Running Header: Plastics as a Building Material 1

BUILDING MATERIAL

PLASTICS
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Plastics are a wide range of synthetic or semi-synthetic organic compounds that

are malleable and so can be moulded into solid objects.

Plasticity is the general property of all materials which can deform irreversibly without breaking

but, in the class of mouldable polymers, this occurs to such a degree that their actual name

derives from this specific ability.

Plastics are typically organic polymers of high molecular mass and often contain other

substances. They are usually synthetic, most commonly derived from petrochemicals, however,

an array of variants are made from renewable materials such as polylactic acid from corn or

cellulosics from cotton linters.

Due to their low cost, ease of manufacture, versatility, and imperviousness to water, plastics are

used in a multitude of products of different scale, including paper clips and spacecraft. They

have prevailed over traditional materials, such

as wood, stone, horn and bone, leather, metal, glass, and ceramic, in some products previously

left to natural materials.

In developed economies, about a third of plastic is used in packaging and roughly the same in

buildings in applications such as piping, plumbing or vinyl siding. Other uses include

automobiles (up to 20% plastic) furniture, and toys. In the developing world, the applications of

plastic may differ—42% of India's consumption is used in packaging. Worldwide, about 50 kg of

plastic is produced annually per person, with production doubling every ten years.

The construction industry uses plastic for a wide range of applications because of its versatility,

strength-to-weight ratio, durability, corrosion resistance, and so on.

Plastic can be manufactured into forms such as; pipes, cables, coverings, panels, films, sheets

and so on; and can be formed or expanded to create low-density materials; and be dissolved in

solvents or dispersed as emulsions.

TYPES OF PLASTICS MAINLY USED IN CONSTRUCTION INDUSTRY

Acrylic

Acrylic Sheet
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The term ‘acrylic’ refers to chemicals that contain the acryloyl group, derived from acrylic acid,

such as polyacrylonitrile and poly(methyl methacrylate) (PMMA).

Acrylics generally have good optical clarity, scratch resistance, dimensional stability

and rigidity. They do not deteriorate in sunlight and they have good adhesion, are thermoplastic,

easy to form and easy to cut. However, they are combustible, are not flexible, suffer

from stress cracking and are not resistant to solvents.

Acrylics have a very wide range of uses in the construction industry:

 Transparent or translucent sheeting such as acrylic glass (‘Plexiglass’ or ‘Perspex’).

 Opaque cladding and panel materials.

 Paints.

 Resins, sealants, adhesives and adhesive tapes

 Flashing materials.

 Concretes, mortars, renders and asphalt.

 Architectural fabrics.

 Baths, shower trays and sinks.

 Coatings for metals, concrete and masonry.

 Flooring and carpets.

 Worktops.

 Signage.

 Light fixtures.
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 LCD screens.

 Furniture.

Composites

A composite material is a combination of two or more constituent materials which have

improved characteristics when together than they do apart. Composites are often composed of a

'matrix' and reinforcement fibres.

The matrix is often a form of resin which keeps the reinforcement fibres in position and bonding

them together so that loads can be effectively transferred. The properties of the composite can be

influenced by cutting, aligning and placing the reinforcement fibres in different ways.One of the

main advantage of using composites is that the reinforcement and matrix combination can be

altered according to the required properties

There are many different types of composites which can be used for a wide range

of construction and engineering purposes. Concrete is the most common composite material,

consisting of aggregate held with cement as the matrix. Other common types

of composites include:

 Fibre-reinforced polymer (FRP).

 Carbon-fibre-reinforced polymer (CFRP).

 Glass-fibre-reinforced plastic (GFRP).

 Aramid fibres, such as Kevlar, that are heat-resistant and strong synthetic fibres often used

in aerospace and the military applications.

 Bio-derived polymers or biocomposites.

 PVC polyestyer.

 PTFE glass.

Composites have many wide use in construction industry and it’s application include:

Architectural

Architectural features such as facades, cladding, domes, roofing and structures such as cupolas, can be made

effectively using composites. They can be lighter, more efficient, more durable and require

less maintenance than traditional materials. If combined with other core materials such as steel or plastics, they are

capable of meeting high structural, fire, security and sound insulation requirements.

