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Federal Highway Administration Research and Technology
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Publication Number: FHWA-RD-07-052
Date: September 2007
This protocol covers the determination of the coefficient of permeability by a constant-head method for the laminar flow of water through unbound base and subbase materials. This protocol is based on AASHTO T 215-70 (Permeability of Granular Soils (Constant Head)). The test shall be performed in accordance with this standard (AASHTO T 215-70), 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 written herein.
The referenced test method shall be performed on representative base and/or subbase samples obtained at designated LTPP sampling locations.
Add the following:
1.2 The term "coefficient of permeability" is often used to describe the coefficient, k, in Darcy's Law. However, in this standard the terms "hydraulic gradient" and "coefficient of permeability" are used interchangeably.
4.2 Delete Note 2.
5.5.1 Compact each layer of soil thoroughly with the vibratory tamper, uniformly distributing the light tamping action over the surface of the layer in a regular pattern. The pressure of contact and the length of time of the vibrating action at each spot should not cause soil to escape from beneath the edges of the tamping foot, thus tending to loosen the layer. A sufficient number of coverages shall be completed to produce the required density. The specimens shall be compacted to within ± 3 percent of the in situ density measured for the layer in the field using the nuclear density gauge. If this density measurement is not available, use 95 percent of the maximum dry density previously determined for the layer (LTPP Protocol P44) as the compaction density.
Record the following on Form T48:
8.1 Sample identification shall include: Laboratory Identification Code, Region, State Code, Experiment Number, SHRP ID, Field Set Number, Sampling Area Number, Layer Number, and Location Number.
8.2 Test identification shall include: Laboratory Test Number, LTPP Test Designation, LTPP Protocol Number, and the Test Date.
8.3 Test Results:
8.3.1 The initial moisture content of the specimen (Wi), as a percentage, to the nearest whole number.
8.3.2 The final moisture content of the specimen (Wf), as a percentage, to the nearest whole number.
8.3.3 The initial dry density of the specimen (DDi), in lb/ft3 (pcf), to the nearest whole number.
8.3.4 The final dry density of the specimen (DDf), in lb/ft3 (pcf), to the nearest whole number.
8.3.5 The hydraulic gradient (H/L) used in the test, to the nearest 0.01.
8.3.6 The average measured hydraulic conductivity (k), in cm/sec (cps) of the specimen, reported with two significant figures in scientific notation, for example 7.1E-6.
8.4 Comments shall include LTPP standard comment code(s), as shown in Section 4.3 of this Guide and any notes as required.
LTPP LABORATORY MATERIAL HANDLING AND TESTING LABORATORY MATERIAL TEST DATA
LAB DATA SHEET T48
UNBOUND GRANULAR BASE/SUBBASE LAYERS
LTPP TEST DESIGNATION UG09/LTPP PROTOCOL P48
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 __ __ __ __
5. LTPP SAMPLE NUMBER __ __ __ __
6. TEST RESULTS
8. TEST DATE __ __-__ __-__ __ __ __
|SUBMITTED BY, DATE||CHECKED AND APPROVED, DATE|
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