OAPA

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OAPA
2007 ANNUAL CONFERENCE
WHEN TO WORRY ABOUT TEST RESULTS
Danny Gierhart, P.E. ODOT Bituminous Engineer
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ANSWER
ALWAYS!
(However, you need to worry about some more than
others)
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What is the test designed to tell you?
What are the potential ramifications of a failing test result?
Are the potential ramifications minor or major?
For this test, how much could the degree out of specification affect pavement performance?
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Test results are often used to document the
degree out of specification so that a
corresponding financial penalty can be assessed.
The very best use of test results is to track the
ongoing quality of a project and make corrections
as necessary to ensure a quality pavement.
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LIQUID ASPHALT
AGGREGATE
HOT MIX ASPHALT
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ASPHALT BINDER TEST DYNAMIC SHEAR RHEOMETER
(DSR)
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ASPHALT BINDER TEST DYNAMIC SHEAR RHEOMETER
(DSR)
What is the test designed to tell you?
The purpose of the test is to address potential
rutting due to binder stiffness.
What are the potential ramifications of a failing test result?
Typical failing DSR tests reveal increased
rutting and/or cracking potential. from
negligible up to an average of 1/4. They can
also indicate whether or not the binder has
sufficient polymer.
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ASPHALT BINDER TEST DYNAMIC SHEAR RHEOMETER
(DSR)
Are the potential ramifications minor or major?
A typical failing DSR test indicates relatively
minor problems. Large deviations can indicate
significant problems.
How much does the degree out of spec affect pavement performance?
DSR tests that are slightly low (running 0.90 to
0.99) are minor. Tests that are ½ the target
indicate a lower grade of binder was sampled.
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ASPHALT EMULSION TEST SAYBOLT-FUROL VISCOSITY
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ASPHALT EMULSION TEST SAYBOLT-FUROL VISCOSITY
What is the test designed to tell you?
The purpose of the test is to show the
as-delivered viscosity, or fluidity of the
material.
What are the potential ramifications of a failing test result?
Failing tack coat results will often be on the
low side, indicating a deficiency of residual
asphalt. This could cause slippage between
lifts. For chip seal emulsions, a low value
could mean that aggregate particles will not
stick well. Results on the high side may be
caused by an old sample.
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Slippage between lifts as a result of
insufficient adhesion.
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ASPHALT EMULSION TEST SAYBOLT-FUROL VISCOSITY
Are the potential ramifications minor or major?
Failing viscosity tests that are an accurate
indicator of low residual asphalt content can,
under the right circumstances, have serious
ramifications.
How much does the degree out of spec affect pavement performance?
Field application has a significant effect on
performance. It is very difficult to establish
how big the problem is based on test results
alone.
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RED FLAG ALERT!
Emulsion test results are only as good as the sample quality. Emulsion samples are particularly susceptible to compromise.
Samples obtained after the emulsion is diluted onsite.
Samples obtained, but not submitted for weeks.
Samples allowed to sit in sun or roll around in truck.
Samples placed in a contaminated container.
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ASPHALT CUTBACK TEST KINEMATIC VISCOSITY
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ASPHALT CUTBACK TEST KINEMATIC VISCOSITY
What is the test designed to tell you?
This test also shows the as-delivered viscosity,
or fluidity of the material. It tells the
supplier about the uniformity of shipments.
What are the potential ramifications of a failing test result?
Low test results indicate a higher ratio of
diluent to asphalt cement. The prime may not
provide the moisture barrier intended. High test
results indicate a lower ratio of diluent to
asphalt cement.
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ASPHALT CUTBACK TEST KINEMATIC VISCOSITY
Are the potential ramifications minor or major?
Failing viscosity tests have a minimal effect on
the quality of prime. For example, both MC-30
and MC-70 are acceptable for use as prime coat.
An out-of-spec high MC-30 may meet or be low for
MC-70.
How much does the degree out of spec affect pavement performance?
Out-of-spec on the high side should not have a
major effect. Tests for MC-30 that are
significantly low will likely result in an
ineffective moisture barrier.
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AGGREGATE TEST - GRADATION
Comparison
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Comparison
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Comparison
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AGGREGATE TEST GRADATION (Max. Agg. Size)
What is the test designed to tell you?
The maximum aggregate size influences allowable
pavement thickness, susceptibility to
segregation, asphalt content, and volumetric
requirements.
What are the potential ramifications of a failing test result?
