•y Journal
BEHAVIOR
of Pavement
Engineering,
OF ASPHALT-RUBBER
DIFFERENT
RUBBER
VOL.10,
2005
BINDERS
PARTICLES
December•z
FOR
SIZE
Ricardo SOUZA1, Kenji HIMENO2 and Akinori KOBAYASHI3
1 Doctoral Student, Department of Civil Engineering, Chuo University
(Kasuga 1-13-27, Bunkyo —ku,Tokyo 112-8551)
2Member of JSCE
, Dr. Eng., Department of Civil Engineering, Chuo University
(Kasuga 1-13-27, Bunkyo —ku,Tokyo 112-8551)
3Member of JSCE, Eng., Taisei Rotec Corporation (1456 Oaza-Kamiya, Konosu-shi, Saitama 365-0027)
The addition of polymers and by product waste materials to straight asphalt has shown improvement of
binder's properties. In this research, the rubber powder by which the waste tire of the passenger motorcar
smashed with the freezing-method is added to the straight asphalt 60/80. Rubber 0.2mm, 0.4mm, 0.6mm,
0.8mm and 1.2mm, respectively, was mixed with asphalt at a rate of 15% by total weight. The viscosities
measured with a rotation viscometer, Complex Shear Modulus (|G*|), phase angle (8) and softening point
temperatures evaluated the behavior at high temperatures. The flexural creep stiffness and slope of
response evaluated the behavior at low temperatures. The improvements on binder properties after rubber
addition showed the same magnitude despite the difference of rubber size.
Key Words: asphalt-rubber, rubber, rutting, fatigue cracking, elasticity
1. INTRODUCTION
surface
texture
asphalt
cements
The increasing amount of scrap tires has become a
serious environmental
problem. In Japan, the amount
of discarded
tires reached 103 million in 20041).
These tires when disposed at inadequate places are in
danger of fire and if this occurs, the air and the
underground water can be polluted.
A literature review shows that scrap tires can be
used in whole form, in small pieces or as ground
grinding
particles. Their use in whole form takes place at
power plants to produce energy, whereas, the small
pieces can be used for vehicles
mudguards
or
padding. The finer/ground particles of rubber may be
mixed with asphalt, acting as an asphalt modifier 2,3).
Japanese
an
rubber
smashed
produces
a
ambient
with
grinding
paper
sizes
evaluate
the
uses
This
is
process
obtained
from
a rough
a very
a
slurry
This
that
retains
way
presents
an
surface
thorough
analysis
reaction
of
rubber
particles.
of
0.2mm,
mixed
0.4mm,
grinding. The ambient grinding method is performed
at ambient temperatures using grinders and screens to
size the material and remove any residual steel and
fiber. The material
resultant
from this process
(grade
of
Phase
angle
presents a very rough surface texture, what improves
the reaction with asphalt cements. The cryogenic
with
a rotation
high
temperatures.
with
penetration)
asphalt-rubber
at
weight.
temperatures,
and ƒÂ
Shear
as
well
as
viscometer
At
were
stiffness
and
behavior
at
low
temperatures.
1.2mm
60/80
by
response
(|G*|)
and
measured
the
behavior
temperatures
the
total
point
viscosity
whereas
of
15%
Modulus
the
evaluated
slope
and
softening
intermediate
studied,
the
Rubber
asphalt
of
The
Complex
(ƒÂ),
use.
0.8mm
rate
to
(straight
to
straight
a
aimed
modified
materials
available
0.6mm,
separately
study
rubber
local
powder)
for
considering
The
Japanese
the
rubber
performed
binders
behavior
and
powder
241
this
considering
asphalt
G*|
it still
ambient
method
stone.
than
with
the
slurry.
asphalt-rubber
binders
grinding consists to cool the tires with liquid nitrogen
and then these cooled tires can be quite easily seized
in a similar way used for ambient grinding. The
rubber powder resultant
presents a very smooth
wet
material
but
reactive
with
grinding
between
in
less
cements4).
different
was
wet
in
showing
This
Scrap tires can be smashed in small particles using
ambient grinding, cryogenic
grinding
or wet
The
finer
asphalt
it
compared
powder
grinding,
texture,
makes
when
process.
coarse
then
what
flexural
analyzed
at
the
creep
|
the
2.
