Some time ago, I have already mentioned in a post that for tank bottom thermal insulation, more expensive boards could be replaced by gravel and the famous GLAPOR RDS system. The cost of the thermal insulation of the tank bottom should be reduced by about 80% and the installation (time) also of the same order.
In this system, the ring (walls of the tank) are supported by the GLAPOR RDS-composite while the bottom of the tank is insulated with cellular glass gravel. Today, GLAPOR RDS is used in Germany, Austria, Switzerland, Italy and Belgium for private houses. In that case, the load bearing walls are put on the GLAPOR RDS composites, while the actual floor is insulated and supported by cellular glass gravel.
But today, this system is already also used for water tanks. Concrete walls are supported by the RDS-composites while the actual bottom of the tank rests on cellular glass gravel. The following pictures are clear. In case of a bitumen of an ammonium tank, the cellular glass gravel layer has just to to be thicker. The price of cellular glass gravel is less than 50€/m³ while boards for tanks costs easily up to 400€/m³. The installation time of gravel is very short compared to boards.
It is not well known that the Czechs were the first in Europe to produce a commercial glass foam, Spumavit. I could find some information about the history of this product but I have to give it in graphical form from the “Legend of the Bohemian glass”, written by Antonín Langhamer.
Two names are mentioned, Vaclav Novak and Frantisek Schill. The last one has written a famous book about cellular glass in the Czech language. There is no English translation available but BELGLAS is searching for sponsors for a decent translation. After that, this site will have a download available.
The Spumavit glass foam was used on the Expo 58 in Brussels in the very successful Czecho-slovak pavilion, winning the first price. I am surprised that thermal insulation was used in 1958 for a temporary building. Production started in 1957 and ended 30 years later in 1988. The combustible polystyrene became a too large and cheaper concurrent.
Everything is pure coincidence but my story is nice. According to my parents, I am conceived in a hotel close to the Expo 58 (it was their honeymoon) and probably they visited (with me in situ) this Czech pavilion with Spumavit cellular glass. Later on, after my PhD, I started to work for Pittsburgh Corning in cellular glass in 1988 when Spumavit ended. After the development of the continuous process (endless foam), I end up in Klášterec nad Ohří in the Czech Republic to start up my dream at about 200 km from the old Spumavit plant. This factory is today the best performing cellular glass plant in the world. Today, I am a consultant for cellular glass and I live together with a Czech goddess. It is clear that cellular glass and Czech have a lot in common, they both make my life extremely interesting. In the mean time, I try to understand the book of Schill by studying the Czech language.
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
- fiber free
- self bearing
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.