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Specific Gravity of Soil Test (IS 2720 Part 3) — NABL Lab India | Global Lab
NABL Accredited · Geotechnical Testing Service

Specific Gravity of Soil Test (IS 2720 Part 3 — Pycnometer Method)

Laboratory determination of the specific gravity (Gs) of soil solids using the pycnometer method per IS 2720 Part 3 — an essential parameter for void ratio, porosity and degree of saturation calculations in geotechnical engineering.

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IS 2720 Pt.3
Standard
±0.01
Accuracy
3 Days
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NABL
Accredited

What is the Specific Gravity of Soil Test?

The Specific Gravity of Soil Solids (Gs) is the ratio of the mass of a given volume of soil solids to the mass of an equal volume of distilled water at 27°C. Determined by the pycnometer (specific gravity bottle) method, Gs typically ranges from 2.60 (organic soils) to 2.80 (heavy minerals), with 2.65–2.70 typical for common Indian soils (sand, silt, clay).

Conducted as per IS 2720 Part 3, Gs is used to calculate void ratio (e), porosity (n), degree of saturation (S) and air void content (Av) from measured dry density and water content — essential for compaction curve analysis, consolidation calculations and phase relationship computations in all geotechnical analyses. Global Lab determines Gs using calibrated 50ml pycnometers at 27°C in our NABL-accredited laboratory.

Pycnometer Method at 27°C

Standard pycnometer specific gravity method per IS 2720 Part 3 at Indian standard temperature.

Three-Decimal Accuracy

Results reported to 3 decimal places (e.g., 2.672) per IS 2720 Part 3.

All Soil Types

Applicable to sand, silt, clay, gravel, organic soils and mixed soils.

Phase Relationship Calculations

Gs enables void ratio, porosity and degree of saturation from bulk density and water content.

NABL Certified Reports

All test and calibration results backed by traceable measurements and standardized procedures.

Compaction Curve Enhancement

Gs required for zero air voids (ZAV) curve on Proctor compaction plot.

Specific Gravity of Soil Test — Site Images

Pycnometer calibration with distilled water at 27°C for specific gravity of soil test
Pycnometer Calibration with Distilled Water at 27°C
Soil sample added to pycnometer and de-aired by gentle heating
Soil Added to Pycnometer — De-airing by Gentle Heating
Specific gravity of soil calculated from four mass measurements per IS 2720 Part 3
Specific Gravity Calculated from 4 Mass Measurements

How the Specific Gravity of Soil Test is Conducted

  1. Pycnometer Calibration

    Empty pycnometer (M1) and pycnometer filled with distilled water at 27°C (M2) weighed precisely.

  2. Soil Sample Addition

    Approximately 10g oven-dried soil added to pycnometer. Pycnometer + soil weighed (M3).

  3. Water Addition & De-airing

    Distilled water added to fill pycnometer. De-aired by gentle heating for 10 minutes. Cooled to 27°C.

  4. Final Mass Measurement

    Pycnometer + soil + water weighed at 27°C (M4).

  5. Gs Calculation & Report

    Gs = (M3−M1) / [(M2−M1) − (M4−M3)]. Temperature correction applied. NABL report within 3 days.

Applicable Test Standards

Standard Title Scope Type
IS 2720 Part 3 Methods of Test for Soils — Determination of Specific Gravity (Section I — Fine-Grained Soils) Specific Gravity Indian Standard
IS 2720 Part 4 Methods of Test for Soils — Grain Size Analysis PSD Reference Indian Standard
IS 2720 Part 7 Methods of Test for Soils — Determination of Water Content-Dry Density Relation Compaction Reference Indian Standard
ASTM D854 Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer Specific Gravity ASTM

Where is the Specific Gravity of Soil Test Used?

Phase relationship calculations — void ratio, porosity and degree of saturation
Zero air voids curve for Proctor compaction test — requires accurate Gs
Consolidation analysis — Cc and Cv calculations from oedometer test data
Hydrometer analysis particle size correction (buoyancy factor uses Gs)
Classification of organic soils — low Gs (<2.60) indicates organic content
Permeability and seepage analysis — void ratio calculation requires Gs

Our Advantages

NABL Accredited ReportsLegally valid IS 2720 Part 3 specific gravity certificates.
3-Decimal PrecisionTemperature-corrected Gs to 3 decimal places for accurate phase calculations.
All Soil Types CoveredSand, silt, clay, gravel, mixed and organic soils all tested.
Fast 3-Day ReportSpecific gravity result and NABL report within 3 working days.
Pan-India CoverageGeotechnical lab at all 7 NABL-accredited locations.
Combined Soil PackageGs + Atterberg + PSD + Compaction as a complete soil characterisation package.

Specific Gravity of Soil Test — FAQs

  • The specific gravity of soil solids (Gs) is the ratio of the mass of soil solids to the mass of an equal volume of distilled water at 27°C. It is a fundamental geotechnical parameter used to calculate void ratio (e), porosity (n), degree of saturation (S) and air voids content — all critical inputs for compaction design, consolidation settlement analysis and soil classification per IS 1498.

  • The specific gravity of soil test is conducted as per IS 2720 Part 3 — Methods of Test for Soils: Determination of Specific Gravity (Section I — Fine-Grained Soils). The test uses the pycnometer (specific gravity bottle) method at the standard Indian temperature of 27°C. The equivalent ASTM standard is ASTM D854.

  • Most Indian soils have Gs values between 2.65 and 2.70 — sand is typically 2.65, silt 2.67 and clay 2.70. Organic soils have lower Gs values below 2.60, while soils with heavy minerals (iron-rich laterites) may reach 2.80. A Gs below 2.60 generally indicates significant organic matter content in the soil.

  • Global Lab issues the NABL-accredited specific gravity of soil test report within 3 working days of sample receipt. Samples can be submitted at any of our 7 lab locations across India — Mumbai, Navi Mumbai, Kolkata, Guwahati, Bhubaneswar, Surat and Ahmedabad — or collected from your site by our team.