ASPHALT-RUBBER
Two
rubber
BINDERS
methods
have
powder.
The
process",
consists
aggregate
for
straight
known
as
rubber
for
"wet
process"
a longer
during
the
asphalt
Arizona,
of
recommends
blending
minutes
at
175•Ž,
temperature
45
State
Highway
ranging
swell,
the
interparticles
of
between
to
since
softens.
The
absorption
rubber
The
aromatic
rubber
chains,
natural
and
sponge
swelling
of
asphalt
which
increased,
as
the
is
binder
viscosity
the
amount
of
addition
to
when
size.
The
the
addition
other
using
results
properties
163•Ž
was
and
of
the
the
particles
is
hand,
15%
viscosities
rubber
tests
time
and
a steel
ball
of
produced
of
30
the
binder's
presented
to
best
On
MATERIALS
AND
for
in
This
evaluation
penetration),
used
whose
straight
physical
a
of
the
of
60/80
characteristics
hours
modified
at
binders
(grade
are
242
asphalt
cement9).
metal
previously
bigger
to
the
after
it
can
temperatures
magnitude,
before
Viscosity
a
binder,
25.4
mm
powder
temperatures
increase
of
considering
after
is
through
rubber
binder's
the
that
presented
and
change
displacing
point
seen
possible
asphalt
mixing
be
of
temperature
after
an
is
passes
with
Further,
at
weight
way,
The
softening
proving
rutting.
size,
for
the
effect
all
same
sizes
order
aging.
test
viscosity
can
1,
the
the
a phase
ball
plate,
Fig.
this
which
filled
reference
asphalt,
rubber
In
at
standard
temperature
support
flowing.
temperature
illustrates
the
cannot
a
a
straight
The
starts
ring,
analyzed,
PROCESS
asphalt
Thin-Film
five
aforementioned.
the
touches
10)
material
of
and
resistance
workability.
MIXING
the
after
test
cement
the
became
the
(2)
3.
the
binder
for
determines
asphalt
when
As
showed
180-C,
minutes
and
particles
5, 6, 7, 8)
during
little
these
using
1.2mm,
bottles
way,
inconvenience
point
establish
read
rubber
accomplished.
temperature
mixing
of
different
elsewhere
of
almost
the
an
occurs
several
rate
this
oxidize
experiment
which
to
lubricate
previously
the
Softening
This
binder
best
and
running
to
respectively,
0.8mm
a
The
oxidized
binders
of
the
short.
Modified
left
In
machine,
overcome
(1)
properties.
to
oxidation.
used
for
machine
out
being
in
mention
the
improves
oils
respectively,
published
of
for
mechanical
the
provides
reacted
of
(TFO)
into
rubber
period
blown
process,
place
services
0.4mm,
163•Ž.
aged
aging
takes
will
"aging",
0.6mm,
were
that
(RTFO)
rubber
at
0.2mm,
Oven
particles
asphalt-rubber
the
digestion.
compaction
as
and
minutes
and
to
components
performed
one
short-term
oxidation
Oven
asphalt
standard
determine
for
short-term
sections
just
Film
aging
and
and
following
aging
RTFO
reduced3).
as
After
oven
binder
The
binder
mixing
The
85
the
original
the
respectively,
a
a water
binder
aromatic
mechanical
in
the
a
250RPM.
660RPM.
kept
binders.
plant
field.
straight
into
due
evaluated
simulate
the
rubber
to
in
is
to
during
it swells
adhesive
of
was
to
using
of
the
at
perform
modified
Rolling-Thin
the
melt
placed
The
develop
the
not
similar
rubber
properties.
investigation
so
key
asphalt
powder
FINDINGS
study
short-term
to
a chemical
do
Natural
synthetic
and
Furthermore,
the
mix
speed
minutes
resultant
to
to
rubber
finished,
30
3.
180•Ž+1•Ž,
rotation
addition
LABORATORY
the
and
is
asphalt
180•Ž+1•Ž
during
tend
not
water,
at
tries
minutes.
