Suggested Changes to Tests in Superpave Mix Design
The following table contain tests that are used in the Superpave mix design and lists test-method changes that have been recommended by the FHWA Superpave Mixtures Expert Task Group. These suggested changes have been forwarded to AASHTO for consideration. AASHTO is expected to act on these changes by Fall 1996.


Test Area Name of Test Changes Recommended
AASHTO T 2 Sampling of Aggregates No Changes Recommended
AASHTO T 248 Reducing Sample Size No Changes Recommended
AASHTO T 27 Sieve Analysis of Fine and Course Aggregates
  1. Section 6.3 Change sample size for "Aggregate with at least 95 percent passing . . ." from 100 grams to 300 grams.

    Also change "Aggregate with at least 85 percent passing a 4.75-mm sieve . . . " from 500 grams to 300 grams

    AASHTO Materials Reference Library indicated no difference in precision between 300 g and 500 g samples. Based on AASHTO, ASTM changed to 300 grams for fine aggregate sieve analysis.
  2. Add note after section 7.4 for sieving time
"Minimum time depends on sieve shaker type, sample size and aggregate. Time will vary."

Note emphasizes that time is not the end point determination for the sieve analysis.

AASHTO T 11 Washed Sieve Analysis No Changes Recommended
AASHTO T 30 Mechanical Analysis of Extracted Aggregate 1. Typo in Section 6.5 "0.015 mm" should be "0.075 mm"
AASHTO T 37 Sieve Analysis of Mineral Filler For Road and Paving Materials No Changes Recommended
AASHTO T 84 Specific Gravity and Absorption of Fine Aggregate
  1. Add note in Section 6.1 "If a sample has less than 10% retained on the 2.36-mm sieve, bulk specific gravity of the retained material can be assumed equal to the bulk specific gravity of the material passing the 2.36-mm sieve."
  2. Add sentence to the end of section 3.1 " For asphalt mixtures, the bulk specific gravity shall be determined on the oven-dry basis."
  3. In section 3.3, change sentence "The laboratory standard for absorption is that obtained after submerging dry aggregate..." to read "after submerging oven-dry aggregate..."
  4. In section 6.2.1 following the sentence "When the aggregate slumps slightly ..." add a note, ""Slumps slightly" may be considered to be when 25% of the circumference slumps."
  5. Section 6.1.1 add note "Potable water should be used"
  6. Section 12.1 Change "Report specific gravity results to the nearest 0.01 and ..." to read "to the nearest 0.001 and ..."
  7. Add note in section 12.1 "Rounding procedures contained in AASHTO R11 should be used"
AASHTO T 85
LTPP P11 		Specific Gravity and Absorption of Coarse Aggregate 1. Section 10.1 Change "Report specific gravity results to the nearest 0.01 and ..." to read "to the nearest 0.001 and ..."

3. Section 8.1 add note "Potable water should be used"

4. Add note in section 10.1 "Rounding procedures contained in AASHTO R11 should be used"
AASHTO T 96 Resistance to Degradation of Small Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine No Changes
AASHTO T 100 Specific Gravity of Soils
  1. Section 7.1 change "The pycnometer shall be filled wih distilled water (Note 3) essentially at room temperature." to read "essentially at room temperature ensuring that all air bubbles are removed."
AASHTO T 104 Soundness of Aggregate by Use of Sodium Sulfate or Magnesium Sulfate No Changes
AASHTO T 112 Clay Lumps and Friable Particles in Aggregate No Changes
AASHTO T 164
LTPP P04 		Quantitative Extraction of Bitumen From Bituminous Paving Materials 2. Section 11.1, add note. "When extracted asphalt is to be used for Abson recovery, moisture-content determination is not required."

3. Section 11.6 add note. "When extracted asphalt is to be used for Abson recovery, determination of the amount of mineral matter in the extract is not required."

4. Section 12.0 add note. "When extracted asphalt is to be used for Abson recovery, determination of the asphalt content is not required."

6. Section 28.1, add note. "When extracted asphalt is to be used for Abson recovery, moisture content determination is not required."

7. Section 28.2.9, add note. "When extracted asphalt is to be used for Abson recovery, determination of the amount of mineral matter in the extract is not required."

