ASTM D854 Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer

Get Certified ASTM D854 for Reliable Soil Specific Gravity Testing

To ensure specific gravity is used correctly to calculate a soil’s void ratio and degree of saturation, geotechnical laboratories conduct ASTM D854 testing. Standardizing the pycnometer technique and controlling temperature minimize inter-technician and round-to-round variation. 

The scope of ASTM D854 includes:

• Material type: The material consists of the soil particles that pass through a sieve with a size of 9.5 mm (3/8 in.) or less and is tested either as a moist sample or as an oven-dried one.
• Purpose: To determine the specific gravity of the soil solids so that it can be used in phase-relationship calculations. 
• Property evaluation: The assessment of property involves calculating specific gravity based on the relationship between the mass of soil solids and that of water. 
• Testing method: The method used involves placing the soil sample and the water into a pycnometer with the temperature kept under control, after which the calculation compares the mass of the soil solids with that of an equal volume of water. 
• Results: The specific gravity was given at the test temperature, and the density of the soil solids was included when required. 
• Test limitation: The limitation of the method is that Method A can only be used on moist specimens, whereas Method B is applicable only to oven-dry specimens, excluding those which are organic, highly plastic, from tropical soils, and from soils containing halloysite. 
• Use conditions: The procedure requires that the analysts get rid of the air trapped in the pycnometer and then note the mass of the pycnometer, the water, and the soil solids at the temperature of the test. 
• Application: The application enables calculations involving the void ratio, the degree of saturation, and the density of the soil solids in the field of geotechnical engineering. 

What are the Uses of ASTM D854 Testing?

ASTM D854 testing helps geotechnical engineers calculate the phase relationships of a soil, including void ratio and degree of saturation. Laboratories also multiply the specific gravity by the density of water at 20 °C to calculate soil solids density for design calculations. This standard-

• Supports void ratio and degree of saturation calculations for a given soil.
• Calculates soil solids density through the specific gravity and water density relationship.
• Assists foundation design and earthwork engineering calculations.
• Compares soil solids specific gravity across borrow sources and construction sites.
• Supports laboratory classification and characterization of soil samples.
• Provides data for compaction and settlement analysis in geotechnical projects.

Which materials can be tested according to ASTM D854?

ASTM D854 applies to soil solids that are passed through a 9.5-mm (3/8-in.) or finer sieve and have been tested as a moist or oven-dry specimen. Organic soils, highly plastic fine-grained soils, tropical soils, and soils containing halloysite can only be tested by Method A. Soils that have been disturbed by the test procedure, contaminated soils, or highly organic materials, such as floating fibrous matter, are excluded from this test method, as are those soils that would be more appropriately tested using Test Method D5550 if the solids dissolved or floated in water.

Why is ASTM D854 Important?

Accurate specific gravity data is critical to nearly all phase-relationship calculations performed by a geotechnical engineer. A pycnometer that contains trapped air or is tested at an improper temperature will produce erroneously high or low specific gravity, which then taints density calculations of the soil or other engineered materials. Accurate testing according to ASTM D854 maintains the integrity of soil characterizations and results in reliable geotechnical engineering calculations.

ASTM D854 Testing Process and Data Collection

A technician selects a representative soil specimen and prepares it as a moist or oven-dry sample depending on the method chosen. The pycnometer receives the soil solids and water, and the technician removes entrapped air before the contents reach the test temperature. The technician records the mass of the pycnometer with water alone and with water and soil solids combined. Laboratories calculate the specific gravity from the recorded masses and compile the result into the specimen’s analysis report.

Common Challenges and Troubleshooting

The air that becomes trapped in the pycnometer is one of the most frequent causes of error when determining specific gravity, as the presence of trapped air alters the measured volume relationship between the soil solids and water. The fact that the temperature is not consistently controlled during both the measurement of water alone and that of the soil-water mixture also leads to an inaccurate calculated specific gravity. To overcome these problems, technicians apply a vacuum or use aspiration until the air bubbles cease rising in the sample, maintain close control of the test temperature, and calibrate the pycnometer’s volume using only water before carrying out the test on the soil solids.

• Laboratories report specific gravity as a dimensionless value, with many common mineral soils typically falling between 2.60 and 2.80.
• Analysts commonly interpret values near 2.65 as consistent with soils containing substantial quartz or similar silicate minerals.
• Analysts calculate soil-solids density using ρs = Gs × ρw. A specific gravity of 2.65 corresponds to a particle density of approximately 2.65 g/cm³ or 2650 kg/m³ when water density is approximated as 1.00 g/cm³.
• Engineers use the specific gravity value to calculate soil phase relationships such as void ratio, porosity, and degree of saturation.
• Laboratories record the test temperature with the result because water density varies with temperature and affects the specific-gravity calculation.
• Analysts investigate unusually low or high values because organic matter, dense minerals, entrapped air, or improper temperature control can influence the measured result.
• Engineers use the final ASTM D854 result with other soil properties when evaluating compaction, settlement, earthworks, and foundation conditions.

Link to ASTM D854