Vent: A homeowner in Tempe asked me why we don't use more recycled glass in the mix

I was finishing a driveway for a guy last Friday and he was watching us work. He asked if we ever put crushed glass in the concrete for sparkle, said he saw it online. I told him it can mess with the cure and cause weak spots. He just said 'Shame, seems like a waste.' It got me thinking about how often we just say no to new stuff without really looking into it. Has anyone actually had a good run with glass aggregate on a non-decorative pour?

3 comments

3 Comments

jade32mo agoOG Member

My cousin's crew did a patio with some recycled glass mixed in. They kept it under ten percent of the total rock, used the really fine crushed stuff. It held up okay for a couple summers, but then you could see these weird shiny flecks popping out where the surface wore down. Just didn't stick for the long haul.

xena_rivera632mo ago

My buddy tried it on a small garage slab about five years back. He used finely crushed bottle glass, maybe twenty percent of the aggregate. The finish looked nice, but hairline cracks showed up everywhere within a year. He figures the glass just didn't bond right with the cement paste.

the_julia11d ago

The bonding issue is real but it's not just about the glass size. @jade3 Your cousin's crew probably would have had better luck if they washed the glass first with a mild acid. Bottle glass has a slick surface from manufacturing and the tiny scratches from crushing aren't enough. Your buddy xena_rivera63 probably had the same problem. Twenty percent is a lot to add without treating the glass first. A quick vinegar bath before mixing can give the cement something to grab onto. I've seen it work on small projects where the glass was prepped right.