A long time ago, cellular glass was a thermal insulation which is vapor tight and has a large compressive strength. Later on, I realized that it is a thermal insulating material which can replace bricks, it is a construction material. But recently, I learned as suggested by Michael Ashby that cellular glass is the lightest material between the ones which can support there own weight.

The following table shows a list of all kind of materials. We consider a beam with a certain span and width and allow a certain deflection under its own weight. The thickness is a free parameter. We calculate weight and also embodied energy, which is the primary energy needed to produce the beam. We have rescaled the weight by dividing by the weight of the GLAPOR PG600 beam.

Like can be observed, GLAPOR cellular glass is the lightest material that support its own weight but it has also the smallest embodied energy like shown in the GLAPOR cellular glass EPD. And in a near future, it will also be the cheapest material in the list.

This means that cellular glass can replace concrete in unloaded situations, when non-combustibility and water tightness are an iussue. Besides light, ecologic and cheap, cellular glass can be produced in about 10 hours while concrete takes several days.

Although this application of cellular glass is straightforward, it became only realistic after GLAPOR developed the continuous foaming process, delivering large boards upto 2.8m x 1.2m based on direct foamed recycled glass with prices below 200€/m3. The mould process and the cellular glass based on a special composition can never compete in this discipline.

In this post, I like to put the attention on more academic / laboratory contributors. Indeed, cellular glass is born on the scale of a cup of coffee and later on further extended to larger dimensions, today up to 2.8m x 1.2m.

Bernard Long, a scientist working once for St Gobain Glass, filed in 1938  patent US2337672 about the foaming of glass. He used carbon as foaming agent and describes the reduction of an oxide as the gas evolution source. I guess this is the first closed cell cellular glass patent and this foam could be used as floating device for the curtains in the harbours against submarines.

Boris K. Demidovich,  has published in 1972 a book about the production and use of cellular glass. It is the perfect description of the knowledge at that time and is the advised work to study for each cellular glass starter. It was so important that the American Army translated the work in English. Personally I was impressed by the knowledge in Czecho-slovakia, with a plant in Usti nad Labem in 1947. Sixty years later, a cellular glass plant was built in 2007 at about 80 km from the first plant.

Prof. Dr. Bernardo Enrico, a professor at the University of Padua developed the cold foaming of glass like already described in a previous blog. This open cell foam can be made from bottom ash and fly ash from waste incinerators. Up to now, open cell foams were not popular but this will change in the near future.

Prof. Dr. Lorna Gibson is a cellular solids expert at MIT. By studying her work, people become aware of the opportunities of the cellular version of a material. Glass is already extraordinary  and the cellular version extend largely the importance of that product.

Prof. Dr. Michael F. Ashby is a material engineering expert at Cambridge Univerisity, which is already mentioned in a previous blog. He described cellular glass as the most efficient  material to support its own weight. Since GLAPOR is delivering large boards by 2.8m x 1.2m, this property can be applied everywhere to replace unloaded concrete beams.

Prof. Dr. Christian Maes, Physics department of the KU Leuven, Belgium discovered that cellular  glass fails under a compressive load in a diffusive way. This important statement is probably valid for all kind of fragile heterogeneous materials. This was already discussed in a previous post.

The previous heroes were all experts with the dry powder method. The following heroes have worked or are working with the wet method (or water glass method).

Recently there was a meeting of a group of people, who will change the cellular glass world thoroughly and even a large part of the mineral insulation world. It is a combination of knowlegde, huge ecology loving capital and direct communication without any hiearchical borders.

Dr. Oleg Sharykin (second from right) is an important investor in the Russian cement industry, who believes strongly that ecology is the future for this planet. A long time ago, he recognized the assets of the GLAPOR technology and invested in the further development of that company. Today, GLAPOR has the technology (and a booming market) to produce a product of excellent ecologic quality, like shown in a GLAPOR EPD (Environmental Product Declaration), certified by the world famous IBU (Institut Bauen and Umwelt, Germany). It will be a mistery forever whether two technologies, namely gluing sand particles with cement and sintering waste glass particles belonging to the same investor is a coincidence or not. Indeed, in a lot of applications, concrete boards can be replaced by cheaper and lighter cellular glass boards.

