Best Practices

Benefits of Glass Recycling:

Why Recycle Glass? Glass recycling is both simple and beneficial.

Glass recycling is good for the environment. A glass bottle that is sent to a landfill can take up to a million years to break down. By contrast, it takes as little as 30 days for a recycled glass bottle to leave your kitchen recycling bin and appear on a store shelf as a new glass container. Glass Recycling is Efficient and Sustainable; Saves Energy and Natural Resources. Glass containers are 100-percent recyclable, which means they can be recycled repeatedly, again and again, with no loss of purity or quality in the glass. Every ton of glass that is recycled saves more than a ton of the raw materials needed to create new glass, including: 1,300 pounds of sand; 410 pounds of soda ash; and 380 pounds of limestone. Over 40K lbs of windshield glass is land filled in one month per larger cities. One of the first steps in glass recycling is to crush the glass and create a product called “cullet.” Making recycled glass products from cullet consumes 40 percent less energy than making new glass from raw materials, because cullet melts at a much lower temperature. Because glass is made from natural materials such as sand and limestone, it's glass containers have a low rate of chemical interaction with their contents. As a result, glass can be safely reused. Besides serving as the primary ingredient in new glass containers, recycled glass also has many other commercial uses—from creating decorative tiles and landscaping material to rebuilding eroded beaches.

Best Practices in Glass Recycling

Issue: Recycled glass aggregate is a relatively new construction aggregate material. For this Best Practice, glass aggregate includes 100% glass and glass-aggregate mixtures. In general, glass aggregate is durable, strong, and easy to place and compact. For each application, specifications regarding the cullet content, cullet gradation, debris level, and compaction level are required. Specifications should be generated based on criteria that are related to the engineering behavior of the in-place material. When the material is used in structural load applications, the behavior and properties must be especially well understood.

Issue: Glassphalt has been used since the early 1970’s as an alternative to conventional hot-mix bituminous asphalt pavement. In order to meet roadway pavement standards, glassphalt must be properly mixed and placed, requiring some modifications to generally accepted asphalt procedures.

Issue: Processed recycled glass has been sold as an abrasive blasting medium under several brand names in different parts of the United States. However, limited public information is available regarding the performance of finely sized crushed glass in abrasive applications because manufacturers have developed their own proprietary data. Historically, the predominant material used for abrasive blasting was silica sand, hence the common reference to “sandblasting.” Other media include garnet, staurolite and industrial by-products such as coal slag, copper slag, nickel slag and steel grit. Even walnut shells and plastic beads have been used for abrasive blasting. Individual abrasive media performance depends on hardness, shape, size, weight, and other characteristics. Health- considerations are sometimes significant in evaluating blasting abrasives. For example, concerns about silicosis due to the presence of crystalline silica have resulted in very little silica sand now being used in abrasive blasting. Tests have shown that recycled container glass contains less than 1% crystalline. Lower health risk represents a potential competitive market advantage for recycled glass, which can be processed to physical characteristics similar to silica sand for use as an abrasive.

Issue: Material handling and compaction procedures usually represent a greater cost in a construction fill operation than the fill material itself. Engineers, permitting authorities, and contractors must be familiar with proper handling methods and compaction characteristics of fill material so that practical  specifications can be written, permits can be issued, costs can be estimated, and the fill operation can be performed. Because recycled glass is a relatively new fill material for construction applications, it is especially important to understand its handling characteristics. Dissemination of the best practice information will help engineers, contractors and permitting authorities to understand that: (1) cullet fill has been successfully used on construction sites, (2) cullet fill is a viable alternative to natural materials, and (3) no special machinery or preparation is required.

Issue: Fiberglass insulation manufacturing has grown to be one of the largest uses for recycled glass.

Because fiberglass does not have glass’s clarity, there is an assumption among some that fiberglass raw materials can tolerate higher levels of contaminants than container manufacturing. In fact, metal, organic, and ceramic contaminants can be costly to fiberglass quality and production equipment.

Issue: Epoxy binders are used in countless applications to manufacture composite materials. Some of these applications can use recycled glass as the aggregate. The physical properties required for the application will determine whether glass is an appropriate aggregate. Abrasive flooring is an example of surface texture modification by aggregates. Coefficient of friction floors are increasingly being used in industrial environments where oils or fats on the floor can cause slipping.

Issue: HYDROPONIC ROOTING MEDIUM: This technology briefly describes the results from a study of the use of crushed recycled glass as hydroponic rooting medium. Tests were conducted to compare the performance of crushed recycled glass and an expanded clay aggregate on plant growth. The glass used is crushed, mixed-color recycled bottle glass. While the experiment indicates that glass can serve as a hydroponic rooting medium, its use as such will not likely create a large market for crushed mixed-color cullet. It may, however find a niche market among environmentally minded hobbyists. The results of the experiment also suggest that crushed glass will not negatively affect plant growth when used in gardening and landscaping applications, such as decorative pebbles for indoor bulb gardening, or gravel for garden paths. Crushed, graded recycled glass can be an attractive ground cover or plant mulch.

Issue: Sand filters are a common adjunct to conventional on-site septic treatment systems. Glass can be processed to be a clean, relatively inert, granular material that can be graded in any way required for filtration applications. Slow rate filtration is only one example of a filtration application for which glass appears to be suitable. Investigations into local potential filtration uses could result in new markets for glass processors. Sand filters are part of a nonproprietary anaerobic septic treatment system in which the sand acts as a mechanical and biological filter. Research suggests that using crushed recycled glass in place of sand may lower construction costs and minimize the potential of system failures.

