The Glass is the magical building material as it is used in doors, windows, and building façades according to characteristics & properties of glass. The People have many choices depending on safety, security, functions related to environment (self-cleaning, sunlight and heat transparency, visibility) and qualities like scratch resistance etc.
Based on the important characteristics & properties, it is considered as best future material for building construction. Following are the properties and characteristics of the glass.
Characteristics of glass as Building Material:
Hardness and Brittleness:
It is a hard material as it has greater impact resistance against applied load. But at the same time it is brittle material as its breaks immediately when subjected to load.
It is weather resistant as it can withstand the effect of rain, sun and wind. It can absorb, reflect and refract light as it enables us to control and manipulate natural light to influence our daily activities and frame of mind.
It has greater dimensional stability as it has low thermal expansion value. (I.e. Its change in volume with respect to temperature change as compared to other materials is very low.)
It is an excellent insulator against heat, electricity and electromagnetic radiation. It has a good insulating response against visible light transmission.
Certain special type of glass has high resistance against ultra-violet, infrared and x-ray transmission. It has an excellent resistance against sound transmission, provided used with proper thickness.
It can withstand the effect of the chemical reaction under different environment conditions or acidic effects.
It has excellent resistance to most chemicals, including solutions of inorganic alkalies and acids, such as ammonia and sulfuric acid.
Colour and Shape Varieties:
It can be blown, drawn and pressed to any colour, shape, and varieties.
Nowadays so many colour and shape varieties are available in the market depending upon their use, dimensional requirements, and safety requirement.
It is also possible to change some of its properties to suit different purposes. The major surface modification processes are listed below, and their names itself suggest the different properties of glass to which it can be modified depending upon their use in the building.
List of Surface modification Process of Glass:
- Anti-fogg coating
- Anti-reflective coating
- Chemically strengthened glass (Safety glass, toughened glass, wire-mesh glass, and laminated glass)
- Anti-corrosion coating (Resistance to water)
- Dealkalization coating (Surface layer that has a lower concentration of alkali ions)
- Hydrogen darkening layer (Chemical process that interferes the passage of light)
- Insulated coating or double glazing or double pane (for heat and or sound insulation)
- Sand blasting or acid etching process (Frosted Glass)
- Low emissivity coating (Coating helps to reduce heat transfer)
- Pyrolytic coating (Coating for excellent performance)
- Self-cleaning coating
- Sandwichable film or Smart film coating (Alter the light transmission property when voltage, light or heat is applied)
- Water repellent coating (Making hydrophilic surface)
- Sol-gel coating (Preparation of thermally stable, transparent super-hydrophobic silica films)
Properties Of Glass as Building Material:
The density of building glass is around 2500 kg per cubic metre at 200 C temperature, which gives flat glass a mass of 2.500 kg per square meter per mm of thickness.
Glass Compressive Strength And Tensile Strength:
The compressive strength of glass is 1000 N per Sq.mm (10197.2 Kg per Sq.cm) at 200 C temperature, which is very high. It means 10 tonnes of load is required to break a 1 cm cube of glass.
The tensile strength of glass is significantly lower than that of compressive strength. The resistance to tensile strength (deflection) is 40 N per Sq.mm (407.88 Kg per Sq.cm) at 200 C temperatures for annealed glass and 120 to 200 N per Sq.mm (1223.66 to 2039.43 Kg per Sq.cm) at 200 C temperature for toughened glass.
Glass Young’s Modulus or Modulus of Elasticity:
The young’s modulus (Force per unit area) of any material is a measure it’s the stiffness. Larger the value of young’s modulus means stiffer the glass. The young’s modulus of glass is 70 GPa at 200 C temperature (The young’s modulus of concrete is 30 to 50 GPa at 200 C temperature).
Glass Poisson’s Ratio:
Poisson’s Ratio is directly related to elongation and contraction of material when load is applied in one direction, and it is also known as lateral contraction co-efficient. The cross section area of glass decreases as it is stretched. The Poisson’s ratio of glass is 0.22.
Glass Linear Expansion or Co-efficent of Thermal Expansion:
Linear expansion is a stretch per unit length for a variation of 10 C temperature. The co-efficient of linear thermal expansion is 9 x 10-6 m/ 0 C.
The user can effectively choose correct application for glass after referring above mentioned points. Based on the important properties & characteristics it is considered as best future material for building construction.