Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method. Soil testing is performed for a variety of reasons, from agricultural to environmental. Find out why the ASTM G57 standard may be helpful for. Geotechnical and power engineers, find out how to perform a fall-of-potential or ASTM G57 test.
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The latter method permits precise mathematical treatment, such as cumulative probability analysis.
The degree of electrode polarization will also affect the size of such currents. Do not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc. In the case of soil resistivity measurements reproducibility may be characterized by a coefficient of variation, Cv, representing the reproducibility standard deviation divided by the average result and expressed in percent. Otherwise, use distilled water. Where mean or median values cannot be estimated with reasonable accuracy, sequential sampling techniques can be employed.
The soil should be well-compacted in layers in the soil box, with air spaces eliminated as far as practicable. The current can be provided by either a cranked ac generator or a vibrator-equipped dc source. Measure the voltage drop across the inner electrodes and record both the current and voltage drop if a separate ammeter and voltmeter are used.
ASTM G57 Standard
In either case, use pedological surveys in the planning and interpretation of any extensive survey. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.
Terminals should be of good quality to ensure that lowresistance contact is made at the electrodes and at the meter. When a metallic structure is immersed in a conductive medium, the ability of the medium to carry current will in? The a spacing should equal the maximum depth of interest.
The former method is suited to graphical presentation and plotting resistivity versus distance, and will identify gradients and abrupt changes in soil condition. An unaltered dc source can be used if the electrodes are abraded to bright metal before immersion, polarity is regularly reversed during measurement, and measurements are averaged for each aetm.
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The data from this evaluation are available from Awtm in a research report. Where a resistivity meter is used, read the resistance directly and record.
To evaluate contamination effects when a new route is being evaluated, soil samples can be obtained at crossings of existing pipelines, cables, etc, or by intentional sampling using soil augers. A soil box can be calibrated using solutions of known resistivity.
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Current edition approved April gg57, Available pedological data should be used to facilitate interpretation. Since the number of soil sections that could be inspected is essentially unlimited, in?
The multi-participant test program results indicate a repeatability Cv of 6. The sample should be reasonably large and thoroughly mixed y57 that it will be representative. It will also be necessary to prepare a mixed sample. NOTE 1—The spacing between the inner electrodes should be measured from the inner edges of the electrode pins, and not from the center of the electrodes.
Conductive structures such as pipes and cables should not be within 1? A summary of these data is given in Table 1. Since most pipelines are installed at depths of from 1. The resistivity, r, is then: The effect of variations in compaction and moisture content can be reduced by fully saturating the sample before placing it in the box.
A superscript epsilon e indicates an editorial change since the last revision or reapproval. The box should be readily cleanable to avoid contamination by previous samples. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters.