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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Conductive structures such as pipes and cables should not be within 1?
It will also be necessary to prepare a mixed sample. Surplus water should not be poured off as this will remove soluble constituents. 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. Do not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc.
Where available, use aztm water from the sample excavation for saturation. This standard is subject to revision at any xstm by the responsible technical 5g7 and must be reviewed every? Last previous edition G 57 — Measurements could be made in each soil classi?
The meter used may limit the upper range of resistivity, which can be measured. Planning and Interpretation 7. 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.
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. Available pedological data should be used to facilitate interpretation. 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.
The resistivity, r, is then: 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.
A nomograph for this correction is shown in Fig. The latter method permits precise mathematical treatment, qstm as cumulative probability analysis. Summary of Test Method 3.
Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. 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. The multi-participant test program results indicate a repeatability Cv of 6.
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The former method is suited to graphical presentation and plotting resistivity versus distance, and will identify gradients and abrupt changes in soil condition. 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.
Both materials may require heat treatment so that they are sufficiently rigid to be inserted in dry or gravel soils. 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.
When a metallic structure is immersed in a conductive medium, the ability of the medium to carry current will in? Alternatively, the resistance can be measured directly. Where a resistivity meter is used, read the resistance directly and record.
Originally published as G 57 — Measure the voltage drop across the inner electrodes and record both the current and voltage drop if a separate ammeter and voltmeter are used.
Triplicate soil resistivity measurements by seven participants each using different meters. Surface contamination tends to concentrate in existing ditches with surface run-off, appreciably lowering the resistivity below the natural level.
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If error exceeds this limit, prepare a calibration curve and correct all measurements accordingly. The resulting resistivity measurement represents the average resistivity of a hemisphere of soil of a radius equal to the electrode separation. The two-electrode technique is inherently less accurate than the four-electrode method because of polarization effects, but useful information can be obtained zstm the characteristics of particular strata.
In either case, use pedological surveys in the planning and interpretation of any extensive survey. Using dimensional analysis, the correct unit for resistivity is ohm-centimetre. Since the number of soil sections that could be inspected is essentially unlimited, in?
The degree of electrode polarization will also affect the size of such currents. Where mean or median values cannot be estimated with reasonable accuracy, sequential sampling techniques can be employed. 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 box should be readily cleanable to avoid contamination by previous samples. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. A superscript epsilon e indicates an editorial change since the last revision or reapproval. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters.
The data from this evaluation are available from ASTM in a research report. The effect of variations in compaction and moisture content can be reduced by fully saturating the sample before placing it in the box.
Since most pipelines are installed at depths of from 1. Sharp changes in resistivity with distance and appreciable variations in moisture content and drainage are indicative of local severe conditions. The multiparticipant test program results indicate a reproducibility Cv of It is desirable to sample each type separately.
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.
Current edition approved April 15, More precise procedures may be employed in laboratory investigations and these should be de? Otherwise, use distilled water.