INTRODUCTION• Plastic is the generic name for a family

of synthetic materials derived from petrochemicals.

• It is often product of two or more components.

• There are many families of plastics and polymers being used in construction industry.

• Examples of plastics used in building are:

Acrylic

Composites

Expanded Polystyrene

Polycarbonate

Polyethylene

Polypropylene

Polyvinyl Chloride

PROPERTIES• Plastics are strong yet lightweight, and so

they are easy to transport & manoeuvre.• They are durable, knock-and scratch

resistant with excellent weatherability.• They do not rot or corrode.• Plastics are easy to install; many have a

snap-fit kind of jointing procedures.• Plastics offer limitless possibilities in design

achieved by extrusion, bending, moulding etc.

• They can be given any range of colours by adding pigments.

• The plastics are low conductors of heat and thus are used as insulation materials in green building concepts.

• The plastics products can achieve tight seals.

• They can be sawn and nailed employing standard carpentry tools and skills.

• They can be easily removed and recycled.• They are bad conductors of electricity.

POLYMERS IN CONSTRUCTION• Polymer materials account for the highest growth

area in construction materials. • Polymers are very long molecules typically made up

of many thousands of repeat units. They include plastics, rubbers, thermoplastic elastomers, adhesives, foams, paints and sealants.• Applications of polymers in construction include

areas such as flooring, windows, cladding, rainwater, pipes, membranes, seals, glazing, insulation and signage. • Performance and properties of polymers are

relatively new compared to traditional material types that have been in use for years.

TYPES AND USESPolymer Type Applications

Epoxy resinsSolid resin and Terrazzo flooring, Anchor fixings, Adhesives

Ethyl vinyl acetate (EVA)

Solar panel encapsulants

Expanded polystyrene (EPS)

Concrete moulds, Insulation, Packaging

PolycarbonateLighting housings, Fittings in hot water systems, Glazing

Polymer Type Applications

Polyester (thermosetting)

FRP Bridge sections, Cladding Panels, Sinks, Surfaces, Coatings

PolyethyleneFoam underlay, Damp-proof membranes, Coatings

Polyisobutylene (PIB) Glazing sealants, Waterproof membranes

Polymethylmethacrylate / Acyrlic (PMMA) Surfaces, Sinks

Polypropylene (PP) Sound insulation, Water pipes, Waste pipes

Polyurethane (PU) Sealants, Concrete jointing

Polyvinylchloride (PVC)

Sealants, Concrete jointing

Rubber Bridge bearings, Flooring

PREFERENCE OF EACH TYPE

ELASTOMERS

•Rubber is the most important of all elastomers. •Must of the rubber used these days is a synthetic variety called styrene-butadiene rubber.

PLASTICS

•Thermoplastics soften on heating and harden on cooling while thermosets,on heating, flow and cross-link to form rigid material which does not soften on future heating•Thermoplastics accont for majority of commercial usage.

FIBRES

Fibres represent a very important application of polymeric materials.Synthetic polymers posess desirable characteristics such as high softening point to allow for ironing high tensile strength , adequate stiffness, and desirable constuction requirements.

ADVANTAGES• Low density• Corroision resistance• Easy to manufacture and can be moulded

into complex shapes• Used for electrical insulation• Low thermal conductivity• Require low finishing cost• Tough and ductile

DISADVANTAGES• Low use temperature• Time temperature dependance• Low strength• Fatigue sensitivity• Swell with water if left for longer time• Toxicity and flammability• U.V. light sensitivity

CLASSIFICATION• Depending on how they are linked or joined (chemical bonds or intermolecular forces) and on the arrangement of the different chains that forms the polymer, the resulting polymeric materials can be classified as:• Thermoplastics• Elastomers• Thermosets

THERMOPLASTICS• It may melt before passing to a gaseous

state.• Allow plastic deformation when it is heated.• They are soluble in certain solvents.• Swell in the presence of certain solvents.• Good resistance to creep.• Examples and applications of thermoplastic

plastic materials:• High pressure polyethylene as applied to

rigid material covered with electrical machines, tubes, etc...

• Low pressure polyethylene elastic material used for insulation of electrical cables, etc...

• Polystyrene applied 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...

ELASTOMERS• Depending on the distribution and degree of

the chemical bonds of the polymers, elastomeric materials can be classified into:

• Thermoset Elastomers - are those elastomer materials which do not melt when heated.

• Thermoplastic Elastomers - are those elastomers which melt when heated.

Properties of elastomer materials:Can not melt, before melting they pass into

a gaseous state

Swell in the presence of certain solvents Are generally insoluble. Are flexible and elastic. Lower creep resistance than the

thermoplastic materials

THERMOSETS• You can not melt.• Generally do not swell in the presence of certain

solvents• They are insoluble.• High resistance to creep• Examples and applications of thermoset plastic

materials:• Epoxy resins - used as coating materials, caulks,

manufacture of insulating materials, etc ...• Phenolic resins - tool handles, billiard balls,

sprockets, insulation, etc ...• Unsaturated polyester resins - manufacture of

plastics reinforced fiberglass commonly known as polyester, fillers, etc ...

LIMITATIONS• Plastics may be degraded under the action of

direct sunlight which reduces their mechanical strength.

• Many plastics are flammable unless treated.• High embodied energy content• Low modulus of elasticity: makes them unsuitable

for load-bearing applications.• Thermoplastics are subject to creep and soften at

moderate temperatures.• Thermal expansion for most plastics is high:

adequate thermal movement has to be allowed in detailing.

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