Foam glass grain is an excellent bulk material for civil construction and insulation purposes. Foamed glass, otherwise known as Cellular glass is a lightweight, extremely fine-pored expanded glass with millions of hermetically sealed pores. Since no diffusion can take place, the material is watertight and achieves an efficient barrier against soil humidity.
Foam glass grain is the product of choice wherever a finely grained, free-flowing bulk material is required. It is especially suitable for thin-walled thermal insulations, such as for window frames, cement bricks and insulating plasters.
Foam glass roof insulation is made of a lightweight cellular glass, a rigid material comprised of millions of completely-sealed, non-interconnecting glass cells. Foam glass is mainly made from glass, mixed with foaming agent, in a process of heating and roasting in tunnel furnace, then annealed into bulk blocks, and cut into bricks or blocks in our standard dimension.
Foam glass is a new kind of inorganic heat insulating material with a structure of equally closed cells. It is mainly made of glass added with adequate foaming agents after heating and baking in high-temperature tunnel furnace, then annealing and cooling. Because it well reserves the chemical stability of inorganic glass, it has the following features: low density, low thermal conductivity, vapor impermeability, no water absorption, incombustibility, protection from mould and rat eating, high mechanical strength but easy to cut and able to bear all kinds of chemical erosions except the hydrofluoric acid.
Foam glass, nontoxic in itself, has stable chemical properties and good heat insulating performance protecting from deteriorating at a wide temperature range from ultra-low temperature to high temperature. At the same time, it can protect from humidity, fire and erosion. It is praised as ^^permanent heat insulating material with no need of renewal^^ because it is not only safe but also durable in rigor condition of low and cryogenic temperature, underground, open air, flammability, moisture sensitivity and even chemical erosion. Consequently, it is applied widely as follows:
Foam glass can be manufactured fully out of waste glass, with only a minimum of virgin additives. Foam glass is a unique material, purely composed of glass cells.
Foam glass has been created in 30th years last century in the USSR (MHTI Mendeleev Chemical Technological University in Moscow) and at the beginning of the 14th years by firm Corning Glass Work. At first it was proposed to apply as a floating material. But it was soon found out, that it possesses also high heat and sound-insulating properties, easily it is subjected to machine processing and agglutination. Concrete slab with heat-insulated layer from cellular glass have been applied for the first time in 1946. This experience was so successful, that the material has received a general recognition at once as durable isolation for a roof, partitions, walls and floors of all kinds of constructions.
Production technology of foam glass
Finely crushed glass and cullet are crushed, using ball mill in mixture with gasifier (coal) in a thin powder, are loaded into forms from heatproof steel with kaolin coating. Forms are given to the tunnel furnace on trolleys by the roller conveyor. Softening of particles of a glass powder and its sintering occur under action of high heat. Gases, escaping during gasifier burning and decomposition bloat viscous glass mass. Material with cellular structure forms during cooling. Slow cooling (annealing) promotes of uniform cooling of articles whole volume, therefore there are no internal stress or crack formation in them. The cooled products are sawed up then packed.
Foam glass blocks are got as a result of the given production phases. The chemistry of foam glass by 100 % coincides with a chemistry of classical glass and includes oxides silicon, calcium, sodium, magnesium, aluminium.
Cellular construction of foam glass where walls and units of cells consist of such strong material as glass is caused its unique durability and ability to resist to mechanical loadings. The matrix of units and communications of foam glass structure represents the optimal space-volumetric configuration capable to stand the maximal loadings at the minimal density. Critical parameters of a foam glass cell are characterized by following parameters: at average diameter of a cell 2 000 microns walls cells´ thickness varies in an interval from 20 up to 100 microns.
Vapour permeable and vapour non-permeable foam glass
The basic advantages of foam glass deserve more detailed consideration.
1. Life cycle
The guaranteed foam glass blocks life cycle with preservation of physical characteristics values is equal to term of building operation and exceeds 100 years.
Experimental researches of the objects warmed with foam glass more 50 years ago have shown absence of essential changes in a foam glass structure. The factor of preservation of heat-shielding properties during all building existence is especially important in view of inaccessibility heat-insulated material after the end of works. Foam glass is not subject to ageing for some reasons since its unique properties resist to active factors showing themselves eventually:
Foam glass is the strongest of all effective heat-insulated materials. Foam glass is unique that is not compressed material absolutely. Moreover, less strong than foam glass heat-insulated material demands anchoring and pintle fastening to a bearing structure of a construction.
3. Stability of physical parameters
Foam glass is the material consisting from hermetically closed hexagonal and spherical cells. Such structure of a material excludes interaction of the gas environment of cells with an atmosphere and causes invariance in time of material’s characteristics. That is, there is no change of such parameters of foam glass blocks as heat conductivity, strength, stability, form, etc. Eventually a factor of keeping heat-insulated material’s properties is important especially at upkeep of buildings and constructions in view of inaccessibility of a material after end of works.
4. Chemical and biological action stability
Glass of which foam glass consists by 100 % , is not decomposed with chemical reagents, is not nutrient medium for fungus, mould and microorganisms, is not damaged with roots of plants, is absolutely impassable for insects and rodents and represents an ideal barrier to similar pests.
Foam glass in addition is very good abrasive material. This feature of foam glass is used actively at a heat-shielding of granaries, industrial food refrigerators, warehouses since foam glass is reliable barrier on a way of wreckers besides a heat-protection layer.
5. Incombustibility and fire resistance
Foam glass is completely non-inflammable material as it does not include oxidized or organic components. The "know-how" of foam glass is such, that a finished article is fabricated as a result of manufacturing in furnaces at the temperature close to 1000°C, therefore at foam glass heating up to warm temperature it only melts as usual glass without extraction of gases or vapor. This factor is important for fire-prevention properties of a construct.
6. Moisture resistance, water resistance and non hygroscopic property
Water does not render on foam glass any influence for two reasons. First it consists of hermetically closed cells which walls` material is usual silicate glass. Secondly it does not absorb moisture and does not pass it, and it is an additional hydro barrier at use in a building envelope. At damage of a waterproofing distribution of water is not supposed both in vertical and in horizontal directions.
Water resistance of foam glass allows it to prevent ice formation for long, to provide overall protection against corrosion and excellent thermoregulation. Foam glass is steady to action both fresh and salty water.
7. Ecological and sanitary safety
Ecological and sanitary safety of foam glass allows to warm filler structures not only for housings in which the raised cleanliness of the air is necessary (buildings of educational and medical function, sports constructions; museums; hi-tech manufactures, etc.), but also for buildings with special sanitary-and-hygienic requirements (the food and pharmacological industry; baths and saunas; pools; cafe, restaurants, dining room, etc.)
Most foam glass is made by grinding glass from a glass melt into small particles and then mixing it with a carbon containing material and then reheating it up above the melting point of the glass in a box mold. The carbon material reacts with the glass to make carbon dioxide to make the foam. The glass used is mostly recycled glass, but the double heating and the grinding process makes the product expensive, but the product has as very long life compared to organic products and more durability.
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