GLAPOR foamed glass gravel certified for street construction in the Netherlands

Some regions in the Netherlands have a large problem with soil stability. Indeed, the soil is sinking due to the load of streets, etc. This is nicely demonstrated in a movie in Dutch. It is shown that in some cases the streets have sinked so much that people cannot enter anymore there garage with their cars. In order to reinstall the original height of the streets, ordinary soil is not used because this increaes even more the sinking behaviour. Several light weight materials are tested on mechanical stability and leaching out.

Garage not anymore useable for cars due to soil instability

The Netherlands have their special method to put a limit on the leaching out of materials in contact with the soil. Where other countries put a limit in relation to the health risk with several molecules, the Netherlands have as rule that the actual composition of the soil should not change more than a certain value in 100 years due to leaching out. In this way, they obtained a much more severe limit on Sb (Antimony) than on As (Arsenic), while the last one is much more dangerous for the health. As a consequence, several European cellular glass producers failed for the test and for example, EPS was used as filling material, which is questionable.

Gravel cellular glass production

However, GLAPOR celluar glass succeeded as the first supplier to pass all the test by adapting the recipe and other critical issues and obtained the very difficult to obtain KIWA certificate. It is expected that in the next years one million cubic meter “Holland” gravel will leave Mitterteich for the Netherlands. This is nicely demonstrated in another movie, partially in Dutch.

Truck leaving GLAPOR Mitterteich, Germany for road reconstruction in the Netherlands

The first Thermal Energy Storage in Germany is built with GLAPOR cellular glass.

During summer, Europe has a lot of excess heat production by power plants and other industries besides solar energy. This heat can be stored below 100°C in large water tanks or pits, like we already discussed in a previous post. Indeed, water has a large specific heat and does not contaminate soil.

In Meldorf, Germany, the first Pit Thermal Energy Storage (PTES) is build to heat public buildings in winter by Ramboli and Solmax. First a large pit is dug (100m x 100) like shown hereunder.

The sides and bottom of the pit are covered with HDPE-foil to make the pit watertight like hereunder.

The pit is filled with water and an 2.5mm HDPE-foil is covering and floating on the water. It is perfectly possible to walk on this HDPE-foil. On this foil, a layer of Glapor PG600 cellular glass is installed (800 x 600 mm boards) and later on a layer PIR and tapered EPS is installed. On top of the EPS, a rain-membrane is installed, where the tapered is installed in such a way that the rain water can be easily drained. Hereunder, the installation of the cellular glass and PIR on the HDPE-foil is shown.

More information will be given later about this historal step. In the past, the first layer was (hot) PE-foam, which is too much creeping at 80°C under the weight of a puddle water, which becomes larger and larger by the creeping. GLAPOR PG600 cellular glass does not creep measurable under even the load of 15m water load below 400°C.

GLAPOR tankbase at INDAVER

Indaver is a large company all over the world with a plant in Antwerp, Belgium. In that plant, they build a new system to recycle plastics to base materials (P2C). One part of the plant are a few tanks with 15m height like shown hereunder.

The tanks are insulated at the bottom with tapered Glapor PG 600. This is shown schematically hereunder.

The 6 tanks passed the hydrotest at 150 kPa, like could be expected. In this way, GLAPOR entered officially the tankbase world. The tanks were installed by the company Verwater in Belgium and will be used up to 120°C. In fact, plastics are recycled, partially on recycled glass, transformed in GLAPOR cellular glass.

Cellglas and Tversted house in the picture

Cellglas is a Swedish company, which works with cellular glass. Quite fast, they changed for GLAPOR cellular glass, because this is made for 100% from recycled glass and available in larger boards. They are specialized in using cellular glass under the floor on a sand bed. This is nicely shown in the following video.

The cellular glass is used as thermal insulation of concrete plate (bottom and sides) and as formwork for pooring the concrete.

But an even more inventive concept is Tversted House, which is built without concrete or steel. After use, it can be simple unmounted and the materials reused. This is shown in following document.

Tversted HouseDownload

The architects Jonas Aarsø  and Alexandra Nikolova use only GLAPOR cellular glass and wood in the foundations. The end result is a nice and ecologic building.

GLAPOR participates in seasonal thermal energy storage (PTES) to contribute to renewable energy solutions

In Germany, we have every year about 1000 kWh/m² sunshine (equivalent of 100 l diesel / m²) but most of it is available in summer when we do not need heating. By storing this thermal energy (TES), we are able to overcome the winter with what we have collected in summer. The easiest medium is liquid water with its high specific heat (water 4182 J/kgK compared to concrete 800 J/kgK). A typical method is working with a large pit, covered with thermal insulation (PTES) although other methods are also available. A nice introduction is given in the following paper.

