Standard Test Methods for Water Content and Density of Soil In situ by Time Domain Reflectometry (TDR)

Importancia y uso:

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.

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: 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. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.

Subcomité:

D18.08

Referida por:

D8153-22

Volúmen:

04.09

Número ICS:

13.080.20 (Physical properties of soil)

Palabras clave:

compaction test; construction control; density; dielectric constant; electrical permittivity; electromagnetic waves; field control; field tests; inspection; moisture content; quality control; soil compaction; soil density; time domain reflectometry; water content;