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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 P44
Test Method for Moisture-Density Relationsof Unbound Granular Base and Subbase Materials (UG05)

This LTPP Protocol covers the determination of the moisture-density relations of unbound granular base and subbase materials. This protocol is based on AASHTO T180-86 ("Moisture-Density Relations of Soils Using a 10-lb [4.54 kg.] Rammer and an 18-in. [457 mm] Drop"). The test shall be carried out in accordance with this standard (AASHTO T180-86), as modified herein. Those sections of the AASHTO standard included in this protocol by reference and without modification shall be strictly followed. All other sections of this protocol shall be followed as herein written.

Determination of moisture-density relations using Protocol P55 shall be performed on the bulk samples of the unbound granular base or subbase layer, after; (1) assigning the appropriate layer number, (2) determining the natural moisture content (Protocol P49) from jar samples of the layer, (3) performing the sieve analysis test (Protocol P41), (4) determining the Atterberg Limits (Protocol P43), and (5) completing the classification and description test (Protocol P47). The results of the moisture-density test (Protocol P44) will be recorded in the PPDB and are also used to ascertain molding water content and density values. These parameters will be used to reconstitute test specimens from the bulk samples of the unbound granular layer for the resilient modulus testing (Protocol P46).

The test shall be performed on a representative test sample obtained from the bulk samples of each layer of unbound granular base and subbase. The test results shall be reported separately for the test samples obtained from each designated sampling area.

The locations and sample numbers for P44 testing are as shown on the laboratory testing plans developed for each project.

When bulk samples of each unbound granular base and subbase layer are retrieved from BA1, BA2, BA3... type 12-inch (305-mm) diameter boreholes, the bulk samples are combined, prepared and reduced to a representative test size in accordance with AASHTO T87-86 and AASHTO T248-83. Because the bulk samples are combined, the Location Number of the sample should have an asterisk placed as the third digit. Similarly, the LTPP Sample Number should have an asterisk placed as the third and fourth digits.

The following definitions will be used throughout this protocol:

(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. For unbound granular materials, layer thickness is determined from field exploration logs (bore hole logs and/or test pit logs).

(b) Bulk Sample: That part of the pavement material that is removed from an unbound layer from the borehole(s) and the test pit at the designated locations. The bulk sample of each layer is shipped in one or more bag(s) to the participating laboratory. The material from one layer should never be mixed with the material from another layer-even if there is less than the desired amount to perform the specified test.

(c) Test Sample: That part of the bulk sample of an unbound layer 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.

1. SCOPE

1.1 This method of test covers the determination of the relationship between the moisture content and density of unbound granular base and subbase materials when compacted in a 6-in. (152-mm) diameter mold with a 10-lb (4.54-kg) rammer dropped from a height of 18 in. (457 mm). Two alternate procedures are provided as follows:

Method B - A 6-in. (152-mm) mold: Soil material passing a No. 4 (4.75-mm) sieve.

Method D - A 6-in. (152-mm) mold: Soil material passing a ¾-in. (19-m) sieve.

1.2 Select Method "B" or "D" as appropriate based on the results of the gradation test (Protocol P41).

1.3 As stated in Section 1.3 of AASHTO T180-86.

2. APPLICABLE DOCUMENTS

2.1 ASTM Standards

ASTM D653 Terms and Symbols Relating to Soil and Rock.

2.2 AASHTO Standards

AASHTO T180-86 Moisture-Density Relations of Soils Using a 10 lb [4.54 kg.] Rammer and 18 in. [457 mm] Drop.

AASHTO R-11 Recommended Practice For Indicating Which Places of Figures Are To Be Considered Significant In Specified Limiting Values.

AASHTO T19-88I Unit Weight and Voids of Aggregate.

AASHTO M231-87I Weighing Devices Used in the Testing of Materials.

AASHTO M92-85 Wire-Cloth Sieves for Testing Purposes.