A gradation on the maximum sieve size that is
less than 100 indicates the presence of
over-sized particles. This could result in
compaction difficulties, segregation, and asphalt
content problems.
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AGGREGATE TEST GRADATION (Max. Agg. Size)
Are the potential ramifications minor or major?
Gradations results showing less that 100 passing
the maximum sieve size are rare and usually only
slightly less than 100. Potential ramifications
are minimal.
How much does the degree out of spec affect pavement performance?
Results deviating by 10 or more indicate that a
different type of HMA was sampled than expected.
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Comparison
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AGGREGATE TEST GRADATION ( Passing 200)
What is the test designed to tell you?
The passing the 200 sieve influences
compaction, asphalt content, and volumetric
requirements.
What are the potential ramifications of a failing test result?
A low passing the 200 may result in high air
voids, permeability, and a lower AC demand. A
high value may result in low air voids and VMA, a
higher AC demand, and a tender mix.
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Check cracking as a result of a high passing
the 200 sieve combined with a low binder content
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High passing the 200 gives the HMA a lighter
appearance, indicating a lower film thickness and
lower durability.
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AGGREGATE TEST GRADATION ( Passing 200)
Are the potential ramifications minor or major?
High dust portions can have major ramifications
on the longevity of a roadway. They are
typically accompanied by lower than necessary
binder contents which reduce pavement durability.
How much does the degree out of spec affect pavement performance?
Deviations inside the tolerance of 2 typically
dont have too much of an effect. Deviations
greater than 2 should be addressed immediately.
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Comparison
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AGGREGATE TEST GRADATION ( Passing 8)
What is the test designed to tell you?
The passing the 8 sieve has a major influence
on voids and permeability.
What are the potential ramifications of a failing test result?
A low passing the 8 sieve may result in a
permeable mix. A high value is not as worrisome
as a low value.
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Low passing the 8 indicates a mix that is
subject to permeability, which in turn can lead
to stripping.
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AGGREGATE TEST GRADATION ( Passing 8)
Are the potential ramifications minor or major?
A low passing the 8 sieve can have major
ramifications on the longevity of a roadway.
They are often accompanied by permeability issues
which can lead to stripping.
How much does the degree out of spec affect pavement performance?
Gradations near the lower broad band are
especially of concern when accompanied by a low
passing the 200 sieve.
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AGGREGATE TEST SAND EQUIVALENT
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AGGREGATE TEST SAND EQUIVALENT
What is the test designed to tell you?
The test is intended to show the relative
proportions of fine dust or clay-like material in
the aggregate.
What are the potential ramifications of a failing test result?
A low sand equivalent result indicates a high
percentage by volume of clay-like fines. These
fines may cause the asphalt binder to debond from
the aggregate in the presence of moisture.
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Low sand equivalents indicate a high percentage
of clay-like fines, which can cause a poor bond
with the asphalt binder.
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AGGREGATE TEST SAND EQUIVALENT
Are the potential ramifications minor or major?
Although extremely rare, a failing sand
equivalent test indicates a very poor aggregate
quality, which can have major ramifications to
the longevity of the pavement.
How much does the degree out of spec affect pavement performance?
Sand equivalent results do not have to be much
out of spec to be a cause for concern.
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HOT MIX ASPHALT TEST TENSILE STRENGTH RATIO
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HOT MIX ASPHALT TEST TENSILE STRENGTH RATIO
What is the test designed to tell you?
The test is intended to show the susceptibility
of the HMA to moisture damage.
What are the potential ramifications of a failing test result?
A failing TSR indicates the mix is inherently
susceptible to stripping and raveling.
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Tensile Strength Ratio AASHTO T 283

• Moisture Sensitivity
• Prepare set of 6 specimens
• 6.5 to 7.5 voids
• Represents anticipated in-service voids
• Use 3 specimens as controls
• Remaining 3 specimens are vacuum saturated 70 to
  80
• Min. 16 hour freezing at 0oF
• 24 Hours in 140oF water bath
• Bring all specimens to test temperature (77oF)
  and determine indirect tensile strength

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Tensile Strength Ratio AASHTO T 283
Saturating Specimens
Freezing Specimens
Specimens in Hot Water Bath
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Moisture SensitivityAASHTO T 283
Determine the indirect tensile strengths of both
sets of 3 specimens
Calculate the Tensile Strength Ratio (TSR)
Minimum of 75 required for field tests
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HOT MIX ASPHALT TEST TENSILE STRENGTH RATIO
Are the potential ramifications minor or major?