Rubber
the
are
45
powder
rubber.
while
tacky
rubber
from
synthetic
stability
being
the
hour
This
increased2).
is
components.
oils
become
is
a
for
binder
(oxidized)
Florida
reduced
particles
absorbs
thermal
is
reaction
sponge
properties
This
dry
the
to
rubber
continued
of
at
for
particles
Table
used
addition
accomplished
the
60
190•Ž
particles
powder
these
of
absorb
10
binder
binder.
hard,
the
for
the
was
described
rubber
in
method
The
mixer
that,
4.
temperatures
rubber
rubber
for
to
hand,
distance
of
asphalt
As
175-C
reaction,
In
blending
175•Ž
blending
asphalt-rubber
compressed,
best
range
of
swelling
reaction
tests
the
150•Ž
time
elastic
rubber
advises
from
bath.
and
other
process
was
for
Highway
California
the
analysis
presented
powder.
passenger
straight
State
in
On
the
viscosity
Arizona
asphalt
minutes.
Along
to
sieve
from
components
USA,
temperatures.
whereas
may
during
the
the
high
wet
powder
chemical
gradation
rubber
mixing
and
in
the
When
mixtures.
powder
at
the
1. Rubber
the
A
mechanical
of
especially
rubber
instance,
mixing
asphalt
2.
The
and
measured
of
Table
and
properties
be
developed,
accomplished
for
before
the
in
asphalt
asphalt
Table
showed
with
method,
mix
in
tires
showed
mixing
second
time,
production
"dry
before
to
can
addition
is
The
of
and
particles
The
way,
the
asphalt
called
time
consists
binder
researches
show
them.
this
asphalt-rubber
Several
of
period
In
mix
rubber
period
with
to
method,
blend
short
asphalt
controlled
used
first
to
a
aggregates.
been
presented
car
be
requirement
pumped
and
aims
mixed
to
with
insure
aggregate.
that
the
The
Table
1. Physical
characteristics
of straight
asphalt
Table
2. Rubber
powder
chemical
components
Table 3. Rubber gradation for passenger car tires (PS)
Fig.
1 Softening
before
apparent
viscosity
determined
rotate
is
measured
a spindle
rotational
This
original
registered
and
that
determined
binders
The
(Figure
considering
hot
at
torque
asphalt
viscosities
the
2),
their
the
175•Ž
required
at
at 30,
average
as
the
swelling
viscosities
and
after
60
and
calculated12).
size
of
particles
after
mixing
when
to
only
90
seconds
It
was
increase
with
for
hour
rubber
powder
to
asphalt
maximum
value for binders
using particles
0.6mm,
decreasing
from this point on. The authors performed
further studies13' 14) and observed
that rubber particles
bigger than 0.4mm require bigger times of digestion
so
as to absorb the aromatic
oils from asphalt and then,
swell and increase the viscosity.
Despite this, after one
hour of digestion,
all rubber modified binders presented
acceptable
viscosities
and good workability.
a constant
one
adding
they develop higher friction contact and the viscosity
tends to become higher, improving
the consistency
of
modified
binders.
Such
enhancement
presented
a
be
The
11).
study
digestion.
the
into
can
viscometer.
through
plunged
speed
binders
rotation
2 The viscosity
the straight
aging
asphalt
a
Fig.
temperatures
and after
of
using
viscosity
point
of
were
found
and
asphalt,
243
Fig. 3 |G*|
values
at high temperatures
before
Fig.
5 Phase
angle
temperatures
(3)
Dynamic
test
is
Rheometer
short-term
be
determined
Modulus
(|G*|)
the
desired
The
and
binder
to
lag
strain
it
material
the
so
When
viscous
tested,
the
high
lag
90
degrees.
and
times
the
5•Ž
is
a
were
performed
asphalt
and
of
the
the
difference
the
4),
The
way,
to
straight
susceptibility
is
Figs.
angle
3
are
presented
(ƒÂ)
This
components
behavior
to
these
plate
of
of
The
same
DSR
rubber
a
the
gap
particles.
12%
constant
rubber
The
as
All
of
Considering
2.5
bigger
tests
showed
strain
presenting
1.59Hz.
244
the
despite
this
analyzing
modified
and
binders
after
aging.
antioxidant
compounds.
presented
magnitude,
this,
In
temperature
the
tire
of
rutting.
Besides,
before
binders
a result
to
that
the
higher
values
the
In
with
the
difference
of
size.
the
temperature
between
determined
modified
order
as
from
in
showed
a
higher
resultant
present
addition,
considering
values.
and
was
considering
was
configuration.
diameter
size
binders
65•Ž,
plate
upper
of
and
resistance
values
be
aging
increasing
oxidation.
similar |G*|
may
values
bindcrs
showed
seen
straight
Further,
After
However,
be
the
became
the |G*|
unmodified
it could
when
change.
size,
presented
after
4,
| to
magnitude.
the |G*|
asphalt
and
rubber
it's
the
among
not
asphalt
on
increased
resistance
values
did
45•Ž.
reduce
reduction
applied
zero.
and
at
binders
Even
magnitude
of
straight
tendency
higher
of
of
modified
the
the |G*|
order
values
powder
So,
binders
same
temperature,
the
binder
phase
despite
similar
elastic
(ƒÂ)
modified
modified
improved.
difference
and
(Fig.
strain
resulting
an
the
rubber
and
asphalt
showed
of
the
to
hot
the
25mm
a frequency
ratio
perfectly
angle
large
parallel
the
A
phase
like
is the
sheared9).
response
between
respective
at
or
45•Ž
measured
lower
ran
instant
temperatures,
used
(ƒÂ).
binders
loading.
and
smaller;
and
aging.
grow
resistance
stress
of
deformation
aging
asphalt
before
temperature
Shear
(ƒÂ) at high
after
addition
permanent
shear
repeatedly
angle
from
machine
and
when
the
values
binders
of
maximum
total
applied
time
of
to
the
the
lag
increments
the
(rmax)
represents
time
evaluated
plates
stress
liquids
approaches
asphalt
(|G*|)
phase
the
(ƒÂ) of
Modulus
present
stress,
angle
Complex
3),
G*|
service
the
Shear
deformation
will
At
phase
aging
angle
straight
binders.
intermediate
frequency
between
is
at
measures
(Fig.
unaged,
asphalt
and
shear
(ƒÁmax),
time
and
the
of
and
Shear
asphalt
temperature
Complex
maximum
high
Dynamic
aged
behavior
DSR
at high temperatures
temperatures
evaluates
long-term
at
The
the
and
elastic
values
6 Phase
Comparing
and
and
temperatures.
at
Fig.
aging
by
machine
aged
viscous
can
(ƒÂ) at high
before
performed
(DSR)
4 |G*|
after
Shearing
This
The
Fig.
aging
phase
increased,
for
both
higher
angle
the ƒÂ
types
of
susceptibility
a higher
decrease
(ƒÂ) (Fig.
values
binder.
to
of
5),
tended
Modified
temperature
phase
angles
when
to
the
become
binders
change,
as
the
Fig.
7 |G*|
values
temperatures
Fig.
9 Phase
angle
aging
(ƒÂ) at
intermediate
temperature
for
grew.
binders
other
However,
using
hand,
binders
straight
at
presented
lower
individually,
a higher
aging
lower ƒÂ
In
despite
the
the
the
binders.
and
the
order
binders
At
intermediate
took
10•Ž
40•Ž,
these
parallel
plate
and
upper
plate
was
the
size
performed
considering
a
frequency
oxidation,
of
of
for
as
rubber
the
as
constant
and
shows
unmodified
5•Ž
a
2.5
and
times
binder.
and
ran
7,
before
binders,
7 and
8, the |G*|
after
oxidation,
were
similar
or
the
(Fig.
temperature
for
245
as
the
temperature
bigger
for
addition
of
compared
both
rubber
with
asphalt,
that
enhancing
cracking.
This
using
fact
bigger
straight
values
effect
of
increased
modified
smaller |G*|
more
Comparing
asphalt
whereas,
the
was
particles
respectively).
oxidative
Considering
the
behavior
was
a
binders
after
aging.
reduced
after
addition.
binders
at
cracking.
size.
the
for
to
decreased,
fatigue
became
1.2mm,
a
resistance
similar
8),
binders
and
little
rubber
strain
Fig.
for
Figs.
the
tests
rubber
as
presented
the
to
the |G*|
fatigue
and
binders
showed
straight
for
the
place,
binders
However,
for
measured
took
resistance
of
reduced
Therefore,
that
way,
binders
(Fig.
the
All
the
(0.8mm
than
lower.
binders
decreasing
this
values
showed
measured
lower
asphalt-rubber
the |G*|
rubber
used
plates
between
As
of
In
of
remarkable
of
machine
values.
to
modified
modified
oxidation
measured
between
10•Ž
After
of
became
for
tendency
difference
powder
evaluation
increments
particles.