AASHTO T87-86 Dry Preparation of Disturbed Soil and Soil Aggregate Samples for Test.

AASHTO T248-83 Reducing Field Samples of Aggregates to Testing Size.

2.3 LTPP Protocols

P41 Gradation of Unbound Granular Base and Subbase Materials.

P47 Classification and Description of Unbound Granular Base/Subbase Materials.

P49 Determination of Natural Moisture Content.

P55 Moisture-Density Relations of Subgrade Soils.

P46 Resilient Modulus of Unbound Granular Base and Subbase Materials and Subgrade Soils.

3. APPARATUS

The apparatus for moisture-density relations testing shall conform to the requirements of Section 2 of AASHTO T180-86 with the following exceptions:

3.1 Molds - As required in Sections 2.1, 2.1.2 and 2.1.3 of AASHTO T180-86. DELETE Section 2.1.1 and Note 1 of AASHTO T180.86.

LTPP PROTOCOL P44 - METHOD "A"

Note - 4-inch (102-mm) molds will not be used in this test, therefore Method A of AASHTO T180-86 will not be used as is. However, Method A is not deleted from this protocol because part of the procedure contained in Method A (Sections 3 and 4) of AASHTO T180-86 is used in Method B.

LTPP PROTOCOL P44 - METHOD "B"

4. SAMPLE

4.1 Prepare the test sample in accordance with Sections 4.1 and 7 of AASHTO T87-86 (Dry Preparation of Disturbed Soil and Soil Aggregate Samples for Test).

4.2 The weight of the sample should approximately be 20 lbs (8 kg). Check the gradation test results (Protocol P41) for percentage of coarse material passing the 1 ½-in. (38-mm) sieve and retained on the No. 4 (4.75-mm) sieve. If this percentage is up to 5% then Method B of Protocol P44 shall be used. Include this coarse fraction in the test sample for the moisture-density test. Record this deviation from the AASHTO T180-86 standard by using a special comment code 74 (See Section 10.4 of Protocol P44) on Form T44.

4.3 If there is more than 5% coarse material passing the 1 ½-in. (38-mm) sieve and retained on the No. 4 (4.75-mm) sieve, then use Method D of Protocol P44 to perform the moisture-density test. Use special comment code 75 (See Section 10.4 of Protocol P44) to record this condition on Form T44.

4.4 Discard any coarse material larger than the 1 ½-in. (38-mm) sieve size and do not use this material for the moisture-density test. Use special comment code 76 (See Section 10.4 of Protocol P44) to record this condition on Form T44.

5. PROCEDURE

5.1 Follow the same procedure as described in Section 6 of Method B and Section 4 of Method A of AASHTO T180-86, as appropriate.

5.2 The point at which the wet unit mass either decreases or does not change should be achieved within 3 to 5 water addition increments for this test. If the optimum moisture cannot be found by the fifth increment, note this using a special comment code on Form T44.

LTPP PROTOCOL P44 - METHOD "C"

Note - 4-inch (102-mm) molds will not be used in this test, therefore Method C of AASHTO T180-86 will not be used as is. However, Method C is not deleted from this protocol because part of the procedure contained in Method C (Section 7 and 8) of AASHTO T180-86 is used in Method D.

LTPP PROTOCOL P44 - METHOD "D"

6. SAMPLE

6.1 Prepare the test sample in accordance with Sections 4.1 and 7 of AASHTO T87-86 (Dry Preparation of Disturbed Soil and Soil Aggregate Samples for Test).

6.2 The weight of the sample should approximately be 30 lbs (12 kg). Check the gradation test results (Protocol P41) for percentage of coarse aggregate material passing the 1 ½-in. (38-mm) sieve and retained on the ¾-in. (19-mm) sieve. If this percentage is up to 5% then Method D of Protocol P44 shall be used. Include this coarse fraction in the test sample for the moisture-density test. Record this deviation from the AASHTO T180-86 standard by using special comment code 77 (See Section 10.4 of Protocol P44) on Form T44.

