Cellular concrete versus cellular glas

logo_smallCellular concrete is much better known under the name autoclaved aerated concrete (AAC) and is nothing less than foamed concrete. Glass and concrete are both mineral but glass is vapour tight while concrete allows transport of vapour. It makes sense to compare both products which is done on the basis of this document in Dutch.

220px-AAC_blocks_fed_in_to_autoclaveWhile the lowest density for AAC is about 350 kg/m³ , cellular glass can be foamed to 100 kg/m³. As a consequence, the thermal conductivity of AAC is much larger (0.11 W/mK) in comparison with GLAPOR cellular glass (0.050 W/mK) even in case of an equivalent compressive strength (0.06 W/mK). It means that we need the double thickness with AAC to obtain the same thermal resistance.

220px-Autoclaved_aerated_concreteAAC needs about 200 kWh/m³ primary energy for the production while GLAPOR cellular glass is satisfied with 400 kWh/m³, however for a much better (halve) thermal conductivity (and so reduced thickness). GLAPOR cellular glass is 100% foamed from recycled glass while AAC uses predominatly fresh raw materials.

AAC can be produced in blocks and large panels and this is also the case for GLAPOR cellular glass. A recent pricelist shows that AAC blocks are costing 170€/m³ for 0.1 W/mK while low cost cellular glass with 0.050 W/mK can be bought for 250 kg/m³ regardless of the dimension. AAC panels up to 2.4 m length are costing 240€/m³. It is clear that GLAPOR cellular glass is a price competitive product as a building brick and panel if we consider the distinct smaller thermal conductivity.

Both products started once around1920 with smaller blocks and evoluted to larger panels and both claim also to be able to recycle all old material. In fact, everything which could be produced in AAC can be produced in GLAPOR cellular glass. We have just to look to cellular glass in the same way as to AAC, namely as a (insulating) brick / panel and not only as thermal insulation of a brick / concrete structure.

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