The constituents of this building material are lime, silica sand, cement, gypsum, an expansion agent and water. Sometimes fly ash is used to replace some of the sand. The expansion agent, most often aluminium powder added to this slurry, reacts with the alkali compounds to generate a multitude of small gas bubbles. This gas-bubble structure increases the volume of the final product up to five times the volume of the raw materials and gives the material its characteristic porous structure. In the subsequent autoclaving process the reaction continues and the calcium silicate hydrate tobermorite is form, which hardens and strengthens the final material.
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Large agglomerate built up of numerous smaller particles
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Close-up of agglomerate showing smaller particles
of fibrous or flaky appearance. This is likely to be
tobermorite which is formed during the production process.
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Agglomerate showing a rigid network of crystals.
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X-ray spectrum acquired from the agglomerate
showing the high contents of Ca, Si and O. Mg and Al
are also present.
Norwegian key words: gassbetong, lettbetong