MEMORANDUM
TO:
File
FROM:
Stephen
Hoffman
MISWD/
OSW
RE:
Definition
of
Transportation
Uses
of
Chat
DATE:
9/
7/
05
Source:
User
Guidelines
for
Waste
and
By­
Product
Materials
in
Pavement
Construction
Publication
No.
FHWA­
RD­
97­
148
April
1998,
US
Department
of
Transportation,
Federal
Highway
Administration,

page
24­
1
notes:

Six
major
pavement
applications
are
described
in
this
chapter.
These
applications
,
which
are
considered
the
primary
applications
where
waste
and
by­
product
materials
may
be
incorporated,
include:

asphalt
concrete,
Portland
cement
concrete,
granular
base,
embankment
or
fill,
stabilized
base,
flowable
fill
applications.

Other
applications
exist(
e.
g.
curb
and
gutter,
medians,
etc.)

Asphalt
concrete
Asphalt
concrete
pavements
consist
of
a
combination
of
layers,
which
include
an
asphalt
surface
constructed
over
a
granular
or
asphalt
base
and
a
subbase.
The
entire
pavement
structure
is
constructed
over
the
subgrade.
Pavements
can
be
constructed
using
hot
mix
or
cold
mix
asphalt.
Since
aggregates
used
in
bituminous
mixtures
comprise
approximately
95
percent
of
the
mixture
by
mass
and
roughly
80
percent
by
volume
they
must
meet
performance
specifications.
General
specifications
for
asphalt
paving
aggregates
are:

ASTM
D692
ASTM
D1073
AASHTO
M29
ASTM
D1139
ASTM
D693
Portland
cement
concrete
(
PCC)

Portland
cement
concrete
(
PCC)
pavements
consist
of
a
PCC
slab
that
is
usually
supported
by
a
granular
or
stabilized
base
and
a
subbase.
In
some
cases
the
PCC
slab
may
be
overlaid
with
a
layer
of
asphalt
concrete.
Coarse
and
fine
aggregate
use
in
PCC
comprise
about
80
to
85
percent
of
the
mix
by
mass
(
60
to
75
percent
of
the
mix
by
volume).
General
specifications
related
to
the
addition
of
aggregates
into
cement
are:

ASTM
C33
ASTM
C94
AASHTO
M241
ASTM
C295
ASTM
C40
ASTM
C142
ASTM
D2419
Granular
bases
Granular
bases
are
typically
constructed
by
spreading
aggregates
in
thin
layers
of
150
mm
(
6
inches)
to
200
mm
(
8
inches)
and
compacting
each
layer
by
rolling
over
it
with
heavy
compaction
equipment.
The
aggregate
base
layers
serve
a
variety
of
purposes
including
reducing
the
stress
applied
to
the
subgrade
layer
and
providing
drainage
for
the
pavement
structure.
The
granular
subbase
forms
the
lowest
(
bottom)
layer
of
the
pavement
structure
and
acts
as
the
principal
foundation
for
the
subsequent
road
profile.
General
specification
for
granular
base
are:

ASTM
D2940
Embankment
or
Fill
Embankment
refers
to
a
volume
of
earthen
material
that
is
placed
and
compacted
for
the
purpose
of
raising
the
grade
of
a
roadway
above
the
level
of
the
existing
surrounding
ground
surface.
A
fill
refers
to
a
volume
of
earthen
material
that
is
placed
and
compacted
for
the
purpose
fo
filling
in
a
hole
or
depression.
General
specifications
for
embankments
and
fill
are:

ASTM
D422
ASTM
D29
ASTM
D698ASTM
D1556
ASTM
D2850
ASTM
D2435
ASTM
D1883
ASTM
D2434
ASTM
G51
Stabilized
Base
Stabilized
base
refers
to
a
class
of
paving
materials
that
are
mixtures
of
one
or
more
sources
of
aggregate
and
cementitious
materials
blended
with
a
sufficient
amount
of
water
that
result
in
the
mixture
having
a
moist
nonplastic
consistency
that
can
be
compacted
to
form
a
dense
mass
and
gain
strength.
The
class
of
base
and
subbase
materials
is
not
meant
to
include
stabilization
of
soils
or
aggregates
using
asphalt
cement
or
emulsified
asphalt.
The
purpose
fo
a
stabilized
base
or
subbase
layer
is
to
provide
a
transitional
load
bearing
strata
between
the
pavement
layer
and
the
underlying
subgrade
soil.
Aggregates
comprise
the
major
portion
of
a
stabilized
base
(
80
to
95
percent
by
weight).
The
key
to
strength
development
in
a
stabilized
base
is
in
the
matrix
that
binds
the
aggregate
particles
together.
The
material
that
has
been
most
frequently
used
in
Portland
cement
however
coal
fly
ash
has
also
been
successfully
used.
AASHTO
has
published
a
Guide
Specification
for
Pozzolanic
Stabilized
Mixture
(
PSM)
Base
Course
or
Subbase
(
see
AASHTO
M147,
ASTM
D2940).

Flowable
Fill
Flowable
fill
refers
to
a
cementitious
slurry
consisting
of
a
mixture
of
fine
aggregate
or
filler,
water,
and
cementitious
materials
which
is
used
primarily
as
a
backfill
in
lieu
of
compacted
earth.
This
mixture
is
capable
if
filling
all
voids
in
irregular
excavations,
is
self
leveling,
and
hardens
in
a
matter
of
a
few
hours
without
the
need
of
compaction
in
layers.
Most
applications
for
flowable
fill
involve
unconfined
compressive
strengths
of
2.1
MPa
(
300
lb/
in3)
or
less.
Flowable
fill
materials
are
primarily
used
in
below
grade
applications
such
as
utility
trenches.
Fine
aggregates
provide
the
solids
needed
to
develop
strength
and
usually
have
particle
sizes
ranging
less
than
0.075
mm
(
No.
200
sieve).
Fly
ash
and
cement
are
often
added
to
aggregate
to
make
up
flowable
fills.
Specifications
for
flowable
fill
include:

ASTM
C150
ASTM
C595
ASTM
C845
ASTM
C618
