ASTM D6780/D6780M-12
Standard Test Method for Water Content and Density of Soil In situ by Time Domain Reflectometry (TDR)

Standard No.

ASTM D6780/D6780M-12

Release Date

2012

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM D6780/D6780M-19

Latest

ASTM D6780/D6780M-19

Scope

5. Significance and Use

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5.1 This test method can be used to determine the density and water content of naturally occurring soils and of soils placed during the construction of earth embankments, road fills, and structural backfills.

5.2 Time domain reflectometry (TDR) measures the apparent dielectric constant (Procedure A) and the apparent dielectric constant, first voltage drop and long term voltage (V₁ and V_f) (Procedure B) of soil. The apparent dielectric constant is affected significantly by the water content and density of soil, and to a lesser extent by the chemical composition of soil and pore water, and by temperature. The first voltage drop and long term voltage (V₁ and V_f) are affected significantly by the water content, density, and the chemical composition of the in situ pore water, and to a lesser extent the chemical composition of the soil solids. This test method measures the gravimetric water content and makes use of a different relationship between the electrical properties and water content from Test Method D6565 which measures the volumetric water content.

5.3 Soil and pore water characteristics are accounted for in Procedure A with two calibration constants and for Procedure B with five calibration constants. The two soil constants for Procedure A are determined for a given soil by performing compaction tests in a special mold as described in Annex A2. The five soil constants for Procedure B are determined in conjunction with compaction testing in accordance with specified compaction procedures, for example, Test Method D698 as described in Annex A3. Both Procedures A and B use Test Method D2216 to determine the water contents.

5.4 When following Procedure A, the water content is the average value over the length of the cylindrical mold and the density is the average value over the length of the multiple-rod probe embedded in the soil. When following Procedure B, the water content and density is the average values over the length of the multiple-rod embedded in the soil.

Note 1?span class="note">The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. User............

ASTM D6780/D6780M-12 Referenced Document

• ASTM D2216 Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• ASTM D3740 Standard Practice for Minimum Requirements for Agencies Engaged in the Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• ASTM D4753 Standard Specification for Evaluating, Selecting, and Specifying Balances and Scales for Use in Soil, Rock, and Construction Materials Testing
• ASTM D6026 Standard Practice for Using Significant Digits in Geotechnical Data
• ASTM D653 Standard Terminology Relating to Soil, Rock, and Contained Fluids
• ASTM D6565 Standard Test Method for Determination of Water (Moisture) Content of Soil by the Time-Domain Reflectometry (TDR) Method
• ASTM D698 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12 400 ft-lbf/ft³ (600 kN-m/m³))
• ASTM E1 Standard Specification for ASTM Thermometers

ASTM D6780/D6780M-12 history

• 2019 ASTM D6780/D6780M-19 Standard Test Methods for Water Content and Density of Soil In situ by Time Domain Reflectometry (TDR)
• 2012 ASTM D6780/D6780M-12 Standard Test Method for Water Content and Density of Soil In situ by Time Domain Reflectometry (TDR)
• 2005 ASTM D6780-05 Standard Test Method for Water Content and Density of Soil in Place by Time Domain Reflectometry (TDR)
• 2002 ASTM D6780-02 Standard Test Method for Water Content and Density of Soil in Place by Time Domain Reflectometry (TDR)