AASHTOT-269

Standard Method of Test for
Percent Air Voids in Compacted Dense and Open Asphalt Mixtures
AASHTO Designation: T 269-97 (2007)1
ASTM Designation: D 3203-05
1. SCOPE
1.1. This method covers determination of the percent air voids in compacted dense and open
asphalt mixtures.
1.2. This standard may involve hazardous materials, operations, and equipment. This standard does
not purport to address all of the safety concerns associated with its use. It is the responsibility of
the user of this standard to establish appropriate safety and health practices and determine the
applicability of regulatory limitations prior to use.
DOCUMENTS
2. REFERENCED
2.1. AASHTO Standards:
T 166, Bulk Specific Gravity of Compacted Hot Mix Asphalt Using Saturated Surface-Dry Specimens
T 209, Theoretical Maximum Specific Gravity and Density of Hot Mix Asphalt (HMA)
T 275, Bulk Specific Gravity of Compacted Bituminous Mixtures Using Paraffin-Coated Specimens
T 331, Bulk Specific Gravity and Density of Compacted Hot Mix Asphalt (HMA) Using Automatic Vacuum Sealing Method
2.2. ASTM Standards:
D 3549, Thickness or Height of Compacted Bituminous Paving Mixture Specimens
D 4460, Calculating Precision Limits Where Values are Calculated from Other Test Methods
E 1547, Standard Terminology Relating to Industrial and Specialty Chemicals
3. TERMINOLOGY
3.1. The terms specific gravity and density used in this test method are in accordance with ASTM
E 1547.
3.2. Definitions:
3.2.1. air voids—the pockets of air between the asphalt-coated aggregate particles in a compacted
asphalt mixture.
3.2.2. dense asphalt mixture—asphalt mixtures in which the air voids are less than 10 percent when
compacted.
3.2.3. open asphalt mixture—asphalt mixtures in which the air voids are 10 percent or more when
compacted.
3.2.3.1. For borderline cases, an asphalt mixture shall be designated an open asphalt mixture if the
calculated percent air voids, based on either Section 6.1 or 6.2, is 10 percent or more.
AND
USE
4. SIGNIFICANCE
4.1. The percent air voids in an asphalt mixture is used as one of the criteria in the design methods and
for evaluation of the compaction achieved on asphalt paving projects.
5. SAMPLING
5.1. Samples for testing shall consist of specimens from laboratory-molded mixtures or cores from
field-compacted mixtures.
6. PROCEDURE
6.1. For dense asphalt mixtures, determine the bulk specific gravity of the compacted mixture either by
T 166, T 275 or T 331. Determine the theoretical maximum specific gravity in accordance with
T 209 on a comparable asphalt mixture to avoid the influence of differences in gradation, asphalt
content, etc.
6.2. For open asphalt mixtures, determine the density of a regularly shaped specimen of compacted
mixture from its dry mass (in grams) and its volume (in cubic centimeters). Obtain the height of
the specimen by ASTM D 3549. Measure the diameter of the specimen at four locations, and
average the measurements. Calculate the volume of the specimen based on the average height and
diameter measurement. Convert the density to bulk specific gravity by dividing by 0.99707 g/cm3
or 997 kg/m3, the density of water at 25ºC (77ºF). Determine the theoretical maximum specific
gravity in accordance with T 209 on a comparable asphalt mixture to avoid the influence of
differences in gradation, asphalt content, etc.
For reference purposes, determine both the bulk specific gravity and the theoretical maximum
specific gravity on portions of the same sample of compacted asphalt mixture.
7. CALCULATIONS
7.1. Calculate the percent air voids in a compacted asphalt mixture as follows:
A B
=−(1)
Percent Air Voids1001(/)
where:
A= the bulk specific gravity, and
B= the theoretical maximum specific gravity.
7.2. Report the percent air voids to one decimal place.
8. PRECISION AND BIAS
8.1. The precision of this test method depends on the precision of test methods for bulk specific
gravity and theoretical maximum specific gravity. It is computed by a procedure described in
ASTM D 4460. Since the computation for percent air voids in Section 7.1 involves the quotient
of bulk specific gravity divided by the theoretical maximum specific gravity, the quotient formula
is used:
σ=(2)
x y
where:
σx/y= the standard deviation for determining the precision limits of test results for a standard
based on the quotient of two test results from two other standards,
x= the mean (average) value of the x standard (bulk specific gravity) test results,
y= the mean (average) value of the y standard (theoretical maximum specific gravity) test
results,
σx= the standard deviation from the precision statement of the x standard, and
σy= the standard deviation from the precision statement of the y standard.
Note 1—The x standard (T 166, T 275, or T 331) is used to compute bulk specific gravity, and
the y standard (T 209) is used to compute theoretical maximum specific gravity.
8.2. Criteria for judging the acceptability of percent air voids test results that are obtained by using
T 275 and T 209 for nonporous aggregates are:
Test and Type Index Standard Deviation Acceptable Range of Two Results
Single-Operator Precision 0.32 0.91
Multilaboratory Precision — —
8.3. Criteria for judging the acceptability of percent air voids test results that are obtained by using
T 166 and T 209 for nonporous aggregates are:
Test and Type Index Standard Deviation Acceptable Range of Two Results
Single-Operator Precision 0.51 1.44
Multilaboratory Precision 1.09 3.08 APPENDIX
(Nonmandatory Information)
CALCULATION OF PRECISION
X1. EXAMPLE
X1.1. Assume the following precision data:
Bulk Specific Gravity, x
When the average x = 2.423 and the standard deviation of x = 0.007.
Theoretical Maximum Specific Gravity, y
When the average y = 2.523 and the standard deviation of y = 0.004.
Then using Equation 2:
σ==(X1.1)
0.00316
x y
This value is in terms of air voids; therefore, the value should be multiplied by 100 to convert it
into a percentage. Therefore:
()
0.00321000.32%
σ==(X1.2)
x y
1 Similar, but not technically identical to ASTM D 3203-05.。