Bridges

Composites can be used in the construction of entire bridge structures, bridge decks and bridge enclosures. They are

useful for their high stiffness-to-weight and strength-to-weight ratios in comparison with

conventional materials such as steel and reinforced concrete.

Civil engineering and infrastructure

Composites are often used in modular structures, masts, towers, pipes, tanks, access covers

and water control structures. They are also commonly used in rail applications such as trackbeds, platform systems,

and gantries.

Housing

Composites lend themselves well to prefabricated offsite construction for components commonly used

in housebuilding, such as sanitaryware, fixtures and fittings, and architectural mouldings.

Refurbishment

Composites can be used to strengthen existing structures such as beams, columns, floors, cooling

towers and chimneys.

Advantages of Composites

There are a wide range of advantages offered by composite materials, including:

 Greater durability for use in extreme environments.

 Light weight composition.

 Faster construction times.

 Structures can often be repaired in situ.

 Low maintenance.

 Flexible in terms of colour, shape and texture.

 Can be made fire resistant.

 High ratios of strength and stiffness to weight.

Polystyrene (Expanded)

Expanded Polystyrene

Polystyrene is made by stringing together, or polymerising, styrene, a building-block chemical

used in the manufacture of many products. Styrene also occurs naturally in foods such as

strawberries, cinnamon, coffee and beef.

It is a versatile plastic used in a number of different forms to make a wide variety

of consumer products:

 As a hard, solid plastic, it is often used in products that require transparency, such as

food packaging and laboratory ware.

 When combined with colourants, additives or other plastics, polystyrene is used to

make appliances, electronics, automobile parts, toys, gardening pots and equipment, and

so on.
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 When made into a foam material, called expanded polystyrene (EPS) or extruded

polystyrene (XPS), it is valued for its insulating and cushioning properties.

Foam polystyrene can be more than 95% air and is widely used to make home

and appliance insulation, lightweight protective packaging, surfboards, food service and

food packaging, automobile parts, roadway and roadbank stabilisation systems, and so

on.

ETFE (ethylenetetrafluoroethylene) 

An ETFE Covered Building

ETFE (ethylenetetrafluoroethylene) consists of modified copolymers of ethylene and

tetrafluoroethylene. It is closely related to PTFE (polytetrafluoroethylene or Teflon), and has

many similar properties. It has been widely used in the construction industry in recent years.
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ETFE is available as a flexible film. This enables it to be used to create curved transparent

facades. It is a super-lightweight material; a double layer cushion weighs only 0.70 kg/m2,

whereas a single layer of glass (6 mm thickness) weighs 15 kg/m2. As a double layered cushion

of ETFE only weighs approximately 4.5% that of conventional glass less structural support is

needed; reducing the amount of raw materials used, reducing build time, and

reducing building costs.

It has been suggested that use of ETFE in construction can reduce build costs by 10% on

small projects and up to 60% on large-scale projects. Construction costs are also reduced during

the installation process, when sheets of ETFE film can be 'welded' together with a blow torch

and spans of up to 180 ft can be achieved with sufficient structural support. This 'thermoforming'

has excellent dimensional stability; i.e. the material does not shrink or expand when heated.

ETFE is highly transparent to light from the whole visible light spectrum and can allow large

amounts of natural light into the building, creating a 'bright and open space that can emulate

the outdoors'. ETFE can retain this transparency and strength for over 30 years. In

addition, ETFE has a high level of heat retention, retaining long wave thermal radiation and

creating a 'greenhouse effect', which can reduce energy costs by up to 30%.

The structural properties of ETFE can be shown on a stress-strain curve. The long sweeping

curve indicates the ductility of the material; it can be stretched at high loads without fracturing.

In fact, ETFE is able to stretch up to three times its original length without losing its elasticity.