6.3 If there is more than 5% coarse material passing the 1 ½-in. (38-mm) sieve and retained on the ¾-in. (19-mm) sieve then the test sample for the moisture-density testing shall be sieved using a ¾-in. (19-mm) sieve to separate the coarse fraction retained on the ¾-in. (19-mm) sieve. Discard this coarse fraction from the test sample for the moisture-density testing. Use a special comment code 78 (See Section 10.4 of Protocol P44) to record this condition on Form T44.

6.4 Discard any coarse material larger than the 1 ½-in. (38-mm) sieve size and do not use this material for the moisture-density test. Use a special comment code 76 (See Section 10.4 of Protocol P44) to record this condition on Form T44.

7. PROCEDURE

7.1 Same as described in Section 10.1 of Method D and Section 8 of Method C of AASHTO T180-86.

7.2 The point at which the wet unit mass either decreases or does not change should be achieved within 3 to 5 water addition increments for this test. If the optimum moisture content cannot be found by the fifth increment, note this using a special comment code on Form T44.

8. CALCULATION

8.1 Same as described in Section 11.1 of AASHTO T180-86.

9. MOISTURE - DENSITY RELATIONSHIP

9.1 Same as described in Section 12.1 of AASHTO T180-86 except: DELETE "or kilograms per cubic meter".

9.2 Optimum Moisture Content - As required in Section 12.2 of AASHTO T180-86 except: DELETE "or kilograms per cubic meter".

9.3 Maximum Dry Density - As required in Section 12.3 of AASHTO T180-86.

10. REPORT

The following information is to be recorded on Form T44.

10.1 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.

10.2 Test identification shall include: LTPP Test Designation, LTPP Protocol Number, Laboratory Test Number, Test Date.

10.3 Test Results

Report the following:

10.3.1 The method used (Method B or Method D).

10.3.2 The optimum moisture content (OMC), as a percentage, to the nearest whole number.

10.3.3 The maximum density (MD), in lb/ft3 (pcf), to the nearest whole number.

10.3.4 Attach optimum moisture content curve plot, prepared in accordance with Section 12 of AASHTO T180-86, with Form T44.

10.4 Comments shall include LTPP standard comment code(s), as shown in Section 4.3 of this Guide and any other note as needed. Additional codes for special comments associated with the moisture-density testing of bulk samples of the unbound granular base or subbase layer are given below.

Code Comment
61 Insufficient size of test sample because the quantity of the bulk sample was significantly less than that required for the tests.
62 Presence of roots and other organic matter in the bulk sample retrieved from the field.
63 Presence of mica in the bulk sample retrieved from the field.
64 The bulk sample contained cobbles or large size aggregates (stone fragments passing the 12-in. [305-mm] sieve and retained on the 3-in. [76-mm] size sieve).
65 The test sample included shale chunks, claystone, mudstone, siltstone and sandstone which convert into soils after field and/or laboratory processing (crushing, slacking, etc.).
70 Test could not be completed within five water addition increments. Additional increments were made.
71 Degradation of the test sample was observed during the moisture-density test.
72 The quantity of the test sample was inadequate to complete the moisture-density test. Additional quantity was taken from the other test samples or extra material to complete the moisture-density test.
73 Free water appeared at the bottom of the mold (i.e., seeped onto the plate).
74 The gradation test results (Protocol P41 and Form T41 or Protocol P51 and Form T51, as appropriate) indicate up to 5% coarse material passing the 1 ½-in. (38-mm) sieve and retained on the No. 4 (4.75-mm) sieve. This coarse fraction was included in the test sample for the moisture-density test.
75 The coarse fraction passing the 1 ½-in. (38-mm) sieve and retained on the No. 4 (4.75-mm) sieve was more than 5%. Method D was used to perform the moisture-density test.
76 The test sample contained coarse materials larger than the 1 ½ in. (38-mm) sieve. This coarse material was removed and not used for the moisture-density test.
77 The gradation test results (Protocol P41 and Form T41 or Protocol P51 and Form T51, as appropriate) indicate up to 5% coarse material passing the 1 ½-in. (38-mm) sieve and retained on the ¾-in. (19-mm) sieve. This coarse material was included in the test sample for the moisture-density test.
78 The coarse fraction passing the 1 ½-in. (38-mm) sieve and retained on the ¾-in. (19-mm) sieve was more than 5%. The test sample for the moisture-density testing was sieved using a ¾-in. (19-mm) sieve to separate the coarse fraction from the test sample.

