Properties of Plastics as a Construction Material
Each plastic material has its own peculiar properties to suit its particular uses. The success of plastic as an engineering material will depends up on the selection of variety of plastic. Following are the general properties of plastic.
- Chemical resistance
- Dimensional stability
- Electric insulation
- Fire resistance
- Melting point
- Optical property
- Sound absorption
- Thermal property
- Weather resistance
1. Appearance of Plastics
In the market there are so many types of models of plastics are available such as transparent, colored etc. suitable pigments are added in the process of manufacturing of plastic material to get these different properties. So, these will give good appearance to the structure and makes it attractive.
2. Chemical Resistance of Plastics
Plastics offer great resistance against chemicals and solvents. Chemical composition of plastics during manufacturing will decide the degree of chemical resistance. Most of the plastics available in the market offer great corrosion resistance. So, corrosive metals are replaced by plastic in the case of water carrying pipes, etc.
3. Dimensional Stability
Thermo-plastic types of plastics can be easily reshaped and reused. But in the case of thermo-setting type plastics, it is not possible to reshape or remold the material.
4. Ductility of Plastics
Ductile nature of plastic is very low. When tensile stress are acting on plastic member they may fail without any prior indication.
5. Durability of Plastics
Plastics with sufficient surface hardness are having good durability. Sometimes, plastics may affected by termites and rodents especially in the case of thermo-plastic types, however it is not a serious problem because of no nutrition values in plastic.
6. Electric Insulation
Plastics are good electric insulators. So they are used as linings for electric cables and for electronics tools.
Any type of finishing treatment van be given to the plastics. Mass production of plastic particles with uniformity of surface finish is done by having technical control during manufacturing.
8. Fire Resistance
The resistance to temperature or fire for varieties of plastics considerably varies depending upon the structure. Plastics made of cellulose acetate are burnt slowly. PVC made plastics do not catch fire easily. Plastics made of phenol formaldehyde and urea formaldehyde are fire proof materials.
Fixing of plastic materials is so easy. We can bolt, drill or glued to fix plastic material position.
The plastics made up of cellulosic materials are affected by the presence of moisture. The plastics made of poly vinyl chloride (PVC pipes) offers great resistance against moisture.
Maintaining of plastics are so simple. Because they do not need any surface finishing coats or paints etc.
12. Melting Point
Generally plastics have very low melting point. Some plastics may melt at just 50oC. So, they cannot be used in the positions of high temperature. Thermo setting type of plastics are having high melting point than thermo plastic type plastics. However, thermo setting types are cannot used for recycling. To improve the heat resistance of the plastics, glass fiber reinforcement is provided in its structure.
13. Optical Property
There are so many types of plastics. Some plastics are transparent which allows light in its original direction and some are translucent nothing but semi-transparent which allows light but changes light rays direction.
14. Recycling of Plastics
Disposal of plastics in the environment causes severe pollution. But it is not a serious problem because of its recycling property. We can use plastic waste disposal conveniently to produce drainage pipes, fencing, hand rails, carpets, benches etc.
15. Sound Absorption
By the saturation of phenolic resins we can produce acoustic boards. These acoustic boards are sound absorbents and provide sound insulation. Generally for theatres, seminar halls this type of acoustic ceilings are used.
Practically we can say that plastic is strong material but ideal section of plastic which is useful for structural component is not designed yet. Generally by reinforcing fibrous material into plastic improves its strength. If the strength to weight ratio of plastic is same as metals, then also we cannot give preference to plastics because of various reasons like, heavy cost, creep failure may occur, poor stiffness and sensitive against temperature.
17. Thermal Property
The thermal conductivity of plastics is very low and is similar to wood. So, foamed and expanded plastics are used as thermal insulators.
18. Weather Resistance
Most of the plastics except some limited varieties are capable of resistance against weathering. But, major problem is plastics when the plastics are exposed to sunlight, they are seriously affected by ultra violet rays and gets brittle. To prevent this, plastics are incorporated by fillers and pigments which helps to absorb or reflect the UV rays to surface.
19. Weight of Plastics
The Plastics have low specific gravity generally ranges from 1.3 to 1.4. So they are light in weight and easily transportable to any place in a large quantity.
Uses of Plastics in Building Construction
Plastics are manufactured in different forms such as moulding pipes, sheets and films. They are formed or expanded to produce materials of low density. Dissolved in solvents or dispersed as emulsions, they are used in paints, varnishes and adhesives.
At present, plastics find use in buildings mainly in thin coverings, panels, sheets, foams, pipes etc. skilful use of plastics will expand the usefulness and life of conventional building materials and help them to function more efficiently and economically.
A wide range of applications of plastics in buildings are given below:
1. Uses of plastics in façade panels, exterior covering, carpentry etc.
- Sandwich panels covering with PVC (polyvinyl Chloride), plasticized plates and polyurethane foams.
- Sandwich panels – asbestos cement covering and polyurethane foam core
- Sandwich panel – polystyrene foam core and various coverings
- Sandwich panel – covering with polyester laminated sheet and polyurethane foam core
- Sandwich panel – enameled iron covering and polyurethane foam core.
