Glass in Concrete collaborative

Using post-consumer glass in concrete as a cement replacement

In many US cities today, there is a surplus of post-consumer glass collected by municipal recycling programs. The colored glass and small pieces that cannot be used to produce new bottles are many times sent to landfill. 

This post-consumer glass can be used to produce glass pozzolan, a material that can replace cement in concrete. To achieve this, we focus on on:

  • Diverting post-consumer glass from landfill

  • Producing glass pozzolan from post-consumer glass

  • Utilizing glass pozzolan as a cement replacement in concrete


Current Quantities & Uses of Glass and Other Cement Replacements

(Hover or click on chart for quantities)

1. Iron and steel slag quantities (Source: USGS)
2. Slag use as cement replacement (Source: Slag Cement Association)
3. Other figures (Source: ASTM, forthcoming)

Connecting glass recycling and concrete production

Mixed Colored & Small 1 Bottle Glass Concrete Batch Plant Job Site (Cast-in-place) Cement Slag Fly Ash CEMENT REPLACEMENTS Glass Pozzolan Manufacturer Glass Pozzolan Electronics Recycling CRT Panel Glass 2 Demolition and Retrofits Curbside Recycling Window Glass

1 - Pieces smaller than 3/8 inch, which can’t be separated by existing optical sorters.

2 - For more information on CRT panel glass use as a feedstock in pozzolan, see these two case studies by the NY State Pollution Prevention Institute.

Points of Diversion in Post-consumer glass Recycling

Drivers for Change

Many benefits are realized by using post-consumer ground glass pozzolan as a cement replacement. Some primary drivers for this technology are as follows:


Reutilize post-consumer glass

Currently 11 million tons of post-consumer glass are generated every year — 75% of it is landfilled.


Reduce cement use and emissions

Today, 90 million tons of Portland Cement are produced every year, resulting in 90 million tons of carbon dioxide (CO₂) emitted.

concrete_repair_Decorative Concrete King.jpg

Minimize heavy metal content

Other current cement replacements, such as fly ash, may introduce heavy metals in concrete. This can generate health impacts, especially in renovations.

Glass pozzolan is free of heavy metals since it's made of post-consumer glass.


Lessen dependency

On byproducts from non-renewable energy sources, such as fly ash, which is generated in coal-fired power plants.

recycling_mrf_by_Kristian Bjornard.jpg

Nurture regional and circular economies

By resourcing glass debris into beneficial feedstock.

Helps reduce transport emissions and cost, and supports local economies.


Build on strong performance

With workability demonstrated in pilots executed in New York and California.

The Ecosystem

We're currently mapping the Glass in Concrete Ecosystem, including projects, recyclers, manufacturers, and sources. Click on the points in the map below for more info.

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