The ramifications of a failing TSR can be severe.

How much does the degree out of spec affect pavement performance?
Because the test procedure is not one of the most
repeatable, results down to around 70 should be
confirmed by further testing. TSR results less
than 65 would be just cause for immediate work
stoppage to investigate and fix the problem.
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HOT MIX ASPHALT TEST ASPHALT BINDER CONTENT
JMF
Result
Comparison
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HOT MIX ASPHALT TEST ASPHALT BINDER CONTENT
What is the test designed to tell you?
The test shows the percent of asphalt binder by
weight of the total mix.
What are the potential ramifications of a failing test result?
A low binder content can lead to premature aging
of the pavement, stripping, or raveling. A high
binder content can lead to flushing or bleeding
in the pavement.
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Low binder contents can lead to raveling,
stripping, and premature aging.
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High binder contents can lead to flushing or
bleeding.
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HOT MIX ASPHALT TEST ASPHALT BINDER CONTENT
Are the potential ramifications minor or major?
The ramifications would likely be different
depending on the degree out of spec. Whether any
of the potential pavement distresses occur also
depend on other factors.
How much does the degree out of spec affect pavement performance?
Binder content is one of several parameters that
affect each other. However, binder contents very
far out of spec should be a major cause for
concern.
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HOT MIX ASPHALT TEST AIR VOID CONTENT
Specimen 2
Specimen 1
Average
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HOT MIX ASPHALT TEST AIR VOID CONTENT
What is the test designed to tell you?
The test shows the percent air voids in
lab-molded specimens. This test indicates a mix
property, not in-place air voids.
What are the potential ramifications of a failing test result?
With a low air void content, the pavement is
susceptible to rutting, flushing, and bleeding.
For high air void contents, the pavement is
susceptible to premature aging, raveling, and
stripping.
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HOT MIX ASPHALT TEST AIR VOID CONTENT
Are the potential ramifications minor or major?
The ramifications can be severe depending on the
degree out of specification. Whether any of the
potential pavement distresses occur also depend
on other factors.
How much does the degree out of spec affect pavement performance?
All failing void contents need some type of
action. Mixes that are 1 or more out of spec
indicate a need for immediate shutdown for more
trials.
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HOT MIX ASPHALT TEST VOIDS IN MINERAL AGGREGATE
(VMA)
Specimen 2
Specimen 1
Average
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HOT MIX ASPHALT TEST VOIDS IN MINERAL AGGREGATE
(VMA)
What is the test designed to tell you?
VMA is calculated from the binder content test
and lab-molded specimens. It tells about the
total volume of the voids created by aggregates.
What are the potential ramifications of a failing test result?
Samples with low VMA do not have enough void
space to provide the proper amount of binder and
the proper amount of air. Low VMA, depending on
the reason, could result in many distress types.
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HOT MIX ASPHALT TEST VOIDS IN MINERAL AGGREGATE
(VMA)
Are the potential ramifications minor or major?
The ramifications can be severe depending on the
degree out of specification. Whether any of the
potential pavement distresses occur also depend
on other factors.
How much does the degree out of spec affect pavement performance?
Mixes that are 1 or more out of spec indicate a
need for immediate shutdown for more trials.
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HOT MIX ASPHALT TEST ROADWAY DENSITY
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HOT MIX ASPHALT TEST ROADWAY DENSITY
What is the test designed to tell you?
The test indicates the in-place density achieved
by the compactive effort of the rolling operation.
What are the potential ramifications of a failing test result?
Low density may result in permeability,
stripping, raveling, cracking, premature aging,
and premature failure. High density may result
in rutting, flushing, or bleeding.
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HOT MIX ASPHALT TEST ROADWAY DENSITY
Are the potential ramifications minor or major?
The ramifications of failure to achieve proper
density are major. Proper density can in part
make up for other shortcomings. Improper density
can cause failure even if other parameters are
good.
How much does the degree out of spec affect pavement performance?
Any failing density report should cause the
agency to closely examine the rolling operation.
The further out of spec, the shorter the
anticipated pavement life.
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In summary, all failing test results should be
followed up on.
Some test results may be received after all of
the material is already in place.
Some test results will be received in time for
corrective action, which should be immediate.
Remember that a few hours time addressing a
problem may prolong the pavement life by several
years.
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QUESTIONS?