scope:

This method covers the laboratory procedure for determining the minimum resistivity of soil samples. The principal use of this test method is to determine a soil's corrosivity and thereby identify the conditions under which the corrosion of metals in soil may be sharply accentuated. Note 1-When less than 5 percent of a material passes the No.10 sieve, this method may not be indicative of the corrosion potential of the material.

This method covers the dry preparation of soil and soil-aggregate samples, as received from the field, for soil resistivity determination.

The following applies to all specified limits in this standard: for the purpose of determining conformance with these specifications, an observed value or calculated value shall be rounded off "to the nearest unit" in the last right-hand place of figures used in expressing the limiting value, in accordance with ASTM E29.

The values stated in SI units are to be regarded as the standard.

The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of R 18 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with R 18 alone does not completely assure reliable results. Reliable results depend on many factors; following the suggestions of R 18 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.