1%
the
types
a result
values
decreased,
it's
of
varying
The
gap
1.59Hz.
modified
6,
lower ƒÂ
compounds.
the
determined
respective
modified
and
at
modified
despite
aging
However,
improving
Further,
resistance
DSR
configuration.
diameter
thus
angles
for
5
this,
intermediate
temperature
values
higher
deformation
reduced.
The
(ƒÂ) at
the
a reverse
of
aging
after
asphalt.
lower |G*|
susceptibility
considering
8mm
phase
probably
temperatures
values.
the
when
little
result
asphalt.
showed
temperatures,
at intermediate
after
angle
the |G*|
temperature,
Further,
in rubber
also
for
straight
Figs.
stiffening,
was
Phase
increased
40•Ž,
straight
presented
magnitude
temperature
place
and
between
size,
antioxidants
the
modified
for
binders
lower
of
addition,
binders
of
10
presented
ones
temperature.
enhanced.
comparing
then
last
G*|
At
modified
binders
rubber
|
the
showing
at every
measured
modified
presence
and
values
properties
lower
On
the
modified
of
same
that
values
In
that
Moreover,
observed
of
6),
difference
presented
asphalt
elasticity
elastic
was
0.8mm.
temperature,
absolute
than
way,
every
(Fig.
values
this
and
values
temperatures
growth
0.6mm
comparing
Fig.
aging
such
rubber
separately
After
before
8 |G*|
temperatures
before
temperatures
Fig.
at intermediate
both
the
9),
became
types
of
phase
it
angle
was
smaller,
binder.
(ƒÂ),
observed
the ƒÂ
So,
the
for
that
unaged
as
values
decreased
elastic
properties
the
improved.
for
Such
modified
lower
In
improvement
binders
values
compared
addition,
the
showed
the
tendency
with
seen
phase
that
to
After
for
aging
both
of
Therefore,
the
at
straight
10•Ž,
presented
higher
elasticity.
of
order
size.
Again,
The
stiffness
the
Besides,
The
with
the
of
same
order
rubber
size.
presented
of
to
the
Flexural
The
Creep
thermal
of
cracking
determined
at
the
(BBR)
the
machine.
concrete
rapidly
cold
stresses
pavement
layers.
rapidly,
the
If
stresses
As
of
the
to
result
this,
relieve
from
where
the
always
remains
to
the
the
thermal
encountered,
caused
by
limiting
the
pavement
stiffness
the
a
occurs.
stiffness
and
at
reached
at
after
a
but
is
is
is
defined
which
as
temperature
as
slope
a certain
Bending
prismatic
test
fluid
seconds.
deflection
load
beam
bath
Rheometer
deflection
beam
constant
A
Beam
midpoint
of
and
The
of
asphalt
applied
is
loaded
the
load
beam
the
in
with
(BBR)
a
binder
to
placed
test
of
that
a
controlled
a
monitored
to
the
the
and
Further,
load
for
the
midpoint
versus
thermal
240
slopes
time
246
despite
of
response
binders
present
presented
of
lower
response
decreasing
Further,
at
dropping
the
temperature,
observed
and
binders
as
absolute
are
probably
will
fast
enough
difference
modified
for
not
to
the
the
straight
a reverse
of
this,
little
values
so
as
-10•Ž,
a result
showed
temperature
before
values
higher
for
to
temperature
change.
little
the
Further,
respectively
the
was
stress
improved
tended
when
slopes
the
decreased
asphalt.
1.2mm
aged
before
binders
mixing
smaller.
However,
at this
aforementioned
a
beam.
be
of
cracking
values
showed
modified
response
temperature
constant
(980+50mN)
are
of
could
,
m-values.
supported
is subjected
midpoint
however,
rubber
lower
behavior
straight
and
response
tendency
measures
simply
13)
modified
of
observed
binders
became
asphalt,
loading
to
of
(Fig.
of
the
temperature
analysis
to
temperature
of
modified
modified
to
The
oxidation
-30•Ž
The
0.8mm
Again,
at
time9).
the
powder
stiffness
resistance
showed
thermal
modified
lower
dropped.
related
of
0.4mm,
this
seemed
the
tendency
to
rubber
susceptibility
called
specified
stiffness
oxidation,
slightly
temperature
and
temperature
is
rubber
temperature.
temperature
temperature,
low
cycling
cycle
the
after
the
the
difference
12),
same
resistance
mixing
can
down,
low
thermal
This
service
value
up
stiffness
as
critically
thermal
critical
single
binder
cracking
the
cycles
above
a
from
So,
the
the
for
In
change.