Newly installed PTES with polymeric cover

ptes_btes-1Download

Like described, large difficulties are present with the thermal insulation in the cover. Indeed, polymeric foams absorb large quantities of humidity while also spontaneous deforming is present due to the high water temperature and concentration of rain water on the cover. For that reason, the temperature of the water is limited to 75-80°C.

To improve efficiency, it makes sense to use cellular glass and 95°C water to increase the thermal energy content of the PTES. However, to protect the stainless heat exchangers and to avoid biological contamination, the water is kept of pH=9, which stimulates the corrosion of soda lime glass and so cellular glass. For that reason, the cellular glass should be protected against this corrosion. Stainless steel foil has a large corrosion resistance in hot alkaline water and has a matching thermal expansion coefficient with (cellular) glass. GLAPOR proposed a modular solution on the ISEC 2022 conference in Graz, Austria with the following poster.

posterDownload

By working with a modular system, we are able to assemble larger covers than possible today (100 x 100m) and a temperature up to 99°C is possible with these materials. On top of the cover, we can use typical flat roofing technology with polyurea and tapered solution to drain/guide the rain water. Moreover, a second function is possible with this solution, which can be a photovoltaic system, a large greenhouse (in situ heating), a swimming pool (in situ heating), … . This second function will be logic because most PTES will be located near cities, where the land is very expensive. This is certainly not possible with the polymeric solution like shown hereunder. The dramatic situation hereunder can never happen with a cellular glass cover.

Typical deformation and rain water concentration on a polymeric cover for PTES

The (compact) warm roof is dead, long live the inverted roof

The flat roof will be straightforward in the future because it can absorb the maximum of solar energy, independent on the orientation of the building. A flat roof on the other hand accumulates easily humidity in not-vapour-tight thermal insulation like XPS, EPS and mineral wool if there is no perfect vapour screen on the warm side. The perfect vapour screen does not exist and so perfect dry thermal insulation in a flat roof neither. Basically, the reason of this accumulation is the combination of a healthy humidity in house (50% relative), a cold winter and a waterproofing membrane induces humidity where the perfect vapour screen is absent (joints, poor labour, …)

For this reason, the cellular glass compact warm roof (warm roof = water proofing membrane on top of the thermal insulation) is known as the best solution on the condition that the joints are perfectly filled with bitumen. If these joints are partially not filled with bitumen, condensation of the present humidity induces in winter freeze and thaw. This causes open cells and the humidity enters almost permanent in the cells, increasing drastically the thermal conductivity. This has been observed by Prof. Dr. Hugo Hens, KU Leuven in the Belgian climate (interview November 17, 2022). This should certainly not happen when the joints are well filled with bitumen.

Prof. Dr. Hugo Hens

A cellular glass roof, installed with bitumen is hard to recycle at the end of its lifetime. In Germany it is not allowed anymore to use oxydized bitumens while installation with other bitumens is more difficult. As a consequence, the dry installation will become a necessity, even for flat roofs. This means that the surface cells have to be filled to be protected against freeze and thaw. According to Prof. Dr. Künzel, (Fraunhofer Holzkirchen, Stuttgart University and developer WUFI-software) (interview November 30, 2022) at least the top surface and sides of the cellular glass need to be coated against freeze and thaw damage. For the moment, there is no such cellular glass product available but some polymer coatings are straightforward.

Prof. Dr. H. Künzel

If freeze and thaw resistant cellular glass should be available, we have the choice to install above (inverted roof) or under the water-proofing-membrane (warm roof). The major advantage of the inverted roof is that the water proofing membrane is protected against UV-light, temperature variations and mechanical damage. These are the causes that the membrane has a reduced lifetime on the warm roof. A nice paper states that the lifetime of a water proofing membrane at least doubles in an inverted roof compared to a warm roof.

CIB2039 (1)Download

Results for non-insulated(1), insulated without ballast(2), insulated with ballast(3) and inverted roof(4)

Roof 4 is the inverted rood, roof 3 a warm roof with some ballast (protection) and roof 2 the unprotected insulated roof (typical compact roof). Roof 1 is the non-insulated roof. It is clear that an inverted roof with freeze and thaw resistant cellular glass has a life time of about 50 years after which the cellular glass blocks can be reused (no need for disposal or recycling). Using solar energy to the maximum will be a must and so the flat roof. The inverted roof is the logic choice due to its expected lifetime if freeze and thaw resistant cellular glass at (top and side surfaces) is available.

