STATE OF OHIO
DEPARTMENT OF TRANSPORTATION
SUPPLEMENT 1012
METHOD OF TEST FOR RUBBER COMPOUND
April 18, 2008
1012.01 Dispersion. This method of test is intended for the determination of the dispersion of
rubber in a rubberized asphaltic paving mixture, the aggregate in which all passes a No. 4(4.75
mm) sieve.
1.
Apparatus. Use the following:
a)
Funnel - A buchner type porcelain funnel with fixed perforated filter plate, glazed
inside and outside with the exception of the rim, with an inside diameter at the
perforated plate of 91 mm.
b)
Flask - A filter flask, 500 ml. capacity, with side tube for connection to a vacuum
pump, and thick walls to withstand a vacuum.
c)
Stopper - One hole rubber stopper to accept stem of funnel and fit into mouth of
flask.
d)
Filter paper - S & S No. 589, black ribbon, double-washed, soft, 9 cm. diameter,
or its equivalent.
e)
Pipet - A "medicine dropper" with rubber bulb.
2.
Preparation of Test Sample. If the mixture is not sufficiently soft to separate with a
spatula or trowel, place sample in a large flat pan and warm in the oven at 240 ºF (116
ºC) only until it can be handled. Separate the mixture and slowly mix and quarter the
warm material to obtain a portion weighing 5.0 + 0.1 gms. for washing with solvent.
3.
Test procedure. Place the stopper on the stem of the funnel and insert the funnel into the
mouth of the flask. Place the filter paper on the perforated filter plate of the funnel and
spread the sample evenly over the filter paper.
Using the pipet, slowly drop chloroform at room temperature on the particles of the
mixture, washing the rubberized asphalt film from each of the mixture particles, taking
care not to disturb the distribution of the particles. If the solvent accumulates on the
surface, apply a vacuum to the flask through its side tube. Continue to drop the
chloroform on each black particle until it is apparent that the black color will not readily
wash off the particle. Continue washing the sample until the filter paper shows only a
light strain from the rubberized asphalt. The total washing time shall not exceed 30
minutes. Allow the sample to dry.
4.
Report. Report the number of remaining black rubbery particles which are visible to the
naked eye in the sample.
1012.02 Resistance to Flow. This method of test is intended for the determination of the
resistance to flow imparted to a reference asphalt cement by a rubber compound.
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1.
Apparatus. Use the following:
a)
Blending unit - A unit for melting and blending the rubber compound into the
Reference Asphalt, constructed so that the blends are heated indirectly to avoid
localized overheating, equipped with a propeller-type mechanical agitator and
thermometer in the material chamber.
b)
Molds - Amalgamated molds 4 cm. wide by 6 cm. long by 0.32 cm. deep.
c)
Panel - A bright tin panel approximately 16 cm. square.
d)
Stand - A stand designed to hold the panels so that the longitudinal axis of the
specimen at an angle of 75 +/- 1 degree with the horizontal and the transverse axis
horizontal.
e)
Oven - An oven capable of holding the test specimens on the tin panel on the
stand at a temperature of 140 +/- 2 oF (60 +/- 1 oC).
2.
Mix Ingredients. Reference asphalt - 85-100 penetration grade asphalt cement, steamvacuum refined, manufactured from Smackover Crude by Lion Oil Company.
3.
Rubber Compound - The rubber compound to be tested. Proportion the rubber compound
to the reference asphalt so that the net virgin rubber solids content, exclusive of any
extenders included in the rubber compound is 5.0 percent plus or minus 0.1 percent of the
combined weight of the Reference asphalt and the total solids of the rubber compound.
4.
Preparation of Test Blend. Heat 2000 gms. of the Reference asphalt to 149 oC in the
blending unit. Slowly add the rubber compound to the hot asphalt to flash off the volatile
ingredients of the rubber compound while slowly mixing the blend. All of the rubber
compound shall be added within 90 minutes, maintaining a temperature of the blend at
149 oC. Continue heating and mixing until a total mixing time of 150 minutes has
elapsed.
5.
