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Publication Number: FHWA-RD-07-052
Date: September 2007

Long Term Pavement Performance Project Laboratory Materials Testing and Handling Guide

Protocol P14a
Test Method for Fine AGgregate Particle Shape (AG05)

This LTPP protocol covers the determination of the void content and specific gravity of fine aggregate (aggregate passing the 2.36-mm [No. 8] sieve) extracted from AC specimens. This test shall be performed after completion of LTPP Test Designation AG04 (LTPP Protocol P14 - Gradation of Aggregate Extracted from Asphaltic Concrete).


1.1 General

This method covers the sample identification, preparation, and testing of fine aggregate extracted from AC specimens obtained from the LTPP studies.

Through the performance of this test, the laboratory will determine the loose percent voids, specific gravity and absorption of the fine aggregate.

1.2 Sample Storage

The samples of extracted aggregate materials should be kept in an environmentally protected (enclosed area not subject to the natural elements) storage area at temperatures between 5°C (40°F) and 38°C (100°F).

Each sample shall have a label or tag attached that clearly identifies the material, the project number/test section from which it was recovered and the sample number, as a minimum.

1.3 Units - In this protocol, the International System of Units (SI - The Modernized Metric System) is regarded as the standard. Units are expressed first in their "soft" metric form followed, in parenthesis, by their U.S. Customary unit equivalent.


2.1 Testing Prerequisites

The testing described in this protocol shall be conducted after; (1) approval by the FHWA COTR to begin testing, (2) initial layer assignment using Form L04, (3) visual examination and thickness of AC cores and thickness of layers within AC cores using Protocol P01, (4) final layer assignment based on the P01 test results (corrected Form L04 if needed), and (5) completion of all other applicable tests. In order to obtain approval under item (1), the laboratory must, at least, (a) submit and obtain approval of the QC/QA plan for FHWA materials testing, and (b) demonstrate that their testing equipment meets or exceeds the specifications contained in this protocol.

2.2 Test Sample Locations and Assignment of Laboratory Test Numbers

The test shall be performed on the test specimens of asphalt concrete retrieved from BA-type, 305-mm (12-inch) diameter coreholes, from the test pit(s), or from other bulk sampling locations as dictated by the sampling plans for the particular LTPP section.

The test results shall be reported separately for test samples obtained from the beginning and end of a test section as follows:

(a) Beginning of the Section (Stations 0-): samples of each layer that are retrieved from areas in the approach end of the test section (stations preceding 0+00) shall be assigned Laboratory Test Number '1'.

(b) End of the Section (Stations 5+): samples of each layer that are retrieved from areas in the leave end of the test section (stations after 5+00) shall be assigned Laboratory Test Number '2'.

(c) Middle of the Section (Stations 0 to +5): samples of each layer that are retrieved from areas in the middle of the test section (from the paver) shall be assigned Laboratory Test Number '3'.


(a) Layer: That part of the pavement produced with similar material and placed with similar equipment and techniques. The material within a particular layer is assumed to be homogeneous.

(b) Sample: A representative portion of material from one or more pavement layers received from the field. A sample can be a core, block, chunk, pieces, bulk, thin-walled tube, or jar sample.

(c) Test Sample: That part of the sample of an asphalt concrete layer or which is prepared and used for the specified test. The quantity of the test sample may be the same but will usually be less than the bulk sample.

(d) Test Specimen: For the purpose of this protocol, a test specimen is defined as that part of the extracted aggregate sample used for the testing described in this protocol.


4.1 AASHTO Standards

AASHTO T30-87I Mechanical Analysis of Extracted Aggregate.

4.2 ASTM Standards

ASTM C128-84 Test Method for Specific Gravity and Absorption of Fine Aggregate.

ASTM C117-87 Test Method for Material Finer than 75-µm (No. 200) Sieve in Mineral Aggregate; except in this case, a 150-µm (No. 100) sieve will be used to remove minus 150-µm (No. 100) material.

