Volume 28, Issue 4 - July/August 2014

Glass Tech

Before and After
A Close Look at the Recyclability of Glass
by Erin Roberts

Editor’s note: the following column is adapted from the Glass Association of North America’s (GANA) Glass Informational Bulletin (GIB) titled, “Recyclability of Architectural Glass Products.” It was developed by the GANA Decorative Division and approved by the membership and the GANA board of directors. Consult the Tech Center section of the GANA website ( for additional Glass Informational Bulletins and flat glass industry reference resources.

The interest in recycling architectural glass products is growing; however, information on companies offering recycling services is fragmented and difficult to find.

Architectural glass is being recycled throughout North America. Due to the weight of glass, the proximity between the glass fabricator, the recycler and end user is important. The supply chain begins with the glass fabricator shipping its cullet or other glass fragments to a recycling company, which will grind the glass into smaller pieces. This crushed glass generally is placed in 50 pound bags and sold to the end user or manufacturer of derivative product.

Glass Recyclability

A wide variety of architectural glass products can be recycled. Annealed, tempered and low-E glass can be recycled with few restrictions, with the exception of the need to separate contaminants.

Laminated, mirror, back-painted, ceramic frit and insulating glass units, however, are not accepted by all recycling locations. Glass fabrication facilities should establish a working relationship with the nearest glass recycling or processing company prior to shipment to ensure the product is accepted. This will also provide significant transportation savings. Recyclers also typically accept glass from other industries, such as lighting and automotive, and from replacement glazing and refurbishing of existing buildings. Glass received by recyclers may be sorted by color and substrate to ensure the sender receives the highest level of compensation.

Contamination with other elements is a major concern. Aluminum or any other non-glass components will be separated to ensure a quality crushed product. Some recyclers have the ability to handle glass and metal components, but mixed loads should be coordinated with the recycler.

Products Originating from Recycled Glass

Some products made with recycled glass can contribute to LEED® credits. The contribution must be evaluated individually.

Fiberglass: High levels of recycled glass can be found in insulating fiberglass products. In certain cases, recycled glass constitutes 73 percent of product material. Energy savings is a primary benefit of using recycled glass as it reduces the costs associated with manufacturing. According to Owens Corning, a fiberglass manufacturer, the company uses more than 1 billion pounds of crushed glass annually.

Glass Containers: The glass container industry uses recycled glass in its manufacturing process. Companies such as Owens-Illinois Inc. (O-I), can use up to 25 percent of post-consumer glass in its North American plants. The post-consumer glass typically comes from local recyclers. The use of recycled glass in the manufacturing of glass containers also contributes to energy savings. According to O-I, the use of 10 percent recycled glass content contributes to 3-percent energy savings in its finished products.

Roadways: Crushed glass has recently been used as a material for roads and highways. In 2005, the city of Sherbrooke in Quebec used nearly 950 tons of crushed glass as the foundation of a road bed. Similarly, Idaho began using crushed glass in the state’s road beds beginning in 2008. Approximately 1 percent of recycled glass is used in Idaho’s road projects, saving the state about $2 per cubic yard over regular road base. Significant savings also come to the recycler from not having to carry the recycled glass out of the state [Idaho], which was estimated at about $28 per ton. Spokane, Wash., also experienced similar savings by incorporating recycled domestic glass into roadway construction projects.

Highway Paint: Clear, low–iron, and a small percentage of tinted glass are used in the production of highway paint to create a reflective surface. The glass is not mixed into the paint but sprayed on top of it. The average amount of crushed glass needed for one mile of a continuous strip of paint is more than 102 pounds. Potters Industries, for example, delivers 23 million pounds of recycled glass for the highway paint industry in Eastern Canada.

Terrazzo Flooring: Some Terrazzo flooring is produced using 100-percent recycled glass as one of its primary materials. Terrazzo countertop and flooring manufacturers often mix crushed mirror with their glass aggregate for these applications. A floor using crushed glass as a primary material may qualify for LEED® points.

Recycled PVB Interlayers: Laminated glass is used frequently in architectural applications that require lamination as a measure of security by code or simply for aesthetic reasons. It is now possible to recycle not only laminated glass but also the PVB interlayer. Shark Solutions has developed a process to separate the glass and the interlayer, allowing both materials to be recycled. PVB is first separated from the glass. Then, similar to the process of recycling glass, PVB is reduced into different sizes or forms, such as fleck, pallet, liquid or new film. The main consumer of recycled PVB is the carpet industry, which uses recycled PVB in the carpet backing.

Other Usage and Applications

Recycled glass products can be used as abrasive material to strip paint as well as in the aeronautic industry for metal finishing. International companies such as Pratt & Withney and Bombardier are using specific kinds of recycled glass to polish metal. In addition, some companies use recycled glass as decorative glass nuggets for use in landscaping.

As technology continues to evolve, more types of glass products will become recyclable and new industries will be able to use recycled glass in their manufacturing processes. Technologies and the demand for products are changing rapidly. AGG

Erin Roberts is the director of marketing and communications for the Glass Association of North America in Topeka, Kan.

Architects' Guide to Glass & Metal
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