Generating an Environmental Product Declaration involves a lot of work about the transport. Like already mentioned in this blog, transport is indeed an issue but transport over water seems to be more likely. Indeed, the following map shows what is possible in Europe.

The standard cellular glass like GLAPOR is a floating material, which is nevertheless 100% transported by trucks. In case more waterways should be used, transloading from truck to ship and ship to truck  is the big and expensive problem. In the past, this involves always an important structure along the river or canal.

But recently I learned that GRIFF drones are able to load and transport 200 kg, which is more than one typical pallet GLAPOR cellular glass. The drone can operate 30 minutes with one full battery. And now I dream about  barges, floating around Europe, each loaded with the equivalent of many trucks cellular glass. Trucks are waiting along the canal or river on a simple parking place and the barge captain unloads the barge with the help of drone. In principle, the barge does not even have to moor and an intelligent program calculates the best route for truck, ship and transloading.

A typical M8 ship measures 11 x 110 m  or more than 1000 m² loading surface. It can be easily loaded 6m high or about 6000m³ cellular glass, weighing 800 ton while the minimum load is 900 ton (we need to add extra load). Each barge can be seen as a warehouse, guarded by a typical barge crew, transporting ware the equivalent of about 100 trucks. The actual truck transport can be reduced from waterway to job site.

If transloading is indeed possible with the wild idea of drones, this option needs more attention for the transport of all thermal insulation.

Assume you have a large pile of sand, sodaash, limestone and clay. What should we choose to produce with these materials? Cellular glass, a closed cell structure or cellular concrete, an open cell structure. Cellular glass has a higher chemical resistance against water than cellular concrete, is vapour tight and is expected to be stronger in tension and so also in compression than concrete. In the case of cellular concrete, the sand particles are bound with cement while in the cellular glass case, the glass particles are fused into each other, creating a better bond.

Cellular concrete or AAC (Autoclaved Aerated Concrete) can today produced in higher densities (Ytong) and lower densities (Multipor). I found two Environmental Product Declarations, which are describing the process. The Xella Multipor EPD describes the low density (115 kg/m³) process while AKG GAZBETON describes the process for higher densities (385 kg/m³).

For the high density, we read:

The autoclaved aerated concrete products are made of quartzite (40-50%), Portland cement (20-30%), lime (6-12%), gypsum (5-10%), aluminium (0.1-0.2%) and finally recycled waste slurry (closed-loop) (15-20%). In addition, water content of the mix is about 40-50% of the total mixture.

For the low density, we observe:

In all cases, sand, lime (CaO)  and gypsum (CaSO4) are bound with cement. The lime is produced by burning limestone at 800°C. Cement is produced from burning a mixture of limestone and clay at 1400°C and fine grinding the residue to a very fine powder. The foaming is done with Al powder and afterwards, autoclaving happens at 180°C and 12 bar to give the foam its strength. In both cases, a lot of water  (more than 50%) is heated and evaporated. It is clear that the complete process, including the preparation of the “raw materials” is very energy intensive for the production of AAC.

On the other hand, we could melt a soda lime glass at 1600°C with sand, sodaash, calcium sulphate and limestone. This glass can be ground to a fine powder and foamed above 800°C with carbon black or glycerin to a closed cell structure or with (fine) limestone to an open cell foam. However, the melting and foaming process is more energy intensive than the AAC process and also the investments are a lot larger due to the high temperatures used. At the end, cellular glass based on fresh raw materials is more expensive. It makes only sense to use this type of cellular glass instead of AAC in case closed cells are a must. This is typically the case in flat roofs and industrial insulation.

But if a large pile of waste glass is ready to be recycled, it is clear that this glass has to be  foamed to cellular glass with closed or open cells with only one temperature step at 800°C instead of producing cellular glass or cellular concrete with fresh raw materials like sand and limestone with multiple temperature steps. This third option is introduced by GLAPOR in the market and it is easily understood that this option is growing with two digits for ecologic and economic reasons. Especially the current possibility of boards up to 3.2 x 1.5m with compressive strength up to 3000 kPa is responsible for the succes.

We found a nice presentation from the FIW Munchen about “Nachhaltig bauen” which I translate as “sustainable building. In this presentation, cellular glass is compared with XPS, PIR, EPS and other thermal insulation materials. However, it is not clear whether this cellular glass is produced with the mold or continuous foaming process.

GLAPOR cellular glass is produced with the ecologic continuous foaming process and is based on recycled waste glass without remelting at 1600°C but directly foamed. Therefore I added the results for GLAPOR PG600 cellular glass in some figures of the presentation.

The primary energy per kg is one method to describe the different thermal insulations like done in the this graph. We observe that almost all thermal insulations have a higher primary energy content, even after correction for density and thermal conductivity. These corrections are done in the following graph.

Another method is the payback in J (energy) and not in €. Indeed, how much years do you have to use the thermal insulation to save the energy which is used for the production. In this method, we observe that cellulose, low density mineral wool and low density EPS are performing better. But in fact, we are comparing products without mechanical stability (mineral wool, cellulose) and with a poor stability ( EPS 15kg/m³ density )  = 60 kPa at 10% deformation with GLAPOR PG600, which is stable for eternity at 200 kPa without deformation. On top of that, GLAPOR cellular glass is absolutely resistant to rodents, which is also a point of sustainability, which is for unknown reasons never discussed in Europe.

From the above graph, I guess that XPS and PU (and so PIR) have only a short future anymore. The long term future is reserved for the mineral thermal insulations. In fact, the world needs more of this kind of work.

We are currently studying the technology to produce float glass. In a lot of cases, float glass is used as base material to foam directly or to remelt with addition of other raw materials and to be foamed later on.

But since GFT joined CNUD EFCO, we are also interested about the tin bath. Molten tin and hot glass cannot be mixed and for that reason, we can produce window glass direcly on the molten tin. But could we do this also with cellular glass?

Could we put a glass powder with foaming agent on the molten tin and let it foam? In that case, we don´t need a belt or a mold, which are expensive parts in the production process. They have to be replaced regularly and are also heated to 850°C in the foaming process, consuming a lot of primary energy. Also the complete investment of rollers and drive systems can be skipped. On top of that, the typical belt coating with kaoline is not needed anymore, the glass foam does not stick on the molten tin.

The technology to protect the molten tin for oxidation can be used for the foaming with carbon black, where a reducing atmosphere is always needed. The foaming processes with glycerin can probaly skip or reduce  the use of water glass while the SiC process can remain unchanged.

The use of (graphite) fenders for thicker glass is now available to make a perfect rectangular foam (low waste) while top rollers can be used to stretch the cellular glass for an improved thermal conductivity or even to compress the cellular glass for an improved compressive strength without changing density. The bottom of the foam does probably not need any facing improving the efficiency of the process even more. I guess a foaming  efficiency close to 90% becomes possible (90 % of the glass is sold as foam).

Heating above the glass can be done with gas burners, which are also generating the reducing atmosphere. Heating under the foam has to be done in another way, keeping the temperature of the bottom of the foam equal to the top.

The largest part of the above is already published in an old US3361550 patent from 1964, when commercial float glass was born. The general remark on this idea is that a tin bath is too expensive compared with a normal foaming furnace. It is my conviction that a much simpler tin bath can be constructed for this purpose because we don´t have to produce perfect transparant glass without any distortion. The payback is made with less primary energy and refractory steel use and a larger flexibility. The answer on the above question is YES, this is the second generation continuous foaming.

And if we combine this with a small glass melting furnace, we could foam on a molten glass plate. This cellular glass should have one absolutely hard surface, which is frost resistant, could have any color wanted and is absolutely flat. If a less smooth surface is allowed, we could work with two layers of powder: one non-foaming and one foaming. The idea for a new generation cellular glass is born.

We found some papers with new recipes to foam glass. The first paper was written at the Iran University of Science and Technology in Teheran, which seems also to step into cellular glass.  Hereunder, you will find the abstract:

Foam glasses are encountered as one of the most promising solutions for waste glasses recycling issues. Homogeneous pores distribution and high mechanical strength are two main characteristics of these products which many investigations have been done for their optimization. High flexural strength glass foams were fabricated by usage of oxidant agents like Fe2O3 and Co3O4 besides soda lime glass wastes and SiC as a
foaming agent. Glass foams containing 4 wt % SiC and foamed at 850°C for 1 h had 90% porosity and bending strength of 0.75 MPa. Bending strength of specimens using increased to 6.82 MPa and porosity was decreased to 80% by addition of 1.2 wt % Co3O4. Moreover, the effects of Fe2O3 and Co3O4 on porosity, microstructure and mechanical properties of foam glasses were studied. Based on the results, the finest porosities with the highest size distribution homogeneity were observed in foam glasses contained Fe2O3 and Co3O4. Furthermore, Co3O4 addition produced slightly narrower pores size distribution in comparison with Fe2O3.

The same university also did some foaming of Cathode Ray Tube glass from old televisons. This is given in the following paper with abstract:

In the present study, the effect of temperature and oxidising agents such as Fe2O3 and Co3O4 on physical and mechanical properties of glass foam is investigated. The glass foam is made of panel glass from dismantled cathode ray tubes and SiC as a foaming agent. In the process, powdered waste glass (mean particle size below 63 mm) in addition to 4 wt-% SiC powder (mean particle size below 45 mm) are combined with Fe2O3 and Co3O4 (0?4, 0?8 and 1?2 wt-%) have been sintered at 950 and 1050uC. The glass foamed containing 1?2 wt-% Co3O4 has good physical properties, with porosity more than 80% and bending strength more than 1?57¡0?12 MPa. However, by adding different amounts of Fe2O3 in comparison with samples without iron oxide, little changes in porosity and strength are obtained.

Another paper  was written in Turkey at the Izmir Institute of Technology with abstract:

The foaming behavior of a powder residue/waste of a soda-lime window glass polishing facility was investigated at the temperatures between 700 and 950 C. The results showed that the foaming of the glass powders tarted at a characteristic temperature between 670
and 680 C.  The maximum volume expansions of the glass powder and the density of the foams varied between 600% and 750% and 0.206 and 0.378 gcm3, respectively. The expansion of the studied glass powder residue resulted from the decomposition of the organic compounds on the surface of the glass powder particles, derived from an oil-based coolant used in the polishing. The collapse stress of the foams ranged between 1 and 4MP aand the thermal conductivity between 0.048 and 0.079WK1 m1. Both the collapse stress and thermal conductivity increased with increasing the foam density. The foams showed the characteristics of the compression deformation of the open cell brittle foams, which was attributed to the relatively thick cell edges.

In the last paper, the foaming agent is the coolant used for the polishing of the glass. That is an interesting observation.

We got an invitation from GLAPOR to join the tenth birthday in their factory. It means that 10 years ago Walter Frank founded this company to produce and sell cellular glass gravel and boards.

In his philosophy, boards are an extension of the succesfull cellular glass gravel, based on 100% recycled glass with a minimum energy and zero waste production. Today, this philosophy is changing the cellular glass world by putting an enormous price pressure to obtain: “cellular glass for everybody”, which is the mission of BELGLAS.

GLAPOR is not only a cellular glass producer but also a multicultural family, which is celebrating this 10 years old relationship. In that perspective, all family and shareholders are present to enjoy this unique culture. Pimpy Panda is the multicultural music group, which is already announcing the show on YouTube.

GLAPOR is based in Mitterteich, a municipality in the district of Tirschenreuth, in Bavaria, Germany. In fact, GLAPOR is located in the old porcelain factory of Mitterteich, saving and renewing the old experience to work with minerals, furnaces and high temperature equipment. About the old porcelain factory on the GLAPOR site, I copied the following:

Porzellanfabrik Mitterteich A.G. (1917 until 2006)

To match constantly rising demand, a second facility (‘Werk B’) was in 1925 constructed on Hüblteichstrasse and the total number of workers increased to just over 300 in the same year. The second facility was in 1937 followed by a third, ‘Werk C’, located on Schulgartenstrasse. The whole factory used standard coal-fired kilns before completely switching to gas-fired tunnel kilns early in the 1950’s.

A huge fire completely destroyed the ‘Werk C’ part of the facility in 1988 and the required reconstruction took until 1989. With all three locations fully operational again, the factory had a production area of 20,000 square meters and a workforce of around 800 people. The Mitterteich A.G. seemed to cope quite well with the overall situation on the German market. But in August 2005 the small city was rocked by the news that the company, represented by the board of directors, had to file for bankruptcy. For the 360 workers (70 percent of these female), it came as a shock. The small hope of an investor being able to save the company was destroyed by the local banks, who did not want to support the Mitterteich facility any longer. On March 1st 2006 the doors leading to the factory closed for the last time.

In 2007, Walter Frank founded GLAPOR and used the old buildings and infrastructure.                

Cellular 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.

While 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.

AAC 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.

The current shortage of PIR and PUR makes that customers and investors are looking for alternatives. These alternatives are mostly mineral and in this way, low cost cellular glass like GLAPOR comes into the picture.

In that case, it is not clear whether it will be boards or gravel. Like shown in this GLAPOR document, the cellular glass gravel is used for floor insulation, road and railway construction and even landscaping. The boards are mainly used in the building industry from private homes to larger buildings. The combination of boards and gravel, the well known GLAPOR RDS system is today a very performant floor thermal insulation, which in principle can be used also for tankbase bottoms of small and even larger tanks.

In fact, the answer is clear: a low cost cellular glass factory must include gravel and board production lines. Indeed, the waste of finishing cellular glass boards cannot be used again for the board production due to crystallisation after a few cycles but is perfect for the (one cycle) production of gravel. A low cost cellular glass factory with gravel and board lines runs with 95% recycled waste glass and does not generate any waste by itselves. It is the perfect recycled glass absorber by converting it into ecologic durable recycable thermal insulation.

Low cost cellular glass involves a short distance between market, production and recycled glass combined with a confident energy source. The following article explains how the import of cheap bottles is the reason why recycled glass remain in stock instead of being used in Australia.

Nevertheless, Australia is familar with reycling of glass like shown in this link. Even more, glass is considered as ecologic.

• This list of material life times gives 1 million years as life time for glass in sea water while plastic foam (EPS) survives 50 years. The short life time of plastic is a big problem for the health of people, who likes to eat fish.
• Recycling glass fact sheet explains why glass has to be used and how it is recycled within the classical glass industry.
• This document explains focuses on the many times glass can be recycled if not contaminated and how to avoid contamination. It shows also the advantages of recycling for the environment.
• Last but not least repeats the above and mentions that glass is already 2500 years old.

It is clear that a cellular glass plant, converting recycled glass into cellular glass boards and gravel would be the ideal solution to value the recycling efforts of the Australian citizens. Indeed, cellular glass resists the harsh climate of Australia by its high softening point (above 700°C) and all kind of animals, which are halted by cellular glass boards.

We told already that GLAPOR cellular glass is booming but now they have actually reached the top of Germany in a geometric way. Indeed, the GLAPOR cellular glass was selected as thermal insulation for the roof terrace on the Zugspitze, the highest mountain in Germany. The Zugspitze has a webcam, showing the nice neighbourhoud.

The climate is rather hard, which was one reason to choose GLAPOR cellular glass. Heavy sunshine during day and very low temperatures during night are difficult to resist for polymeric foam but are a piece of cake for cellular glass. Between cellular glass producers, GLAPOR was selected for his interesting price.

This price is possible because GLAPOR foams directly recycled glass without any expensive remelting at 1600°C. GLAPOR is installed in a larger thickness to compensate the higher thermal conductivity, which allows to work with larger dimensions (EUROPALLET size) to reduce labour cost.

Like can be observed in the picture, GLAPOR cellular glass is installed in hot liquid bitumen to guarantee a vapour tight roof, without any humidity absorption. More comments can be found in a GLAPOR document.

This project was sold and coached by the succesfull leader of the Austrian GLAPOR sales office, Aladin Hauft-Tulic. For a long time, Austria could not be seduced by cellular glass but Aladin seems to surf very good on the ecologic wave in Austria.