Preparation of Test Specimens. Pour the hot test blend into the amalgamated molds
which have been placed on the bright tin panels. Fill the molds with an excess of
material, allowed to cool to room temperature for at least one-half hour, and then
trimmed flush with the face of the mold with a metal knife or spatula. Remove the mold
from the sample.
6.
Test Procedure. Immediately upon removing the mold from the sample, place the panel
containing the sample on the stand in the oven with the longitudinal axis of the sample at
an angle of 75 +/- 1 degree with the horizontal for 60 minutes, maintaining the oven at
140 +/- 2 oF (60 +/- 1 oC).
7.
Report. Report the change in length in cm. of the specimen during the 60 minute test
period.
1012.03 Toughness, tenacity, elongation, and peak load. This method covers the test for the
toughness, tenacity, elongation, and peak load of a rubberized asphalt. These tests are a measure
of the work and forces necessary to dislodge an embedded, hemispherical head from a sample of
rubberized asphalt.
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1.
Apparatus. Use the following:
a)
Sample container - A 3 oz. (90 mL) seamless ointment can.
b)
Tension head - A polished stainless steel, 7/8" (22 mm) diameter, hemispherical
head mounted on a threaded stem.
c)
2.
Tension head support - A threaded notched spider mounted on the threaded stem of
the tension head.
d)
Tensile testing machine - A machine capable of an accurate and uniform rate of pull
of 20 inches (508 mm) per minute through a distance of 20 inches (508 mm).
e)
Recorder - An instrument to provide an accurate graphic record of the forceelongation measurements.
Procedure. Heat and stir the rubberized asphalt sample slowly as it melts to prevent local
overheating. Remove the air from the sample and maintain a uniform temperature not to
exceed 190 oC. Pour 50 grams of the hot rubberized asphalt into the sample container,
eliminating all bubbles. Immerse the tension head in the air-free hot rubberized asphalt
and suspend and center the tension head by means of the tension head support so that the
upper surface of the head and the surface of the asphalt are in the same plane. Place the
sample with the tension head in position in a constant temperature bath 25 oC for 16 to 20
hours. Place in the testing machine and pull the head from the sample at 20 inches (508
mm) per minute through a distance of 20 inches (508 mm), graphically recording the
force-elongation measurements.
3.
Precautions.
a)
The presence of as little as two percent of residual water or solvent from an additive
will greatly affect the results of this test.
b)
The presence of any air bubbles in the hot rubberized asphalt prior to immersing the
tension head will affect the results of this test.
c)
The graphic recorder must give an accurate record of the force-elongation curve
because any error in recording the force will be multiplied by the elongation
distance. To insure against error, an unload curve should be recorded for zero
pounds tension.
4.
Report. Report the following:
a)
Toughness - the total area in inch-pounds (millimeter newtons) under the forceelongation curve.
b)
Tenacity - the area in inch-pounds (millimeter newtons) under the curve following a
line from the tangential extension of the portion of the curve descending from the
peak load to the intersection of the curve with the zero axis.
c)
Elongation - the total distance in inches (millimeters) that the head is pulled from
the sample before the rubberized strand breaks.
d)
Peak load - The maximum force in pounds (newtons) recorded when the head is
pulled from the sample.
1012.04 Dispersion in mixture. This method of test is intended for the determination of the
effectiveness of a rubber compound together with a method of use in producing a good
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dispersion in a reference rubberized asphalt paving mixture, the aggregate of which all passes a
No. 4 (4.75 mm) sieve.
1.
Apparatus. Use the following:
a)
Sieves - No. 200, No. 100, No. 40, and No. 10 (75mm, 150mm, 425 mm, and 2.00
mm) sieves conforming to the ASTM Designation: E-11.
b)
Mixing machine – Prepare the mixture in a mechanical, bowl-type, high speed
mixer having a 10 to 12 qt.(10 to 12 liters) capacity and which is capable of
producing a well-coated, homogenous mixture in 2 min. or less. Ensure a design so
that fouling of the blades will be minimized and so that each individual batch may
be retrieved in essentially its entirety.
c)
Balance - A balance, having a capacity of 15 g or more and a sensitivity of 0.1
gram.
