New Production Fills Critical Need for Foamed Glass Aggregates in Sustainable U.S. Building, Highway Construction and Landscape Architecture Applications

Eddystone, PA (January 15, 2019) – AeroAggregates, the first vertically-integrated  manufacturer in North America to produce ultra-lightweight, closed cell foamed glass aggregates (FGA), has completed installation and is now operational on its second kiln, doubling production capacity to meet growing U.S. demand.

The kilns at AeroAggregates use 100 percent post-consumer recycled glass to produce a building aggregate that is lightweight, non-combustible, insulating, free-draining, non-absorbent, and resistant to chemicals, rot and acid. This makes FGA superior for construction, lightweight embankments, load distribution platforms and insulating subgrade, as well as lateral load reduction behind retaining walls and structures. Foamed glass aggregates also possess a highly frictional surface which makes it ideal as a lightweight backfill.

“Our ultra-lightweight FGA can solve the challenges of today’s infrastructure projects, especially for those that require fill to be placed over soft compressible materials, weight-bearing structures or over areas with sensitive underground infrastructure,” explained Archie Filshill, CEO and Co-Founder of AeroAggregates. “We’re excited to fire up our second kiln in order to meet increased demand from the civil engineering and construction markets that require sustainable, lightweight materials due to specialized design and constructability requirements.”

With the addition of the new AeroAggregates kiln, the equivalent of more than 140 million recycled curbside glass bottles (or 32,000 tons) will be diverted each year, bringing relief to municipal recycling operations. According to a recent study, municipal recycling programs spend approximately $150 million annually to dispose of unwanted glass. The FGA manufacturing process employed by AeroAggregates can utilize mixed color glass and due to its advanced cleaning system is unaffected by small amounts of residual paper and other contaminates.

The new 60-foot foamed glass kiln was imported from Europe where, for many years, FGA technology and manufacturing have been used heavily by the civil engineering market. A recent report by market research firm BauInfoConsult found that the European architects they surveyed intend to use more natural insulating materials (wood wool, hemp, cork and granules such as FGA) in upcoming residential and commercial construction projects reducing their use of polystyrene, polyurethane and polyisocyanurate. Unlike the non-combustible nature of FGA, materials like expanded and extruded polystyrene, commonly used when lightweight construction materials are specified, are falling out of favor in the industry due to their flammability.

The company’s unique FGA manufacturing process, obtained through an exclusive license from a Europe-based firm, starts with curbside recycled glass powder which is then mixed with a foaming agent. The mixed powder is sent through a kiln and softened by temperatures reaching 1,800 degrees Fahrenheit. During this process, the foaming agent creates bubbles within the softened glass, which ultimately creates foamed glass aggregates. The output produced is a remarkable material that creates a superior building product offering many sustainability benefits.

About AeroAggregates

AeroAggregates is the first vertically-integrated company in North America to produce ultra-lightweight closed cell FGA from 100 percent recycled glass. The company’s manufacturing capabilities include the ability to make several types of foamed glass including both open and closed cell aggregates. The founders of AeroAggregates realized the need for a sustainable solution for lightweight construction materials due to increased design or constructability requirements. Today’s civil engineering challenges include construction on soft soils, lateral load reduction behind retaining walls and structures, insulating subgrade and backfill, and the protection of underground utilities. AeroAggregates provides an answer to many of these challenges by supplying a lightweight material with a high friction angle that is also insulating, free-draining, non-absorbent, non-combustible, and resistant to chemicals, rot and acid. Its manufacturing plant is located in Eddystone, PA, a brownfield redevelopment site that was formerly the location of Baldwin Locomotive Works. Visit www.aeroaggregates.com for more information.

UBP is the German abbreviation of Umweltbelastungspunkte, which is a result of  “Methode der ökologischen Knappheit”. The method is invented in Switzerland , which explains the use of the German language. In English, we speak about the  Ecological Scarcity Method (which has no Wikipedia page).

An EPD gives you for the production of each product how much CO2 is generated, how much fossil energy is used, etc. These 8 numbers don´t say a lot to the common consumer. The UPB combines the impact of all these emissions and material-energy use on the environment, the future of the raw materials and our health in only ONE number. The method is defined in a paper by the Swiss government and also Volkswagen has sponsored a publication. But for the standard consumer, I have the following table with the quantity of products for 1000 UBP.

This method is also applied for thermal insulations on the Swiss market which can be found in this spreadsheet.

GLAPOR communicates 690 UBP per kg cellular glass board for production in Germany and delivery in Switzerland, which is lower than any thermal insulation except foamed glass gravel (also a GLAPOR product) like shown in the following figure. The improved value compared with “Schaumglas” is due to the fact that GLAPOR foams directly recycled glass without melting a special composition. In case production should be in Switzerland, the UBP lowers to 552 UBP/kg.

For a fair comparison of thermal insulations, we have to work with UBP/m² for a certain thermal resistance (R=5 m²K/W) to be obtained. This table is given in the following:

It is clear that according to the UBP system in Switzerland, GLAPOR cellular glass boards are the most ecologic thermal insulation which can take a compressive load of 600 kPa with a safety factor = 2.5. This is a consequence of the direct foaming of recycled glass. Standard cellular glass is made from a special glass composition involving an energy intensive melting step. In case cellular glass gravel is used, it is needed to use the RDS-system of GLAPOR to keep the gravel dry in order to have the best ecological solution.

Every cellular glass factory has his “temperature curve expert”. These experts observe a cellular glass foam and know in a lot of cases how it can be improved by changing temperatures, foaming agents, …. . Their knowledge and availability have a strong influence on the quality and production yield of a factory.

In the past, managers have tried to describe their knowledge in a ISO9000 system or another system with procedures. This has never worked properly because the “book” knows always less than this person. This was always clear when this person was not present in the factory, the yield drops temporarily.

Ten years ago, we needed Kitt in Knight Rider to see a self driven car, but today Tesla and many others have converted this fiction into reality. And I guess that this “machine learning” technology will enter the (cellular) glass factories soon. I expect that neural networks will do the job, because the data for input and output are already available.

Neural networks (NN), programmed in Python, based on Numpy are a good candidate because they are open source and will be fast further developed. Indeed, the NN can be trained with the massive amount of data from the past and present. To obtain a new quality, the NN will find a new solution with data from the past like today the operator is doing by using his experience. Moreover, the NN of collaborating factories can be coupled and the operator experience will not be lost after retirement.

I was very nice surprised about how architects in Europe are looking into the future of thermal insulation. The enquiry was done  by BauInfoConsult with 1600 architects in 8 countries in Europe. 

The tendency is clear:polymer (plastic) thermal insulation like EPS, XPS, PIR and PUR are decreasing while natural  and mineral insulation will increase. Of course the last tendency is interesting. We further have to explain the customer that in case a certain mechanical stability is needed, a cellular structure is more appropiate than a fibrous structure. And if humidity and air tightness are a issue, cellular glass is the only option. 

Once cellular glass is choosen, we have to explain that direct foaming of recycled glass in a continuous system is the cheapest and most ecologic solution. This technology is invented and developed by GLAPOR. After a life in cellular glass, I feel that the future is great without limits. 

Some years ago, we wrote a post about a comparison between mineral wool and cellular glass. And suddenly during the last months, this post became popular like shown hereunder. 

It is not clear which (GOOGLE or WORDPRESS) mechanisms are eventual repsonsible and I assume that some people are just interested. Like explained in this previous post, it is not clear why engineers should choose for fibrous structures when mechanical stability is involved. A cellular glass structure is obviously better for this kind of applications. On top of that, cellular glass with closed cells cannot have any issue with humidity due to internal condensation and water absorption. In that case, you think that the price is the reason to choose for mineral wool. 

As an example, we have taken the data from FLUMROC in Switzerland, a company producing mineral wool since 1950. We consider the three types with a mechanical stability. FLUMROC PRIMA , 341 and MEGA are mineral wool boards with different densities and allowabel loads. The properties and price are listed hereunder. 

For comparison, GLAPOR cellular glass PG600 has an allowable load of more than 250 kPa at 130 kg/m³ and can be bought for 280€/m³ without negociation. This is 6 times the one of FLUMROC MEGA ,160 kg/m³ density priced 438€/m³. After correction for the thermal conductivity (0.045 W/mK) to be compared with 0.054 W/mK for GLAPOR PG600, we arrive at 365€/m³ to be compared with 280€/m³ for GLAPOR cellular glass with 6 times higher stability. 

GLAPOR PG600 involves grinding and foaming at 800°C of 170kg recycled glass while FLUMROC MEGA needs minimum 160 kg basalt and recycled glass, melted at 1600°C and again reheated at 200°C for the binder. It is logic that mineral wool with a 6 times lower stability is more expensive than cellular glass. But is is not logic that people prefer mineral wool with a lower stability, humidity risks and even more expensive unless the acoustic absorption is needed. It seems that some types of cellular glass have a serious marketing problem.