When ETFE does fracture, its strong intermolecular bonds prevent the material from tearing or

shattering like glass. As a fluorocarbon polymer, ETFE has similar non-stick properties to PTFE,

making it 'self-cleaning'. With a low co-efficient of friction typically of 0.23, dust or dirt

that lands on ETFE is washed away by rainwater. Maintenance of ETFE is required

approximately every 3 years. Fluorocarbon polymers are relatively inert, and are especially

unreactive to the weather and chemical attack. ETFE can resist temperatures of up to 270°C

because of its very stable molecular bonding. It is fire retardant as well as 'self-ventilating',

which aids in the removal of smoke and other harmful gases and reduces the need

for smoke extraction.

Applications

ETFE can be made into glass-like sheets or inflated into 'multi-layered' cushions and is being

used in some of the most innovative new buildings around the world. ETFE, has greatly

increased in popularity as a construction material due to its versatility, light weight, tensile

strength and excellent weathering properties.

During the 1990s, ETFE was used in offices, universities, medical facilities, exposition halls, and

zoos across Europe. In 2000, the Eden Project in Cornwall used ETFE to cover the

two geodesic conservatories. Its application created an environment capable

of housing plant species from around the world in tropical rainforest and

Mediterranean style climates. The Eden Project's construction was widely acclaimed as

an engineering marvel, causing ripples of global interest. EFTE's application

in architecture allows the designer to 'turn architectural fantasy into reality' (ref 8).

This is demonstrated for example by the National Stadium and National Aquatic Centre in

Beijing. Both of these buildings showcase innovative applications of ETFE. To protect spectators

from the weather in the national stadium, red ETFE cushions were installed in

the spaces between the 'twigs' of the 'bird's nest'.

The National Aquatic Centre was entirely clad in blue ETFE 'bubbles'. These bubbles allow for

covered spaces of up to 30 ft to be created without internal structure. The Aquatic Centre used

the triple-layer formation which mixes layers of blue film with transparent film thus giving

the façade of the building a sense of depth and shifting colour. It also allowed images to be

projected onto the wall of the centre similar to the Basel football ground or the Allianz-Arena.

Each layer of the cushions can be engineered to transmit, reflect or scatter the projected image,

allowing the full facade to be used as a visual device.

Other uses:

 ETFE is used for covering electrical wiring used in high stress, low fume toxicity

situations. A primary example of its application the electrical wiring of aircraft and

spacecraft. It is also commonly used in the nuclear industry for tie or cable wraps. This is

because ETFE has better mechanical toughness than PTFE.

 It is also used in applications such as wall coverings and anti-graffiti protection in high-

traffic areas.

 As a dual laminate, ETFE can be bonded with FRP (fibre-reinforced plastic or fibre-

reinforced polymer) as a thermoplastic liner. This is then installed in pipes, tanks, and

ships for additional corrosion protection.

 ETFE is also the natural choice in solar panel applications because of its low density

elasticity.

 Further research and other innovations are still being developed. The company Foiltec is

currently testing the possibilities of attaching photovoltaics to ETFE panels for use as

an insulating 'nanogel' to improve a panel's thermal properties.

Polycarbonate Plastics

Different layers of Polycarbonate Sheet Superclass Polycarbonate Sheets

Polycarbonate plastic (PC) is a high-performance, sustainable thermoplastic (it becomes liquid at

its melting point rather than burning). Unlike thermoset plastics, thermoplastics can be heated,

cooled and reheated again without significant degradation. This means they are suitable for be

injection moulding and subsequent recycling.
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Polycarbonate plastics are naturally transparent, and amorphous, that is, they tend to gradually

soften rather than rapidly changing from solid to liquid states as crystalline polymers do.

Polycarbonate was first discovered in 1898 but not patented until 1953. It has been used in a

multitude of commercial applications since the late-1950s. It is widely used

for construction applications that require transparency and high impact resistance, and they can

be used as a lighter alternative to glass.

Applications

 Safety eyewear and other protective equipment.

 Diffusers and light pipes for LEDs and exterior light fixtures.

 Plant and machinery guards.

