Specific Gravity Test of Soil and Aggregate
Determining particle density for soil classification, mix design, and void ratio analysis
The specific gravity of a soil or aggregate is the ratio of the mass of a given volume of the material to the mass of an equal volume of distilled water at a reference temperature. It is a fundamental index property used in nearly every geotechnical calculation, from void ratio to degree of saturation.
What Is the Specific Gravity Test?
Test Parameters & Acceptance Criteria
The following parameters are measured or derived during specific gravity testing. Acceptance criteria depend on the material type and the design application — soil classification, mix design, or earthwork quality control.
| Parameter | Value / Range | Unit | Standard |
|---|---|---|---|
| Specific Gravity of Soil (Fine-Grained) | 2.60-2.80 (typical) | IS 2720 Part 3 Sec 1 | |
| Specific Gravity of Soil (Organic/Peaty) | 1.80-2.50 (typical) | IS 2720 Part 3 Sec 1 | |
| Specific Gravity — Density Bottle (Fine Aggregate) | 2.50-2.70 (typical) | IS 2720 Part 3 Sec 2 | |
| Specific Gravity of Coarse Aggregate (Oven-Dry Basis) | 2.50-3.00 (typical) | IS 2386 Part 3 | |
| Water Absorption of Coarse Aggregate | < 2% (most specifications) | % | IS 2386 Part 3 |
| Apparent Specific Gravity | Higher than oven-dry Gs | IS 2386 Part 3 | |
| Temperature Correction Factor (Ct) | Applied for tests not at 27 °C | IS 2720 Part 3 Sec 1 Table 1 |
Applicable Indian Standards
Methods of Test for Soils — Determination of Specific Gravity (Fine-Grained Soils) — Fine, Medium and Coarse Grained Soils
Methods of Test for Soils — Determination of Specific Gravity — Fine, Medium and Coarse Grained Soils (Density Bottle Method)
Methods of Test for Aggregates for Concrete — Specific Gravity, Density, Voids, Absorption and Bulking
Classification and Identification of Soils for General Engineering Purposes
Methods of Test for Soils — Determination of Water Content
Equipment Used
Pycnometer (1000 ml)
Standard IS pycnometer with brass conical cap
1000 ml capacity, fits fine-grained soil samples up to 400 g
CalibratedDensity Bottle (50 ml)
Borosilicate glass with ground-glass stopper
50 ml capacity, suitable for fine aggregate and soil passing 2 mm sieve
CalibratedWire Basket Apparatus
Stainless steel mesh basket with suspension frame
Accommodates coarse aggregate samples up to 3 kg, mesh aperture 6.3 mm
CalibratedVacuum Desiccator with Pump
Glass desiccator with mechanical vacuum pump
Removes entrapped air from soil-water slurry in pycnometer
CalibratedConstant Temperature Water Bath
Thermostatically controlled stainless steel bath
Maintains temperature at 27 ± 0.2 °C as required by IS 2720 Part 3
CalibratedDigital Weighing Balance
Shimadzu / Mettler Toledo
Least count 0.01 g (for density bottle) and 0.1 g (for pycnometer), NABL-calibrated
CalibratedTesting Process
Sample Collection & Preparation
Day 1A representative soil or aggregate sample is collected from the project site or received at the laboratory. For fine-grained soil, approximately 200-400 g of oven-dried material passing the 4.75 mm IS sieve is prepared. For coarse aggregates, a sample of approximately 2 kg is washed, dried, and graded. The appropriate test method — pycnometer, density bottle, or wire basket — is selected based on particle size.
Calibration of Apparatus
Day 1The pycnometer or density bottle is cleaned, dried, and weighed empty (W1). It is then filled with distilled water (or kerosene for expansive soils), brought to the reference temperature of 27 °C in a constant-temperature water bath, and weighed again (W2). This calibration establishes the mass of water the apparatus holds at the standard temperature, which is essential for all subsequent calculations.
Soil/Aggregate Introduction & De-airing
Day 1The oven-dried soil sample is placed into the pycnometer (W3 recorded), and distilled water is added until the pycnometer is approximately half full. The slurry is gently heated or subjected to vacuum in a desiccator for at least 30 minutes to remove all entrapped air — a critical step, as even small air bubbles cause significant error. For the wire basket method, the saturated surface-dry aggregate is weighed in air (Wa) and then submerged in water (Ww).
Temperature Equilibration & Final Weighing
Day 1After complete de-airing, the pycnometer is topped up with distilled water to the calibration mark, the cap is secured, and the assembly is placed in the constant-temperature water bath at 27 °C for at least 1 hour. Once equilibrated, the pycnometer is removed, dried externally, and weighed (W4). The difference between W2 and W4, corrected for the soil mass, gives the volume of soil solids displaced.
Repeat Determination
Day 1-2To ensure reliability, a minimum of two parallel determinations are performed on separate sub-samples as required by IS 2720 Part 3. If the two values differ by more than 0.03, a third determination is carried out. For aggregate testing per IS 2386 Part 3, duplicate tests are standard practice. This repetition is a core requirement of our NABL quality system.
Calculation & Reporting
Day 2-3Specific gravity is calculated using the formula G = (W3 - W1) / [(W2 - W1) - (W4 - W3)], with a temperature correction factor applied if the test was not conducted exactly at 27 °C. For aggregates, oven-dry, saturated surface-dry, and apparent specific gravities are computed along with water absorption percentage. The NABL-accredited report includes all raw weights, temperature readings, individual and average Gs values, and the applicable IS code reference.
Where This Test Is Used
Detailed Information
The specific gravity test of soil and aggregate is a fundamental laboratory test used to determine the relative density of soil particles and aggregates compared to water. NKMPV conducts specific gravity tests of soil and aggregate in accordance with applicable IS standards to support mix design, soil classification, and quality assessment for construction and infrastructure projects.
What Is the Specific Gravity Test
The soil and aggregate gravity test measures the ratio of the weight of soil or aggregate particles to the weight of an equal volume of water. This property helps engineers understand the composition, density, and quality of materials used in geotechnical and construction applications.
Importance of Specific Gravity in Construction
Specific gravity plays a critical role in:
• Soil classification and identification
• Concrete and bituminous mix design
• Determination of void ratio and porosity
• Assessment of material quality and consistency
• Geotechnical analysis and design calculations
Specific Gravity Test for Soil
For soils, the specific gravity test is used to evaluate mineral composition and particle characteristics. Typical values vary depending on soil type:
• Sands and silts generally range between 2.65 to 2.70
• Clays may have higher values depending on mineral content
The results are essential for compaction analysis, permeability studies, and stability assessment.
Specific Gravity Test for Aggregate
For aggregates, the test determines density characteristics that influence:
• Concrete strength and durability
• Bituminous mix performance
• Water absorption behavior
• Mix proportioning and quality control
Accurate specific gravity values help ensure consistency in construction materials.
Testing Methodology and Standards
The specific gravity test of soil and aggregate is conducted as per relevant Indian Standards (IS). The testing methodology involves controlled measurement of mass and volume using standardized equipment and procedures to ensure accuracy and repeatability.
Applications of this Test
This test is commonly used in:
• Soil and rock testing programs
• Concrete and bituminous mix design
• Quality control of construction materials
• Geotechnical investigations
• Research and laboratory analysis
References Code: IS 2720 (Part 3)
Why Choose NKMPV for Specific Gravity Testing
• NABL-accredited laboratory facilities
• Standardized testing as per IS guidelines
• Experienced technical professionals
• Accurate and reliable test results
• Support for design and quality decisions
Photos & Lab Images
Why Choose NKMPV for Specific Gravity Testing?
NABL Accredited Results
Our specific gravity test reports carry NABL accreditation (ISO/IEC 17025:2017), making them accepted by NHAI, state PWDs, courts, and arbitration tribunals without additional verification.
All Three Standard Methods
We perform the pycnometer method (fine-grained soil), density bottle method (fine aggregates and sand), and wire basket method (coarse aggregates) — covering the full range of materials you may encounter on a project.
Vacuum De-airing for Accuracy
Entrapped air is the primary source of error in specific gravity testing. Our vacuum desiccator setup removes air bubbles far more effectively than manual boiling, yielding reproducible results within ± 0.02 of the true value.
Same-Day Express Option
For urgent projects, we offer same-day specific gravity testing with results delivered within 24 hours. Standard turnaround is 2-3 days including full NABL-accredited reporting.
Comprehensive Soil Package
We combine specific gravity with grain size analysis, Atterberg limits, moisture content, and compaction tests — giving your geotechnical consultant a complete dataset in a single engagement.