Glass Foams

Abstract

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.\ud 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.\ud 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

Comparative Phenomenological Study of Fracture Behavior of Ceramic and Glass Foams under Compressive Stress Using In Situ X‐Ray Microtomography

“…The glass foam formation takes place between the softened glass (glass viscosity between softening and melting point) and gaseous phase at high temperatures. [5] The foaming agents can be differentiated by the foaming mechanism into two groups: foaming agents which decompose above the softening point of the glass with evolution of gases (foaming by thermal decomposition) and foaming agents which react with the glass above the softening point (foaming by reaction). The foaming agents can be classified according to its chemical gas-releasing reaction into the neutralization foaming agents (carbonates, [6][7][8] sulfates, etc.)…”

Closed porosity ceramics and glasses

“…It can be produced from readily available economic‐raw materials, for example waste glass; besides, generally it has a long service life (>100 years). Such issues make it one of the most useful source especially for construction industry where the application temperatures are normally far below 500°C, that is under the softening temperature of the glass matrix. The details for the formation of foam glass can be found in Prof. Scarinci's comprehensive chapter, here aside from the properties of the most recent works documented in Tables , only a brief overview for few compositions will be mentioned.Traditionally, foam glass is produced by grind‐mix, pack and heat treatment procedure.…”

“…Such issues make it one of the most useful source especially for construction industry where the application temperatures are normally far below 500°C, that is under the softening temperature of the glass matrix. The details for the formation of foam glass can be found in Prof. Scarinci's comprehensive chapter, here aside from the properties of the most recent works documented in Tables , only a brief overview for few compositions will be mentioned.Traditionally, foam glass is produced by grind‐mix, pack and heat treatment procedure. The glass powder (usually recycled waste glass) is mixed with “gasifier” which is basically a CBA (PBAs or self‐foaming blends are also possible) and heat treated above the softening (Littleton) temperature.…”

Foam glass obtained through high‐pressure sintering

“…Foam glass consists of a glass skeleton and gas‐filled pores. The glass skeleton is chemically inert and non‐flammable, and the closed pore structure prevents water penetration, and hence, the foam glass exhibits a high freeze‐thaw‐cycle resistance …”