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ASTM G57 PDF

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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Where regular surveys are to be made at?

ASTM G57 Standard

The mean and median resistivity values will indicate the general corrosivity of the soil. The multi-participant test program results indicate a repeatability Cv of 6. The effect of variations in compaction and moisture content can be reduced by fully saturating the sample before placing it in the box. 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.

Otherwise, use distilled water. These commonly use two electrodes mounted on a prod that is inserted in the soil-at-grade in an excavation or a driven or bored hole. The data from this evaluation are available from ASTM in a research report. 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.

If error exceeds this limit, prepare a calibration curve and correct all measurements accordingly. Both materials may require heat treatment so that they are sufficiently rigid to be inserted in dry or gravel soils. Where mean or median values cannot be estimated with reasonable accuracy, sequential sampling techniques can be employed. 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 polarity.

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Terminals should be of good quality to ensure that lowresistance contact is made at the electrodes and at the meter.

Available pedological data should be used to facilitate interpretation. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.

The resistivity, r, is then: A number in parentheses indicates the year of last reapproval. Alternatively, the resistance can be measured directly.

Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Risk and error must be arbitrarily selected to allow determination of the number of measurements. This method permits the determination of the probability of the presence of a soil with a resistivity equal to or greater than a particular value.

Where resistivity information is included in published information, the measurement techniques used should be de? Resistivity is used in preference to conductivity as an expression of the electrical character of soils and waters since it is expressed in whole numbers.

The current can be provided by either a cranked ac generator or a vibrator-equipped dc atsm. Where available, use ground water from the sample excavation for saturation. Where a asttm meter is used, read the resistance directly and record. In the case of soil resistivity measurements, the repeatability may be characterized by a coefficient of variation, Cv, representing the repeatability standard deviation divided by the average result and expressed in percent.

The two-electrode technique is inherently less accurate than the four-electrode method because of polarization effects, but useful information can be obtained concerning the characteristics of particular strata. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every?

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The box should be readily cleanable to avoid contamination by previous samples. The degree of electrode polarization will also affect the size of such currents. Planning and Interpretation 7. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm.

When a metallic structure is immersed awtm a conductive medium, the ability of the medium to carry current will g75 Since a asttm ditch cannot be included in the span of at-grade measurements, soil box samples should be obtained where the opportunity exists. Surface contamination tends to concentrate in existing ditches with surface run-off, appreciably lowering the resistivity below the natural level.

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A superscript epsilon e indicates an editorial change since the last revision or reapproval. Using dimensional analysis, the correct unit for resistivity is ohm-centimetre. 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. Sharp changes in resistivity with distance and appreciable variations in moisture content and drainage are indicative of local severe conditions.

Last previous edition G 57 — A nomograph for this correction is shown in Fig.