d)
Oven - An oven capable of maintaining within plus or minus 2 oF (1 oC) any desired
temperature from room temperature to 325 oF (163 oC).
e)
Funnel - A Buchner type porcelain funnel with fixed perforated filter plate, glazed
inside and outside with the exception of the rim, with an inside diameter at the
perforated plate of 91 mm.
f)
Flask - A filter flask, 500 mL capacity, with side tube for connection to a vacuum
pump, and thick walls to withstand a vacuum.
g)
Stopper - One hole rubber stopper to accept stem of funnel and fit into mouth of
flask.
h)
Filter paper - S & S No. 589, black ribbon, double-washed, soft, 90 mm. diameter,
or its equivalent.
i)
Pipet - A "medicine dropper" with rubber bulb.
2.
Mix Ingredients. Reference aggregate – Compose the reference aggregate for the mixes
of sand and mineral filler blended to give the following combined gradation within plus
or minus 1.0 percent:
Sieve Size
No. 10 (2.00 mm)
No. 40 (425 mm)
No. 100 (150 mm)
No. 200 (75 mm)
Total Percent Passing
100.0
61.0
22.0
12.0
Ensure the aggregate retained on the No. 200 (75 mm) sieve is natural silica sand from
Ottawa Silica Company, Ottawa, Illinois, and is a blend of their "Flint Shot", "Banding
Sand", and "No. 90" grades, sieved and then proportioned to meet the above gradation
requirements when combined with the mineral filler. Ensure the aggregate passing the
No. 200 (75 mm) sieve is limestone dust mineral filler meeting the requirements of
AASHTO M-17.
Reference asphalt - 85-100 penetration grade asphalt cement.
3.
Rubber compound - Proportion the rubber compound to the reference asphalt so that the
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net rubber solids content, exclusive of any extenders included in the rubber compound is
5.0 percent plus or minus 0.1 percent of the combined weight of the reference asphalt and
the total solids of the rubber compound.
4.
Preparation of test mixture. –Mix a total mix weight of 4600 grams. Proportion the
mixture by weight as follows:
Mix Ingredients
Reference aggregate
Reference asphalt plus total
solids of rubber compound
Percent of
Total Mix
Solids
92.5
7.5
Batch Wt.
(Grams)
100.0
4600.0
4255.0
345.0
5.
Preparation and mixing. Sieve the dry reference aggregate to size, proportioned to the
desired weight, placed in an open pan suitable for continuous stirring, and heated to a
temperature of 295 +/- 5 oF (146 +/- 3 oC). Concurrently, ensure the reference asphalt is
brought to a temperature of 295 +/- 5 oF (146 +/- 3 oC). Place the hot reference aggregate
in the mixing bowl and form a crater in the center. Place the bowl, with reference
aggregate, on the balance which is tared for bowl and total mix weight. Pour the proper
weight of hot reference asphalt into the crater, with the material on the outer edge turned
into the crater, by the aid of a trowel or mixing spoon. Complete the operation by
vigorous mechanical mixing until the reference asphalt has coated all the aggregate
particles. Ensure the total mixing time is 2 minutes. Add the rubber compound at the
mixer approximately 15-25 seconds after the wet mechanical mixing has begun.
6.
Preparation of Test Sample. If the mixture is not sufficiently soft to separate with a
spatula or trowel, place sample in a large flat pan and warm in the oven at 240 oF(116 oC)
only until it can be handled. Separate the mixture and slowly mix and quarter the warm
material to obtain a portion weighing 5.0 + 0.1 gms. for washing and solvent.
7.
Test Procedure. Place the stopper on the stem of the funnel and insert the funnel into the
mouth of the flask. Place the filter paper on the perforated filter plate of the funnel and
spread the sample evenly over the filter paper.
8.
Using the pipet, slowly drop chloroform at room temperature on the particles of the
mixture, washing the rubberized asphalt film from each of the mixture particles, taking
care not to disturb the distribution of the particles. If the solvent accumulates on the
surface, apply a vacuum to the flask through its side tube. Continue to drop the
chloroform on each black particle until it is apparent that the black color will not readily
wash off the particle. Continue washing the sample until the filter paper shows only a
light strain from the rubberized asphalt. The total washing time shall not exceed 30
minutes. Allow the sample to dry.