In 1987, I have written my PhD-thesis and Word Perfect was the only text processor available on a PC. In that time, the university was giving some financial support for a PhD-thesis, printed in two colums in landscape. However, with LATEX and a laserprinter, this became very easy and a year later, the financial support was removed. Also Internet was not available in that time and “Open source” was something we did not know and we believed was impossible.

I remember that LATEX was really more difficult to use compared to Word Perfect but it was easy to include formula in your text. After the introduction of Word and Windows, I used Word or an open source version like Libreoffice, because I was to lazy to work with the difficult LATEX.

But times have changed. A LATEX editor like Texmaker and a latex2pdf converter like Miktex under Windows is a good team, which helps to remember all the commands in LATEX. On top of that, GOOGLE helps you with all possible problems by simply copying the error message in the editor.

Today an excel-table is easily incorporated by using the (LATEX) table generator or by including a CSV-file. Also figures are easily included and absorbed in the text in a professional way. Every symbol you can imagine is available if you search in this document. Citations and footnotes are easily included and all kind of accents and fonts are available with any keyboard. I write in Dutch, English, German, French and Czech and in Word you need a lot of keyboards or a very good memory. For tables, figures, formula, citations and footnotes, an automatic numbering system is available. A table of content, list of figures and tables is generated with only one command. There are packages for each style: an article, a letter, a book, a presentation, an invoice, a report, …. . In fact, your hard intellectual work will be presented in the best way possible.

I challenge everybody to find something about typesetting which does not exist with LATEX. In the unexpected case you should succeed, it is possible to program your own package and to upload it in the LATEX society.

But in fact you don´t need to install software on your PC. Overleaf is the best place to start with your document in Latex. And in case you are working under Linux, Latex is probably already preinstalled. Also on Android LATEX editors are available included the converter to pdf. I tried already VerbTeX.

It can be interesting to find out how people arrive at your blog. The blog  “And the lightest beam is … cellular glass “, published in January 2018 is getting a lot of attention with an exponential growth.

Michael Ashby has already mentioned that a glass foam would be the most interesting self supporting material but this statement had less value with monolithic boards measuring maximum 60 x 45 cm. However, since GLAPOR introduced the large monolithic cellular glass boards 280 x 120 cm, produced with the modern continuous foaming method, this statement became very important.

Indeed, the following graph shows the number of the specific blog visits since publication in 2018.

It is also clear that besides the large dimensions GLAPOR cellular glass has the most interesting recipe for this application. Indeed, GLAPOR foams directly recycled glass without melting a special composition. This recipe is interesting from the ecologic and economic point of view.

Float glass technology is quite attractive for cellular glass and writing a blog is good method to think about the advantages and disadvantages. I spent already a blog on a patent and on a paper, which showed that the powder method could be history. One major question is why the flat glass world converted to float glass technology?

Before the float glass process became developed, quality glass needed to be ground and polished to get a smooth surface. Like described in this patent of Pilkington, introducing the hot glass on a molten metal bath with temperature treatment delivered a plan parallel glass pane, which could be used without grinding and polishing. The non-interaction between 100% flat molten metal and molten glass is the main reason for this huge development. However, a fire finished glass surface is not needed for cellular glass.

Like shown in the previous blogs, the tin bath is suggested only to be used as transport carrier during the foaming of the glass. This is a much more expensive solution than the a belt which turns around within the furnace without leaving and so reheating. A glass fleece can be used to avoid sticking of the foam on the steel belt.

The more I think about using a tin bath, I see a lot of  advantages evaporating if compared with a steel belt, turning around strictly inside the furnace. Especially the previous paper, which gives an an alternative to the powder method, could be much easier executed by putting the ribbon on a belt,  instead on a tin bath. But on the other hand, the float process could become a 100% non-waste process because the ribbon should be perfectly flat and plan parallel. If the non-powder method on a belt would be the second generation, on a tin bath would it become the third generation process. I have the feeling that after almost 90 years cellular glass, we are just at the beginning.

2018 was indeed a fruitful year for the development of cellular glass.  In a previous post, I already declared the Aalborg – Ljubljana team as the one who made the largest progress during the last year with consequences on the market the next years.

