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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 P47
Test Method for Classification and Descriptionof Unbound Granular Base/Subbase Materials (UG08)

This LTPP Protocol covers the procedures for classification and description of unbound granular base and subbase materials. The test shall be carried out in accordance with ASTM D2488-00 as modified by the following. The sections of the referenced standard included in this protocol without modifications shall be strictly followed. All other sections of this protocol shall be followed as herein written.

Classification and description using Protocol P47 shall be carried out on the bulk samples of each layer of unbound granular base and subbase materials after; (1) assigning the appropriate layer number, (2) determining the natural moisture content in accordance with Protocol P49, (3) performing gradation tests in accordance with Protocol P41, and (4) carrying out the Atterberg Limits test in accordance with Protocol P43.

The observations made during the bulk sample handling and test sample preparation in the laboratory shall be used in determining the description in accordance with this protocol (P47). The test results shall be reported separately for the test samples obtained form each designated sampling area.

The locations and sample numbers for P47 testing are as shown on the laboratory testing plans developed for each project.

When bulk samples for each layer are retrieved from BA1, BA2, BA3... type 12-inch (305-mm) diameter boreholes, these bulk samples are combined and prepared 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.

  1. 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).
  2. Bulk Sample: That part of the pavement material that is removed from an unbound layer from the bore hole(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.
  3. 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.

1. SCOPE

1.1 This protocol covers ASTM D2488-00, visual-manual procedures for the classification and description of unbound granular base and subbase materials, and for assigning material codes according to the LTPP terminology for pavement materials as described in Table 4.29 of Chapter 4 of this Guide.

1.2 Standard values are in inch-pound units.

2. APPLICABLE DOCUMENTS

2.1 ASTM Standards: As listed in ASTM D2488-00.

2.2 AASHTO Standards:

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

2.3 LTPP Protocols:

P41 Test Method for Gradation of Unbound Granular Base and Subbase Materials.
P43 Test Method for Determination of Atterberg Limits of Unbound Granular Base and Subbase Materials and Subgrade Soils.
P46 Test Method for Resilient Modulus of Unbound Granular Base/Subbase Materials and Subgrade Soils.

2.4 Other LTPP Documents: LTPP Laboratory Material Testing Guide.

3. DEFINITIONS

As listed in Section 3 of ASTM D2488-00.

4. SUMMARY OF METHOD

4.1 As described in Section 4.1 of ASTM D2488-00. This method yields a standardized criteria and procedures for describing and identifying soils based on a visual examination and simple manual tests.

4.2 As described in Section 4.2 of ASTM D2488-00. The material is classified using Table 4.29 of the LTPP Laboratory Testing Guide based on ASTM D2488-00 using visual-manual procedures only.

4.3 Material designations and codes are used to report the description.

5. SIGNIFICANCE AND USE

5.1 As described in Section 5 of ASTM D2488-00 for unbound granular base and subbase materials.

5.2 This protocol is also used to assign "Mr Material Type" (Type 1 or Type 2) for the resilient modulus testing (Protocol P46).

6. APPARATUS

As required in Section 6 of ASTM D2488-00.

7. REAGENTS

As listed in Section 7 of ASTM D2488-00.

8. SAFETY PRECAUTIONS

As required in Section 8 of ASTM D2488-00.

9. SAMPLING

9.1 The bulk sample shall be considered to be representative of the layer from which it was obtained from the field. If the bulk sample is contained in more than one bag, then these bulk samples shall be combined as described in Protocol P41 and considered as the test sample for this protocol.

9.2 If the test sample being examined is smaller than the minimum recommended amount listed in Section 9.3 of ASTM D2488-00, the report shall include an appropriate comment code.

10. DESCRIPTIVE INFORMATION AND CLASSIFICATION FOR TEST SAMPLES

10.1 Use Sections 10 to 15 of ASTM D2488-00 for the descriptive/visual-manual classification information to be assigned to the test samples. In addition, the descriptions and visual-manual classification shall be reported by using the material codes provided in Table 4.29 of Chapter 4 of the LTPP Laboratory Material Testing Guide.