- Sandwich panel – covering with polyester laminated sheet glued to asbestos cement and polyesterene foam core.
- Polyester coated concrete by moulding from an existing plates.
- Sprayed polyurethane with sand and gravel agglomeration.
- Epoxy resins and polyesters on various supporting media
- PVC plasticized plates (spraying, coating or adhesive films)
- Polyester epidermis available as permanent shuttering
- Polymethyl methacrylate
- PVC casing on metal moulding
- Polyester laminated sheet on wooden moulding
- PVC – chlorinated polyethylene compound
- Methyl polymethacrylate
- Polyester glass fibre and phenolic foam core
- PVC/ wood
- Plasticized PVC extruded sections
- Rigid PVC extruded sections
- Polyamide winding gear
- Blinds and sunscreens
- Polyester, PVC
2. Uses of Plastics in Interior Covering, Floors, Walls, Ceilings, Doors, Partitions Etc
a) Wall Lining
- Adhering films – vinyl coated fabrics or paper vinyl sheet doubling on fabric or paper etc.
- Sprayed lining polyurethane
- Laminate – Melamine and phenolic plastics – polyester
- Wall tiles – polystyrene, PVC – tiles or mosaic
- Coating – polyvinyl acetate
b) Floor Covering
- Asbestos plastic slabs (asphalt tile type)
- Vinyl asbestos slabs
- Homogeneous semi-flexible vinyl slabs
- Flexible, homogeneous or multi-layered vinyl slabs.
- Homogeneous vinyl carpets (a) stuck, (b) laid
- Vinyl carpets on felt (applied or coating)
- Multi-layered coating with cellular structure on fabrics
- Multilayered coating on cork structure
- Vinyl carpets on jute cloth.
- Thermosetting resin based covering
- Rubber covering
- Synthetic fibre tensile covering (polyamides, viscose etc.)
Ceilings and Counter Ceilings
- Translucent – polyester, PVC, polyamides, polyurethanes
- Opaque, extruded polystyrene or vinyl copolymers, impact type polystyrene
- Lighting – PVC, polymethylmethacrylate
3. Uses of Plastics in Roof Coverings, Tightness, Domes and Lighting elements
- Flat or corrugated sheets – polyester, PVC, polymethylmethacrylate
- Curved sheets – reinforced polymer
- Domes – polyester, polymethylmethacrylate
- Casements – polymethylmethacrylate, reinforced polyester
- Troughs – class / polyester
- Gutters – Rigid PVC polyester
- vii. Downpipes – PVC
- Polybutylene with or without glass cloth armature
- Butyl rubber
- Multilayered bitumen with PVC film screens and armatures
- PVC sheets
- Welded polyester
4. Uses of Plastics in Sanitary Equipment and Piping
- Sinks – polymethylmethacrylate, polyester, polyamides
- Basins – polyester, polymethylmethacrylate – polyester / glass fibre
- Baths – polyester, polymethylmethacrylate
- Showers – polymethylmethacrylate, polyester
- Pipeworks – PVC, phenolics, ABS – terpolymer
- Fittings – PVC and ABS – terpolymer – phenolic plastics
- Traps – polyamides
- Water – finishings – polystyrene and copolymers, polymer and copolymers, polyethylene
Insulation materials and application of foams
- Formaldehyde urea
5. Other Uses of Plastics in Buildings
Some noteworthy trends in use of plastics are given below:
- Concrete and mortar with thermosetting resin bending agents
- Thermoplastic and thermosetting resin covering applicable to facades and concrete epidermis
- New roof covering and roof tightening materials (accessory covering materials, tightness network), easy to place and standing up well to normal to wear
- Large foam component units and new shaping techniques
- Developing techniques for quick shaping of plastic into large components
- Assembling and fixing processes more suitable for plastics
- vii. New developments in sanitary equipment and piping, applying thermoplastic and thermosetting resins.
- New developments in the way of shuttering and of elements in permanent shuttering
Table: Uses of Plastics in Building Construction
|No.||Plastic Material||Uses||Form in which it is commonly used||Normal colour|
|1||Expanded polystyrene||Thermal insulation||Thin sheets in slabs 12mm thick||White|
|2||Expanded polyvinyl chloride (PVC)||Thermal insulation||Boards 20 to 50 mm thick||Yellow brown|
|3||Foamed urea formaldehyde||Thermal insulation||Foamed in situ||White|
|4||Foamed phenol formaldehyde||Thermal insulation||Sheets and blocks||Deep red|
|5||Foamed polyurethane||Thermal insulation||Sheets and blocks or foamed in situ||Brown|
|6||Expanded ebonite||Thermal insulation||Sheets||Brown or black|
|7||Polythene||Damp-proofing, plumbing||Thin sheets, pipes, cisterns||Transparent to black|
|8||Polypropylene||Domestic drainage, but water overflow tanks|
|9||Unplasticised PVC||Rainwater goods, ventilation, ducts, pipes of water mains|
|10||Acrylic resins||Sinks and baths||Various|
|11||Nylon||Cold water fittings, window furniture||Various|
|12||Phenolic resins||Adhesives for laminates||Dark|