Walter Frank (right side on above picture) is the founder of GLAPOR and took beyond any doubt the largest risk. Therefore, I would rank him as the largest cellular glass hero of all times. Walter was a sales engineer and sold for Horn Glass Industries the first float glass line in Russia, without any reference. But he was also working in the old Coriglas plant where he met cellular glass for the first time. Walter has chosen the recipe of Millcell with glycerin / water glass. He extended the cellular glass gravel process with an annealing furnace and broadend the furnaces to what was standard in the float glass industry. He immideately realized that large cellular glass boards are the future and focused on direct foaming of recycled glass to improve ecology. He did not jump into the thermal conductivity rat race, started by the polymer Pied Piper of Hamelin to hide their own important weakness, which is combustibility. Today his dream is reality, which also means that his dream is gone (is not a dream anymore). His next dream is to jump beyond the typical thermal insulation jobs and to start an entirely new cellular glass market besides the existing one. For that reason, he can not retire during the first ten years.

Otto Anton Vieli is the inventor of the wet process with waterglass and glycerin like already discussed in a previous post. This recipe is applied in a large part of the cellular glass gravel production and for the boards by GLAPOR. This recipe has a huge potential because it foams a low density with rather coarse powder and allows to work in a furnace with efficient stochiometric combustion.

In Thuringen, Germany, there was once a small cellular glass factory, VEB Schaumglas Taubenbach, producing the product Coriglas. After  “Die Wende“, the factory was first owned by Heraklith and later on by an American multinational. The last owner shut down the production exactly 50 years after it was built. The shutdown induced a brain drain to Russia (STES), Ukrain (PINOSKLO) and GLAPOR and is one reason of the current price drop of cellular glass, making it economically available for more people.

In this series of blogs, I will remember the work of some previous cellular glass workers and thinkers. They all took once a big risk to fail and were in that way important in the evolution of cellular glass. For some legal reasons, I cannot mention people, still at work in cellular glass.

Louis Troussart was an expert in the annealing of (cellular) glass as an employee of St. Gobain Glass and a cellular glass manufacturer. Some years ago, he passed away as a well respected man. The reasons for that are obvious:

• Louis was the first to find out that glass has a thermal history. Indeed, by measuring carefully the thermal expansion for different cooling rates, he proved that the physical properties of glass are dependent on the cooling history.
• Later on, he moved to cellular glass and did important published work with finite elements. He optimized for example the guarded hot plate for the measurement of the thermal conductivity.
• Many other work cannot be mentioned because it is not public domain

Charles Beerten, an exponent of accuracy was a chemist working on the glass composition. Today, cellular glass with the best thermal conductivity is produced with “his” glass composition in Europe, China and the USA. Also in his case, most of his work is not public domain. Charles became retired against his will and lives in the “Ardennen” in the south of Belgium.

Pierre Gérard, a smart and fast mechanical civil engineer was also an efficient cost cutter. Pierre understood very fast that the most efficient cost cutting was improving the process. He was an enormous support for me, especially when the tunnel seemed endless long. His father, Paul Gérard was the collaborator of Louis Troussart during the discovery of the thermal history of glass. Pierre is retired and is spending his time with travelling with his wife.

Hugo Frederix, a typical self made man, checked in hardware mode the ideas of the above and also participated to a paper about the stability of cellular glass, like mentioned in a previous post. Hugo lives in Limburg in the east of Belgium.

Jos Bellens, a laboratory chemist passed away much too early. His important R&D work is not public domain but in his second career, he became an outstanding safety engineer. I will never forget him.

Albert Van der Heyden, production engineer and self made man, was an expert in tuning a foaming furnace for the carbon black process with the necessary reducing atmosphere. Albert made once an important experiment, which ignited the continuous foaming process project. Albert is retired and lives in Meldert, Lummen as the very best grandfather.

Marc Kolenberg was about everything: electronic, electrical and mechanical engineer, software developer and most of all production manager for cellular glass. Marc did not know any limit to reach what he considered as possible. Without him, my largest project should never run. Marc is retired and lives close to Diest with his family and dogs.

Robert Havel started as a worker and became production manager of the cellular glass factory, producing the highest quality ever. After having done the startup of a cellular glass factory in China, Robert´s ambition drove him in another direction. He lives in Klasterec Nad Ohri in the Czech Republic with the lovely Jitka Havlova and their child.

Jean Melchior, a civil engineer from Luxemburg is known as an extremely strong marketeer for cellular glass. He understood very early the importance of ecology for the thermal insulation world. Not cost cutting but ecology was his drive to support me for my largest project. From him, I got the nice title “free electron”, although that property let him explode many times. Jean is retired against his will and lives in the center of Belgium, studying Machiavelli.