 | |||||||||||||||||||||||||
 |
| ||||||||||||||||||||||||
▼ What is cellular(foam) glass?
The cellular glass makes uniform cells within glass and can provide adiabatic or sound-absorbing characteristics depending on the type of cells (open, closed).
It is called multi-cellular glass, and "foam glass" is well known as a trademark. Since the matrix is glass, it is an insulator which provides foam features to the advantages of glass itself. Because of no absorption, it has excellent adiabatic effect at ultra low temperature.
In addition, it is not burnt not only at ultra low temperature but also at high temperature, so there is no noxious gas generated during fire. That is why it is widely used as a construction insulator.
In 1930's, Saint-Gobain acquired the patent of manufacturing of foam glass while calcium carbonate is used as a foaming agent; in 1940's, Pittsburgh Corning established the manufacturing method of foam glass while using carbon as a foaming agent.
The cellular glass manufactured by Saint-Gobain was used as a lightweight aggregate of concrete at the beginning, but it has not been used because of non-uniform size and shape of individual cells.
On the contrary, the cellular glass using carbon method has been continuously produced in USA and China and used so far as an insulator, especially as a cooling keeper.
Recently, it is used as a lining material inside stack of thermoelectric power plants because it is better corrosion-preventive, higher adiabatic and lighter than acidity-tolerance blocks or acidity-tolerance special alloy, which have been used as lining materials before.
▼
Features of cellular
glass
Waterproof
- Non-penetration of water and moisture (Water and moisture are main reasons for failure of adiabatic feature)
Non-corrosion, acidity-tolerance
- Since it is safe from water and acidity, no corrosion occurs; its function and shape can be maintained for a long period
High compressive strength
- Shape and thickness are maintained in spite of high pressure and weight; stable adiabatic effect is assured.
Fire-safety
- Because it is incombustible, no noxious gas occurs during fire.
- In case of foreign countries, if cellular glass is selected as a building material, low insurance rate is applied.
Anti-bacterial
- It is safe from mold, virus, rat, venom etc.
Environmental-friendly
- It does not generate CFC, fiber and HFCF; waste glass is recycled
- Semi-permanent recycling is available
Simple construction
- It can be cut using a general saw and built using a bonding agent.
Cheap maintenance cost
- Thanks
to excellent endurance, it can be used
semi-permanently (over 20 years) in any kinds
of environments without additional
cost.
The most widely used foaming agents are calcium carbonate and carbon. Besides, calcium phosphate and silicon carbide can be used, too. In case of calcium carbonate, carbonic acid gas, which is generated by decomposition below 900℃, may contribute to foaming; in case of carbon, forms are generated by oxygen which is provided from the oxygen providing elements such as sulfur trioxide, diarsenic pentoxide and antimony pentoxide inside glass.
If the softening point of glass is high, silicon carbide may play the role of foaming agent. Besides, any compounds which can generate or be transformed into gas state above the softening point of glass have the possibility to be a foaming agent.
In case that cellular glass is manufactured using carbon as a foaming agent, it is dependent upon the content of gas exists inside the glass. In other words, foams are well formed when more oxygen supplying elements exist in the glass. At least 0.1~0.4% SO3 should be included, and this amount is that naturally comes into the glass from the combustion gas.
