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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NOTE 1—The spacing between satm inner electrodes should be measured from the inner edges of the electrode pins, and not from the center of the electrodes. A summary of these data is given in Table 1.
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The latter method permits precise mathematical treatment, such as cumulative probability analysis. A superscript epsilon e indicates an editorial change since the last revision or reapproval. Available pedological data should be used to facilitate interpretation.
Surface contamination tends to concentrate in existing ditches with surface run-off, appreciably lowering the resistivity below asstm natural level.
Triplicate soil resistivity measurements by seven participants each using different meters. Sharp changes in resistivity with distance and appreciable variations in moisture content and drainage are indicative of local severe conditions. A galvanometer type of movement is preferred but astn electronic type instrument will yield satisfactory results if the meter input impedance is at least 10 megaohm.
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Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. The multi-participant test program results indicate a repeatability Cv of 6. The soil should be well-compacted in layers in the soil box, with air spaces eliminated as far as practicable. Where regular surveys are to be made at? The sample should be reasonably large and thoroughly mixed so that it will be representative.
More precise procedures may be employed in laboratory investigations and these should be de? Where available, use ground water from the sample excavation for saturation. Since the number of soil sections that could be inspected is essentially unlimited, in?
Where a resistivity meter is used, read the resistance directly and record. The electrodes should be formed with a handle and a FIG. 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. If samples are retained for subsequent measurement, correct the resistivity if the measurement temperature is substantially different from the ground temperature.
Last previous edition G 57 — This can be done by preparing a stiff slurry of the sample, adding only sufficient water to produce a slight amount of surface water, which should be allowed to evaporate before the slurry is remixed and placed in the box.
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. In either case, use pedological surveys in the planning and interpretation of any extensive survey.
Alternatively, the resistance can be measured directly. Measurements could be made in each soil classi? A number in parentheses indicates the year of last reapproval.
Current edition approved April 15, Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. Both materials may require heat treatment so that they are sufficiently rigid to be inserted in dry or gravel soils.
The degree of electrode polarization will also affect the size of such currents. 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 mean and median resistivity values will indicate the general corrosivity of the soil. Originally published as G 57 — The resistivity, r, is then: It is desirable to sample each type separately. 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.
The a spacing should equal the maximum depth of interest. 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. A nomograph for this correction is shown in Fig. Precision and Bias 9. 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 multiparticipant test program results indicate a reproducibility Cv of Some soils absorb moisture slowly and contain constituents that dissolve slowly, and the resistivity may not stabilize for as much as 24 h after saturation.
Where mean or median values cannot be estimated with reasonable accuracy, sequential sampling techniques can be employed. A soil box can be calibrated using solutions of known resistivity.