In this article we will discuss about:- 1. Formation of Fibre Glass Reinforced Plastic 2. Properties of FRP 3. Applications of FRP in Building Industry.
Formation of Fibre Glass Reinforced Plastic:
The Fibre Glass Reinforced Plastic or FRP is formed by using two materials in conjunction with each other to form a composite material of altogether different properties. It is also sometimes referred to as the Glass Fibre Reinforced Plastic or GRP.
The composite materials are also shortened as composites. They are formed by combining two or more different materials to make better use of their virtues and by minimizing their deficiencies.
The composites can be tailored as per the requirements by using tougher and light materials. Each material retains its physical or chemical properties separate and distinct within the finished product. The composites can be natural or man-made. Wood is a natural composite of cellulose fibres in a matrix of lignin.
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Bricks made from straw and mud in ancient time was man-made composite. The composites are made from at least one of the main constituent materials: matrix and reinforcement.
The matrix material surrounds and supports the reinforcement materials, while reinforcement imports special mechanical and physical properties to enhance matrix properties. Plywood and concrete commonly encountered composites. FRP, GRP, RCC, carbon-fibres reinforced plastic (CFRP), wire reinforced tiles, engineered wood like wood fibre board, pykrete (saw dust in ice matrix), etc., are the examples of composites.
In FRP or GRP, the glass fibres provide stiffness and strength while resin provides a matrix to transfer load to the fibres. The use of various additives lends special properties to the FRP. The combination of glass fibres, resins and additives to fabricate the FRP can be done in a number of ways.
Following are the five principal methods of fibre glass reinforced plastic:
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(i) Filament winding
(ii) Hand lay-up
(iii) Pultrusion
(iv) Resin transfer moulding
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(v) Spray-up.
The FRP offers a combination of properties not easily found in the traditional materials. It has come as a boon especially for the building and construction industry.
The other industries which benefit the most from the continuous use of the FRP can be enumerated as follows:
(i) Chemical process industry;
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(ii) Fertilizer industry;
(iii) Food processing industry;
(iv) Oil and gas producing industry;
(v) Paper industry;
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(vi) Petrochemical industry;
(vii) Pharmaceutical industry;
(viii) Thermal power generation;
(ix) Water and wastewater treatment etc.
Properties of FRP:
Following are the properties which have made the FRP the most commercially successful composite material of construction:
(1) Aesthetic Appeal:
It is available with superb finish and can be adopted for eye catching aesthetics.
(2) Corrosion Resistance:
The FRP has excellent resistance to moisture and chemicals over a large temperature range. It does not rust, rot, corrode or swell. The cost of replacing the corroded equipment has reached the staggering proportions especially with the growth in the chemical and petrochemical industries.
It is estimated that about 40% of the world’s steel production is used to replace other steel which has been destroyed by corrosion. Thus the FRP has found more and more use in the environment where the corrosion is the main concern.
(3) Dimensional Stability:
The FRP component holds its form and shape even under severe mechanical and environmental stresses.
(4) Durability:
The performance of FRP under fatigue or creep is known to be superior to that of metals. It is therefore durable and has a long working life.
(5) Easy to Repair:
The damaged portion of FRP can be repaired very easily and quickly. It requires common skill and little or no equipment. The strength imparted to the repaired portion is the same as that of the parent body.
(6) Effect on Health:
The fibre glass is itself inorganic in nature and hence the FRP is one of the safest materials and its products can be used to virtually store anything as they have no ill effects even after prolonged usage. For instance, the FRP containers, both large and small, are used to store milk.
(7) Energy Saving:
It requires far less energy for production. For instance, it requires only two-third of the energy required to make identical steel part and only one-third of the energy required to make identical aluminium part.
(8) Freedom of Design:
As the constituents of FRP have no inherent shape, they can be easily fabricated in any desired shape with necessary properties. It is thus possible to make use of efficient structural shapes requiring a minimum of material for maximum strength and stiffness.
(9) Light Transmission:
In thinner sections, the FRP products transmit a great deal of light. They can therefore provide a unique combination of a strong enclosure with adequate day lighting.
(10) Light Weight:
The FRP product weighs roughly half the steel component for bearing the same load. It results in the reduction of dead load to be carried by the supporting members and foundations.
(11) Low Investments in Tooling:
The tooling for FRP is inexpensive and fast. It permits quick styling changes from building to building or an inexpensive mould for a single highly creative design.
(12) Maintenance:
The FRP products require the least maintenance as they are pigmented and are unaffected by changing weather conditions.
Applications of FRP in Building Industry:
The FRP is an ideal material for the building industry as seen from its various applications which may be listed as follows:
(1) Concrete Shuttering:
The moulds and forms of FRP give the cast concrete shapes of very high quality. The complicated concrete shapes can be moulded in the FRP eliminating in most cases, the need for final finishing.
(2) Domes:
The domes in enchanting shapes and unique designs with wide dimensions can be created for eye catching aesthetics. The translucent FRP dome-lights can be used on industrial, commercial and public utility buildings and as the structure is self-supporting, it requires less support.
(3) Doors and Window Frames:
The lightweight flush doors and factory made standard window frames of FRP can be suggested for housing schemes due to their long life, easy maintenance and overall reduction in cost. The use of FRP doors for bathrooms and toilets eliminates the problems of rotting and warpage as well as swelling.
(4) Internal Partitions and Wall Panelling:
It is possible to adopt flat, corrugated or fancy FRP sheets for internal partitions of industrial and commercial buildings. The various designs of FRP for wall panelling and ceilings can be made in shape, form and colour for a long lasting trouble free effect.
(5) Roof Sheets:
The translucent FRP sheets provide a versatile medium of lighting. The sheets are available in a variety of forms with the corrugated type being very common. The corrugated sheets are made in a range of profiles which match corrugated steel and asbestos sheets.
Thus they permit an interchange of material to give the desired degree of lighting. If the covered area of FRP translucent roofing system is about 15%, it eliminates the need for electric lighting inside the industrial shed during day time.
(6) Structural Sections:
The available cross-section profiles in steel, aluminium or PVC can also be made in FRP with advantage of equal strength at low weights. The FRP sections have much better properties in flexure and tension. They are corrosion-resistant and grant a choice of colours. They can be machined, bolted, riveted and tapped just like steel sections.
(7) Temporary Shelters:
The FRP modular systems are ideally suited for temporary shelters at project sites, watchman cabins, green houses, defence shelters, vehicle parking sheds, etc. They can be constructed with or without thermal insulation. They may be easily dismantled, carried and re-erected at the next site with minimum labour cost.
(8) Water Storage Tanks:
The FRP water storage tanks are found to be superior to steel, concrete or galvanized iron tanks for the following reasons:
(i) The versatility of the system allows the tanks to be installed either indoors, outdoors or even buried.
(ii) They are easy to install, maintain and clean.
(iii) They are very light in weight and possess high strength to weight ratio.
(iv) They can be fabricated in a variety of shapes to overcome space constraints.
(v) They do not corrode even after prolonged exposure to an adverse environment.
(vi) They do not produce any kind of harmful effect on potable water or impart any taste, colour or odour to the water.
(vii) They do not support bacterial growth of algae and fungi.
(viii) They offer resistance to deposition and sealing.
(9) Miscellaneous:
The properties of FRP are multiple and the applications are limitless. For instance, the FRP chairs and benches can be used for auditoriums, hotels, restaurants, gardens, parks, lounges, theatres, waiting rooms, etc.