Issue: Most molds used for fusing glass are either expensive to make or are waste molds, only useable one time. In order for small-scale glass fusing businesses to develop, permanent, inexpensive, castable molds from readily available materials are needed. Recycled glass aggregate is usable for this mold.

Issue: When glass cullet is indiscriminately combined with Portland Cement, chemical reactions can occur which may reduce the strength of the concrete. These include sugar contamination and an alkali silica reaction. To minimize the adverse effects of these reactions, ingredients and methods used in standard PCC production should be modified. An adverse result of using glass cullet in Portland Cement Concrete (PCC) is the alkali-silica reaction (ASR). The silica from the cullet or aggregate can combine with the alkalis in Portland Cement to form a siliceous gel. This gel will then absorb water and expand, causing structural weaknesses in the concrete. In addition, when mixed in PCC, sugar can cause an unpredictable increase in setting time and a decrease in the ultimate strength. A number of methods have been proposed to minimize sugar residue contamination and ASR, or to reduce their adverse affects. Research shows that increasing the surface area to volume ratio of the glass will reduce the effects

of the reaction. This can be accomplished by using glass with smaller particles and clean float glass (uncontaminated windshield glass). Finer particles tend to accelerate the reaction, which may allow the gel to expand before the concrete hardens. Research has suggested that up to 20% of the total aggregate should be replaced by clean glass 16 mesh and finer particles.

Issue: Art glass, especially products produced at a studio (hot shop) scale by blowing or casting molten glass represents one of the highest value uses for soda-lime glass. The retail value of these glass products is tremendous on a per pound basis. However, these applications are also among the most sensitive both to contaminants that might affect the clarity, and to chemistry that might affect the workability of the glass. This is a critical market barrier for the use of recycled glass. Although virgin raw material costs may appear high compared with recycled glass, in fact they are often a small fraction of the finished product prices in this application, so any risk associated with using recycled glass obviates against its use. However, in the right kinds of businesses, and if appropriate procedures are followed, hot shops can be successful in using recycled glass to create recycled content products.

Issue: Short of sand, beaches might get crushed glass. A beach in Broward County, Fla. The costs and negative impact of dredging has officials looking at crushed glass as an alternative to natural sand.

Picture a beautiful beach spanning miles of coastline, gently lapped by aqua-colored water — and sprinkled with glass. Ouch? Think again. It feels just like sand, but with granules that sparkle in the sunlight. Faced with the constant erosion of Florida's beaches, Broward County officials are exploring using recycled glass — crushed into tiny grains and mixed with regular sand — to help fill gaps. It's only natural, backers of the idea say, since sand is the main ingredient in glass. "Basically, what we're doing is taking the material and returning it back to its natural state," said Phil Bresee, Broward's recycling manager. The county would become the first in the nation to combine disposal of recycled glass with bolstering beach sand reserves, Bresee said. "You reduce waste stream that goes to our landfills and you generate materials that could be available for our beaches," said Paden Woodruff of the state Department of Environmental Protection. Sand is a valuable commodity in South Florida, where beach related business generates more than $1 billion a year for Broward alone. Sand to replenish eroded beaches is typically dredged from the ocean floor and piped to shore — about 13 million tons of it since 1970 in Broward. That's enough sand to fill the Empire State Building more than 12 times over.

Issue: Terrazzo Flooring is a seamless, poured-in-place, ground and polished combination of post–use recycled glass and epoxy resin matrix. While secondary uses for recycled glass are common in Europe, approximately 75% of American glass bottles, mirrors, and plate glass end up in landfills, which is a shameful waste of this amazing resource. Components have been confirmed to be non-hazardous, non-carcinogenic, non-odorous, non-flammable materials. Terrazzo maintenance requirements are environmentally friendly: daily maintenance of just dry or wet mop with pH balanced cleanser and weekly buffing. Epoxy terrazzo has been shown to have the lowest life cycle maintenance cost when compared to other durable flooring materials. Highly resistant to corrosion, bacteria and chemicals, epoxy terrazzo is designed to last the life of the building. Terrazzo is manufactured on–site, minimizing post–commercial waste and transportation costs, while much of the marble and ceramic floor tile used in American construction is manufactured overseas and imported.

Conclusion

This fact sheet has been designed to address the issue of recycling automobile windshields and other glass.

We are seeking assistance in any way possible to start the windshield recycling business in Tucson, Arizona.

We will be helping existing businesses and possible new emerging businesses with the creation of new jobs and a better future for our community.

 










Imagine, if you will, once our company is in full production, someday in the near future you will be walking on any sandy beach whether on your favorite coastline or your favorite lake or pond and you are witnessing the feeling of the softest sand that you have ever felt caressing your feet while the sight of that same sand is glimmering like stars with each step you take. That is but one resource finely crushed glass can accomplish.

  






Now let me take you for a walk through a flower garden filled with the most precious flowers dear to a woman’s heart. Here you don't see the brown soil wrapped around the base of the plants but the beautiful sparkle of glass sand in its place. This glass sand is actually good for those beautiful sights being utilized both for mulch and drainage and yet is aesthetically pleasing to the eye.

  
 








Picturing beautiful Terrazzo flooring with crushed glass. Giving a shimmering gleam of hope and a feeling of a wonderful accomplishment knowing that you have done your part in helping clean up America and are using recyclable products.

    These are but a few scenarios in the midst of many when we begin to recycle windshields, plate glass etc. However we cannot accomplish this feat alone, we need your help.

(Glass Best Practices Absolute Auto Glass LLC 5/2010)