An alternative for bitumen

logo_smallMost Glapor cellular glass is installed with hot bitumen 85/25, which is more or less the standard method. The bitumen is heated to above 180°C and poured on the substrate if possible.The cellular glass blocks are put into the liquid bitumen and pushed against the previous installed blocks. The liquid bitumen creeps upwards in the joints and flows slightly over the surface. This procedure guarantees a vapour tight roof free of internal condensation. Cellular glass, which cracks during this procedure, is not well produced. In case of a steel roof, the blocks are dimpled in hot bitumen bath with the bottom and two side surfaces and installed on the roof. Bitumen is indeed a nice and practical adhesive but it has some important disadvantages:

  • 439388_140409_chams3Bitumen burns and is EUROCLASS F. It can be improved with fire retarders but these improved bitumens are rather hard to find.
  • 439388_140409_chams4Bitumen has IARC classification 1 and has beyond any doubt cancerogenic risks, especially during installation when hot. This risk is reduced when working with cold bituminous products, like Pecimor-DK.

In case a roofing membrane is used, we need to use a flexible organic adhesive. Millennium one step green foamable adhesive is a good choice. It adheres on concrete, steel, wood and on glass. In case of uncoated GLAPOR cellular glass boards,  we have a perfect large surface for adhesion.

Millenium one step green foamable adhesive has the following advantages:

  • It can be applied in all climates but not on a wet surface. In warm and moist climates, it reacts fast.
  • Mixing is not needed, it is a one step adhesive
  • Due to the small foaming, it absorbs small irregularities in the surface.
  • It replaces fasteners through the thermal insulation
  • Equipment is available to reduce labor cost to a minimum.

GLAPOR advises to use this adhesive as an alternative to hot bitumen for reason of fire safety and health.

Recycled glass is pure gold

logo_smallNobody would have believed this 10 years ago, but buying a pile of waste glass brings more added value than bringing that money to the bank. However, converting this pile of glass in windows or even bottles is not possible without proper actions of selecting and ordering this pile into different colours and compositions. But on the other hand, converting into cellular glass is a lot easier, cheaper and brings much more added value.

For a long time, most attention went to the thermal conductivity, the number which was used to compare thermal insulations. In order to improve this number, a lot of primary energy was used to manufacture polymers. On  the other side, fibers were produced and tons of binders were used to assemble these fibers into a workable structure. To improve stability, a higher density was used with even more binder. The minerals were pointing on the combustibility of polymer foams. PIR foams with a lower combustiblity were born, replacing the PUR foams while XPS and EPS were introducing flameretarders in their polystyrene. This is today a problem for the invironment and new flame retarders were developed. The polymer foam industry reacted by generating some doubt about the effect of these mineral fibers in human lungs. For a limited time, mineral fibers got a classification about a risk for cancer. This classification was downgraded to harmless later on. This battle will for sure be continued for the benefit of thermal insulation users.

From heaven, cellular glass manufactures were watching this battle and giving customers an alternative without the above disadvantages, observed with polymer foams and mineral fibers. Comfortable in their 1% niche, they all could work with rather high prices although their production method with molds was rather aged. They were happy with 70 % recycled glass, which did forget that 30% fresh raw materials were still used with a lot of primary energy. Indeed, the polymer foams were using even more energy.

frankAnd suddenly was there GLAPOR, founded and stimulated by Walter Frank, who was inpired by the success of cellular glass gravel. Walter Frank, the Steve Jobs of cellular glass installed an annealing furnace and finishing equipment behind a foaming furnace for cellular glass gravel. With the profits of the cellular glass gravel production, he started testing and improving a board production line with an absolutely free mind. He worked with four principles which are an example of the KISS-principle.

