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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Alternatively, the resistance can be measured directly. The multi-participant test program results indicate a repeatability Cv of 6.
Where a resistivity meter is used, read the resistance directly and record. A superscript epsilon e indicates an editorial change since the last revision or reapproval. Terminals should be of good quality to ensure that lowresistance contact is made at the electrodes and at the meter. Precision and Bias 9. 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.
It will also be necessary to prepare a mixed sample. A galvanometer type of movement is adtm but wstm electronic type instrument will yield satisfactory awtm if the meter input impedance is at least 10 megaohm.
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. In either case, use pedological surveys in the planning and interpretation of any extensive survey. NOTE 1—The spacing between the inner electrodes should be measured from the awtm edges of the electrode pins, and not from the center of the electrodes.
Using dimensional analysis, the correct unit for resistivity is ohm-centimetre.
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Measurements could be made in each soil classi? Where regular surveys are to be made at? Since asttm pipelines are installed at depths of from 1. The multiparticipant test program results indicate a reproducibility Cv of The data from this evaluation are available from ASTM in a research report.
Where mean or median values cannot be estimated with reasonable accuracy, sequential sampling techniques can be employed.
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. The box should be readily cleanable to avoid contamination by previous samples.
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Sharp changes in resistivity with distance and appreciable variations in moisture content and drainage are indicative of local severe conditions. If samples are retained for subsequent measurement, correct the resistivity if the measurement temperature is substantially different v57 the ground temperature.
Since the number of soil sections that could be adtm is essentially unlimited, in? Where resistivity information is included in published information, the measurement techniques used should be de? This standard is subject to revision at any time by the responsible technical committee and must be reviewed every?
ASTM G57 Standard
The former method is suited to graphical presentation and plotting resistivity versus distance, and will identify gradients and abrupt changes in soil condition. A nomograph for this correction is shown in Fig. Current edition approved April 15, 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.
Do not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc. 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.
These commonly use qstm electrodes mounted on a prod that is inserted in the soil-at-grade in an excavation or a driven or bored hole.
It is desirable to sample each type separately. Surplus water should not be poured off as this will remove soluble constituents.
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 summary of these data is given in Table 1. Both materials may require heat treatment so that they are sufficiently rigid to be inserted in dry or gravel soils.
The meter used may limit the upper g5 of resistivity, which can be measured.
This method permits the determination of the astn of the presence of a soil with a resistivity equal to or greater than a particular value.
The effect of variations in compaction and moisture content can be reduced by fully saturating the sample before placing it in the box. Triplicate soil resistivity measurements by seven participants each using different meters. The resistivity, r, is then: