Here's how ordinary, post-consumer recycled glass turns into a sustainable building material. Recycled glass is prepared with cleaning and grinding, before mixing with a foaming agent and being kiln fired.

Glass Processing

Foam glass starts as post-consumer recycled glass. Container glass is received from local Materials Recovery Facilities, where it’s crushed into a coarse powder and cleaned to <1% impurity. Foam glass can be cleaned to a lesser extent, but that can create consistency issues. Cleaning glass to such a stringent extent will give Glavel’s foam glass superior materials properties. The coarse glass powder is ground into a find powder using a ball mill, which is then prepared for foam glass firing.

Recycled glass to foam glass. Photo: Oliver Parini
crushed glass

Glass Firing

The conversion of glass powder into foam glass begins with blending the powder with an environmentally-friendly foaming agent. The mixture is then fed through a continuous belt in a tunnel furnace.  As the mixture is heated to a specific thermal profile, the glass softens, while gases formed by chemical reactions create a network of suspended micropores. These micropores become the closed cell network, giving foam glass its thermal insulation and waterproof structure. Upon cooling, thermal stress causes the foam glass sheet to crack into aggregate sized pieces, which are then fed off the kiln belt and into a bunker for packaging. 

crushed glass

After production, foam glass is packed into 4 cubic yard bags, which are stored and ready to be shipped. Since foam glass is made entirely from recycled glass, it carries the physical properties of glass with it remaining deformation-free, chemical free, watertight, and wear-free. For more information about foam glass uses and properties, find our products page.