  • Work only with recycled glass, which is not suited anymore for the rest of the glass industry.
  • Minimize the energy consumption by choosing a recipe which allows to work with efficient combustion.
  • Produce large boards, which can be cut to smaller plates later on if requested by the customer.
  • Use only products without any cancerogenic classification

With these principles, he came to a cellular glass product which needs to be thicker to attain the R-value of boards produced by alternative cellular glass producers. These thicker plates are a lot cheaper to produce and the investment in equipment is only of the order of a cellular glass gravel plant. On top of that, these boards are due to their thickness a lot more stiff which is a basic request for large cellular glass boards up to 2.8 x 1.5m. These eur_palette_stapelGLAPOR boards, mostly reduced to EURO-pallet dimensions are really succesfull on the market and are an improved alternative for high density mineral wool. As a side effect, classical cellular users and architects are also finding on their own the way to this product and are enjoying price and size. GLAPOR never stepped into the race of the best thermal conductivity, organized by PIR, XPS, EPS, MW, VIP and the nano-materials. Thin insulation is never strong, a major request by the building industry.

It is clear that for the future other waste minerals will be used and even larger sizes will be produced. Today, up to 7000€/ton is paid to dump mineral wool insulation.  Float glass is produced with a width of at least 5m and there is no reason why this is not possible with a cellular glass boards. Besides the possibilities in prefab building with these large boards, doubling the width halves the labor cost in a cellular glass plant.

imagesWe expect a time where a prefab cellular glass house will be free of charge, construction with guarantee included. The cellular glass producer will be paid by the ones who have to dump mineral wool thermal insulation. In fact, the cellular glass house will be the final grave where converted mineral wool will be “dumped”. All the used energy (thanks to the special recipe) will be clean electricity, produced by wind, solar and the combustion of PIR, XPS and EPS. Indeed, waste (glass) is gold … if converted into cellular glass.


Intelligent prefab with large boards cellular glass

logo_smallIt is clear that the rigidity of large monolithic cellular glass boards (2.8 x 1.5m) can be used as self supporting thermal insulation instead of insulating a brick wall. And we had some ideas like for example the catenerary house.

logoIn Norway, a very creative solution for a cellular glass house without frame or bricks was developed based on cellular glass: the C-element. The elements are a sandwich with a cellular glass kernel and is glued under vacuum. The construction of the elements is patented. The elements are glued together and connected without any cold bridge. The whole system is shown in the website, which includes a movie explaining everything.


The system will be a lot simplified and more rigid when large cellular glass boards as produced by GLAPOR can be used as kernel. Typically, thick cellular glass is used but the structure can be further insulated on the outside with less rigid thermal insulation up to passive housing standards. The cellular glass kernel avoids any problem with humidity in the extra thermal insulation.

We are extremely interested in the evolution of this nice cellular glass project, which uses the mechanical strength and thermal insulation effect of cellular glass for facades.

Reaction to fire

logo_smallRecent fire incidents, where (thermal) insulation has killed many persons has put non-combustibility as a priority. Today, reaction to fire is a big issue in Romania due to the Colectiv nightclub fire. In this club, polyurethane foam, installed as acoustic absorber, started to burn and killed 64 people.

camere_de_supraveghere_la_colectivFire brigade officers are very reluctant to give a  permission for public buildings (especially schools) when combustible thermal insulation is used. Without that permission, the building is not ready (unfit to use) and the contractor do not receive the last part of the money, which is usually more or less his margin. As a consequence, even contractors in Romania are reluctant to use combustible thermal insulation. In case a certain rigidity is needed, they choose cellular glass, even for sloped roofs. The picture on the left is more than enough reason to avoid combustible material. It shows a lot of people in panic in a dead run due the fire in the nightclub.

To classify the building materials according to fire, the EC installed the EUROCLASS system. If a material does not contribute to fire, does not smoke and does not form droplets, which can fall and injure people, it gets EUROCLASS A1 as “reaction to fire” classification. Some materials does not need testing because they contain less than 1% organics homogeneous distributed. Monolithic uncoated cellular glass, like GLAPOR cellular glass has EUROCLASS A1 classification because it (glass) can not burn, does not smoke and does not form droplets.