10.2 The material shall also be assigned Mr Material Type "1" or "2" for use in the resilient modulus testing (Protocol P46). According to Protocol P46, all unbound granular base and subbase materials and subgrade soils are categorized as Type 1 or Type 2 according to the following rules:

  1. All unbound granular base and subbase materials are categorized as "Type 1" materials.
  2. All unbound subgrade soils which meet the criteria of 70 percent maximum passing the No. 10 (2.00-mm) sieve and 20 percent maximum passing the No. 200 (0.075-mm) sieve with a PI = 10 are also categorized as "Type 1" materials.
  3. All unbound subgrade soils not meeting the criteria given in (b) above with a PI > 10 are categorized as "Type 2" materials.
  4. All thin-walled tube samples of the subgrade soils are also categorized as "Type 2" materials.

11. REPORT

The following information is to be recorded on Form T47.

11.1 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.

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

11.3 Test Results

Report the following:

11.3.1 Visual-manual Description based on ASTM D2488-00.

  1. Range of particle size (as described in Section 10.10 of ASTM D2488-00).
  2. Maximum particle size (as described in Section 10.11 of ASTM D2488-00).
  3. Color description (as required in Section 10.3 of ASTM D2488-00).
  4. Codes for other properties according to Table 4.27 of the LTPP Laboratory Material Testing Guide. Up to 10 four-digit codes are allowed.

11.3.2 A visual-manual classification using a three-digit code from Table 4.29 (Base and Subbase Material Description) of the LTPP Laboratory Material Testing Guide.

11.3.3 "Mr Material Type" based on the guidelines provided in Section 10.2 of this protocol. Assign "1" to all unbound granular base and subbase materials.

11.4 Comments shall include LTPP standard comment code(s), as shown in Section 4.3 of this Guide and any other note as needed. Use codes 61 to 65 as given below for additional comments.

Code Comment
61 Insufficient size of the 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 material 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-inch (305-mm) sieve and retained on the 3-inch (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.)

11.5 Use Form T47 (Test Sheet T47) to report the above information (Items 11.1 to 11.4).

LTPP LABORATORY MATERIAL HANDLING AND TESTING LABORATORY MATERIAL TEST DATA
CLASSIFICATION AND DESCRIPTION

LAB DATA SHEET T47

UNBOUND GRANULAR BASE/SUBBASE LAYERS
LTPP TEST DESIGNATION UG08/LTPP PROTOCOL P47

LABORATORY PERFORMING TEST:______________________________________________________________
LABORATORY IDENTIFICATION CODE: __ __ __ __
REGION _________________ STATE ___________________ STATE CODE __ __
EXPERIMENT NO _____ SHRP ID __ __ __ __
SAMPLED BY: ______________________________________________ FIELD SET NO . __
DATE SAMPLED: __ __-__ __-__ __ __ __
LAYER MATERIAL (CIRCLE ONE): BASE/SUBBASE

1. LAYER NUMBER (FROM LAB SHEET L04) __
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 the third and fourth digit) __ __ __ __ __ __ __ __
6. VISUAL-MANUAL DESCRIPTION (Section 11.3.1 of Protocol P47)
     a) RANGE OF PARTICLE SIZE _____________________ _____________________
     (b) MAXIMUM PARTICLE SIZE _____________________ _____________________
     (c) COLOR DESCRIPTION _____________________ _____________________
     (d) CODES-OTHER PROPERTIES __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
(Table 4.27 of LTPP LAB GUIDE) __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
7. VISUAL-MANUAL CLASSIFICATION (Section 11.3.2 of Protocol P47) __ __ __ __ __ __
8. Mr MATERIAL TYPE (Section 11.3.3 of Protocol P47) ___ ___
9. COMMENTS (Section 11.4 of Protocol P47)
     (a) CODE __ __ __ __ __ __ __ __ __ __ __ __
__ __ __ __ __ __ __ __ __ __ __ __
     (b) NOTE ____________________ ____________________
10. TEST DATE __ __-__ __-__ __ __ __ __ __-__ __-__ __ __ __
GENERAL REMARKS:___________________________________________________________________________
SUBMITTED BY, DATECHECKED AND APPROVED, DATE
____________________________________________________________
LABORATORY CHIEF
Affiliation______________________
Affiliation______________________

 

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