Making Tracks with Recycled Glass
As I contemplated what I would discuss in this
first column on recycling glass, I thought of many issues related
to the history of glass recycling, the different types of glass
in the waste stream, options for processing and the markets for
recycled glass products. While I will get to all these issues,
first I’d like to have some fun and reflect on how recycled
glass is being used in a variety of “tracks.”
What is a track? The WorldNet Dictionary defines
it as a set of parallel rails providing a runway for wheels. Processed
to the consistency of a fine aggregate, recycled glass is a commodity
that the railroad industry is interested in using as fill between
railroad ties. The construction and maintenance of railway tracks
requires huge quantities of uniform aggregate that drains well.
It needs to be the same size gradation as the natural aggregates
they currently use and be free of sharp edges. If waste glass
is crushed and pulverized to reduce the size, round the edges
and remove the debris, the resultant glass aggregate will drain
nine times faster than comparably sized natural aggregates, and
it is easier to handle. This is a great choice for the railroad
construction or maintenance company, if they can find an adequate
supply of pulverized glass aggregate to purchase. If they find
it…you have glass on the tracks.
A track may also be a course over which races
are run. The cost and care taken to construct a good horse racing
track is significant and the track base must be well-drained,
absorb impact well but not be so soft as to stress the horse’s
feet and legs. Perma-Turf is a tire chip product preferred by
the equine industry for track construction. For best results,
well-drained “sharp” sand is the preferred aggregate
to be used for horse track construction. When it is pulverized
and screened to a sand consistency, recycled glass is considered
“sharp” sand, not because it could cut when handled,
but because the angular surfaces, as seen under a microscope,
provide more open spaces between the granules. This provides better
drainage and prevents “clumping” when wet. When you
build the best tracks for horse racing…there is always glass
on the tracks.
Recently, I watched the construction of a rather
unique track. First, a roll of fabric about 3 feet wide and 25
feet long was rolled out across the lawn. Pulverized glass sand
- 1/8” to 100 mesh in size - was layered on top of the fabric.
Bystanders lent a foot by compacting the sand with many “tracks.”
On top of the path of recycled glass sand, recycled glass gravel
- 1/8” to 3/8” in size - was layered. A lawn roller
pressed the tumbled glass gravel down into the glass sand base.
A good rain brought out the sparkle and the expected sun for the
wedding gave the bride her wish. She walked down the aisle on
a path of diamonds, emeralds and topaz. For that special day,
there was glass on the wedding track.
A track is also known as a mark left by something
that has passed along; a course or route along which something
travels or moves. Glass recycling has a long track record for
providing responsible and cost effective solutions for the reuse
of a material that would otherwise take a million years to decompose
in a landfill. Glass recycling is also forging ahead, making new
tracks with advancements in processing technologies and the development
of new applications in the market.
Looking back upon the course it has come, I’m
of the belief that glass recycling is finally on the right track.