(Fig.
showed
aging.
and
cracking
when
or
stress
cracking
Thermal
cycle
binders
the
asphalt.
binders
temperature
oxidation
between
lowest
benefit
the
modified
to
After
very
the
Besides,
5•Ž
the
performance
despite
of
measured
as
the
similar
susceptibility
the
pavement.
develops
stresses.
is
asphalt
which
pavement
temperature
Cracking
exceed
concrete
was
slope
performed
of
straight
significant
Moreover,
binders
size.
within
occurs
more
be
the
stiffness
11,
such
the
"m-value")11).
enhanced
and
the
to
and
stiffness
rubber
the
this
should
was
Fig.
to
time.
According
increments
compared
of
of
creep
the
The
of
sample,
(called
to
cracking
decreased.
asphalt
at
log
seconds
point
lowest
addition
thermal
become
pavement
up
contraction
asphalt
be
temperature
the
build
eventually
the
one
temperature
of
the
the
to
Rheometer
As
to
develop
can
cracking
when
the
can
of
way
Beam
temperatures.
ability
a
Bending
begin
relaxation
a result
temperatures
results
at
contracts,
to
service
Thermal
pavements
drops
binders
the
result
binders
-10•Ž,
quotient
strain.
a
flexural
According
binders
way,
asphalt
low
using
to
temperature,
Stiffness
tendency
60
times
the
parameters
at
this
the
loading
the
time.
unmodified
values.
modified
(4)
at
study,
-30•Ž
these
(S)
loading
deflection.
on
as
two
stiffness
and
from
aging.
with
maximum
maximum
left
decreases
line
this
modified
that
is
times
same
the
versus
and
tangent
for
the
load
span
The
the
through
plotted
of
loading
respective
beam
and
midpoint
for
seconds.
and
the
the
dimensions,
for
increases,
the
In
whereas
similar
240
specification
analyzed,
higher
change,
behavior
(S)
beam
calculated
then
the
Superpave
for
of
is
stress
longer
its
the
dimensions
is
deformation
stiffness
and
at
from
to
calculated
(S)
(S)
little
120
is
above
stiffness
a
60,
its
between
so
applied
strain
dropped.
angles
difference
showed
before
and
temperature
binders
from
binders
phase
asphalt
30,
times
modified
values,
values
15,
it's
decreased
However,
the
8,
stress
calculated
load
bending
acquisition11).
bending
is
and
the
higher
modified
the
showed
beam
of
10•Ž,
enhanced.
lower ƒÂ
to
modified
to
angles
and
Further,
susceptibility
magnitude
temperature
behavior.
straight
length,
data
maximum
specified
phase
the
properties
despite
the
binders
Analyzing
40•Ž
a computerized
The
asphalt.
showed
the
as
asphalt
binders
of
using
change.
10),
little
magnitude,
observed
from
binder
similar
proved
modified
same
rubber
elastic
binders
modified
asphalt
(Fig.
types
for
temperature
important
presented
straight
of
angles
more
angles
for
the
straight
susceptibility
that
angles
difference
of
phase
with
phase
values
despite
was
whose
at
higher
of
slopes
that
the
gain
contribute
to
relax
prevent
cracking.
small
of
binders
rubber
size,
showed
of
the
Fig.
11 Stiffness
at low temperatures
before
Fig.
13 Slope
temperatures
Fig.
12 Stiffness
at low temperatures
after aging
aging
of response
before
at low
Fig.
aging
values with the same order of magnitude.
After aging (Fig. 14), for modified and
unmodified binders, the slopes of response became
smaller when the temperature dropped. So, the ability
to relieve the thermal stresses by asphalt flow
decreased, raising the propensity of thermal cracking.
Moreover, comparing both types of binder, as the
temperature became smaller, straight asphalt tended
to produce lower m-values at lower temperatures.
Even though the m-values for modified binders at
lower temperatures are higher than that measured for
straight asphalt, probably they are not big enough to
relieve the thermal stresses. On the other hand,
despite the difference of rubber size, the slopes of
response for modified binders showed values with
the same order of magnitude. Once more, modified
binders proved better behavior to temperature
susceptibility change.
14 Slope
of response
temperatures
after
asphalt-rubber
weight.
tests
the
behavior
and
at
evaluated
at intermediate
at low
aging
Conventional
and
of
low
such
Superpave
binders
temperatures.
at
It
high,
was
found
that:
•@
At
high
temperatures,
addition
of
increased
G*|
the
oxidation,
to
•@
and
the
asphalt
and
measured
the
showed |
for
to
temperatures,
straight
permanent
before
binders
phase
fatigue
and
presented
angles,
after
lower |G*|
improving
the
resistance
cracking.
and
•@
after
temperature,
modified
the
the
resistance
to
seemed
to
aging,
lowest
binders
Therefore,
This paper presented a comparative analysis
among straight asphalt and asphalt-rubber binders
mixing respectively rubber particles with different
size. Rubber powder 0.2mm, 0.4mm, 0.6mm, 0.8mm
and 1.2mm were mixed separately to straight asphalt
60/80 (grade of penetration) at a rate of 15% of total
aging,
angles
resistance
modified
Before
5. CONCLUSIONS
straight
improved.
intermediate
values
after
to
phase
that
the
and
temperatures
the
than
Thus,
deformation
At
point
whereas
values
asphalt.
powder
softening
values,
lower
before
rubber
the
compared
of
more
the
measured
straight
rubber
cracking
become
lowest
stiffness
with
addition
thermal
the
for
asphalt.
enhanced
and
the
such
significant
benefit
at
lower
temperatures.
•@The
addition
of
improvements
of
enhancement
magnitude
particles
247
of
rubber
asphalt
presented
despite
used.
the
powder
properties,
the
different
showed
but
same
size
such
kind
order
of
rubber
of
•@ The
influence
of
remarkable
size
when
rotation
of
rubber
particles
measuring
the
7)
more
with
a
viscometer.
ACKNOWLEDGMENTS:
supported
This
by
the
aid
of
Group.
This
financially
by
University
Research
Chuo
Projects
Research
at
acknowledges
the
International
of
2005
Advanced
main
author
support
Cooperation
the
of
The
financial
supported
one
Promotion
8)
Rubber
was
as
School.
was
Asphalt
paper
for
Graduate
study
Japan
Research
Japan
was
viscosities
also
provided
Agency
9)
by
(JICA).
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1)
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Automobile
JATMA:
2)
Tire
Hicks,
R.G.,
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Modifier.
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R. O.,
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Rubber
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Size.
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Society
369-372,
R.,
Influence
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with
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1992.
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ゴ ム 粉 の サ イ ズ の 違 い に よ る ア ス フ デル
リカ ル ド
ソ ウザ
・
トラ バ ー バ イ ン ダ の 特 性 に 関 す る 検 討
姫 野
賢治
・ 小 林 昭 則
ス トレー トア ス フ ァル トにポ リマ ー や 他 産 業廃 棄物 を加 え る こ とに よ りバ イ ン ダ の特 性 が改 良 され る こ
とが 分 か っ て い る.本 研 究 は,ス トレー トア ス フ ァル トに 一般 車 用 の廃 タイ ヤ の ゴ ム粉 を混 合 した際 の ア
ス フ ァル トバ イ ン ダ の挙 動 に関 す る検討 で あ る.ア ス フ ァル トの 全 重 量 に 対 し15%の 割 合 で0.2mm,0.4mm,
0.6mm,0.8mm,1.2mmの
サ イ ズ の ゴム粉 を それ ぞれ 混 入 した.高 温 時 にお い て,回 転 粘 度 計 で測 定 した粘
性,複 素せ ん断 係 数￨G*￨),位
相 角(δ),軟
化 点 の挙 動 を検 討 し,さ らに,低 温 時 にお け るた わ
み ク リー プ ステ ィ フネ スや 応 力 リラ クゼ ー シ ョ ンの挙 動 も検 討 した.ゴ ム粉 のサ イ ズ に よ る違 い は あ る も
の の,ゴ ム粉 を混 入 す る こ と よ りバ イ ンダ の 特性 は 改 良 され る こ とを示 した.
248