However, if a large cellular glass board is manufactured by assembling small cellular glass plates with an organic adhesive and paper, the EUROCLASS A1 classification is not given and EUROCLASS E becomes possible. The following table lists all the classifications.



Generally, only EUROCLASS A1 and A2 can be considered as absolutely safe. GLAPOR cellular glass boards with dimensions 80 x 60 cm up to 150 x 280 cm are EUROCLASS A1. For rigid thermal insulation EUROCLASS A1 with these sizes, only GLAPOR Werk Mitterteich GmbH is able to deliver today.

In some cases, polymer thermal insulation manufacturers have included  HBCD in their polymer to improve the reaction to fire. “HBCD is listed for elimination, but with a specific exemption for expanded polystyrene (EPS) and extruded polystyrene (XPS) in buildings.” But this became a problem in Europe because the EC 850/2004  regulation on this is working since October 2016. It reads: “the placing on the market and use in buildings of expanded polystyrene articles and extruded polystyrene articles that contain hexabromocyclododecane as a constituent of such articles and are produced before or on 22 March 2016 shall be allowed until 22 June 2016″.

This will induce another shift to rigid mineral thermal insulation like GLAPOR cellular glass boards or a new formulation like we could find: “BASF is one of the first European manufacturers to have switched its entire portfolio of polystyrene-based insulation products for the European market to a new flame retardant, nine months ahead of the deadline laid down in the EU REACH Regulation on chemicals. Both EPS (expandable polystyrene) products (Styropor® and Neopor®) and XPS (extruded polystyrene) products (Styrodur®) will be manufactured in Europe using a polymeric flame retardant (PolyFR), which has a much better environmental profile than the HBCD (hexabromocyclo­dodecane) used in the past.” In our opinion, all these regulations and change of formulations and still a flashover of less than 2 minutes (600 m for a young talented sprinter) is ridiculous and dangerous like shown above. There is only one definitive solution: GO MINERAL


Cellular glass with 57% discount

logo_smallBetween Turkish building contractors, it is well known that today cellular glass with thermal conductivity 0.041 W/mK can be purchased with 57% discount on the offical price list. It was not clear whether the source is Chinese, European or American but it is important news. It seems that cellular glass as a niche product is almost dead and low margin mass production cellular glass is the future. I started this blog with the following mission: “It is our mission to lower the prices to make cellular glass available for a larger group of people.” and this seems to happen after less than 3 years.

In our view, GLAPOR cellular glass has contributed a lot in this price drop due the development of the following technologies:

  • foaming recycled glass, unfit for botlle or flat glass production with a revolutionary recipe based on glycerin and water glass. This avoids the investment in and use of a glass melting furnace.
  • continuous foaming of a 3m wide ribbon, approaching the final rectangular shape.
  • direct grinding and sawing to larger dimensions (2.8 x 1.5 m) avoiding the use of an (organic) adhesive and paper to manufacture a (larger) sandwich with small cellular glass plates.

In our opinion after further R&D within 3 years, cellular glass, directly foamed from recycled glass (0.050 W/mK) will be sold at 150€/m³ while cellular glass with a special glass composition (ZES cellular glass = 0.040 W/mK) will be priced 200€/m³. To reduce labour cost, the low density boards will be generally sold with  80 x 120 cm (Europallet) dimensions. The mold process is obsolete and will disappear, except for extreme thicknesses (>20cm) and special shapes.

The melting furnace and grinding equipment are still a heritage from the bottle glass / cement industry. We expect that they will be replaced by a one step process reducing the energy consumption with about 50%. At the end, cellular glass will be a direct competitor of mineral wool at the same price level. We expect that the current price drop is only the start like small earth vibrations are announcing an earthquake.

But moreover, we expect that many cellular glass gravel production lines (700,000m³/year at 50€/m³) will be converted to board lines by adding an annealing furnace (CNUD EFCO) and finishing equipment increasing largely the production capacity of low priced cellular glass boards. We also expect that the smart glass recyclers will make the money with this evolution.