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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Do not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc. The current can be provided by either a cranked ac generator or a vibrator-equipped dc source.
Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Current edition approved April 15, A superscript epsilon e indicates an editorial change since the last revision or reapproval.
The multi-participant test program results indicate a repeatability Cv of 6. Where regular surveys are to be made at? 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 a spacing should equal the maximum depth of interest.
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Surface contamination tends to concentrate in existing ditches with surface run-off, appreciably lowering the resistivity below the natural level. The effect of variations in compaction and moisture content can be reduced by fully saturating the sample before placing it in the box.
Alternatively, asttm resistance can be measured directly. The sample should satm reasonably large and thoroughly mixed so that it will be representative. If samples are retained for subsequent measurement, correct the resistivity if the measurement temperature is substantially different from the ground temperature.
Terminals should be of good quality to ensure that lowresistance contact is made at the electrodes and at the meter. The electrode separation should be selected with consideration of the soil strata of interest. The latter method permits precise mathematical treatment, such as cumulative probability analysis. 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.
To evaluate contamination effects when a new route is being evaluated, soil samples adtm be obtained at crossings of existing pipelines, cables, etc, or by intentional sampling using soil augers.
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. Ast, published as G 57 — Triplicate soil resistivity measurements by seven participants each using different meters.
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A nomograph for this correction is shown in Fig. Since a pipeline ditch cannot be included in the span of at-grade measurements, soil box samples should be obtained where the opportunity exists. The meter used may limit the upper range of resistivity, which can be measured. 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.
Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every? Where available, use ground water from the sample excavation for saturation.
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. 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.
In either case, use pedological astj in the planning and interpretation of any extensive survey. Where mean or median values cannot be estimated with reasonable asttm, sequential sampling techniques can be employed.
Using dimensional analysis, the correct unit for resistivity is ohm-centimetre. The soil should be well-compacted in layers in the soil box, with air spaces eliminated as far as practicable.
When a metallic structure is immersed in a conductive medium, the ability of the medium to carry current will in? Where a resistivity meter is used, read the resistance directly and record.
Measure the voltage drop across the inner electrodes and record both the current and voltage drop if a separate ammeter and voltmeter are used. A soil box can be calibrated using solutions of known resistivity. Users 5g7 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.
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. Where resistivity information is included in published information, the measurement techniques used should be de? Since most pipelines are installed astj depths of from 1.