a low modulus of elasticity and the
elongation under pressure disappears slowly, when pressure is
removed.
 Soft plastics are available in a large range of colours, sizes and
particularly shapes.
USES: Used in making children’s toys e.g.: rattles etc., fishing baits.

13. Elastomers
These plastics are soft and elastic materials with a low modulus of
elasticity. They deform considerably under load at room
temperature and return to their original shape, when the load is
released. The extensions can range upto ten times their original
dimensions.

14. properties
 APPEARANCE: Some plastics are completely transparent in appearance. With
the addition of suitable pigments, the plastics can be made to have appearance
of variety of attractive, opaque, stable and translucent colours.
 CHEMICAL RESISTANCE: The plastics offer great resistance to moisture,
chemicals and solvents. The degree of chemical resistance depends on the
chemical composition of plastics. Many plastics are found to possess excellent
corrosion resistance. Hence they are used to convey chemicals.
 DIMENSIONAL STABILITY: This property of plastic favours quite satisfactory with
that of other common engineering materials.
 DUCTILITY: The plastics possess excellent electric insulating property. They are
far superior to ordinary electric insulators.

15. properties
MELTING POINT: Most of the plastics have low melting point and the melting
point of some plastics is only about 50 ͦC. They cannot therefore be used in
positions having high temperatures or to convey boiling water.
 OPTICAL PROPERTY: Several types of plastics are transparent and
translucent.
 RECYCLING: The most environmentally aware people condemn the use of
plastics for the amount of pollution caused by them in disposal. The plastics
used for soft-drink bottles, milk and juice bottles, bread bags, syrup bottles,
coffee cups, plastic utensils, etc. can be conveniently recycled into carpets,
detergent bottles, drainage pipes, fencing, handrails, grocery bags, car battery
cases, pencil holders, benches, picnic tables, roadside posts, etc.

16. properties
STRENGTH: An ideal section of plastics for structural member has yet
not been designed. The plastics are reasonably strong. The strength of
plastics may be increased by reinforcing with various fibrous materials.
Following considerations are responsible to discourage the use of
plastics as the structural material:
1. The plastics are costly.
2. The plastics are subject to creep under constant heavy loads.
3. The behaviour of plastics is very sensitive to the changes in
temperature.
4. The stiffness of plastics is very poor

17. properties
WEATHER RESISTANCE: Only limited varieties of plastics can be
exposed to weather. The certain plastics are seriously affected by
ultraviolet light in the presence of sunlight. The resistance to
sunlight of such plastics can be improved by incorporating fillers
and pigments which absorb or reflect the ultraviolet light at the
surface. Thus the interior of plastics is protected.
 WEIGHT: The plastics, whether thermo-plastic or thermo-
setting, have low specific gravity, the average being 1.30 to 1.40.
The light weight of plastics reduces the transport costs and
facilitates fixing.

18. ADVANTAGES of plastic
 Corrosion resistance
 Very Low electrical and thermal conductivity, insulator
 Easily formed into complex shapes, can be formed, casted
and joined.
 Wide choice of appearance, colors and transparencies

19. DISADVANTAGES of plastic
 Low strength
 Low useful temperature range (up to 314
o
C)
 Less dimensional stability over period of time (creep effect)
 Aging effect, hardens and become brittle over time
 Sensitive to environment, moisture and chemicals
 Damages due to sunlight

20. Uses of plastic
 There are more than 10000 different kinds of plastics available in the market
and their performance abilities span those of every other known material from
soft rubber to steel.
 The typical uses of plastics in building are summarized as follows:
 Bath and sink units
 Cistern ball floats
 Corrugated and plain sheets
 Decorative laminates and mouldings
 Electrical conduits
 Electrical Insulators
 Films for water proofing, damp
proofing and concrete curing
 Floor tiles
 Foams for thermal insulation
 Jointless flooring
 Lighting fixtures
 Overhead water tanks
 Paints and varnishes
 Pipes to carry cold water
 Roof lights
 Safety glass
 Wall tiles
 Water resistance adhesives

21. Fig: GRP Pipes: Glass-Fiber Reinforced Plastic Pipes

22. GLASS (Introduction)
Glass is an amorphous (non-
crystalline) solid which is often transparent
and has widespread practical, technological,
and decorative usage in things like window
panes, tableware, and optoelectronics.
The most familiar, and historically the
oldest, types of glass are based on the
chemical compound silica (silicon dioxide),
the primary constituent of sand.

23. Main types of glass
• Annealed glass
• Toughened glass
• Laminated glass
• Coated glass
• Mirrored glass
• Patterned glass

24. Annealed (Normal) glass
• Annealed glass is the basic flat glass product that is
the first result of the float process(manufacturing).
• It is common glass that tends to break into large,
jagged shards.
• It is used in some end products and often in double-
glazed windows.
• It is also the starting material
used to produce more
advanced products through
further processing such as
laminating, toughening,
coating, etc.

25. Toughened glass
• Toughened glass is made from annealed glass
treated with a thermal tempering process.
(A sheet of annealed glass is heated to
above its "annealing point" of 600°C; its
surfaces are then rapidly cooled while the inner
portion of the glass remains hotter. The
different cooling rates between the surface
and the inside of the glass produces different
physical properties, resulting in compressive
stresses in the surface balanced by tensile
stresses in the body of the glass.)

