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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Since most pipelines are installed at depths of from 1. 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. Surplus water should not be poured off as this will remove soluble constituents.
The a spacing should equal the maximum depth of interest. A soil box can be calibrated using solutions of known resistivity. Conductive structures such as pipes and cables should not be within 1?
ASTM G57 Standard
The electrodes should be formed with a handle and a FIG. Measure the voltage drop across the inner electrodes and record both the current and voltage drop if a separate ammeter and voltmeter are used.
If samples are retained for subsequent measurement, correct the resistivity if xstm measurement temperature is substantially different from the ground temperature.
The multi-participant test program results indicate a repeatability Cv of 6. The multiparticipant test program results indicate a reproducibility Cv of Adtm not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc.
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Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. In either case, use pedological surveys in the planning and interpretation of any extensive survey. 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 mean and median resistivity b57 will indicate the general corrosivity of the soil.
The former method is suited to graphical presentation and plotting resistivity versus distance, and will identify gradients and abrupt changes in soil condition. 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 asym evaporate before the slurry is remixed and placed in the box.
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.
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. Available pedological data should be used to facilitate interpretation.
The degree of electrode polarization will also affect the size of such currents. The sample should be reasonably large and thoroughly mixed so that it will be representative.
Since a pipeline ditch cannot be included in the span of at-grade measurements, soil box samples should be obtained where the opportunity exists. 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.
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.
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A galvanometer type of movement is preferred but an electronic type instrument will yield satisfactory results if the meter input impedance is at least 10 megaohm. When a metallic structure is immersed in a conductive medium, the ability of the medium to carry current will in?
Where mean or median values cannot be estimated with reasonable accuracy, sequential sampling techniques can be employed.
A number in parentheses indicates the year of last reapproval. Your comments are ast, either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters.
The meter used may limit the upper range of resistivity, which can be measured. It is desirable to sample each type separately. A nomograph for this correction is shown in Fig.