The inverted roof was originally patented by Dow Chemical for XPS like discussed in a previous post. However, XPS is a closed cellular structure based on polystyrene, which has a diffusion coefficient for water vapour, which is about 1 billion larger than in ordinary glass. For that reason, perfectly installed XPS absorbs humidity by diffusion in an inverted roof. This became even worse in the green roof, with its almost constant > 95% relative humidity, again according to Prof. Dr. Künzel by experiments and WUFI-simulations. In 20 years the thermal conductivity doubles and disposal is needed. This disposal is very expensive because the cost goes pro kg. After 20 years, XPS absorbs about 6 times its weight in a green inverted roof …

Although there are a lot of (negative and false) dogma about the inverted roof, in my opinion it will conquer the world with freeze and thaw (top and sides) resistant cellular glass. Disposal of the water proofing membrane after minimum 50 years and reuse of the cellular glass will be the arguments to get rid of the compact warm roof and its bitumen, causing a shorter life time and a high disposal cost. The first signs are already present. Austrian accredited expert Hannes Guggenberger states (telephone November 29, 2022) that he has already 4 years a good experience with a cellular glass inverted roof. If it works in the Austrian climate, I guess it works everywhere in Europe.

Austrian accredited roof expert Hannes Guggenberger

Recent patent about facades thermally insulated without cold bridges

Installation of very light thermal insulation with a rendering on a new facade can in principle be done with an adhesive. However, most people don’t trust this because it depends on the state of the facade (wet by rain, contamination due to traffic, etc.). At that moment, they want mechanical fixings, which are anchored in the facade.

Large cold bridge fixation

In case of a ventilated surface with more heavy thermal insualtion like cellular glass and with a heavy cladding, an improved mechanical fixing is needed.The patent of Willy Trittenbach, once a collegue is a nice example of such a very stable fixings. But stainless steel has thermal conductivity of 15 W/mK and GLAPOR cellular glass about 0.05 W/mK or a factor 300. This means that a 6mm screw cinducts the same amount of heat as a cylinder GLAPOR cellular glass with a diameter of 100 mm, which is a huge cold bridge. Besides the screw, also the legs are passing the cellular glass. The patents mention at least one fixing in every boards 450 x 600 or a cold bridge of about 10% of the thermal insulation. To remove this cold bridge, a new patent was taken.

This new patent eliminates works with a double layer insulation, separated by a board, which is fixed on the walls. In this case, there is no direct connection by a long screw between the surface of the thermal insulation and the wall.

Small cold bridge fixation

However, in Germany ventilated facades have to be insulated with thermal insulation with melting point above 1000°C according to DIN 4102-17. Check the German product datasheet before ordering the thermal insulation in case of Germany.

Tribute to the father of cellular glass: Professor Isaak Ilyich Kitaygorodskiy

In 2022, it is 90 years ago that Professor Ilya I. Kitaygorodsky presented cellular glass at the All-Union conference on standardization and production of new materials in Moscow. Therefore, BELGLAS BV conducted some research about this man, with which we share a common respect for cellular glass.

Professor Isaak Ilyich Kitaygorodskiy

Professor Isaak Ilyich Kitaygorodskiy was the founder of the Department of Chemical Technology of Glass and Sitals at the D. Mendeleev University of Chemical Technology of Russia. In the following, I copy a part of an interview with Vladimir Nikolaevich Sigayev.

The Department of Glass is a legendary one. It was founded almost 90 years ago, in 1932, by the famous Soviet scientist, technologist #1 in the field of glass, Isaak Ilyich Kitaygorodskiy. Suffice it to mention that the ruby stars of the Moscow Kremlin were created on the basis of his developments related to glass coloring processes. I should remind you that the towers of the Kremlin were originally decorated with two-headed eagles. The builders of communism got to them only in 1937, and the eagles were replaced by metallic stars, which, however, were not visible at night and did not make a good impression at all. Therefore, it was decided to replace them by ruby-colored glass stars which fitted perfectly well into the architectural appearance of the Kremlin. It was a very beautiful design that complemented the brilliant work of Aristotle Fioravanti. 

Let us return to the foundation of the department. 1932 was a landmark year not only in the context of its founding. It was the same year when the famous article by William Zachariasen, the largest scientist of crystal chemistry, who laid the foundation for the theory of the glassy state structure, was published. By the way, this two-page work remains the most cited article in glass science to date. 

Kitaygorodsky, the founder of the department, worked as a chief engineer at a glasswork in Zaprudna near Moscow before the events of the 1917 revolution. Kitaygorodsky set up the production of light bulbs at this, judging by the preserved photographs, quite ruined facility. In fact, as they say today, he started the process of import substitution, and beginning from 1913 Russia has been using domestic light bulbs. After 1917, when the entire country was electrified under the GOELRO plan, they began to be called “Ilyich bulbs,” referring not to Isaac Ilyich, but to Vladimir Ilyich, which I find a major historical injustice. 

