Long Term Pavement Performance Project Laboratory Materials Testing and Handling Guide

Protocol P02
Test Method for Bulk Specific Gravityof Asphaltic Concrete (AC02)

This LTPP protocol covers the determination of the bulk specific gravity of asphaltic (bituminous) concrete cores and this test shall be carried out in accordance with AASHTO T166-88I (Method A) as modified by the following. Only sections of the referenced standard which have been modified are included below. In all other sections the standard (AASHTO T166-88I, Method A) shall be followed as written. This test shall be performed on cores obtained from test sections included in the LTPP experiments.

1. SCOPE

1.2 This method should not be used with samples that contain open or interconnecting voids and/or absorb more than 2 percent of water by volume, as determined by LTPP Protocol P02.

2. TEST SPECIMENS

2.1 Test specimens will be cores obtained from a bituminous pavement section.

2.2 Size of specimens: The size of the bituminous concrete cores will be as specified in the laboratory test program.

2.4 Care shall be taken to avoid distortion, bending or cracking of specimens during and after the removal from the pavement, and during storage in the laboratory. Specimens shall be stored in a safe, cool place.

2.5 If required, specimens may be separated from other pavement layers by sawing.

4. PROCEDURE

4.1 Follow the guidelines of Note 3, first the immersed mass, then the surface dry mass and finally the dry mass.

5. CALCULATION

5.3 If the percent water absorbed by the first specimen in Section 5.2 exceeds 2 percent, use Appendix A (Bulk Specific Gravity of Compacted Bituminous Mixtures Using Paraffin-Coated Specimens) to LTPP Protocol P02.

6. APPARATUS (METHOD B)

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7. PROCEDURE (METHOD B)

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8. CALCULATIONS (METHOD B)

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9. PROCEDURE (METHOD C)

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10. CALCULATIONS (METHOD C)

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12. REPORT

12.1 Sample Identification shall include: Laboratory Identification Code, Region, State, State Code, SHRP ID, Layer Number, Field Set Number, Sample Area Number, Sample Location Number, LTPP Sample Number.

12.2 Test Identification shall include: Laboratory Test Number, Test Date, LTPP Test Designation, LTPP Protocol Number.

12.3 Test Results

1. Bulk Specific Gravity (BSG) to three decimal places.
2. Percent Water Absorbed by Volume, percent (to the nearest whole number).
3. Bulk Specific Gravity (paraffin-coated specimen) to three decimal places.

12.4 Comments shall include LTPP standard comment code(s) listed in Section 4.3 and any other note as needed.

12.5 Use Form T02 (Test Sheet T02) to report the above information (Items 12.1 to 12.4).

APPENDIX A
BULK SPECIFIC GRAVITY OF ASPHALTIC CONCRETE USING PARAFFIN-COATED SPECIMENS.

This appendix to LTPP Protocol P02 covers the determination of bulk specific gravity of paraffin-coated cores of asphaltic (bituminous) concrete and this test shall be carried out in accordance with AASHTO T275-83 (Method A) as modified and described in the following. The test shall be carried out only if more than two percent of water is absorbed by the specimen using LTPP Protocol P02. This test shall be performed on cores obtained from test sections included in the LTPP experiments.

1. SCOPE

1.1 This method of test covers the determination of bulk specific gravity of specimens of compacted bituminous mixtures as defined in AASHTO M 132, Terms Relating to Density and Specific Gravity of Solids, Liquids and Gases.

1.2 This method should be used with samples that contain open or interconnecting voids and/or absorb more than 2 percent of water by volume, as determined by LTPP Protocol P02.

1.3 The bulk specific gravity of the compacted bituminous mixtures may be used in calculating the unit weight of the mixture.

2. TEST SPECIMENS

2.1 Test specimens will be cores obtained from a bituminous pavement section. The mixtures may be surface or wearing course, binder or leveling course, or bituminous base.

