Some nice work about cellular structures

logo_smallCellular materials are smart materials. Two architects of this idea are Michael Asby and Lorna Gibson. Lorna was once a PhD student of Michael. They investigated the mechanical and thermal behaviour of all kind of foams.

In the following, I add the PhD-thesis of Lorna  and a very good introduction to foams by Michael.



Cellular glass is radon tight … so what?

logo_smallToday there are too much lawyers on this world and they are boring themselves to death. And as a consequence, they become politican and find out laws, which we do not need. One such a thing is the radon tightness of closed cell cellular glass.

Gavel in courtroom working office of lawer legislation.If cellular glass is vapour tight, we can expect that it is also Radon tight. But this logic is not accepted by our lawyer world. For that reason, GLAPOR has ordered a RADON diffusion experiment with is described in this report.


What-is-Radon920x426_menuIndeed, a layer of 50 mm cellular glass is 250 times the diffusion length, which means that Radon cannot diffuse through the cellular glass without decaying in the cellular glass. In that way, it is impossible that Radon decays in the lungs of humans and animals behind the cellular glass.

01_06_04It is needed to install the boards with hot bitumen (which is also Radon tight) but pinholes in the bitumen remain a small risk in the joints. For that reason, it is advised to work with large boards (GLAPOR cellular glass: 2800 mm x 1200 mm) to reduce the number of joints as much as possible. Dry installation of the boards will only minimally protect against Radon.

Styrene is probably cancerogenic for humans

logo_smallI was surprised when I found the following in the Lancet, a medical magazine. It states that: ” The Working Group classified styrene in Group 2A, “probably carcinogenic to humans” based on limited evidence in humans and sufficient evidence in experimental animals for carcinogenicity.”  This is a new classification since March 2018 because the older one gives a less dramatic one.

whale1Like described in this recent paper and this older paper, styrene is used to produce polystyrene and the latter one is foamed to expanded (EPS) or extruded (XPS) polystyrene. I don´t believe that XPS or EPS or cancerogenic during the use as thermal insulation but disposal is not straightforward.

Indeed, the landfill method is not a good method because these products are reduced spontaneously to small particles, which are not biogredable and end up in all kind of organisms and also later on in humans. Combustion has to be done above 1000°C to avoid all kind of flue gases while standard incinerators are working at 850°C.

For that reason, a lot of American cities have already banned the use of polytsyrene  for the following reasons:

  • It does not biodegrade. It may break into small pieces, even minuscule pieces. But the smaller EPS gets, the harder it is to clean up.
  • It is made of fossil fuels and synthetic chemicals. Those chemicals may leach if they come in contact with hot, greasy or acidic food. Yes, they keep your coffee hot – but they may also add an unwanted dose of toxins to your drink.
  • Animals sometimes eat it. Turtles and fish seem to mistake EPS for food, and that can kill them. Not only can they not digest it, but the foam could be full of poisons that it has absorbed from contaminants floating in the water.
  • It can’t be recycled. Some commercial mailing houses may accept packing peanuts, but for the most part community recycling centers do not accept throwaway foam food containers

To me it is clear. EPS and XPS are not needed in the building industry and can be replaced by cellular glass. GLAPOR cellular glass is in that case the most ecologic alternative.

Protecting against radon with cellular glass boards

logo_smallRadon is a natural radioactive gas that causes cancer when it is present in the lungs. In regions with a lot of Uranium and Thorium in the soil, this Radon gas is present in higher concentrations. When accumulated in a building, a real health problem is present being the second cause of lung cancer. The situation in Europe is shown in the following picture. Everything more tha yellow deserves measures against radiation.


radonThe American government educates its citizen how to build houses to avoid Radon accumulation like shown in this leaflet. The standard method is to use a ventilated space under the floor.

The need of this ventilated space is clear if cellular glass is not taken into account. A German paper of Keller shows how Radon diffuison is measured in building materials and gives a tabel (see hereunder) with the diffusion length for Radon. This is the length Radon diffuses before it decays with harmfull radiation. A Radon barrier should have a thickness three times this diffusion length to withstand 95% of the Radon.


It is clear that a concrete beam of 200mm thickness is on the limit and that for polymer materials the joints are uppermost important. Indeed, not using a ventilated space under these systems is a risk.

radonBut like already mentionned in a previous post, cellular glass boards are a perfect light barrier against radon. A compact layer of cellular glass boards in bitumen is a perfect screen (100 mm cellular glass is 100 times the diffusion limit of Radon) serving also as thermal insulation and avoiding expensive radon ventilation systems. The bitumen joints are the only risk but using large GLAPOR cellular glass boards  280 x 120 cm reduces this risk for radon leaks with a factor 12  compared with 59.9 x 44.9 cm boards.

On top of that, if for passive housing these GLAPOR boards are installed on a thick layer of (implicit ventilated) GLAPOR cellular glass gravel with the RDS system, even the presence of negligible concentrations of Radon in the house is eliminated and a passive housing standard thermal insulation is installed under the floor at a very good price.

The contributions of Elena Yatsenko for cellular glass

logo_smallProf. Elena Yatsenko has a chair at the Platov South-Russian State Polytechnic University (NPI) in Russia. While the universities of Aalborg, Ljubljana and St. Petersburg are recycling glass, prof. Yatsenko is converting slag into cellular glass.


I found the following publications:


Today, most of the recycled glass is used for the standard glass industry and a minor part, which cannot be recycled for bottles and windows is today used for cellular glass. However, reusing slag waste for cellular glass is a new step in the recycling industry. Today, slag is used in the cement industry and also slag wool can be produced for thermal insulation. But it seems that a new future, namely cellular slag is arriving. Indeed, glass powder for foaming should be at least 10 times more expensive than slag powder.

