ASPHALT WAQTC FOP AASHTO R 47 (19)
REDUCING SAMPLES OF ASPHALT MIXTURES TO TESTING SIZE
FOP FOR AASHTO R 47
Scope
This procedure covers sample reduction of asphalt mixtures to testing size in accordance with
AASHTO R 47-19. The reduced portion is to be representative of the original sample.
Apparatus
• Thermostatically controlled oven capable of maintaining a temperature of at least 110°C
(230°F) or high enough to heat the material to a pliable condition for splitting.
• Non-contact temperature measuring device.
• Metal spatulas, trowels, metal straightedges, or drywall taping knives, or a combination
thereof; for removing asphalt mixture samples from the quartering device, cleaning
surfaces used for splitting, etc.
• Square-tipped, flat-bottom scoop, shovel or trowel for mixing asphalt mixture before
quartering.
• Miscellaneous equipment including hot plate, non-asbestos heat-resistant gloves or
mittens, pans, buckets, and cans.
• Sheeting: Non-stick heavy paper or other material as approved by the agency.
• Agency-approved release agent, free of solvent or petroleum-based material that could
affect asphalt binder.
• Mechanical Splitter Type B (Riffle): having a minimum of eight equal-width chutes
discharging alternately to each side with a minimum chute width of at least 50 percent
larger than the largest particle size. A hopper or straight-edged pan with a width equal to
or slightly smaller than the assembly of chutes in the riffle splitter to permit uniform
discharge of the asphalt mixture through the chutes without segregation or loss of
material. Sample receptacles of sufficient width and capacity to receive the reduced
portions of asphalt mixture from the splitter without loss of material.
• Quartering Template: formed in the shape of a cross with equal length sides at right
angles to each other. Template shall be manufactured of metal that will withstand heat
and use without deforming. The sides of the quartering template should be sized so that
the length exceeds the diameter of the flattened cone of asphalt mixture by an amount
allowing complete separation of the quartered sample. Height of the sides must exceed
the thickness of the flattened cone of asphalt mixture.
• Non-stick mixing surface that is hard, heat-resistant, clean, level, and large enough to
permit asphalt mixture samples to be mixed without contamination or loss of material.
Sampling
Obtain samples according to the FOP for AASHTO R 97.
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ASPHALT WAQTC FOP AASHTO R 47 (19)
Sample Preparation
The sample must be warm enough to separate. If not, warm in an oven until it is sufficiently
soft to mix and separate easily. Do not exceed either the temperature or time limits specified
in the test method(s) to be performed.
Selection of Procedure (Method)
Refer to agency requirements when determining the appropriate method(s) of sample
reduction. In general, the selection of a particular method to reduce a sample depends on the
initial size of the sample vs. the size of the sample needed for the specific test to be
performed. It is recommended that, for large amounts of material, the initial reduction be
performed using a mechanical splitter. This decreases the time needed for reduction and
minimizes temperature loss. Further reduction of the remaining asphalt mixture may be
performed by a combination of the following methods, as approved by the agency. The
methods for reduction are:
• Mechanical Splitter Type B (Riffle) Method
• Quartering Method
− Full Quartering
− By Apex
• Incremental Method
Procedure
When heating of the equipment is desired, it shall be heated to a temperature not to exceed
the maximum mixing temperature of the job mix formula (JMF).
Mechanical Splitter Type B (Riffle) Method
1. Clean the splitter and apply a light coating of approved release agent to the surfaces that
will come in contact with asphalt mixture (hopper or straight-edged pan, chutes,
receptacles).
2. Place two empty receptacles under the splitter.
3. Carefully empty the asphalt mixture from the agency-approved container(s) into the
hopper or straight-edged pan without loss of material. Uniformly distribute from side to
side of the hopper or pan.
4. Discharge the asphalt mixture at a uniform rate, allowing it to flow freely through the
chutes.
5. Any asphalt mixture that is retained on the surface of the splitter shall be removed and
placed into the appropriate receptacle.
6. Reduce the remaining asphalt mixture as needed by this method or a combination of the
following methods as approved by the agency.
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ASPHALT WAQTC FOP AASHTO R 47 (19)
7. Using one of the two receptacles containing asphalt mixture, repeat the reduction process
until the asphalt mixture contained in one of the two receptacles is the appropriate size
for the required test.
