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.
|Published (Last):||14 January 2012|
|PDF File Size:||10.87 Mb|
|ePub File Size:||17.84 Mb|
|Price:||Free* [*Free Regsitration Required]|
Surplus water should not be poured off as this will remove soluble constituents. 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.
Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
Surface contamination tends to concentrate in existing ditches with surface run-off, appreciably lowering the resistivity below the natural level. The resulting resistivity measurement represents the average resistivity of a hemisphere of soil of a radius equal to the electrode separation.
Where regular surveys are to be made at?
Active Risk Management
Risk and error must be arbitrarily selected to allow determination of the number of measurements. Sharp changes in resistivity with distance and appreciable variations in moisture content and drainage are indicative of local severe conditions.
Terminals should be of good quality to ensure that lowresistance contact is made at the electrodes and at the meter. Summary of Test Method 3. The soil should be well-compacted in layers in the soil box, with air spaces eliminated g7 far as practicable. Measurements xstm be made in each soil classi? It is desirable to sample each type separately.
A number in parentheses indicates the year of last reapproval. Do not include large nonconductive bodies such as frozen soil, boulders, concrete foundations, etc.
Aztm nomograph for this correction is shown in Fig. More precise procedures may be employed in laboratory investigations and these should be de? The a spacing should equal the maximum depth of interest. The electrode separation should be selected with consideration of the soil strata of interest. Since most pipelines are installed at depths of from 1. In either case, use pedological surveys in the planning and interpretation of any extensive survey.
Planning and Interpretation 7. Using dimensional analysis, the correct unit for resistivity is ohm-centimetre. 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. Last previous edition G 57 — Where mean or median values cannot be estimated with reasonable accuracy, sequential sampling techniques can be employed.
Both materials may require heat treatment so that they are sufficiently rigid to be inserted in dry or gravel soils.
ASTM G57 Standard
Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. 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.
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 xstm the slurry is remixed and placed in the box. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every? Since the number of soil sections that could be inspected is essentially unlimited, in? Where available, use ground water from the sample excavation for saturation.
Measure the voltage drop across the inner electrodes and record both the current and voltage drop if a separate ammeter and voltmeter are used. Where a h57 meter is used, read the resistance directly and record.
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. Precision and Bias 9. The multiparticipant test program results indicate a t57 Cv of The latter method permits precise mathematical treatment, such as cumulative probability analysis. Some soils absorb moisture slowly and contain constituents 5g7 dissolve slowly, and the resistivity may not stabilize for as much as 24 h after saturation.
If samples are retained for subsequent measurement, correct the resistivity if the measurement temperature is substantially different from the ground temperature. B57 will also be necessary to prepare a mixed sample.
Alternatively, the resistance can be measured directly. A soil box can be calibrated using solutions of known resistivity.