ASTM C136-84 Sieve Analysis of Fine and Coarse Aggregates.

4.3 LTPP Protocols

P04 Asphalt Content (Extraction)
P14 Gradation of Aggregate Extracted from Asphaltic Concrete and Attachment.

4.4 National Aggregates Association Documents

Proposed NAA Method for Particle Shape and Texture of Fine Aggregate Using Uncompacted Void Content - Appendix A. (A similar test method is in the process of being standardized by ASTM).


5.1 Samples accompanied by a copy of Test Sheet T14 will be identified corresponding to the LTPP identification, which includes: Region, State, State Code, Experiment No., SHRP ID, Field Set Number, Layer Number, Laboratory Test Number, Location Number, and LTPP Sample Number.

5.2 The sample is initially scalped on a 4.75-mm (No. 4) sieve to remove the oversize material. The plus 4.75-mm (No. 4) material will be discarded. The portion passing the 4.75-mm (No. 4) sieve shall be split by the use of a sample splitter or quartering to produce a test portion weighing 500 to 1000 grams (1.1 to 2.2 lbs) and washed over a 150-µm (No. 100) sieve to remove minus 150-µm (No. 100) sizes. Return particles retained on the 150-µm (No. 100) sieve to the test portion and dry to constant weight at 105°C (220°F). This sample is then used to determine specific gravity.


6.1 Specific Gravity and Absorption. Use ASTM C128 with the following exceptions. Add at least 4 percent moisture, stir, and cover the sample. Allow sample to stand at least overnight. Uncover sample and dry (with the aid of warm flowing air) to approximate saturated surface dry (SSD) condition. This process takes 10 to 15 minutes. When the sample appears to be at SSD, weigh approximately 500 to 600 grams (1.1 to 1.3 lbs) of the SSD sand (SSD weight = D) and then place it in the pycnometer in accordance with ASTM C128. Roll and agitate the pycnometer to eliminate entrapped air bubbles. Allow the sample to stand in a controlled temperature environment for at least 4 hours. Adjust water level and weigh the sample, H2O and flask (weight = C). Remove sample and H2O from pycnometer and oven dry the sample. Remove sample from oven, allow to cool and weigh (oven dry weight = A). All weights should be recorded to at least the nearest one-tenth gram.

Note 1: Pre-weighed pans are used to facilitate the weighing/drying process.

6.2 Calculate the Bulk Dry Specific Gravity as follows:

Bulk dry specific gravity is the ratio of A over the result of B plus D minus C

where: A = Oven dry weight of fine aggregate; grams

B = Weight of pycnometer with water only; grams

C = Weight of pycnometer with fine aggregate and water; grams

D = SSD weight of fine aggregate sample; grams

Calculate the bulk specific gravity and report to three decimal places.

6.3 Calculate the percent absorption as follows:

Absorption in percent equals 100 times the ratio of D minus A over A.

where: A = Oven dry weight of fine aggregate; grams

D = SSD weight of fine aggregate sample; grams

Report the percent absorption to the nearest two decimal places.

6.4 Sieving. Sieve the dried sample over the nested fine aggregate sieves in a mechanical shaker for 5 minutes. Do not record the weights of each of the size fractions. Maintain the individual size fractions in a dry condition in separate containers for use in the void content test.

6.5 Prepare the void content sample from the individual sieve size fractions as follows:

2.36 mm (No. 8) - 1.18 mm (No. 16) 44 grams (1.6 oz)
1.18 mm (No. 16) - 600 µm (No. 30) 57 grams (2.0 oz)
600 µm (No. 30) - 300 µm (No. 50) 72 grams (2.5 oz)
300 µm (No. 50) - 150 µm (No. 100) 17 grams (0.6 oz)
190 grams (6.7 oz)

The tolerance on each of these weights is ± 0.2 g (0.01 oz).

If there is not enough in one or more of the size fractions to make up the required sample, additional fine aggregate can be sieved to provide the required sizes. (Fine aggregate left over from the SSD material can be dried and sieved as needed).

