Drying Shrinkage of Soil
(Shrinkage Limit — IS 2720 Part 6)
Laboratory determination of shrinkage limit, shrinkage ratio and volumetric shrinkage of fine-grained soils per IS 2720 Part 6 — assessing drying shrinkage potential for foundation design on expansive and fine-grained soils.
What is the Drying Shrinkage of Soil?
The Shrinkage Limit (SL) is the water content below which further reduction in water content does not cause any decrease in the volume of the soil mass. Below the shrinkage limit, the soil is fully saturated and further drying causes cracking rather than further volume reduction. The shrinkage limit is the lowest of the Atterberg limits and completes the consistency index picture along with PL and LL.
Conducted as per IS 2720 Part 6, the shrinkage limit test involves drying a wet soil pat in a shrinkage dish, measuring the volume change using mercury displacement, and calculating the shrinkage limit from the mass-volume relationship. Shrinkage Ratio (SR) and Volumetric Shrinkage (VS) are also calculated. Global Lab tests shrinkage parameters in our NABL-accredited geotechnical laboratory.
Drying Shrinkage of Soil — Site Images
How the Drying Shrinkage of Soil is Conducted
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1Specimen PreparationSoil mixed with distilled water to just above liquid limit consistency. Filled into greased shrinkage dish (45mm dia × 12mm deep) in 3 layers, tapped to remove air.
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2DryingSpecimen air-dried until colour changes from dark to light (surface drying complete). Then oven-dried at 105°C to constant mass.
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3Dry Volume by Mercury DisplacementDry soil pat placed in mercury-filled container. Mercury displaced by soil measured — volume = mercury mass / 13.6.
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4Wet Volume CalculationWet volume = volume of shrinkage dish. Dry volume from mercury displacement.
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5SL, SR, VS Calculation & ReportSL = w - [(Vw-Vd)/Md × 1] × 100. SR = Md/Vd × 1/Gw. VS = (Vw-Vd)/Vd × 100. NABL report within 5 days.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| IS 2720 Part 6 | Methods of Test for Soils — Determination of Shrinkage Factors | Shrinkage Limit | Indian Standard |
| IS 2720 Part 5 | Methods of Test for Soils — Determination of Liquid and Plastic Limit | Atterberg Limits | Indian Standard |
| IS 1498 | Classification and Identification of Soils for General Engineering Purposes | Soil Classification | Indian Standard |
| ASTM D4943 | Standard Test Method for Shrinkage Factors of Cohesive Soils by the Wax Method | Shrinkage Test | ASTM |