ASTM G57-06

Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method

SIGNIFICANCE AND USE
Measurement of soil resistivity is used for the control of corrosion of buried structures. Soil resistivity is used both for the estimation of expected corrosion rates and for the design of cathodic protection systems. As an essential design parameter for cathodic protection systems, it is important to take as many measurements as necessary so as to get a sufficiently representative characterization of the soil environment that the entire buried structure will experience.
SCOPE
1.1 This method covers the equipment and procedures for the field measurement of soil resistivity, both in situand for samples removed from the ground, for use in the control of corrosion of buried structures.
1.2 To convert cm (metric unit) to metre (SI unit), divide by 100.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Oct-2006
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: G01 - Corrosion of Metals
• Drafting Committee: G01.10 - Corrosion in Soils

Relations

• Replaces: ASTM G57-95a(2001) - Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method
• Effective Date: 01-Nov-2006
• Referred By: ASTM G162-18 - Standard Practice for Conducting and Evaluating Laboratory Corrosion Tests in Soils
• Effective Date: 01-Nov-2006
• Referred By: ASTM E2277-14(2019) - Standard Guide for Design and Construction of Coal Ash Structural Fills
• Effective Date: 01-Nov-2006
• Referred By: ASTM G200-20 - Standard Test Method for Measurement of Oxidation-Reduction Potential (ORP) of Soil
• Effective Date: 01-Nov-2006
• Referred By: ASTM G218-19 - Standard Guide for External Corrosion Protection of Ductile Iron Pipe Utilizing Polyethylene Encasement Supplemented by Cathodic Protection
• Effective Date: 01-Nov-2006
• Referred By: ASTM D6429-23 - Standard Guide for Selecting Surface Geophysical Methods
• Effective Date: 01-Nov-2006
• Referred By: ASTM G187-18 - Standard Test Method for Measurement of Soil Resistivity Using the Two-Electrode Soil Box Method
• Effective Date: 01-Nov-2006
• Referred By: ASTM D420-18 - Standard Guide for Site Characterization for Engineering Design and Construction Purposes
• Effective Date: 01-Nov-2006
• Referred By: ASTM G51-18 - Standard Test Method for Measuring pH of Soil for Use in Corrosion Testing
• Effective Date: 01-Nov-2006
• Referred By: ASTM G158-98(2021) - Standard Guide for Three Methods of Assessing Buried Steel Tanks
• Effective Date: 01-Nov-2006
• Referred By: ASTM D6431-18 - Standard Guide for Using the Direct Current Resistivity Method for Subsurface Site Characterization
• Effective Date: 01-Nov-2006

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
Designation:G57–06
Standard Test Method for
Field Measurement of Soil Resistivity Using the Wenner
1
Four-Electrode Method
This standard is issued under the fixed designation G57; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope separation should be selected with consideration of the soil
strata of interest. The resulting resistivity measurement repre-
1.1 This test method covers the equipment and procedures
sents the average resistivity of a hemisphere of soil of a radius
for the field measurement of soil resistivity, both in situ and for
equal to the electrode separation.
samples removed from the ground, for use in the control of
3.2 A voltage is impressed between the outer electrodes,
corrosion of buried structures.
causing current to flow, and the voltage drop between the inner
1.2 To convert cm (metric unit) to metre (SI unit), divide by
electrodes is measured using a sensitive voltmeter. Alterna-
100.
tively, the resistance can be measured directly. The resistivity,
1.3 This standard does not purport to address all of the
r, is then:
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
r,V·cm 5 2p aR ~a in cm!
priate safety and health practices and determine the applica-
5 191.5 aR~a in ft!
bility of regulatory limitations prior to use.
where:
2. Terminology
a = electrode separation, and
2.1 Definition:
R = resistance, V.
2.1.1 resistivity—the electrical resistance between opposite
Using dimensional analysis, the correct unit for resistivity is
faces of a unit cube of material; the reciprocal of conductivity.
ohm-centimetre.
Resistivity is used in preference to conductivity as an expres-
3.3 If the current-carrying (outside) electrodes are not
sion of the electrical character of soils (and waters) since it is
spaced at the same interval as the potential-measuring (inside)
expressed in whole numbers.
electrodes, the resistivity, r is:
2.1.2 Resistivity measurements indicate the relative ability
b
of a medium to carry electrical currents. When a metallic
r, V·cm 5 95.76bR/ 1 2
S D
b 1 a
structure is immersed in a conductive medium, the ability of
the medium to carry current will influence the magnitude of
where:
galvanic currents and cathodic protection currents. The degree
b = outer electrode spacing, ft,
of electrode polarization will also affect the size of such
a = inner electrode spacing, ft, and
currents. R = resistance, V.
or:
3. Summary of Test Method
b
r, V·cm5pbR/ 1 2
3.1 The Wenner four-electrode method requires that four S D
b 1 a
metal electrodes be placed with equal separation in a straight
where:
line in the surface of the soil to a depth not exceeding 5 % of
b = outer electrode spacing, cm,
the minimum separation of the electrodes. The electrode
a = inner electrode spacing, cm, and
R = resistance, V.
1
This test method is under the jurisdiction of ASTM Committee G01 on
3.4 For soil contained in a soil box similar to the one shown
Corrosion of Metals and is the direct responsibility of Subcommittee G01.10 on
in Fig. 1, the resistivity, r, is:
Corrosion in Soils.
Current edition approved Nov. 1, 2006. Published December 2006. Originally
r, V·cm 5RA/a
approved in 1978. Last previous edition approved in 2001 as G57 – 95a (2001).
DOI: 10.1520/G0057-06.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
G57–06
FIG. 1 Typical Connections for Use of Soil Box with Various Types of Instruments
cathodic protection systems. As an essential design parameter
where:
for cathodic protection systems, it is important to take as many
R = resistance, V,
A = cross sectional area of the container perpendicular to measurements as necessary so as to get a sufficiently represen-
2
tative characterization of the soil environment that the entire
the current flow, cm , and
a = inner electrode spacing, cm.
buried structure will experience.
NOTE 1—The spacing between the inner electrodes should be measured
5. Apparatus
from the inner edges of the electrode pins, and not from the center of the
5.1 At-Grade Measurements in situ:
electrodes.
5.1.1 The equipment required for field resistivity measure-
4. Significance and Use
ments to be taken at grade consists of a current source, a
4.1 Measurement of soil resistivity is used for the control of
su
...