Material: Recycled
Glass
Issue: Epoxy binders are used in countless applications to manufacture
composite materials.
Some of these applications
can use recycled glass as the aggregate. The physical properties required for the application
will determine whether glass is
an appropriate aggregate.
Best
Practice: “Epoxy” is a term referring to a family of resins, usually thermosetting,
capable of forming tight cross-linked
polymer structures marked by toughness,
strong adhesion, and high corrosion
and chemical resistance. Epoxies are generally two-part systems consisting
of a resin and a hardener or activator
that are combined in specific proportions
to initiate a curing process.
Epoxies are sometimes used
by themselves in applications such
as industrial tooling.
However, epoxies are also
used as binders to make composite
materials. In most of these cases, epoxies are combined with inert aggregates
to achieve specific properties.
When epoxies are combined with aggregates, the purpose
of the aggregates may be to lower
the cost of the composite by adding
volume to the epoxy, change the
surface texture, increase the wearability
of the surface by adding a harder
aggregate, or improve the aesthetics
of the surface by adding colored
aggregate to clear epoxy.
When epoxies are used to make molds, the epoxy may
be the most expensive component
in the mold mixture. Other inert materials may be added to decrease the expense of the
mold.
At the same time, the addition
of appropriate lightweight inert
aggregates may also lighten the
weight of the mold.
In some cases, denser materials
may be added to increase the density
of the mold.
Abrasive flooring is an example of surface texture
modification by aggregates.
Coefficient of friction floors
are increasingly being used in industrial
environments where oils or fats
on the floor can cause slipping.
Hard aggregates may either
be combined with epoxy binders before
applying to the existing base floor,
or may be broadcast onto the surface
after the epoxy has been applied,
but before it has hardened.
Some abrasive tools are made by combining hard aggregates
with epoxy binders. The aggregate
is harder, sharper, and wears slower
than the epoxy.
The epoxy holds the aggregates
together while the aggregates abrade
the target surface. The binders and epoxies wear together, constantly
exposing a new abrasive surface.
Many composition countertops are made with epoxies
and aggregates.
The epoxy is clear.
The aggregate adds color
and improves surface properties
such as resistance to knife cuts. In all of the applications described above, the important
characteristics of the aggregate
are that it possess the correct
physical properties for the application,
and that the epoxy binders adhere
adequately to the surface of the
aggregate.
Crushed, graded recycled
glass has been tried in a number
of epoxy/aggregate applications.
Coefficient of friction floors
using glass instead of the standard
grit have been laid.
Countertops using crushed
glass rather than colored stone
have been made. In countertops, it has been found that, while
glass adds aesthetic appeal, machining
the glass/epoxy countertop wore
out tools faster than machining
the stone aggregate/epoxy countertop.
Experience to date indicates that the epoxies tried
have adhered properly to the glass
surfaces.
Since epoxy appears to adhere
adequately to glass surfaces, the
functionality of glass as an aggregate
in these applications will depend
largely on the specific physical
properties desired and the cost
of the glass.
In most cases, it will be
necessary for the glass to be processed
to industrial minerals qualities
in the appropriate gradation for
the glass to be acceptable.
Implementation: A glass processor seeking a market for crushed, graded glass
may want to contact businesses manufacturing
epoxy composites. The physical characteristics of the glass,
the capabilities of the processor,
and cost will determine the market
potential.
Benefits:
Glass is an inert, hard,
sterile material which, when properly
processed, may find markets as an
aggregate in epoxy composite materials.
Application
Sites: Manufacturers of epoxy
composites
Contact: For more information about this Best Practice, contact
CWC, mailto:info@cwc.org. Issue
Date / Update: November 1996 |