But yesterday, I found a new paper, published in 2018 with an extremely important experimental fact. This paper proves that it is possible to produce a glass foam with an homogeneous and CLOSED cell structure with only a melting step at 1100°C without grinding and sintering process. I give here under the abstract:

Glass foams are being widely used as constructional materials due to their unique properties in thermal insulation, fire retardation, and shockwave absorption. However, the cost of energy consumption and processes in a conventional glass foam production limited the use of glass foams as sustainable materials. In this study,
for the very first time, thermally tunable CaO−SnO2−P2O5−SiO2 glass foams with controllable pore size were presented as a novel category of melt-casting and float-manufacturable glasses. It was found that the pore size and thermal properties become tunable by manipulating the glass network, i.e., connecting linear chained Sn−P
network with [SiO4] units. In addition, the unique combination of thermal properties and porous structure of CaO−SnO2−P2O5−SiO2 glasses shows potential in float glass foam production, which can produce glass foams sheet-by-sheet with less complexity in
manufacturing processes.

This means that this glass foam can be formed with the floating method on a tin bath, generally know as the float glass process, invented by Sir Alistair Pilkington.

This foam should have NOX gases in the cells but density, thermal conductivity and compressive strength are not given. The authors claims that this will be the route to low cost cellular glass. I see the following positive and negative points.

• By working with top rollers like for float glass, it could be possible to flatten the cells and to tune the couple thermal conductivity / compressive strength. 
• There are no belts or molds which have to be replaced, molten tin is doing this. 
• There is one heating step to 1100°C to be compared with a heating to 800°C after energy intensive grinding. 
• The glass composition with phosphates and tin oxide is probably costly.
• It is not clear that replacing tin is less costly than replacing a steel belt or molds.
• A lot of (expensive) heat has to be extracted at the bottom of the tin bath to avoid that molten tin hits the steel casing. 
• It is not clear how we keep the same temperature under and above the foam because heating the molten tin is not needed for float glass. 
• A typical float glass line costs typically 130 000 000€ while a low cost cellular glass production line, based on direct foaming of waste glass costs less than 20 000 000€.

Nevertheless, this invention is of major importance especially when the waste glass becomes less available and in that way more expensive. In fact, we could speak about the continuous foaming second generation and it will be a major challenge to develop this new process. Alistair is dead, long live Alistair.

In a very short time, I see that phosphates are introduced in the cellular glass world. The first time as a crystallization inhibitor, the second time now for a “grinding-sintering free” cellular glass process.

In this blog, we have written about boards, gravel and boards made of foamed glass granulate. But up to now, we never discussed the foamed glass granulate itself. Foamed glass granulate is produced in a rotary furnace. I guess that white granulates  are foamed by using white sodalime glass with Calciumcarbonate as foaming agent. The following picture shows a rotary furnace from Liaver.

The Genius group, an organization which focuses on innovation, uses foamed glass granulate for fire protection and to absorb liquids. I give hereunder a citation from their website

• PyroBubbles^® have been positively tested by the MPA Dresden (in compliance with DIN EN 3-7) as an extinguishing agent for solid and liquid flammable materials (Fire Classes A, B, D and F).
• PyroBubbles^® are the ideal filler for storing and transporting lithium-ion batteries (UN3480, UN3090) and are lighter than sand (approximately 235 kg/m³).
  PyroBubbles^® consist mainly of silicon dioxide with an average grain size of 0.5 to 5 mm.
• PyroBubbles^® absorb electrolytes (BAM tested).
• PyroBubbles^® have a low thermal conductivity and electrical conductivity and are electrically insulating.
• PyroBubbles^® are heat resistant to approx. 1050°C. At higher temperatures they begin to melt and form a closed and thermally insulating layer around the source of the fire.
• PyroBubbles^® float on the surface of the liquid and are particularly well suited for fighting flammable liquid fires, independent of polarity.
• PyroBubbles^® can be collected and to a large extent be reused after every application.
• PyroBubbles^® are hydrophobic and resistant to aging.
• PyroBubbles^® comprise porous hollow glass granules and are classified as Class A1 building materials (DIN 4102 and EN13501); they feature excellent processing capabilities.
• PyroBubbles^® require no maintenance and thus generate low maintenance costs.

This is clearly a new approach to clean up (industrial) disasters with waste glass and it can be recovered to be used again. In the datasheet, they mention a thermal conductivity and acoustic absorption. These properties are important for boards produced with these granulates like already mentioned in a previous post.