If one or more sizes are only very slightly short of the required amount, use a proportionately smaller sample as long as it is adequate to fill the receiving container in the void content test to overflowing. For example, using a 90 percent sample:

2.36 mm (No. 8) - 1.18 mm (No. 16) 39.6 grams (1.4 oz)
1.18 mm (No. 16) - 600 µm (No. 30) 51.3 grams (1.8 oz)
600 µm (No. 30) - 300 µm (No. 50) 64.8 grams (2.3 oz)
300 µm (No. 50) - 150 µm (No. 100) 15.3 grams (0.6 oz)

Note 2: After every ten tests, the tenth test specimen shall be put aside and retested the following day or within a few days of the initial test. This will provide a good indication of the repeatability of the test procedure.

6.6 Save small portions of excess sizes in paper cups for archival purposes. (If enough excess material is not available, the void content sample can be used for this after the void content is run). At least 300 particles randomly sampled from each of the four sieve fractions from the paper cup should be placed on a stiff paper card, held on by double-sided tape, so that each of the four sizes can be viewed conveniently. Insert the card (with sample identification) into an envelope and send the material to the Materials Reference Library (MRL). These samples will serve as a record of the sample and will be saved for archival purposes.

6.7 Uncompacted void content procedure. Run in accordance with Appendix A of this protocol, NAA-JRL Method of Test for Particle Shape and Texture of Fine Aggregate Using Uncompacted Void Content. Calculate and record the uncompacted void content.


7.1 The test results should be reported in a flat-file spreadsheet format (Excel and ASCII format). The format of the spreadsheet is described in Appendix B. The flat file spreadsheet is intended for use by laboratories that will conduct a high volume of P14A tests. If a laboratory will only conduct a small number of tests (i.e., less than fifteen), then the optional data sheet provided at the end of this protocol may be used to report the data results.

7.2 The following information will be included in the spreadsheet.

7.2.1 The specimen identification shall include: Laboratory Identification Code, State Code, SHRP ID, Layer Number, Field Set Number, Sampling Area No. (SPS-only), Sample Location Number, and LTPP Sample Number.

7.2.2 Report the following: Comment Code and Notes to comments (if any) as described in 7.3 (the note section may contain up to 40 characters). Bulk Dry Specific Gravity (to three decimal places). Absorption, Percent (to two decimal places). Duplicate test determinations and the average Uncompacted Void Content, Percent (to two decimal places). Diff (test 1 - test 2). Difference between duplicate void content tests on the same sample.

Note 3: Cases where the specific gravity is reported and the void content is not reported indicate that the sample was deficient in at least one size fraction to determine the uncompacted void content.

Note 4: If a void content is needed, but the specific gravity is not available, the specific gravity of the next closest sample obtained from the same layer shall be used in the calculation of void content.

7.3 Comments shall include LTPP standard comment code(s), as shown in Section 4.3 of this Guide and any other notes as needed. Additional codes for special comments associated with this protocol are given below.

Code Comment
61 Insufficient sample to complete tests.
99 Other comment (describe in a note).

8. Retention/Disposal of Samples

8.1 Obtain, label and save a sample of at least 50 grams (0.1 lb) of the minus 4.75-mm (No. 4) as-received material left over after quartering to obtain the test sample. This sample shall be shipped and stored at the MRL.

8.2 All void content samples (nominal 190-gram [0.4-lb] sample) will be saved in suitable containers. One void content sample from each sample shall be shipped and stored at the MRL.



1.1 This method covers the determination of the loose uncompacted void content of a fine aggregate for use as a measure of its angularity and texture.

1.2 Procedures are included for the measurement of void content using sand separated into individual sieve fractions and recombined to a standard grading.


2.1 A nominal 100-cm3 (6.1-in3) cylinder is filled with fine aggregate of prescribed gradation by allowing the sample to flow through a funnel from a fixed height into the cylindrical container. The cylinder is struck off and weighed. Uncompacted void content is calculated as the difference between the cylinder volume and the absolute volume of the measured weight of fine aggregate collected in the cylindrical container. It is calculated using the bulk dry specific gravity of the sand. Two runs are made on each sample and the results are averaged.


