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Best Practices in Wood Waste Recycling Click here for printable PDF version Specification for Inorganic Bonded Fiber Composites
Material: Wood Waste
Issue: Inorganic bonded fiber composites include building materials such as
wood-cement
board
or
wood-gypsum
board.
The
materials
consist
of
a
wood
fiber
or
particle
component
that
is
bonded
within
an
inorganic
mineral
matrix.
Aged
wood
waste
often
performs
better
than
virgin
wood
in
this
application.
Degradation
of
wood
fiber’s
hemicellulose
improves
wood-cement
bonding
strength. These weather and fire-resistant products are
produced
for
sub-flooring
panelboard,
roofing
shakes
or
shingles,
tiles,
siding,
fencing,
cladding,
or
building
blocks.
Currently in
the
U.S.
wood-cement
composites
are
produced
in
the
form
of
cement-bonded
particleboard
roofing
products
and
cement-bonded
building
blocks
and
slabs.
Production
volume
of
these
products
are
low
compared
to
the
traditional
resin-bonded
wood
composites.
However,
the
potential
market
for
these
products
are
significant.
Cement-bonded
particleboard
manufacturers
do
not
presently
use
wood
waste
feedstocks,
but
have
expressed
interest
in
using
this
resource.
Slab
and
block
products
have
the
greatest
potential
for
integrating
wood
waste
feedstock.
Satisfying
the
cement
composite
manufacturer’s
specifications
and
product
quality
expectations
are
critical
to
sustaining
the
captured
market
share. A lack of understanding or failure to achieve them leads to price
reductions,
rejection
of
delivered
products,
or
termination
of the business relationship between supplier
and
manufacturer.
Best Practice: This Best Practice recommends that wood waste processors and end-users agree to specific product quality requirements in writing. Wood waste processors need to develop these agreements with each individual customer, since the particular details of feedstock specifications vary from one customer to another. The variations in feedstock specifications are determined by the customer’s processing equipment and techniques. Wood waste feedstock requirements include:
Wood Species There are species restrictions. However, some manufacturers might restrict
the
species
mix
to
a
few
or
a
single
specie
to
maintain
process
and
product
uniformity.
Size Distribution
Acceptable Geometry Manufacturers prefer a sharp-edged, pulp-type chip.
Maximum Allowable Contaminant Levels Manufacturers rely on virgin feedstock which contain
low
levels
of
contaminants.
However,
the
opportunity
to
use
wood
waste
feedstock
exists. The feedstock must be free of non-wood contaminants such as: dirt, rock, metal, rubber, plastics, silicon,
hazardous
wastes,
and
other
foreign
material.
Also,
feedstock
must
contain
no
more
than
8%
bark.
Color/Brightness Since many manufacturers are currently relying on virgin
feedstock,
they
are
accustomed
to
bright
chips,
but
there
is
no
inherent
requirement
for
this
color.
Moisture Many manufacturers rely on virgin feedstock, so they
are
accustomed
to
a
uniform
chip
moisture
content
in
the
range
of
10
to
50
percent.
However,
the
real
concern
is
consistent
moisture
content
throughout
the
load
and
from
load
to
load
from
a
supplier.
Implementation: Wood waste processors should work with each manufacturer’s fiber buyer to develop and adhere to written specifications for their unique production systems and product requirements. A quality control program should be in place to ensure product consistently complies with the paper manufacturer’s specifications. The goal of the quality control program should be to detect and correct any problems before shipping the processed wood to the manufacturers.
However, if problems are identified, they should be resolved properly, quickly, and objectively. Regardless of whether the supplier (wood waste processor) failed to meet the required specifications or the buyer (the paper manufacturer) changed the agreed upon specifications and expectations, both parties should work together to resolve the problem. Maintaining an open communication and diplomacy throughout the settlement process would foster a healthy business relationship and avoid future problems.
Benefits: Consistently providing high quality feedstock and adhering to the specifications improves the marketability of the material and potentially increases the price and use of it. Arbitrating problem loads promptly, adjusting specifications mutually, and continuously making equipment and process modifications are practices that could improve the use of the wood waste processor’s material. Wood has only 1/7 of the coefficient of thermal expansion, compared to plastics. Application Site: Manufacturing Site and Processing Facility. Recipe: 1/3 wood + 2/3 plastic. Contact: For
more
information
about
this
Best
Practice,
contact
CWC
(206)
443‑7746,
e-mail
info@cwc.org.
References:
1.
Moslemi, Al.
University
of
Idaho. Moscow, ID.
2.
McGinty, Bill.
American
Cemwood.
Albany,
OR.
3.
“Inorganic
Bonded
Wood
and
Fiber
Composite
Materials”;
Al
Moslemi;
Forest
Products
Society;
Proceedings
from
the
Second
International
Inorganic
Bonded
Wood
and
Fiber
Composite
Materials
Conference;
1991. 4. “Panels: Products, Applications and Production Trends - 2nd Edition”; Pease, David A.; Wood Technology Special Report; Miller-Freeman; San Francisco, CA; 1996. Issue
Date
/
Update: March
1997
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