ASTM D6758-08
Standard Test Method for Measuring Stiffness and Apparent Modulus of Soil and Soil-Aggregate In-Place by Electro-Mechanical Method

Standard No.

ASTM D6758-08

Release Date

2008

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM D6758-18

Latest

ASTM D6758-18e1

Scope

The apparatus and procedure described provides a means for measurement of the stiffness of a layer of soil or soil-aggregate mixture from which a Young''s modulus may be determined for an assumed Poisson''s ratio. Low strain cyclic loading is applied by the apparatus about a static load that is consistent with highway applications (1).

This method is useful as a non-destructive method for monitoring or controlling compaction so as to avoid under-compaction, over-compaction or wasted effort. Through an understanding of how stiffness relates to density for a particular material, moisture content and compaction procedure, the stiffness achieved can be related to % compaction in connection with density based compaction control or specifications, for example, to meet the requirements of Method D 698 using standard effort or Method D 1557 using modified effort.

This method applies to silty and clayey materials containing greater than 20 % fines. In such cases, the relationship between stiffness and dry density or dry unit weight is sensitive to the water content. Water contents should be determined by use of: Test Method D 2216, D 4643, or D 4959. If the determination cannot be made immediately at the time of the stiffness measurements, then soil samples shall be preserved and transported in accordance with Practice D 4220, Section 8, Groups B, C, or D soils.

This method is useful in the construction of road bases or earthworks, including the installation of buried pipe (2).

The rapid, non-penetrating nature of this method is suited to production testing, for example, it provides a means of testing that does not necessarily interfere with or delay construction.

This method is suitable for mitigating the risk of pavement failure. By assuring the relative uniformity of highway subbase, subgrade and base stiffnesses, stresses on the pavement is more uniformly distributed. In this way the life of a pavement is extended and repairs minimized.

This method is suitable for determining when the surface of a soil or soil-aggregate structure is capable of supporting design loads. This is useful for stabilized fills where the material hardens (stiffens) over time without measurable changes in density or moisture content.

This test method is suitable for the in-place determination of a Young''s and a shear modulus of soil and soil-aggregate mixtures (3, 4). Stiffness, as measured by this method, is related to modulus (5) from an assumption of Poisson''s ratio and from the radius of the foot of the apparatus as follows:

where:
Kgr	=	stiffness of the ground layer being measured, MN/m (klbf/in.),
R	=	outside radius of the apparatus'' foot, m (in.),
ν	=	Poisson''s ratio,
E	=	Young''s modulus, MPa (kpsi), and
G	=	Shear modulus, MPa (kpsi).

The stiffness and modulus of silty and clayey material.......

ASTM D6758-08 Referenced Document

• ASTM D1557 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft³ (2,700 kN-m/m³))
• 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 D4220 Standard Practices for Preserving and Transporting Soil Samples
• ASTM D4643 Standard Test Method for Determination of Water Content of Soil and Rock by Microwave Oven Heating
• ASTM D4944 Standard Test Method for Field Determination of Water (Moisture) Content of Soil by the Calcium Carbide Gas Pressure Tester Method
• ASTM D4959 Standard Test Method for Determination of Water Content of Soil By Direct Heating
• ASTM D653 Standard Terminology Relating to Soil, Rock, and Contained Fluids
• ASTM D698 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12 400 ft-lbf/ft³ (600 kN-m/m³))*， 2024-04-19 Update

ASTM D6758-08 history

• 2018 ASTM D6758-18e1 Standard Test Method for Measuring Stiffness and Apparent Modulus of Soil and Soil-Aggregate In-Place by Electro-Mechanical Method
• 2018 ASTM D6758-18 Standard Test Method for Measuring Stiffness and Apparent Modulus of Soil and Soil-Aggregate In-Place by Electro-Mechanical Method
• 2008 ASTM D6758-08 Standard Test Method for Measuring Stiffness and Apparent Modulus of Soil and Soil-Aggregate In-Place by Electro-Mechanical Method
• 2002 ASTM D6758-02 Standard Test Method for Measuring Stiffness and Apparent Modulus of Soil and Soil-Aggregate In-Place by an Electro-Mechanical Method