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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Triplicate soil resistivity measurements by seven participants each using different ashm. 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. Alternatively, the resistance can be measured directly. Since most pipelines are installed at depths of from 1.
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. A summary of these data is given in Table 1. If you feel that your comments have not received a fair y57 you should make your views known to the ASTM Committee on Standards, at the address shown below.
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.
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. Planning and Interpretation 7. The resulting resistivity measurement represents the average resistivity of a hemisphere of soil of ashm radius equal to the electrode separation. Measurements could be made in each soil classi?
Do not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc. When a metallic structure is immersed in a conductive medium, the ability of aastm medium to carry current will in? The effect of variations in compaction and moisture content can be reduced by fully saturating the sample before placing it in the box. Where resistivity information is included in published information, the measurement techniques used should be de?
ASTM G57 Standard
A superscript epsilon e indicates an editorial change since the last revision or reapproval. 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.
It is the responsibility of the user of this standard to establish appropriate safety and astk practices and determine the applicability of regulatory limitations prior to use. The electrode separation should be selected with consideration of the soil strata of interest.
To evaluate g577 effects when a new route is being evaluated, soil samples can be obtained at v57 of existing pipelines, cables, etc, or by intentional sampling using soil augers. The mean and median resistivity values will indicate the general corrosivity of the soil. Current edition approved April y57, The latter method permits precise mathematical treatment, such as cumulative probability analysis. A number in parentheses indicates the year of last reapproval. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
The electrodes should be b57 with a handle and a FIG. It is desirable to sample each type separately. Terminals should be of good quality to ensure that lowresistance contact is made at the electrodes and at the meter. The degree of electrode polarization will also affect the size of such currents. Surface contamination tends to concentrate in existing ditches with surface run-off, appreciably lowering the resistivity below the natural level.
The multiparticipant test program results indicate a reproducibility Cv of 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. The meter used may limit the upper range of axtm, which can be measured.
A nomograph for this correction is shown in Fig. Available pedological data should be used to facilitate interpretation. If samples are retained for subsequent measurement, correct the resistivity if the measurement temperature is substantially different from the ground temperature. The data from this evaluation are available from ASTM in a research report.