8. Section 29.0, add note. "When extracted asphalt is to be used for Abson recovery, determination of the asphalt content is not required."
AASHTO T 166
LTPP P02 		Bulk Specific Gravity of Compacted Bituminous Mixtures Using Saturated Surface Dry Specimens
  1. Section 2.6, add note. "Care should be exercised to ensure sawing does not damage specimen."
  2. Section 3.2, add note. "Care should be taken to ensure no trapped air bubbles exist under the specimen.
  3. Section 4.1, add two notes. "Each specimen shall be immersed and weighed individually." and "Terry cloth has been found to work well for an absorbent cloth. "Damp" should be considered to be when no water can be wrung from the towel."
  4. Precision and bias statement needed. Perhaps same data can be used as shown in ASTM.
  5. Add new section, Section 12 Reporting. Require BSG reported to 0.001.
AASHTO T 176 Plastic Fines in Graded Aggregate and Soils by Use of the Sand Equivalent Tests No changes.
AASHTO TP 209
(draft revision) 		Standard Test Method for Determining the Maximum Specific Gravity of Bituminous Paving Mixtures 2. Section 9.1, add note. "Cores and bag samples should be reheated in warm oven only to the point where the mix can be broken apart (typically 70 C). Use procedure in Section 11 to ensure that no water has been absorbed into the aggregate."

3. Section 9.4, add note. "Vacuum should be achieved within 2 minutes."

4. Section 9.4 change "... until the residual pressure manometer reads 30 mm or less." to "... until the residual pressure manometer reads 30 mm +/- 2 mm."

5. Section 9.4 change "Maintain this residual pressure for 5 to 15 min." to "Maintain this residual pressure for 15 +/- 1 min."

6. Section 9.4 change "... by vigorous shaking at intervals of ..." to read "by vigorous shaking for 15 seconds at intervals of ..."

AASHTO T 283 Resistance of Compacted Bituminous Mixture to Moisture Damage Mix ETG is studying.
AASHTO T 287 Determination of Asphalt Content Using a Nuclear Asphalt Content Gauge No change...
AASHTO TP 48 Standard Test Method for Viscosity Determinations of Unfilled Asphalts Using the Brookfield Thermosel Apparatus This test method is not written for current generation of equipment. Needs to be updated and made generic.
ASTM D 4791 Standard Test Method for Flat or Elongated Particles in Coarse Aggregate 1. Section 1.1. Expand scope to include "This test can be done on virgin aggregate or on aggregate recovered from hot mix."

2. Add note "The sample can be obtained from extracted aggregate from T 164 or from ignition-oven test."

ASTM is updating test method to include "percent flat and elongated"

AASHTO TP 33 Standard Test Method for Uncompacted Void Content of Fine Aggregate (As Influenced by Particle Shape, Surface Texture and Grading)
  1. Section 1.1. Expand scope to include "This test can be done on virgin aggregate or on aggregate recovered from hot mix."
  2. Add note "The sample can be obtained from extracted aggregate from T 164 or from ignition-oven test."
  3. Section 9.1 change "2.36 mm (No. 8) to 1.18 mm (No. 16)" to read "passing 2.36 mm (No. 8), retained on 1.18 mm (No. 16)" Change other listings in table similarly.
ASTM D4125 Determination of Asphalt Content by Use of NCAT Ignition Oven No change.
Draft ASTM procedure Percentage of Fractured Particles in Coarse Aggregate.
  1. Section 1.1. Expand scope to include "This test can be done on virgin aggregate or on aggregate recovered from hot mix."
  2. Section 2. Add to references "T 11 Washed Sieve Analysis, Procedure A"
  3. Section 6.1 Add explanation that sample can be obtained from extracted aggregate from T 164 or from ignition oven test.


Suggested Changes To Superpave Mixture Design Manual

The following report was produced by SHRP researchers and serves as the mix design manual for Superpave:

R. J. Cominsky, G. A. Huber, T. W. Kennedy, and R. M. Anderson, "The Superpave Mix Design Manual for New Construction and Overlays," Strategic Highway Research Program, SHRP-A-407, 1994.
The following changes are being recommended to be added to the Superpave mixture design manual for each of the tests listed below.

AASHTO T 100

Specific Gravity of Soils

2. For Superpave distilled water must be used.

AASHTO T 164

Quantitative Extraction of Bitumen From Bituminous Paving Materials

1. For Superpave mixtures, this test method is not to be used for asphalt-content determination, but only to collect asphalt for Abson recovery.

5. For Superpave asphalt recovery vacuum extractor should be similar to Figure 6b and 6c. Extractor as shown in Figure 6a is not acceptable."

AASHTO T 166

Bulk Specific Gravity of Compacted Bituminous Mixtures Using Saturated Surface Dry Specimens

4. Method B is not acceptable for use in Superpave mix design.

AASHTO T 176

Plastic Fines in Graded Aggregate and Soils by Use of the Sand Equivalent Tests

1. For Superpave mix design, the test must be performed with a mechanical shaker.

2. For Superpave mix design, the test must be performed with a mechanical shaker.

AASHTO TP 209 (draft revision)

Standard Test Method for Determining the Maximum Specific Gravity of Bituminous Paving Mixtures

1. Water aspirator not allowed for Superpave mix designs.

Those with questions pertaining to these test method changes may contact Gerry Huber or Bob McGennis.



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