ASTM D1557 Soil Compaction Characteristics in the Laboratory

Scope: 

Test procedures described in ASTM D1557 standard are only applicable to soils (materials) that retain 30% or less by mass of their particles on a 3/4-in. (19.0-mm) screen and have not been compacted in the laboratory; compacted soil should not be reused. There are three different methods to choose from. The method to be used must be specified in the specification for the substance to be tested. If no method is stated, the material gradation should be used to make the decision.

Test Procedure: 

The processes used in ASTM D1557 standard to indicate how data is collected/recorded or calculated are considered industry standards. Furthermore, they are symbolic of the significant digits that should be maintained in most cases.

Material variation, the purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives are not taken into account by the procedures used; it is common practise to increase or decrease significant digits of reported data to be commensurate with these considerations. Significant digits utilised in analytical procedures for engineering design are outside the perview of these test methods.

There are three different methods to choose from. The method to be used must be specified in the specification for the substance to be tested.

Method A of testing

If the material retains 25% or less by mass on the No. 4 (4.75-mm) sieve, it can be used. Method A can be utilised if 5 to 25% of the material by mass is retained on the No. 4 (4.75-mm) sieve, but oversize corrections will be necessary (See 1.4), and there are no advantages to utilising Method A in this situation.

Method B of testing

If the material retains 25% or less by mass on the 3/8-in. (9.5-mm) sieve, it can be used. Method B can be utilised if 5 to 25% of the material is retained on the 3/8-in. (9.5-mm) sieve, although oversize adjustments will be necessary (See 1.4). The sole advantages of utilising Method B over Method C in this scenario are that a smaller sample is required and the smaller mould is easier to use.

Method C of testing

If 30 percent or less (see 1.4) of the material’s mass is retained on the 3/4-in. (19.0-mm) sieve, it can be used.

Specimen size: Unless these test techniques exceed the rules for significant digits and rounding published in Practice D6026, all observed and computed values must conform to the guidelines for significant digits and rounding provided in Practice ASTM D1557. The measured or computed value(s) shall be rounded to the closest decimal or significant digits in the defined limits for the purpose of comparing them to the specified limits.

The values in inch-pound units should be considered standard. Except for mass units, the numbers in parenthesis are mathematical conversions to SI units supplied for information only and are not considered standard. The mass units are only specified in SI units, such as g or kg.

Specimen size:

Unless these test techniques exceed the rules for significant digits and rounding published in Practice D6026, all observed and computed values must conform to the guidelines for significant digits and rounding provided in Practice ASTM D1557. The measured or computed value(s) shall be rounded to the closest decimal or significant digits in the defined limits for the purpose of comparing them to the specified limits.

The values in inch-pound units should be considered standard. Except for mass units, the numbers in parenthesis are mathematical conversions to SI units supplied for information only and are not considered standard. The mass units are only specified in SI units, such as g or kg.

Result:

When a material is evaluated at the same active effort in different size moulds, the results vary slightly, with the smaller mould size often producing higher unit weight and density values.