 Greenhouses.

 Security glazing.

 Flat or curved glazing.

 Noise barriers.

Polycarbonate has very good heat resistance and pliability. It can be combined with flame

retardant materials without suffering significant degradation.

Although it is highly impact-resistant, polycarbonate is prone to scratching. In some applications

where this is likely to prove a problem (such as with safety eyewear), a scratch-

resistant coating can be applied.

Polyethylene (Polythene)
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Polyethylene, also known as polythene, is one of the most common types of plastic. There are

many different kinds of polyethylene, most of which are identified by the chemical formula

(C2H4)n. Polyethylene is produced from ethylene which is typically obtained from petroleum

or natural gas, as well as from less common renewable sources. Polyethylene has a wide range of

uses, predominantly as packaging in the form of bags, sacks, films, geomembranes,

containers, pipes, and so on.

Polythene Film being used in Construction

Polyethylene has high ductility and impact strength as well as low friction and is

a good electrical insulator. It also has good resistance to moisture. However, its uses are limited

by its relatively low melting point of around 80 °C (176 °F), its low strength, hardness

and rigidity.
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Polyethylene can pose problems for waste management as it is non-biodegradable and so

accumulates in large quantities in landfill sites. If it is incinerated, it can, under some

circumstance, produce harmful gaseous emissions.

Its precise properties depend on the variable extent and type of branching, molecular weight and

crystal structures. Different classifications are used for different applications; for example, high-

density polyethylene is often used for pipes that are corrosion-resistant and leak-free.

In addition to pipes, some of the most common applications

of polyethylene in construction include:

 Sheet (film) to provide protection for materials and seal off rooms.

 Damp-proof membranes (DPM).

 A loose lining material for foundations.

 To protect concrete during the curing process.

 A temporary flashing material for doors, windows and so on.

Polypropylene (P.P)
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Polypropylene Construction Frames

Polypropylene (PP, also known as polypropene or polymerised propene) is a type

of thermoplastic polymer resin that has similar qualities to polyethylene (PE) but is slightly

harder and has better resistance to heat and organic solvents. After PE, polypropylene is the

second-most widely produced commodity plastic with a global market (2013) of around 55

million tonnes.

A member of the polyolefin family of resins, PP can be injection moulded and extruded into

many shapes and products such as cups, cutlery, containers, housewares and car parts

e.g batteries. It is also spun into fibres for inclusion in industrial and domestic textiles, including

for clothing.

As a plastic it is extremely versatile and found in common household items and used in both

commercial and industrial applications.

Properties
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 Lightweight, tough and flexible

 Heat resistant (high melting point (around 160°C) – used in microwaves, dishwashers,

food containers

 Chemically inert

 Impact and freeze-resistant

 High shatter resistance

 Low moisture absorption

 Mould resistant

 Low density allows lower-weight mouldings to be made

 Resistant to fats and organic solvents

 Accepts colour and dye without degrading

 Reasonably inexpensive

 Does not contain BPA (bisphenol A - which some claim can leach into food products)

 Fatigue resistance – allows use as a plastic hinge

 It can float in water

Applications

 PP fibres are added to concrete to increase strength and reduce cracking and spalling

 Non-woven fabrics for ground stabilisation

 Roofing membranes (waterproofing top-layer in single-ply systems)

 Reinforcement in construction and road paving

 Electrical cable insulation (alternative to PVC)

 Piping systems

 Carpets, rugs and upholstery

 Medical and laboratory equipment

 Reusable containers

 Plastic machine parts

 Industrial rope and cordage

Polyvinyl Chloride (PVC)

Polyvinyl chloride (PVC) sometimes known as ‘vinyl’, is a plastic material that has widespread

use in building, transport, electrical, healthcare and packaging. It has been produced widely since

1933 and now accounts for approximately 20% of all plastic manufactured around the world,

second only to polyethylene (polyethene). In the UK, approximately 500,000 tonnes are

produced each year.