Later, the activity of the department covered all the variety of glass technologies, including all the new challenges coming from the needs of instrumentation, medicine, and ecology. The main challenge was related to the improvement of sheet glass and organization of its multitonnage production (95% of all glass production is oriented on the creation of window sheet glass, i.e., glass used in architecture). The problem of sheet glass production was finally resolved with the aid of the so-called float technology, which makes it possible to obtain nearly perfect glass sheets up to six meters wide by melting the glass mass into liquid tin. In Russia, this problem has been solved when foreign companies came to the Russian market such as “AGC,” “Guardian,” “Pilkington,” etc. It is difficult to overestimate the contribution of Kitaygorodsky and his students in the development of sheet glass, electrovacuum, medical glass, foam glass, and seals.

The Russian university where Professor Ilya I. Kitaygorodskiy teached

Today, a lot of research about cellular glass is again performed in Russia. I guess that our spiritual father will be pleased.

The rebirth of the inverted cellular glass roof

The inverted roof has the thermal insulation on the waterproofing membrane. A better but less known name is the Protected Membrane Roof (PMR). Another contraction was IRMA (Inverted Roof Membrane Assembly), which was once a registered trademark of the Dow Chemical Company. Moreover, Dow Chemcial company had once a patent on the inverted roof. It was filed in 1965, which means that there was no absolute freedom to install this type of roof in the USA untill 1985.

The patent describes that the thermal insulation has to be watertight and should not absorb humidity. It is a surprise that this patent showed up 24 yeasr after the invention of the XPS. The patent mentions also cellular glass in its introduction: The thermal insulating layer, employed in the practice of the present invention, beneficially is a closed cellular material which is substantially water impermeable. Particularly beneficial and advantageous, for use in the pres ent invention, are cellular plastic foams of a closed cell configuration including styrene polymer foams, styrene acrylonitrile copolymer foams, styrene-methylmethacry late copolymer foams, polyvinyl chloride foams, poly ethylene foams and other water impermeable materials available in cellular foam form which are well known to the art. Foam glass is particularly advantageous when it is desired to omit a protective layer over the thermal in sulating material. A protective layer beneficially is employed when synthetic resinous organic cellular thermal insulating layers are utilized. Such organic materials are generally subjected to decomposition when exposed to weather and more particularly when exposed to Sunlight.

Cellular glass can not be used in freezing countries because freezing water in the open cells on the top surface will induce cracking and water absorption. For that reason, cellular glass was only used under the water proofing membrane like shown in the many applications of GLAPOR cellular glass. However, if your are able to solve the problem of open cells at the surface of cellular glass, the way is open to use cellular glass in an inverted roof. The advantages in these sustainable times are clear.

Since less than one year, a patent was published, which claims to solve this problem. This patent from a Belgian inventor works with a mineral protective coating on the cellular glass surface.

Hytherm CG inverted roof with cellular glass

This patent does not refer to the original inverted roof patent but is on the other hand very extended. It describes a few detailed methods how to prepare a mineral protective coating on the cellular glass. All these coatings are based on alkali silicate solutions with mineral fillers and even some testing in a climatic chamber for facades is included. The coating is proven to be resistant to UV, higher temperatures and freezing water. I guess that a mineral coating, based on hydraulic lime could also be suited. I used it once for a “sculpture” and it survives already 15 years in a Belgian climate, even the horizontal part.

Choosing between a warm roof (thermal insualtion under the water proofing membrane) or an inverted roof is choosing between the risk for damage / wear at the thermal insulation or damage / wear of the water proofing membrane. I guess that the second risk is at least more acute. An inverted roof needs ballast on the thermal insulation, which makes the roof construction more expensive. But Germany is going in the direction to make ballast on the water proofing membrane an obligation for every flat roof.

If the roof construction can bear ballast and cellular glass with a mineral coating is available, an inverted roof with loose-laid cellular glass is the most durable solution. Indeed, the life time of the membrane will be very long (no UV, stable temperature and no mechanical damage) and recycling at the end of the roof life (building life) will be much easier. These coated cellular glass blocks can be found at Hytherm CG and I guess other suppliers of cellular glass will follow. In the UK, non-combustible thermal insulation is an issue since the incident with the Grenfell Tower, while the inverted roof with the combustible XPS was very popular there. Mineral coated cellular glass is there a big opportunity today.

In my opinion: “The warm roof is dead, hurray the inverted roof”

In the mean time, we learn the above patent has been aborted.

3D printed house with GLAPOR cellular glass

Recently, a nice YouTube-movie appeared about full printing a 3D-house. The house was put on GLAPOR cellular glass gravel, while the flat roof was insulalted with GLAPOR-boards.

The movie shows the use of cellular glass gravel and the printing of the house, layer by layer. In fact, the house was printed by only two people and a huge cement mortar printer. The challenge was to develop a mortar, which allows printing but which does not flow after printing.

On the flat roof, GLAPOR cellular glass boards were installed with bitumen. Although, the main target was to use only mineral materials, bitumen, as an exception on the rule, was used to have a firm adherence to resist important wind loads.

More information about the printing can be found in another YouTube movie.