3.1 This procedure provides a numerical result in terms of percent void content determined under standardized conditions which correlates with the particle shape and texture properties of a fine aggregate. An increase in void content by this procedure indicates greater angularity and rougher texture. Lower void content results are associated with more rounded smooth sands.

3.2 This test of a regraded sample is most useful as a quick test which indicates the particle shape properties of a graded fine aggregate. Typically, the material used to make up the standard graded sample can be obtained from a single sieve analysis of the fine aggregate.

3.3 Generally, the bulk dry specific gravity of the sand, graded as received, is used for calculating the void content. Occasionally, if the mineralogy of the size fractions varies markedly, it may be necessary to determine the specific gravity of the size fraction used.

3.4 Void content information will be useful as an indicator of properties such as: the mixing water demand of PCC; in AC the effect of the fine aggregate on stability and voids in the mineral aggregate; or the stability of the fine aggregate phase of a base course aggregate.


4.1 ASTM Standards

ASTM C117-87 Test Method for Material Finer than 75-µm (No. 200) Sieve in Mineral Aggregate; except in this case, a 150-µm (No. 100) sieve will be used to remove minus 150-µm (No. 100) material.

ASTM C128-84 Test Method for Specific Gravity and Absorption of Fine Aggregate.

ASTM C136-84 Sieve Analysis of Fine and Coarse Aggregates.


5.1 Funnel -- The lateral surface of the right frustum of a cone sloped 60 ± 4° from the horizontal with an opening of 12.7 ± 0.64 mm (0.50 ± 0.025 in.) in diameter. The funnel shall be smooth on the inside and at least 38 mm (1.5 in.) high. (Pycnometer top C9455 sold by Hogentogler and Co., Inc., 9515 Gerwig, Columbia, Maryland 21045, 301-381-2390 appears to be satisfactory, except that the size of the opening has to be enlarged and any burrs or lips that are apparent should be removed by light filing or sanding.) It shall have a volume of at least 200 cm3 (12.2 in3) or shall be provided with a supplemental container to provide the required volume.

5.2 Funnel stand -- A support capable of holding the funnel firmly in position with its axis collinear with the axis of the measure and the funnel opening 114 ± 3 mm (4.5 ± 0.1 in.) above the top of the cylinder. A suitable arrangement is shown in Figure 1 and Figure 2.

5.3 Measure -- A right cylinder of approximately 100 cm3 (6.1 in3) capacity having an inside diameter of 38.6 ± 1.3 mm (1.52 ± 0.05 in.) and an inside height of approximately 85.6 mm (3.37 in.) made of drawn copper water pipe meeting ASTM Specification B 88 Type M (Type M copper drain, waste and vent pipe should have outside and inside diameters of approximately 1.63 (41.4 mm) and 1.52 (38.6 mm) inches, respectively) or equally rigid material. The bottom of the measure shall be at least 6.3 mm (0.25 in.) thick, shall be firmly sealed to the tubing, and shall be provided with means for aligning the axis of the cylinder with that of the funnel.

5.4 Pan -- A metal or plastic pan of sufficient size to contain the funnel stand and to prevent loss of material. The purpose of the pan is to catch and retain sand grains that overflow the measure during filling or strike off.

5.5 A metal spatula about 100 mm (4 in.) long with sharp straight edges. The end shall be cut at a right angle to the edges. The straight edge of the spatula is used to strike off the fine aggregate.

5.6 Scale of balance capable of weighing the measure and its content to ± 0.1 grams.


6.1 Weigh the dry, empty measure with a flat, glass plate slightly larger than its diameter and with the top edge of the container lightly coated with grease. Fill the measure with water at a temperature of 18 to 24°C (65 to 75°F). Place the glass plate on the measure, being sure that no air bubbles remain. Dry the outer surfaces of the measure and determine the combined weight of measure, glass plate, grease and water.