This coarse fraction was discarded from the test sample and not used in the moisture-density test.The test sample was, therefore, not truly representative of the bulk sample.
83 Due to insufficient size of the bulk sample, the test sample for the moisture-density test (Protocol P44 or P55) was saved after the test and re-used for the resilient modulus test (Protocol P46).
84 Due to insufficient size of the bulk sample, the sample for the moisture-density test (Protocol P44 or P55) was obtained from the gradation test sample. The gradation test (Protocol P41 or P51) was performed by dry sieving only.

10.5 If the type of face of the rammer is other than 2-in. (51-mm) circular face described herein, please describe the rammer that was used on Form T44.

10.6 Use Form T44 (Test Sheet T44) to report the above information (Items 10.1 to 10.5).

LTPP LABORATORY MATERIAL HANDLING AND TESTING
LABORATORY MATERIAL TEST DATA
MOISTURE-DENSITY RELATIONS
LAB DATA SHEET T44

UNBOUND GRANULAR BASE/SUBBASE LAYERS
LTPP TEST DESIGNATION UG05/LTPP PROTOCOL P44

LABORATORY PERFORMING TEST:______________________________________________________________

LABORATORY IDENTIFICATION CODE:__ __ __ __

REGION _________________ STATE ___________________ STATE CODE __ __

EXPERIMENT NO _____ SHRP ID __ __ __ __

SAMPLED BY: ______________________________________________ FIELD SET NO. __

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

1. LAYER NUMBER (FROM LAB SHEET L04) __

LAYER MATERIAL (CIRCLE ONE): BASE/SUBBASE

2. SAMPLING AREA NO. (SA-) __ __ __ __
3. LABORATORY TEST NUMBER __ __
4. LOCATION NUMBER (Enter an asterisk as the third digit) __ __ __ __ __ __
5. LTPP SAMPLE NUMBER (Enter an asterisk as third and fourth digit) __ __ __ __ __ __ __ __
6. TEST RESULTS (Section 10.3 of Protocol P44)
(a) METHOD USED (B OR D) ___ ___
(b) OPTIMUM MOISTURE CONTENT (OMC), % __ __. __ __.
(c) MAXIMUM DENSITY (MD), PCF __ __ __. __ __ __.
7. COMMENTS (Section 10.4 of Protocol P44)
      (a) CODE __ __ __ __ __ __ __ __ __ __ __ __
__ __ __ __ __ __ __ __ __ __ __ __
      (b) NOTE __________________ __________________
__________________ __________________
8. TYPE OF RAMMER FACE (If other than that described in Section 10.5 of Protocol P44) __________________ __________________
9. TEST DATE __ __-__ __-__ __ __ __ __ __-__ __-__ __ __ __

NOTE: 1. INCLUDE THE OPTIMUM MOISTURE CONTENT CURVE WITH TEST SHEET T44 (SECTION 10.3.6 OF PROTOCOL P44).

GENERAL REMARKS:___________________________________________________________________________
SUBMITTED BY, DATECHECKED AND APPROVED, DATE
____________________________________________________________
LABORATORY CHIEF
Affiliation______________________
Affiliation______________________

 

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