Glass - Building Material
- 2. DEFINITION • The term Glass signifies an amorphous solid substance that has been formed by super cooling; a liquid solution containing chiefly silica and some other selected components. • In General usage glasses are defined as super cooled liquid.
- 3. MANUFACTURING • The basic raw material for the manufacturing of good quality glass is silica, which in nature occurs as quartz ( SiO2 ), the material melts at 1700 0C and is cooled rapidly without allowing It to undergo recrystallization. • Quartz and other desired components are heated in special melting furnace. The molten glass comes out, rather flows, from these furnaces continuously. Various Glass shapes are obtained from this molten glass by one of the following process.
- 5. PRESSING BLOWING DRAWING Air is blown in a controlled manner through the molten glass in proper containers. This air pressure drags the glass liquid to a desired shape. Moulds of the required shapes are filled with the molten glass. It is then cooled while under desired pressure. Sheets of glass are made by this method. In this process, stream of molten glass is made to pass through the molten rolls. It comes out from the other side in the desired drawn from on cooling. MANUFACTURING PROCESS
- 7. PROPERTIES • Glass has quite high tensile strength. In very fine wires drawn from melts glass may show tensile strength as high as 7.0 x 10 5 kg/ cm2 . •The ordinary glass thread possess tensile strength of 700 to 1400 kg/ cm2 • The modulus of elasticity of glass is also very high. Both these properties . However show great variation depending upon the composition of the glass and method of manufacturing. • Glasses have low ductility, low conductivity and low coefficient of thermal expansion. • Glasses are resistant to acids and many other chemicals hence they are ideal material for storage of chemicals. • Glasses are very good electrical Insulators •They have very high softening point and can be used at high temperature.
- 8. Many varieties of glass are made by adding special compounds in the silicon dioxide at the time of fusion. Following are some commonly used types of commercial Glass Silica Glass • It is pure Silica SiO2 , without any additives. Its use is restricted to high temperature applications. It has a high softening temperature. Soda Lime Glass • This is the most common type of glass used extensively for domestic purpose; window panes, plate Glass, Light Bulb, and Containers. It is composed of SiO2 , Na2O, CaO. TYPES OF GLASS
- 9. Leaded Glass This glass has a high reflective Index. This property is Induced into the Glass by adding lead Oxide with Silica during the manufacturing Stage. A usual Composition of lead glass is SiO2 , PbO, K2O, Na2O. This Lead glass has special application such as; • In Making shields for protection against gamma radiations. • In the manufacturing of optical Instruments • For Making Neon Signs. TYPES OF GLASS
- 10. Borosilicate Glass ( Pyrex) • It is special type of glass made by adding Boron Oxide as the chief additive with Silica at the time of Manufacturing. This property of boron oxide gives the special property of increasing its melting point and resistance against thermal shock. This Glass can be heated or cooled again & again without any risk of damage. This is because the coefficient of expansion gets reduced considerably by the addition of boron Oxide • Borosilicate Glass is used extensively in high temperature conditions such as; • Making of Laboratory wares for experiments; • Cooking Utensils • It is also used for telescope and Glass piping. • Pyrex is the trade name for Borosilicate. TYPES OF GLASS
- 11. Glass used in industry in variety of forms, some common forms are as follows; Pressed Glass • This is prepared by molding the fused glass into sheets and other shapes under pressure. These sheets are starting material for making Glasswares and Structural Blocks. Glass Building Blocks • These are manufactured from pressed glass by fusing two or more sheets in such a way that partial vacuum is caused in the interior of the blocks. These blocks are used in masonry construction for permitting transmission of Light without being transparent and without bearing any load. INDUSTRIAL FORMS OF GLASS
- 12. INDUSTRIAL FORMS OF GLASS Glass Fibres • It has been found that very thin fibres of Glass possess very high tensile strength. The thinner the fibre the higher the strength. This property has resulted in a separate industry of considerable importance the glass fibre industry fibre of glass are made in a special manner the molten glass is forced out through numerous minute openings in the form of thin streams upon these stream is impinged a blast of air or stream under a pre-calculated pressure. The stream solidifies into thin fibres. The Glass-reinforced plastic is commonly known as FIBRE GLASS and has acquired a place of its own as a composite engineering Material.
- 13. LaminatedGlass • These are made by bounding together two or more plates of glass. Sometimes, layer of a third material like asphalt, rubber or resin are also made a part of the laminated glass. Laminated Glass can be characterized as : • Shattering Resistance • Its pieces do not fly away in all the direction on it broken suddenly under impact. This makes the laminated Glass an ideal material for use as a safety glass in automobile and air craft. • Shock Resistance • It can bear safely sudden impacts up to desired value. This property also plays in laminated glass being Used as a safety Glass. INDUSTRIAL FORMS OF GLASS
- 14. INDUSTRIAL FORMS OF GLASS Bullet Resistant Glass • This is specially useful in vehicles and other automobiles used for security reasons. It is in fact a variety of laminated glass which is made by pressing to- geather several layers of glass and vinyl resins in alternate manner. Thickness of such Glass varies from 12 mm to 75 mm or more.
- 15. USES OF GLASS Glass has a very wide field of Industrial Applications; For an Architect; • Glass is an indispensible architectural material. In all the modern building including the high-rise buildings, Glass curtain walls make the skyline.
- 16. USES OF GLASS For an Civil Engineer; • It is one of the most important material for construction which cannot be avoided. For An Electrical Engineer; • Glass is a useful insulating material in many situations, and is also an essential material for making tubes and valves.
- 17. USES OF GLASS For a Mechanical Engineer; • Glass alone or in a composite material is an integral part in automobiles and other locomotives including railway wagons To a Chemical Engineer; • It is packaging material without any easy alternative. • Glass finds its application from the kitchen of poor man to most advanced scientific devices and in palatial building and Cabinet Rooms. It can be made in varieties possessing a combination of mechanical, electrical, optical, and chemical resistant properties that make them ideal industrial Material for variety ofApplications.