6.2 Calculate the volume of the measure as follows:

V equals the ratio of W over 0.998

where: V = volume of cylinder in cm3

W = net weight of water in grams


7.1 The sample(s) used for this test shall be obtained from aggregate extracted from an AC specimen. The sample is washed over a 150-µm (No. 100) sieve and then dried and sieved for 5 minutes into separate size fractions using ASTM C136 procedures. Maintain the necessary size fractions obtained from one (or more) sieve analyses in a dry condition in separate containers for each size.


8.1 Graded Sample -- weigh out and combine the following quantities of dry sand from each of the sizes:

Individual Size Fraction Weight, grams
2.36 mm (No. 8) - 1.18 mm (No. 16) 44 grams (1.5 oz.)
1.18 mm (No. 16) - 600 µm (No. 30) 57 grams (2.0 oz.)
600 µm (No. 30) - 300 µm (No. 50) 72 grams (2.5 oz.)
300 µm (No. 50) - 150 µm (No. 100) 17 grams (0.6 oz.)
190 grams (6.7 oz.)

The tolerance on each of these weights is ± 0.2 grams. Mix the test sample until it appears homogeneous.


9.1 If the sand has become moist, dry the sand to the constant weight in accordance with Method C136 and cool to room temperature. Tare out the weight of the cylindrical measure, and then center the measure under the funnel.

9.2 Mix the test sample until it appears homogeneous. Using a finger to block the opening, pour the test sample into the funnel. Remove the finger, and allow the sample to fall freely into the measure.

9.3 After the funnel empties, remove excess sand from the measure by a single pass of the spatula with the blade vertical using the straight part of its edge in light contact with the top of the measure. Until this operation is complete, exercise care to avoid vibration or disturbance that could cause compaction of the fine aggregate in the measure. Brush adhering grains from the outside of the measure and weigh the contents to the nearest 0.1 grams (0.004 oz). Retain all sand grains.

Note 1: After strike-off, the measure may be tapped lightly to compact the sample to make it easier to transfer the measure to scale or balance without spilling any of the sample.

9.4 Collect the sample from the retaining pan and measure, and repeat the procedure again.

9.5 For each run, record the weight of the sand in the measure.


10.1 Calculate the uncompacted voids for each determination as follows:

U equals the ratio of V minus the ratio of W over G over V times 100

where: V = volume of measure in cm3.

W = net weight of fine aggregate in measure.

G = bulk dry specific gravity of fine aggregate measured in accordance with Method C128, Test for Specific Gravity and Absorption of Fine Aggregate.

U = uncompacted voids, percent.

Note 2: For most aggregate sources, the fine aggregate specific gravity does not vary much from sample to sample or from size to size in the minus 2.36-mm (No. 8) fraction. Therefore, unless there is reason to believe that the specific gravity of individual sizes is appreciably different, it is intended that the value used in this calculation may be from a routine specific gravity test of an as-received grading of the fine aggregate. If significant variation between different samples is expected, then specific gravity should be determined on material from the same field sample from which the uncompacted void content sample was derived. Normally, the as-received gradation can be tested for specific gravity, particularly if the 2.36-mm (No. 8) to 150-µm (No. 100) size fraction represents more than 50 percent of the as-received grading.

10.2 For the Graded Sample, calculate the average uncompacted voids for the two determinations and report the result as UG.


11.1 For the Graded Sample report:

11.1.1 The Uncompacted Voids (UG), percent (to two decimal places).

11.1.2 The Specific Gravity value used in the calculation.


12.1 Within Laboratory -- Analyses of within laboratory data from sixteen laboratories which made void content tests on independent samples of three similar sources of rounded sands, graded in accordance with the graded standard sand in C778, resulted in a within laboratory standard deviation (1S) of 0.13 percent voids for repeat determinations on the same sample.

Differences greater than 0.37 percent voids between duplicate tests on the same sample by the same operator should occur by chance less than 5 percent of the time (D2S limit).