PVC is relatively inexpensive, durable and long lasting. It can be either rigid (uPVC, or

unplasticised PVC) or flexible and can be manufactured in a variety of colours or can be

transparent.
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PVC Building Products

PVC is derived from common salt (chlorine) and carbon (predominantly from oil or gas).

There are five basic steps in the PVC manufacturing process:

 The extraction of salt and hydrocarbons.

 The production of ethylene and chlorine from salt and hydrocarbons.

 The mixing of chlorine and ethylene to produce vinyl chloride monomer.

 The polymerisation of vinyl chloride monomer to produce PVC.

 The blending of PVC polymers with other materials such as plasticisers.

Application in Construction
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PVC has extensive use in a construction products. Its strong, lightweight, durable and versatile

characteristics make it ideal for products such as window profiles and its flexibility, flame

retardant and electrical insulation properties make it ideal for cabling applications.

Examples of PVC construction products include:

 Window and door profiles and conservatories.

 Pipes and fittings.

 Power, data and telecoms wiring and cables.

 Internal and external cladding.

 Cable and ducting.

 Roofing membranes.

 Flooring.

 Wallcoverings.

PTFE (Polytetrafluroethylene)

Polytetrafluoroethylene (PTFE) is a thermoplastic compound noted for its very significant

chemical inertness and heat resistance. Commonly encountered as a non-stick coating for pots

and pans it is sometimes referred to by the trade name ‘Teflon’ or 'Syncolon'. It is widely used

for a variety of engineering and chemical applications.

PTFE is a synthetic fluoropolymer of tetrafluoroethylene discovered accidentally by Dr Roy

Plunkett in 1938 while working for DuPont in the US. With a high molecular weight, it consists

entirely of carbon and fluorine. Displaying reduced stress cracking and corrosion, it is also

hydrophobic, which means it cannot be wetted by water or water-containing liquids. It also

displays one of the lowest coefficients of friction of any solid so that even geckos and insects

cannot crawl up it.

Its properties include:

 Very low friction coefficient.

 Resists corrosion.

 Significantly chemically inert.

 Withstands wide temperature ranges.

 Good abrasion resistance.

 Non-porous.

Support structure & ETFE/PTFE Membranes

Applications in Construction Industry

Generally in construction and infrastructure, PTFE’s main applications are for providing friction-

control performance wherever components move in relation to one another e.g in

the fabrication and erection of steelwork to minimise the stresses produced by the imperfect

alignment of steel members; for expansion joints, slide bearings, on bridge

bearings and dams, gaskets and electrical insulation; also, as an insulator to prevent thermal

bridging e.g where a pipe passes through an external wall.

PTFE is closely related to ETFE (ethylene-tetra-fluoro-ethylene) which comprises modified

copolymers of ethylene and tetrafluoroethylene. It has many similar properties to PTFE.

 Some of these plastics main uses in the construction industry are:

 Cladding panels.

 Cables.

 Pipes and gutters.

 Windows and doors.

 Shuttering

 Wall linings

 Floor covering

 Ceiling panels.

 Roof coverings.

 Sinks, basins, baths, and showers.

 Worktops

 Insulation materials.

 Membranes.
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MERITS OF USING PLASTICS IN CONSTRUCTION

The advantages of using plastic in construction are that it is lightweight yet strong which makes

it easier to transport and shift around sites. It is also resistant to rot and corrosion and has strong

weather ability due to it being capable of achieving tight seals. Plastic can also be flexible, and is

easily extruded, bent, moulded, 3D printed, and so on. Plastic can also be easily removed and

some plastics can be recycled.

DE-MERITS OF PLASTICS IN CONSTRUCTION

The disadvantages of plastic are that it has a high embodied energy content and a low modulus of

elasticity, meaning that it is generally unsuitable for load-bearing applications. Unless treated,

most plastics are also ignitable and have a high thermal expansion rate which requires detailing

to allow for adequate thermal movement.

There are environmental concerns about some plastics because of difficulties recycling them,

there persistence in the environment after disposal, and concerns regarding chemical additives

used to make plastics flexible, resistant to fire, and adhesive.