Soda lime glass

0.25-1 usd/kg
Circularity potential
Very high
Strength
Medium
Production energy
Low
Stiffness
High
Embodied CO2
Low
Density
Medium

Soda lime is the most common type of glass, and is used in packaging, products, furniture and lighting. Glass sheet made from much the same ingredients – called float glass due to the process – is just as widely used, but consumed in the most significant quantities as glazing in buildings and automotive applications.

Soda lime glass, also called soda lime silica (SLS), is made by melting together sand (silica), soda ash (sodium carbonate) and lime. Recycled glass is an important ingredient too, because it improves the efficiency of production. Magnesia (magnesium oxide, MgO), alumina (aluminium oxide, AlO) and zirconium (Zr) are used to enhance specific properties. The exact ingredients are adjusted according to the method of production and application requirements. Heated in a furnace to above 1,200 degC, the minerals form a viscous mass of molten glass ready for shaping. At the end of its useful life, it can be recycled without any loss of quality.

Transparency depends on the ingredients. For example, the typical green tint is the result of iron impurities, such as found in sand. Transmission – whether colourless or coloured – is controlled with the addition of additives such as metallic oxides, sulphides or selenides.



Glass packaging is a valuable post-consumer recycled (PCR) material, which can be fully circular and provides an important ingredient in new glass production, helping to reduce the heat and energy needed in production. Contamination is removed using floatation, magnets and eddy currents (non-ferrous metals), for example. The glass is crushed and colours are separated. As a result, high quality clear and coloured glass can be 100% recycled.


Design properties
Cost usd/kg
0.25-1
Embodied energy MJ/kg
11.5
Carbon footprint kgCO2e/kg
0.1-0.85
Density kg/m3
2470
Tensile modulus GPa
70
Tensile strength MPa
30-60
Shear modulus GPa
28.5
Compressive strength MPa
800
Hardness Mohs
5.5
Poissons ratio
0.22
Thermal expansion (µm/m)/ºC
8.8
Melt temperature ºC
1000
Thermal conductivity W/mK
1
Temperature min-max °C
-40 to 300
Thermal
insulator
Electrical
insulator