Glass Foams

Foam glass possesses an unique combination of properties, since it is lightweight, rigid, compression resistant, thermally insulating, frost resistant, non-flammable and flame resistant, chemically inert and non toxic, rodent and insect resistant, bacteria resistant, water and vapour resistant. Moreover, foam glass involves quicker construction times and requires low transport cost, it is easy to handle, cut and drill, and to combine with concrete. Such combination of properties makes this material practically irreplaceable both in construction (e.g. for the insulation of roofs, walls, floors and ceilings, under hot or cold conditions) and in many other fields. Foam glass is generally obtained by the action of a gas-generating agent (termed gasifier or foaming agent, mostly carbon or carbonaceous substances), which is grounded together with the starting glass to a finely divided powder. The mixture of glass powder, foaming agent and occasionally other mineral agents is heated to a temperature at which the evolution of gas from the foaming agent occurs in a pyroplastic mass, determined by the viscous flow sintering of the softened glass particles. The evolved gas leads to a multitude of initially spherical small bubbles which, under the increasing gas pressure, assume a honeycombe structure containing polyhedral cells, that, after the cooling of the glass constitute the pores in the foam glass. The properties of finished foamed glass products depend strongly on the type and quantity of the added foaming agents, on the initial size of the glass particles and on the firing regime. The result is a foam glass with high compressive strength and dimensional stability, characterized by a density of only 0,13 to 0,3 g cm-3.