Recycled glass countertops
Recycled glass countertops are composed of 100% recycled glass (post consumer and pre-consumer) in a cement or petroleum based binder. A finished recycled glass countertop often ranges from 70 to 85 percent in recycled content.
The glass used in recycled glass countertops is sourced from both post-consumer and pre-consumer sources. Post-consumer recycled glass sources are numerous, but the most common sources are curbside recycling and salvaged glass from demolished buildings.
Curbside recycled glass from homes and businesses is the largest source of post consumer recycled glass (California recycled 79% of its glass bottles in 2008), but salvage glass is an emerging new source. Many more state and municipal governments have begun to mandate the separation and recycling of the glass pulled from demolished buildings.
Where the recycled glass countertops are made is another variable that is taken into account when determining the sustainability of a recycled glass countertop. At this time most of the companies manufacture their products in the United States, but recycled glass countertops have gained international interest. Now some foreign companies have begun to export recycled glass countertops to the USA. This practice of importing heavy (14.5 lbs/sqr ft) recycled glass countertops from overseas when there is such a large quantity of recycled glass in the USA has quickly come under scrutiny. The Leadership in Energy and Environmental Design (LEED) certification program has begun to put increasing weight on the importance of regional manufacturing to reduce the carbon footprint of building materials. This focus on materials made in the USA has the secondary affect of encouraging the support of US business in a time of economic downturn.
Several recycled glass countertop manufacturers have committed to providing green jobs to the low-income neighborhoods surrounding their manufacturing facilities. Some, but not all of the manufacturers use facilities that are solar powered and/or day-lit by south facing skylights. These manufacturers will also incorporate some degree of water recycling in their polishing process.
Cement vs. petroleum binders
The use of cement versus petroleum based binders has raised some questions about the sustainability of petroleum binders for a number of reasons. The use of a petroleum binder creates a less expensive product, but its performance withstanding heat is diminished and therefore shortens the lifetime of the product. Unlike the products that use the cement binder, the petroleum binder products are not as easily recyclable at the end of their life. However, cement-based products are the second largest contributor of greenhouse gases.
Petroleum based binders do present the advantage that they do not need to be sealed once to twice a year like cement based recycled glass countertops. However, the sealing process is a simple 20 minute procedure: clean surface, spray on a stone sealer available at any hardware or garden store, let sit 20 minutes and wipe away.
The potential environmental benefits of finding a secondary market for recycled glass may be outweighed by the vast amounts of greenhouse gas produced in the production of standard cement. With nearly a ton and a half of CO2 released in the manufacturing of a single ton of cement, the binder used in these composites is among the planet's most egregious polluters.
The Alkali-Silica Reaction (ASR), which occurs when glass aggregate is combined with cement, produces production difficulties for recycled glass surfaces that may compromise structural integrity if left unaddressed. Ongoing research at Columbia University and Argonne National Labs has ruled out glass and cement composites as a viable alternative to conventional surface materials, but new technologies are under development which may mitigate the challenges of producing these surfaces.
USGBC LEED Website - http://www.usgbc.org/DisplayPage.aspx?CategoryID=19
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