2.2 Size of Specimens: The size of the bituminous concrete cores will be as specified in the laboratory test program.

2.3 Care shall be taken to avoid distortion, bending, or cracking of specimens during and after the removal from the pavement and during storage in the laboratory. Specimens shall be stored in a safe, cool place.

2.4 Specimens shall be free from foreign materials such as seal coat, tack coat, foundation material, soil, paper, or foil.

2.5 If required, specimens may be separated from other pavement layers by sawing.

3. APPARATUS

3.1 Balance - Conforming to the requirements of AASHTO M231, for the class of balance required for the sample weight of the sample being tested. The balance shall be equipped with suitable suspension apparatus and holder to permit weighing the specimen while suspended from the center of scale pan of balance. (Note 1)

Note 1 - the holder should be immersed to a depth sufficient to cover it and the test sample during weighing. Wire suspending the holder should be the smallest practical size to minimize any possible effects of a variable immersed length.

3.2 Water Bath - For immersing the specimen in water while suspended under the balance, equipped with an over low outlet for maintaining a constant water level.

4. PROCEDURE

4.1 Mass of Uncoated Specimens - Weight the specimen after it has been dried to a constant mass. Designate this mass as A. (Note 2).

Note 2 - Constant shall be defined as the mass at which further drying as 125 ± 5°F (52 ± 3°C) does not alter the mass 0.05 percent. The sample shall initially be dried overnight at 125 ± 5°F (52 ± 3°C) and then weighed at two hour drying intervals.

4.2 Mass of Coated Specimen in Air - Coat the test specimen on all surfaces with melted paraffin sufficiently thick to seal all voids. Allow the coating to cool in air at room temperature for 30 minutes and then weigh the specimen. Designate this mass as D. (Notes 3 and 4).

Note 3 - The specimen shall be dusted with powdered talc prior to coating in order to utilize the specimen for further tests which require the removal of the paraffin coating.

Note 4 - Application of the paraffin may be accomplished by chilling the specimen in a refrigerating unit to a temperature of approximately 40°F (4.5°C) for 30 minutes and then dipping the specimen in warm paraffin (10°F [5.5°C] above melting point). It may be necessary to brush the surface of the paraffin with added hot paraffin in order to fill any pinpoint holes.

4.3 Mass of Coated Specimen in Water - Weigh the coated specimen in water bath at 77 ± 2°F (25 ± 1°C). Designate the mass as E.

4.4 Specific Gravity of Paraffin - Determine the specific gravity of the paraffin at 77 ± 2°F (25 ± 1°C), if unknown, and designate this as F.

5. CALCULATION

5.1 Calculate the bulk specific gravity of the specimen as follows (report the value to three decimal places):

Where: A = mass of the dry specimen in air, g,

D = mass of the dry specimen plus paraffin coating in air, g,
E = mass of the dry specimen plus paraffin in water, g,
F = specific gravity of the paraffin at 77°F ± 2°F (25 ± 1°C).

6. REPORT

Report the test result in item 12.3(c) of LTPP Protocol P02.

LTPP LABORATORY MATERIAL HANDLING AND TESTINGs
LABORATORY MATERIAL TEST DATA
BULK SPECIFIC GRAVITY
LAB DATA SHEET T02

ASPHALT CONCRETE LAYER (ASPHALTIC CONCRETE PROPERTIES)
LTPP TEST DESIGNATION AC02/LTPP PROTOCOL P02

LABORATORY PERFORMING TEST:______________________________________________________________

LABORATORY IDENTIFICATION CODE:__ __ __ __

REGION _________________ STATE ___________________ STATE CODE __ __

EXPERIMENT NO _____

SAMPLED BY: ______________________________________________ FIELD SET NO. __

DATE SAMPLED: __ __-__ __-__ __ __ __

1. LAYER NUMBER (FROM LAB SHEET L04 AND FORM T01B) __

(Do not use the test result with water absorption of more than 2 percent.)