How tons of old TV and computer displays could become new sustainable buildings

The death of cathode-ray tube (CRT) displays—once commonplace for TVs and computers—is a far too familiar story of what happens when a popular technology becomes obsolete. Once expensive, sought after equipment is suddenly, in the blink of an eye, obsolete junk. But what happens when there’s nowhere to put that junk, not even a landfill? 

CRTs contain funnel and panel glass. The former, funnel glass, is made with lead and has been classified as hazardous waste by the U.S. Environmental Protection Agency (EPA). Left in a landfill, the lead can leach into local water supplies and soil, putting communities and the environment at risk. A once booming international aftermarket for recycling CRTs has receded, making it too expensive for salvage companies in the U.S. to ship them overseas. The capacity for recycled CRTs stands at 128,000 tons, but that’s 78,000 tons shy of the estimated 206,000 tons expected to be collected in the U.S. this year. 

This market shift has resulted in a stockpile of about 270,000 tons of CRTs across 14 U.S. states. Additionally, the Association of State and Territorial Waste Management Officials reported in 2017 that over 150,000 tons of CRTs had been abandoned by salvagers nationally.  

Never say “unrecyclable”

Louis Grasso Jr. is the managing director of Urban Mining Northeast (UMNE) in New Rochelle, New York. While at an event held at Google’s headquarters in Mountain View, California, Grasso was challenged to find a sustainable solution for the CRT glass problem. He was up for the challenge—difficult-to-recycle glass is UMNE’s bread and butter, after all. 

UMNE manufactures a high-performance pozzolan called Pozzotive®. It is not only made entirely from postconsumer glass, but glass that would otherwise go into a landfill. 

Over the past fifteen years, the amount of glass put out for recycling that ends up in landfills has skyrocketed. That’s largely due to the wide-scale adoption of single-stream collection in the U.S., where all material—paper, plastic, metal, and glass—goes into one bin. It makes life easier for residents, but there’s a tradeoff: The percentage of glass that gets recycled has dropped from 90% to 40%. Most people would be surprised to learn that 40% of the glass that goes into their single-stream recycling bin ends up in a landfill. That’s a jump from only 2% in a dual- or multi-stream system. 

UMNE sources glass from material recovery facilities (MRFs)—known as MRF (say “murf”) glass—as a feedstock for its innovative building material. But Pozzotive® isn’t only diverting a problematic waste into a profitable use. As a pozzolan, it’s also reducing the greenhouse-gas footprint of concrete construction as a replacement for cement. The production of traditional cement—ordinary Portland cement (OPC)—is incredibly energy-intensive, using roughly ten times the national average ratio for energy-to-gross-output of goods and services.

Soon after his trip to Google, Grasso partnered with Staples, the office supplies, furniture, and technology retailer, and Electronics Recyclers International Inc., an electronics recycler with facilities across the U.S. Together, the companies posed a question: Would the glass components of a CRT work as a feedstock for Pozzotive®? 

A concrete answer

“The results have assured us that this is a winning solution for the electronics, recycling, and building industries: eliminating a growing waste glass problem and creating a superior product for green building.” - Louis Grasso Jr., Managing Partner, Urban Mining Northeast LLC 

To find the answer, the groups sought the assistance of NYSP2I. Researchers at NYSP2I outlined a plan for generating the data and performing the analysis that would support an informed engineering and sustainability decision. 

The NYSP2I team’s first step was to determine the functional feasibility of CRT panel glass—the lead-containing funnel glass can’t be used—as a Pozzotive® ingredient. This work was performed at material-testing labs at Clarkson University in Potsdam, New York, an NYSP2I partner.  

The researchers knew that CRT panel glass wouldn’t work as a pozzolan on its own. Their goal was to determine the degree to which it could be blended with the MRF glass in Pozzotive® and still perform as well as traditional OPC. To do this, they created two blends: one containing 5% CRT panel glass and another with 15%. 

Both blends proved to perform as well as traditional OPC. The study also confirmed that they met the ASTM International’s standard for pozzolan use in concrete, making it viable as an industrial product.

Next, the researchers evaluated if using CRT glass would lower or improve the overall sustainability of the original Pozzotive®. To do this, a life-cycle assessment (LCA) was performed to measure the environmental impacts of the original Pozzotive® compared to the two formulas containing CRT panel glass. The LCA assessed all raw materials used and impact contributions from transportation and manufacturing processes. Finally, this LCA data were used to compare the sustainability of both the Pozzotive® and the CRT-MRF glass blends to that of OPC. 

The CRT-MRF blend not only performed just as well as OPC, it was also far more sustainable. Armed with clear analysis and data, Urban Mining and their partners were able to make an informed, strategic decision for investing in a business opportunity that addresses a serious waste problem in the U.S., advances green building materials, and shows concretely how the circular economy works.  

Read “The functional and environmental performance of mixed cathode ray tubes and recycled glass as partial replacement for cement in concrete” by Brian Hilton, Kimberly Bawden, and Kathryn Winnebeck of RIT, and Cathurani Chandrasiri, Erandi Ariyachandra, and Sulapha Peethamparan of Clarkson University here.