26. Toughened glass
• Toughened glass is treated to be far
more resistant to breakage than
simple annealed glass due to
counteracting stresses and to break
in a more predictable way when it
does break, thus providing a major
safety advantage in almost all of its
applications.
• Car windshields and windows, glass
portions of building facades, glass
sliding doors and partitions in houses
and offices, glass furniture such as
table tops, and many other products
typically use toughened glass.

27. Laminated glass
• Laminated glass is made of
two or more layers of glass
with one or more
"interlayers" of polymeric
material bonded between the
glass layers.
• Rather than shattering on
impact, laminated glass is
held together by the
interlayer giving more safety
as well as, to some degree,
reducing the security risks
associated with easy
penetration.

28. Laminated glass
The interlayer also
provides a way to
apply several other
technologies and
benefits, such as
colouring, sound
dampening, resistance
to fire, ultraviolet
filtering and other
technologies that can
be embedded in or
with the interlayer.

29. Coated glass
Surface coatings can be
applied to glass to modify its
appearance and give it many
of the advanced
characteristics and functions
available in today's flat glass
products, such as low
maintenance, special
reflection/ transmission/
absorption properties,
scratch resistance, corrosion
resistance, etc.

30. Coated glass
Coatings are usually applied
by controlled exposure of
the glass surface to vapors,
which bind to the glass
forming a permanent
coating.
The coating process can be
applied while the glass is still
in the float line with the
glass still warm, producing
what is known as "hard-
coated" glass.

31. Mirrored glass
• To produce mirrored
glass, a metal coating is
applied to one side of
the glass. The coating
is generally made of
silver, aluminum and
gold etc.
• For simple mirrored
glass, a fully reflective
metal coating is
applied and then
sealed with a
protective layer.

32. Mirrored glass
To produce "one-way"
mirrors, a much thinner
metal coating is used,
with no additional sealing
or otherwise opaque
layer.
Mirrored glass is gaining a
more prominent place in
architecture, for
important functional
reasons as well as for the
aesthetic effect.

33. Patterned glass
Patterned glass is flat glass whose surfaces display a
regular pattern.
The most common method for producing patterned
glass is to pass heated glass (usually just after it exits
the furnace where it is made) between rollers whose
surfaces contain the negative relief of the desired
pattern(s).
Patterned glass is mostly used in internal decoration
and internal architecture.

34. Different uses
• Supply of natural
daylight
• Protection from rain,
wind, and cold
• Transparency
• Means of
communication
• Heat protection
• Sound protection
Object and personal protection
Fire protection
Temporary heat and solar
protection
Use of solar energy
Means of design
Electromagnetic dampening.

35. Structural glass systems
Structural glass facades are most easily
categorized by the structure types that
support them.
Mullion
Truss Systems
Cable Truss
Grid shells
Cable Net
Glass Fins

36. Mullion glass structure
The simplest form includes a steel
or aluminum section positioned at
every vertical joint in the glazing
grid. These steel and aluminum
sections can be designed in open
or closed positions.
Mullion components often consist
of built up custom structural
sections capable of
accommodating long spans in both
vertical and horizontal positions
(vertical being the most common)

37. Truss system
Truss systems employ a planar
truss design, often in a
hierarchical system that may
combine other element types
including tension components.
Truss designs vary widely, with
an emphasis on fine detailing
and draftsmanship.
Rod or cable elements may be
incorporated into the truss
design, and lateral tensile
systems are often used to
stabilize the facade structure.

38. Cable truss
One type of truss system utilizes a
minimalist structural form called a
cable truss.
The main spinal compression
element is removed, leaving the
spreader struts as the sole
compression elements in this
truss type.
As with cable nets, these systems
rely on the pre-tensioning of truss
elements to provide stability, and
thus benefit significantly from the
early involvement of the facade
design/build team.

39. Grid shells
Grid shell structural systems are
another means to minimize the visual
mass of structure.
Configurations can be vaulted, domed
and double-curved.
Systems can be welded, bolt-up, or
some combination of each.
Grid shell structures with integrated
cable bracing can produce a highly
efficient structure with a refined
aesthetic.
Grid shells can be used in vertical and
overhead applications, as well as to
form complete building enclosures.

40. Cable net
• This new generation of glass walls
allows for the design of highly
transparent facades and blast resistant
applications.
• The glass is supported by a net
geometry of pre-tensioned cables.
• A clamping component locks the cables
together at their vertices and fixes the
glass to the net.

41. Glass fins
This technology was
popularized by the Willis
Faber & Dumas Building,
Ipswich, England circa
1972.
In this glass plates are
suspended and laterally
stiffened by the use of
glass fins set perpendicular
to the plates at the vertical
joints between them.

42. Glass for green buildings
Reflective glasses come with
reflective coating that filters
heat and let optimum light into
the building.
Reduce the heat gain
inside the building, and thus
reduces electricity and cooling
costs
Allow optimum light (natural
daylighting) inside the building,
and thus reduces the cost for
artificial lighting