8. After each split, remember to clean the splitter hopper and chute surfaces if needed.
9. Retain and properly identify the remaining unused asphalt mixture sample for further
testing if required by the agency.
Quartering Method
1. If needed, apply a light coating of release agent to quartering template.
2. Dump the sample from the agency approved container(s) into a conical pile on a hard,
“non-stick,” clean, level surface where there will be neither a loss of material nor the
accidental addition of foreign material. The surface can be made non-stick by the
application of an approved asphalt release agent, or sheeting.
3. Mix the material thoroughly by turning the entire sample over a minimum of four times
with a flat-bottom scoop; or by alternately lifting each corner of the sheeting and pulling
it over the sample diagonally toward the opposite corner, causing the material to be
rolled. Create a conical pile by either depositing each scoop or shovelful of the last
turning on top of the preceding one or lifting both opposite corners.
4. Flatten the conical pile to a uniform diameter and thickness where the diameter is four to
eight times the thickness. Make a visual observation to ensure that the material is
homogeneous.
5. Divide the flattened cone into four equal quarters using the quartering template or
straightedges assuring complete separation.
6. Reduce to appropriate sample mass by full quartering or by apex.
Full Quartering
a. Remove diagonally opposite quarters, including all of the fine material, and place in a
container to be retained.
b. Remove the quartering template, if used.
c. Combine the remaining quarters.
d. If further reduction is necessary, repeat Quartering Method Steps 3 through 6.
e. Repeat until appropriate sample mass is obtained. The final sample must consist of
the two remaining diagonally opposite quarters.
f. Retain and properly identify the remaining unused portion of the asphalt mixture
sample for further testing if required by the agency.
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ASPHALT WAQTC FOP AASHTO R 47 (19)
Reducing by Apex
a. Using a straightedge, slice through a quarter of the asphalt mixture from the center
point to the outer edge of the quarter.
b. Pull or drag the material from the quarter with two straight edges or hold one edge of
the straightedge in contact with quartering device.
c. Remove an equal portion from the diagonally opposite quarter and combine these
increments to create the appropriate sample mass.
d. Continue using the apex method with the unused portion of the asphalt mixture until
samples have been obtained for all required tests.
e. Retain and properly identify the remaining unused portion of the asphalt mixture
sample for further testing if required by the agency.
Incremental Method
1. Cover a hard, clean, level surface with sheeting. This surface shall be large enough that
there will be neither a loss of material nor the accidental addition of foreign material.
2. Place the sample from the agency approved container(s) into a conical pile on that
surface.
3. Mix the material thoroughly by turning the entire sample over a minimum of four times:
a. Use a flat-bottom scoop; or
b. Alternately lift each corner of the sheeting and pull it over the sample diagonally
toward the opposite corner, causing the material to be rolled.
4. Create a conical pile by either depositing each scoop or shovelful of the last turning on
top of the preceding one or lifting both opposite corners.
5. Grasp the sheeting and roll the conical pile into a cylinder (loaf), then flatten the top.
Make a visual observation to determine that the material is homogenous.
6. Remove one quarter of the length of the loaf and place in a container to be saved; by
either:
a. Pull sheeting over edge of counter and drop material into container.
b. Use a straightedge at least as wide as the full loaf to slice off material and place into
container.
7. Obtain an appropriate sample mass for the test to be performed; by either:
a. Pull sheeting over edge of counter and drop cross sections of the material into
container until proper sample mass has been obtained.
b. Use a straightedge at least as wide as the full loaf to slice off cross sections of the
material until proper sample mass has been obtained and place into container.
Note 1: When reducing the sample to test size it is advisable to take several small increments, determining the
mass each time until the proper minimum size is achieved. Unless the sample size is grossly in excess
of the minimum or exceeds the maximum test size, use the sample as reduced for the test.
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ASPHALT WAQTC FOP AASHTO R 47 (19)
8. Repeat Step 7 until all the samples for testing have been obtained or until final quarter of
the original loaf is reached.
9. Retain and properly identify the remaining unused portion of the asphalt mixture sample
for further testing if required by the agency.
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ASPHALT WAQTC FOP AASHTO R 47 (19)
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