D6938-15 Standard Test Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)推荐.pdf

Designation: D6938 − 15 Standard Test Methods for In-Place Density and Water Content of Soil and Soil- Aggregate by Nuclear Methods (Shallow Depth)1 This standard is issued under the fixed designation D6938; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval. 1. Scope* The neutron source and the thermal neutron detector are both 1.1 This test method describes the procedures for measuring located at the surface of the material being tested. The water in-place density and moisture of soil and soil-aggregate by use content most prevalent in engineering and construction activi- of nuclear equipment. The density of the material may be ties is known as the gravimetric water content, w, and is the measured by direct transmission, backscatter, or backscatter/ ratio of the mass of the water in pore spaces to the total mass air-gap ratio methods. Measurements for water (moisture) of solids, expressed as a percentage. content are taken at the surface in backscatter mode regardless 1.4 Two alternative procedures are provided. of the mode being used for density. It is the intent of this 1.4.1 Procedure A describes the direct transmission method subcommittee that this standard replace D2922 and D3017. in which the probe extends through the base of the gauge into 1.1.1 For limitations see Section 5 on Interferences. a pre-for