U.S. Department of Transportation
Federal Highway Administration
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Washington, DC 20590
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
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Publication Number: FHWA-RD-07-052
Date: September 2007
This LTPP Protocol covers the determination of the liquid limit (LL), plastic limit (PL) and plasticity index (PI) of unbound granular base and subbase materials and subgrade soils. This protocol is based on the test standards AASHTO T89-87I ("Determining the Liquid Limit of Soils - Method B") and AASHTO T90-87I ("Determining the Plastic Limit and Plasticity Index of Soils"). The protocol encompasses LTPP Test Designation UG04 for unbound granular base/subbase and LTPP Test Designation SS03 for subgrade soils. The test shall be carried out in accordance with these standards (AASHTO T89-87I - Method B and AASHTO T90-87I), as modified herein. Those sections of the AASHTO standards included in this protocol by reference and without modifications shall be strictly followed. All other sections of this protocol shall be followed as herein written.
The test shall be performed on a representative test sample weighing approximately 150 grams (0.33 lb) obtained from the bulk samples of each layer of unbound granular base, subbase and subgrade. The sample shall be prepared for testing by following the instructions in Sections 4.1, 4.2.1, 5.2 and 6.1 of AASHTO T87-86, Dry Preparation of Disturbed Soils and Soil Aggregate Samples for Test. The test results shall be reported separately for the test samples obtained from each designated sampling area.
The locations and sample numbers for P43 testing are as shown on the laboratory testing plans developed for each project.
When bulk samples of each layer are retrieved from BA1, BA2, BA3... type 12-inch (305-mm) diameter boreholes, these bulk samples are combined and then a representative test sample is obtained in accordance with AASHTO T87-86. 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). The subgrade layer may not conform to the above definition. Subgrade soils are prepared and compacted before the placement of subbase and/or base layers. For the LTPP material sampling and testing program the subgrade layer is considered to be representative of the subgrade soils within 12 inches (305 mm) below the top of the subgrade, unless otherwise indicated on the field exploration 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 size.
This test covers the determination of the LL, PL and PI of unbound granular base and subbase materials and subgrade soils. This test is to be conducted in accordance with AASHTO T89-87I (Method B) and AASHTO T90-87I.
As required in Section 10 of AASHTO T89-87I.
As required in Section 4 of AASHTO T90-87I.
4.1 Liquid Limit:
4.1.1 Calculate the moisture content as required in Section 11 of AASHTO T89-87I.
4.1.2 Delete Section 7 of AASHTO T89-87I.
4.1.3 Delete Section 8 of AASHTO T89-87I.
4.1.4 Calculate the LL as required in Section 12.1, 12.2, or 12.4 of AASHTO T90-87I.
4.1.5 Delete Section 12.3 of AASHTO T89-87I.
4.2 PL: Calculate the PL as required in Section 5.1 of AASHTO T90-87I.
4.3 PI: Calculate the PI of the test sample according to Section 5.2 and 5.3 of AASHTO T90-87I.
The following information is to be recorded on Form T43.
5.1 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.
5.2 Test Identification shall include: LTPP Test Designation, LTPP Protocol Number, Laboratory Test Number, Test Date.
5.3 Test Result
Report the following:
5.3.1 LTPP Test Designation (UG04 or SS03)
5.3.2 Liquid Limit (LL) of the sample, expressed as a percent to the nearest whole number.
5.3.3 Plastic Limit (PL) of the sample, expressed as a percent to the nearest whole number.
5.3.4 Plasticity Index (PI) of the sample, expressed to the nearest whole number, with the following exception:
Report L as 'NP' when (a) LL and/or PL cannot be determined, or (b) PL is equal to or greater than LL.
5.4 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 this testing are given below.
|67||PI reported as 'NP' because the LL and/or PL cannot be determined.|
|68||PI is reported as 'NP' because the PL is equal to or greater than the LL.|
|69||The test specimen slipped in the cup of the LL device.|
5.5 Use Form T43 (Test Sheet T43) to report the above information (Items 5.1 to 5.4).
LTPP LABORATORY MATERIAL HANDLING AND TESTING
LABORATORY MATERIAL TEST DATA
LAB DATA SHEET T43
UNBOUND GRANULAR BASE/SUBBASE LAYERS AND SUBGRADE SOILS
LTPP TEST DESIGNATION UG04, SS03/LTPP PROTOCOL P43
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/SUBGRADE
|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 5.3 of Protocol P43)|
|(LTPP TEST DESIGNATION: __ __ __ __)|
|(a) LIQUID LIMIT (LL), %||__ __ __.||__ __ __.|
|(b) PLASTIC LIMIT (PL), %||__ __.||__ __.|
|(c) PLASTICITY INDEX (PI)||__ __||__ __|
|7. COMMENTS (Section 5.4 of Protocol P43)|
|(a) CODE||__ __ __ __ __ __||__ __ __ __ __ __|
|__ __ __ __ __ __||__ __ __ __ __ __|
|8. TEST DATE||__ __-__ __-__ __ __ __||__ __-__ __-__ __ __ __|
NOTE: 1. RESULTS OF TEST SHEETS T41 AND T43 ARE USED FOR CLASSIFICATION AND DESCRIPTION ON TEST SHEET T47.
|SUBMITTED BY, DATE||CHECKED AND APPROVED, DATE|
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