ASTM D698-12 Laboratory Compaction Characteristics of Soil

Scope of ASTM D698-12:

ASTM D698-12 standard test method defines procedures for compaction tests to be performed on soil or material. The methods help determine the relationship between molding water content and dry unit weight of soils or material, known as the compaction curve. Soils (materials) having 30% or less mass retained on 19.0 mm sieve qualify to be tested by the methods covered in ASTM D698-12. Their different methods are Method A, B or C.

 Test Procedure:

The soil sample at a selected moulding water content is placed in three layers into a mould of given dimensions, with each layer compacted by 25 or 56 blows of a 5.50 lbf (24.47-N) rammer dropped from 12.00 inch (304.8 mm), subjecting the soil to a total compactive effort of about 12 400 ft lbf/ ft3 (600 kN-m/m³). The resulting dry unit weight is determined. The procedure is repeated for enough moulding water content to establish a relationship between the dry unit weight and the moulding water content for the soil. This data, when plotted, represents a curvilinear relationship known as the compaction curve. The values of optimum water content and standard maximum dry unit weight are determined from the compaction curve.

Specimen size:

The minimum specimen (for testing) mass for Methods A and B is about 16 kg, and for Method C is about 29 kg of dry soil.

Data: 

Moist Density is calculated as follows:

where:

ρ_m = moist density of compacted sub-specimen (compaction point), four significant digits, g/cm3 or kg/m3,

M_t = mass of moist soil in mold and mold, nearest g,

M_md = mass of compaction mold, nearest g,

V = volume of compaction mold, cm³ or m³

The equation used to calculate dry density is:

where:

ρ_d = dry density of compaction point, four significant digits,

g/cm³ or kg/m³, and

w = molding water content of compaction point, nearest

0.1%
Conclusion:

ASTM D698-12 describes the test method for determining the compaction characteristics of the soil. Soil is placed as engineering fill (embankments, foundation pads, road bases) is compacted to a dense state to obtain satisfactory engineering properties such as shear strength, compressibility, or permeability. This standard helps evaluate these properties.