12.2 Multi-Laboratory -- Analyses of data from sixteen laboratories which made void content tests on independent samples of three similar sources of rounded sands, graded in accordance with the graded standard sand in C778, resulted in a multi-laboratory standard deviation (1S) of 0.33 percent voids. Since this value includes random variance due to the difference in samples, the standard deviation for multi-laboratory tests on the same sample should be lower. Differences greater than 0.93 percent voids between tests in two different laboratories should occur by chance less than 5 percent of the time (D2S limit) for these rounded sands.

12.3 Additional precision data is needed for tests of sands having different levels of angularity and texture tested in accordance with both procedures included in this Method.


  1. Rex, H.M., and Peck, R.A., "A Laboratory Test to Evaluate the Shape and Surface Texture of Fine Aggregate Particles," Public Roads, V. 29, No. 5, Dec. 1956, pp 118-120.
  2. Bloem, Delmar L., and Gaynor, Richard D., "Effects of Aggregate Properties on Strength of Concrete," ACI Journal, Proceedings, V.60, No. 10, Oct. 1963, pp 1429-1456.
  3. Kalcheff, Ignat V., "Portland Cement Concrete with Stone Sand," Special Engineering Report, National Crushed Stone Association, Washington, D.C., July 1977, 20 pp.
  4. Kandhal, P.S., Motter, J.B., and Khatri, M.A., "Evaluation of Particle Shape and Texture: Manufactured Versus Natural Sands," Transportation Research Record, No. 1301.



The data resulting from this test procedure shall be entered in a computer spreadsheet format as provided to the laboratory. The database shall be provided to the FHWA COTR in printed form and as a Microsoft Excel file and as an ASCII file. The spreadsheet file to be used will be provided to the laboratory by the FHWA COTR.


Data shall be split in columns as follows:

Columns 1-10 - Laboratory Material Test Data
Column 1 - Sequential numbers to facilitate sorting
Column 2 - Region
Column 3 - State Abbreviation
Column 4 - State Code
Column 5 - LTPP Experiment Code
Column 6 - SHRP Test Section Identification
Column 7 - Field Set Number
Column 9 - Organization that obtained the samples
Column 10 - Organization that sent samples to NAA (completed P14)
Columns 11-15 - SHRP Sample Identification Codes
Column 11 - Layer Number (From T14)
Column 12 - Laboratory Test Number
Column 13 - Location Number
Column 14 - LTPP Sample Number
Column 15 - Lot Number (Designation assigned to the sample by the laboratory - optional)
Columns 16-25 - Void Content Data
Column 16 - Bulk Dry Specific Gravity
Column 17 - Absorption, in percent
Column 18 - Void Content - Average of Tests 1 & 2
Column 19 - Void Content - Test 1
Column 20 - Void Content - Test 2 on same sample
Column 21 - Difference between void test 1 and 2 on same sample
Column 22 - Comment Code
Column 23 - Note to Comment Code (optional)
Column 24 - Laboratory Identification Code
Column 25 - Test Date



LABORATORY PERFORMING TEST:______________________________________________________________PRIVATE


REGION _________________ STATE ___________________ STATE CODE __ __

EXPERIMENT NO _____ SHRP ID __ __ __ __

SAMPLED BY: ______________________________________________ FIELD SET NO. __

DATE SAMPLED: __ __-__ __-__ __ __ __ SAMPLING AREA No: SA- __ __




4. LTPP SAMPLE NUMBER __ __ __ __



7. UNCOMPACTED VOID CONTENT 1, (UG1), % __ __.__ __

8. UNCOMPACTED VOID CONTENT 2, (UG2), % __ __.__ __

9. UNCOMPACTED VOID CONTENT AVG, (UGavg), % __ __.__ __



      (a) CODE __ __ __ __ __ __ __ __ __ __ __ __

      (b) NOTE _______________________________________________________

12. TEST DATE __ __-__ __-__ __ __ __

GENERAL REMARKS:___________________________________________________________________________


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