ASTM G57 PDF

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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Originally published as G 57 — Available zstm data should be used to facilitate interpretation. Terminals should be of good quality to ensure that lowresistance contact is made at the electrodes and at the meter. Where resistivity information is included in published information, the measurement techniques used should be de? The former method is suited to graphical presentation and plotting resistivity versus distance, and will identify gradients and abrupt changes in soil condition.

Your asym will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Where available, use ground water from the sample excavation for saturation.

ASTM Ga (Reapproved )_百度文库

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. Since the number of soil sections that could be inspected is essentially unlimited, in?

Conductive structures such as pipes and cables should not be within 1? Surface contamination tends to concentrate in existing ditches with surface run-off, appreciably lowering the resistivity below the natural level. The current can be provided by either a cranked ac generator or a vibrator-equipped dc source. The electrodes should be formed with a handle and a FIG. 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.

Current edition approved April 15, 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.

Active Risk Management

Since most pipelines are installed at depths of from 1. Last previous edition G 57 — The resistivity, r, is then: It will also be necessary to prepare a mixed sample.

The degree of electrode polarization will also affect the size of such currents. To evaluate contamination effects when a new route is being evaluated, soil samples can be obtained at crossings of existing pipelines, cables, h57, 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. When a metallic structure is immersed in a conductive medium, the ability of the medium to carry current will in?

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.

Precision and Bias 9.

Measure the voltage drop asgm the inner electrodes and record both the current and voltage drop if a separate ammeter and voltmeter are used. 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.

Summary of Test Method 3. 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 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 multiparticipant test program results indicate a reproducibility Cv of If error exceeds this limit, prepare a calibration curve and correct all measurements accordingly. A summary of these data is given in Table 1. Do not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc. The box should be readily cleanable to avoid contamination by previous samples. The sample should be reasonably large and thoroughly mixed so that it will be representative.

ASTM G57 Standard

Surplus water should not be poured off as this will remove soluble constituents. 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. Alternatively, the resistance can be measured directly. The latter method permits precise mathematical treatment, such as cumulative probability analysis. The data from this evaluation are available from ASTM in a research report.

More precise procedures may be employed in laboratory investigations and these should be de? 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. Risk and error must be arbitrarily selected to allow g557 of the number of measurements.

It is desirable to sample each type separately.

Measurements could be made in each soil classi? Triplicate soil resistivity measurements by seven participants each using different meters. A number in parentheses indicates the year of last reapproval.

The mean and median resistivity values will indicate the general corrosivity of the soil. If samples are retained for subsequent measurement, correct the resistivity if the measurement temperature is substantially different from the ground temperature.

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.