Russia has always been a home of cellular glass but Russia failed to exploit their knowledge in time. Recently, Russians developed a new type of cellular glass and it seems that this time there is also a marketing machine working.
Vaporglass ETIZ is based on water glass (liquid glass, sodium silicate solution) and is produced by the evaporation of the water at rather low temperatures. The material is a 100% open cell material, which is claimed to be a fiber free acoustic absorber and thermal insulation (0.045 W/mK) at the same time with a very low vapor diffusion resistance.
But more important, this material is sold at 190 €/m³ for the 120 kg/m³ density version. Larger densities up to 180 kg/m³ are available. Dimensions are 600 x 600 mm, which is rather small. The low density version has a compressive strength of 240 kPa with a thermal conductivity of 0.045 W/mK. It is not mentioned how the thermal conductivity is measured.
A m³ of this 120 kg/m³ material involves 300 kg water glass, which costs 50€. The evaporation of the water to induce the foaming takes minimum another 23€. There is also a stabilizer involved and industrial equipment. A price of 190€/m³ is reasonable. However, I have no idea about the chemical resistance of the product against water and else.