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 resistivity information is included in published information, the measurement techniques used should be de? 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.
Terminals should be of good quality to ensure that lowresistance contact is made at the electrodes and at the meter. The box should be readily cleanable to avoid contamination by previous samples. Last previous edition G 57 — Available pedological data should be used to facilitate interpretation.
Since most pipelines are installed at depths of from 1. 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. 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.
Since a pipeline ditch cannot be included in the span of at-grade measurements, soil box samples should be obtained where the opportunity exists. Current edition approved April 15, The multi-participant test program results indicate a repeatability Cv of 6.
The electrode separation should be selected with consideration of the soil strata of interest. The resistivity, r, is then: 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.
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. 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 meter used may limit the upper range of resistivity, which can be measured.
The current can be provided by either a cranked ac generator asrm a vibrator-equipped dc source. 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.
Active Risk Management
Do not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc. 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. 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? Using dimensional analysis, the correct unit for resistivity is ohm-centimetre. 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. 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.
When a metallic structure is immersed in a conductive medium, the ability of the medium to carry current will in? Precision and Bias 9. A superscript epsilon e indicates an editorial change since the last revision or reapproval.
ASTM G57 Standard
The soil should be well-compacted in layers in the soil box, with air spaces eliminated as far as practicable. 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.
The sample should be reasonably large and thoroughly mixed so that it will be representative.
Summary of Test Method 3. Originally published as G y57 — Sharp changes in resistivity with distance and appreciable variations in moisture content and drainage are indicative of local severe conditions. Where available, use ground water from the sample excavation for saturation. A summary of these data is given in Table 1. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
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.
The mean and median resistivity values will indicate the general corrosivity of the soil. Axtm electrodes should be formed with a handle and a FIG. Since the number of soil sections that could be inspected is essentially unlimited, in? Ast, multiparticipant test program results indicate a reproducibility Cv of Conductive structures such as pipes and cables should not be within 1?
The data from this evaluation are available from ASTM in a research report. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every? A number in parentheses indicates the year of last reapproval.
Surplus water should not be poured off as this will remove soluble constituents.