9.
Report. Report the number of remaining black rubbery particles which are visible to the
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naked eye in the sample.
1012.05 Flexure-fatigue. This method of test is intended for the determination of the
effectiveness of a rubber compound in producing flexure-fatigue resistance in a rubberized
asphaltic paving mixture.
1.
Apparatus. Use the following:
a)
Sieves -No. 200, No. 100, No. 40, and No. 10 (75 mm, 150 mm, 425 mm, and 2.00
mm) sieves conforming to the ASTM E-11.
b)
Mixing machine –Prepare the mixture in a mechanical, bowl-type, high speed mixer
having a 10 to 12 quart.(10 to 12 liter) capacity and which is capable of producing a
well-coated, homogenous mixture in 2 min. or less. Ensure a design that prevents
fouling of the blades and so that each individual batch may be retrieved in
essentially its entirety.
c)
Balance - A balance, having a capacity of 15 kg. or more and a sensitivity of 0.1
gram.
d)
Oven - An oven capable of maintaining within plus or minus 1 oC (2 oF) any desired
temperature from room temperature to 325 oF (163 oC).
e)
Specimen molds - Molds, mold guides, and the compaction block shall be as shown
in Fig. 1. The specimen, when molded, shall be 1.5 x 2 x 14 in.(38 x 51 x 356 mm)
f)
Flexure-Fatigue Machine. Ensure the machine consists of a simple, reciprocating,
hinged table, Fig. 2. The specimen is clamped to the table in such a way that
bending is concentrated within a ½ in.(13 mm) section at the center. The number of
flexings which the specimen withstands for a given magnitude of deformation and
temperature without completely fracturing is taken as a relative measure of
specimen quality. The magnitude of deformation may be varied by interchanging
cams so that total displacement of the central section of the specimen may be
increased from a minimum of 1/8 in.(3 mm), to an intermediate stage of 1/3 in.(8
mm), and finally to a maximum of ½ in.(13 mm) above and below the natural axis.
The rate of flexing shall be 26 plus or minus 1 cycle per min.
g)
Temperature control – Maintain the temperature during storage and testing of bar
specimens at 77 +/- 2 oF (25 +/- 1 oC).
h)
Specimen compactor - Hydraulic testing machine having a capacity greater than
6000 lb.(26.7 kN) and capable of increasing the load at uniform rate 0 to 6000
lbs.(0 to 26.7 kN) in one minute.
2.
Mix Ingredients. Reference aggregate. Compose the reference aggregate for the mixes
of sand and mineral filler, blended to give the following combined gradation within plus
or minus 1.0 percent:
Sieve Size
No. 10 (2.00 mm)
No. 40 (425 μm)
No. 100 (150 μm)
Total Percent Passing
100.0
61.0
22.0
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No. 200 (75 μm)
12.0
Ensure the aggregate retained on the No. 200 (75μm) sieve is natural silica sand from
Ottawa Silica Company, Ottawa, Illinois, and is a blend of their "Flint Shot", "Banding
Sand", and "No. 90" grades, sieved and then proportioned to meet the above gradation
requirements when combined with the mineral filler.
3.
Reference asphalt - 85-100 penetration grade asphalt binder.
4.
Rubber compound - The rubber compound to be tested.
Proportion the rubber
compound to the reference asphalt so that the net rubber solids content, exclusive of any
extenders included in the rubber compound is 5.0 percent plus or minus 0.1 percent of the
combined weight of the reference asphalt and the total solids of the rubber compound.
5.
Test specimens. Ensure the bar specimens conform to the dimensional requirements as
shown in Fig. 1. Make three specimens for each test condition, and report the average of
the test results.
6.
Preparation of test specimens. Proportioning of materials – Mix a total mix weight of
4600 grams for use in making three bar specimens. Proportion the mixture by weight as
follows:
Mix Ingredients
Reference aggregate
Reference asphalt plus total
solids of rubber compound
Percent of Total
Mix Solids
92.5
7.5
Batch Wt.
(Grams)
4255.0
345.0
100.0
4600.0
7.
Preparation and mixing. Sieve the dry reference to size, proportioned to the desired
weight, placed in an open pan suitable for continuous stirring, and heated to a
temperature of 295 +/- 5 oF (146 +/- 3 oC). Concurrently, bring the reference asphalt to a
temperature of 295 +/- 5 oF (146 +/- 3 oC). Place the hot reference aggregate in a crater
formed in the center of the mixing bowl . Place the bowl, with reference aggregate, on
the balance which is tared for bowl and total mix weight. Pour the proper weight of hot
reference asphalt into the crater, and the material on the outer edge turned into the crater,
by the aid of a trowel or mixing spoon. Complete the operation by vigorous mechanical
mixing until the reference asphalt has coated all the aggregate particles. Ensure a total
mixing of 2 minutes. Add the rubber compound at the mixer approximately 15-25
seconds after the wet mechanical mixing has begun.
8.
Molding test specimens. Before being filled, heat the molds and compaction block to 240
o
F (116 oC) and cover with a thin film of petroleum jelly. Immediately following
completion of mixing, fill each mold, with guide in place, with 1400 grams of mix (this
amount of material, when compacted, completely fills the mold, and gives a bulk density
of approximately 2.0). As the mix is placed in the molds, only a light tamping and
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troweling is required to smooth off the mix. Place two of the three molds in the oven
maintained at 240 oF (116 oC). Compact mixes when the temperature of the mix is not
less than 225 oF (107 oC). If the temperature drops below 225 oF (107 oC) the sample
may not be reheated and must be discarded. After the compaction block has been placed
in the guide of the third mold, place the entire assembly in a hydraulic testing machine
and loaded to 6000 pounds (26.7 N) at a rate of 6000 lbs.(26.7 N) per minute. Maintain
the load for one minute and then slowly released over a period of 30 seconds. Compact
the two molds remaining in the oven in like manner. After all the specimens have been
compacted and cooled to room temperature, disassemble the molds and place the
specimens on a smooth, level surface. Maintain care in the handling and positioning of
specimens to insure that no bending or deforming takes place prior to testing.
9.
Storing and aging of specimens. After removal from the molds bring all test specimens
to a room temperature of 77 +/- 2 oF (25 +/- 1 oC) for 48 hours. Then place the bars to be
tested in a constant temperature, forced draft oven capable of maintaining a temperature
of 212 +/- 1 oF (100 +/- 0.5 oC). Cure the bars at this temperature for 48 hours. After
oven-aging, cool the bars to and maintain at 77 +/- 2 oF (25 +/- 1 oC) for a period of 48
hours prior to testing for flexure-fatigue.
10.
Test procedure. Clamp the specimen in the holder of the flexure machine, after strips of
waxed paper have been placed between the specimen and adjoining metal surfaces. Flex
each specimen 1/8 in. (3 mm) for 500 cycles; after which, if the specimen has not failed,
flex 1/3 in.(8 mm) for an additional 500 cycles. If the specimen is still intact, it flex to ½
in. (13 mm) for as many times as necessary to cause failure. A specimen is considered
failed only after it has fractured completely across the center section.
11.
Test results. Report the results in "flexural units", defined as the summation of
equivalent 1/8 in.(3 mm) flexings. Calculation of equivalent 1/8 in. (3 mm) flexings is
based on the assumption that the severity of loading is in direct proportion to the
magnitude of displacement. Hence, each cycle at 1/8 in.(3 mm) displacement produces
1.0 flexure unit; each cycle at 1/3 in. (8 mm) displacement produces 2.67 flexural units;
and each cycle at ½ in.(13 mm) displacement produces 4.00 flexural units. Three or more
specimens represent a given test condition. Average them and multiply by the respective
displacement ratios and report the total as the resistance to flexure-fatigue expressed in
flexural units.
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Figure 1, Specimen mold; Figure 2, Flexure-Fatigue Machine
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