Thermal insulation according to Architect Konrad Fisher

logo_smallKonrad Fisher was an herectic against outside thermal insulation on walls with a rendering. According to him, all thermal insulation except (closed cells) cellular glass develops mold and other problems in the rendering, which make look the rendering dirty. The rendering has to be cleaned regularly or to be treated by harmfull and expensive fungicides. Bot operations have a large cost.

konradfischerIn his opinion, cellular glass, due to his closed cell structure is a much better alternative, which does not become wet and will not induce mold on the rendering. He explains everything in a YouTube movie, however in German.

He also mentions the price of cellular glass but he is clearly not aware of the new generation cellular glass from GLAPOR at 250€/m³. In this case, maintenance of the will be much lower, generating a payback for the cellular glass.

mold_rendering                   fisher_schaumglas

Above, you observe a dirty rendering due to mold and on the right the solution according to Konrad Fisher with cellular glass in his hands. These pictures can be found in the YouTube movie.

Stanley Kubrick has known it already a long time …

logo_smallIn 1969, a world famous movie was produced by Stanley Kubrick:   2001: A Space Odyssey. This link on You Tube shows a part of the movie. I give one frame hereunder:


It is clear that Stanley Kubrick predicts the large monolitic  GLAPOR cellular glass boards as the future material (Monoliths) to generate a new evolution step.

In Arthur C. Clarke‘s Space OdysseyMonoliths are machines built by an unseen extraterrestrial species. In the series of novels (and the films based on these), three Monoliths are discovered in the solar system by humans. The response of the characters to their discovery drives the plot of the series. It also influences the fictional history of the series, particularly by encouraging humankind to progress with technological development and space travel.

Indeed today, GLAPOR cellular glass is participating for a future ecological world.

Houses with cellular glass walls

logo_smallIt is already mentioned in this blog that large cellular boards can be used as thermal insulation and also as construction material, giving the stability of the wall. Especially in the passive housing market, this can be important. Today, we have two examples in Europe, where people on their own initiative started to use cellular glass as stability element and thermal insulation.

In this system, cellular glass is used in combination with brick slices by Clean Tech Block.


A passive housing U-value can be reached with normal wall thickness (< 400mm) and cellular glass, directly foamed from recycled glass. In the following system, cellular glass is used in combination with wood by Tebit Oy, Finland.


It is clear that the future is great for not expensive large boards cellular glass like today produced by GLAPOR cellular glass.

Hydroculture with open cell cellular glass

logo_smallBELGLAS is still convinced that there is a market for open cell cellular glass. Acoustic absorption is one application, hydroculture a second like already demonstrated in a post about Growstone.

At GLAPOR, some possibities with open cell cellular glass boards were investigated …


I gTomato isolated on white backgrounduess we eat today the first GLAPOR tomato …. The cellular glass perfectly controls the the stability of the root and the  water and mineral content the plant gets to absorb …

Cellular glass in flat solar collectors

logo_smallFlat solar collectors to heat water have still a large future with an efficiency up to 85% compared with photovoltaic, which is still only 15%. A typical solar collector consists of a glass pane, which allows transmission with minimum refelection of sun radiation on fluid cooled heat exchanger, which is thermally insulated at the backside. This insulation will be mineral because temperatures above the glass temperature of polystyrene (90°C) or another polymer can be expected.

HamSun-Hocheffizienter-Flachkollektor-1-St-202m_b2Cellular glass as thermal insulation was out of the question due to price and dimensions. Indeed, 0.60 x 0.45m boards for solar collectors of 2m x 1m are difficult to use. In the picture, the heat exchanger tube is put on mineral wool in an Al casing for only 245€ VAT included. The efficiency of this cheap solar collector is 75% (cold fluid at entrance) and without fluid flow, the temperature may become up to 208°C. With water, we could attain a pressure of 20 bar in that case, which means we need for example ethyleen glycol (EG) or propyleen glycol (PG) as safe liquid. They have a high boiling point (EG=197°C; PG=188°C) and low freezing point (EG=-12.9°C; PG=-59°C). With a fluid flow rate of 100l/hour, we have a pressure drop of 50 mbar.

For that reason, we could consider to replace the mineral wool with meander tube by a large GLAPOR cellular glass board with the meander channel, milled directly into the cellular glass. The glass cover (eventual a double pane) closes the channel at the top. In this case, the radiation is absorbed directly into the water reducing the temperature gradient between solar radiation aborber and water. This means that the water will be warmer in winter reducing the need for extra heating.

However, this idea is not new. Patent DE102014007805A1 from end 2015 describes exactly the above.


However, an earlier PatentanmeldungWO2012093062A2 (2011) describes also such a system based on foamed glass from recycling glass.


CGcellThis patent was based on research, sponsord by the German government and performed at the Univerity of Freiberg. This is the second time we met this university in the cellular glass world. It was  first with vacuum cellular glass and now with a solar collector.

A solar collector based on large cellular glass boards with the above structure should be much cheaper than the standard equipment, which is today used with a higher efficiency. Cellular glass is heat absorber, thermal insulation and casing at the same time. The difficult problem will be the connection of these cellular glass channels to metal tubes to be able to connect the solar collector on the system. But this problem can be solved with one of the many adhesives on the market. The major problem, the avialability of large cellular glass boards 2.8 x 1.2m is already solved by GLAPOR cellular glass.