Today, two cellular glass boards are on the market as acoustic absorbers. Quietstone and Reapor are equivalent products, probably based on the same production process. In fact both assemble boards with a molding process from foamed glass granulates.

Liaver is a producer of foamed glass granulates from recycled glass. Fine glass powder is mixed with a foaming agent and granulated, probably in the mixer. The granulates are transported through a rotating kiln with temperatures between 750°C and 900°C. The end result is partially open celled glass foam granulate.

By bonding this granulates to boards or other shapes, an acoustic absorber is produced with voids smaller than 1mm in the granulates and voids of a few mm between the granulates. This allows to absorb a broad spectrum of noise like shown in this datasheet.

Both products have nice leaflets: Reapor and Quietstone. For the readers who are not familiar with acoustics, the following educative leaflet of Isover is a good start. The advantages of the cellular glass as an acoustic absorber are

• non-combustible
• fiber free
• self bearing
• light-weight

However, the product has a cost of about 1000€/m³, a lot more than closed cell cellular glass boards. It is clear that the development of a continuous foamed open celled cellular glass at 250€/m³ has huge possibilities in this market, even with a 50% of the absorption of the material here under. In that case, we have just to double the surface.

However, these cellular glass boards cannot be sold as cellular glass boards for building applications although the thermal conductivity is 0.08 W/mK with a high compressive strength (1200 kPa) because the water vapor transmission is way too high. This was already mentioned in a previous post.