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IS 9259:1979 is the Indian Standard (BIS) for liquid limit apparatus for soils. This standard specifies the requirements for the liquid limit apparatus used for determining the liquid limit of soils. It covers the material, dimensions, and constructional details of the components, including the brass cup, hard base, cam mechanism, and grooving tools.
! The hardness of the ebonite base is a critical parameter for obtaining accurate results and it degrades over time. It should be checked periodically.
! The 10mm height of drop must be calibrated frequently using the gauge on the grooving tool's handle or a separate block.
! The point of contact between the cup and base should be kept clean and free from soil particles to ensure a consistent drop.
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
soilbrassebonite
International Equivalents
Similar International Standards
ASTM D4318-17ASTM International, USA
HighCurrent
Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
Specifies apparatus requirements within the overall test method standard.
BS 1377-2:1990British Standards Institution (BSI), UK
HighCurrent
Methods of test for soils for civil engineering purposes. Classification tests
Defines the liquid limit apparatus specifications within the soil classification test suite.
ISO 17892-12:2018International Organization for Standardization (ISO), International
HighCurrent
Geotechnical investigation and testing — Laboratory testing of soil — Part 12: Determination of liquid and plastic limits
Provides detailed specifications for the liquid limit device (Casagrande cup method).
AASHTO T 89-20American Association of State Highway and Transportation Officials (AASHTO), USA
HighCurrent
Standard Method of Test for Determining the Liquid Limit of Soils
Specifies the apparatus as part of the standard test method, closely mirroring ASTM D4318.
Key Differences
≠The IS code specifies a grooving tool that creates a 'V' shaped groove, whereas ASTM D4318 and AASHTO T 89 primarily specify a flat-bottomed grooving tool, which can yield different liquid limit values.
≠The method for specifying the hardness of the apparatus base differs. IS 9259 uses a resilience test (rebound height of a steel ball), while ASTM and ISO specify hardness using a Durometer (Shore A) or IRHD scale, respectively.
≠There is a significant difference in the specified mass. IS 9259 states the cup mass is approximately 100g, while ASTM D4318 specifies the mass of the cup and its hanger assembly to be 200 ± 20g.
Key Similarities
≈All standards are based on the same fundamental operating principle of a brass cup repeatedly dropping from a fixed height onto a hard base to close a groove in a soil sample.
≈The specified height of drop for the cup is universally set at a nominal 10 mm, with very tight and similar tolerances across all standards.
≈The recommended rate of operation is consistent, specified as approximately 2 drops (or crank revolutions) per second across all mentioned standards.
≈The general geometry of the cup, being a segment of a sphere, is a common feature, ensuring a similar contact and shearing action on the soil paste during the test.
Parameter Comparison
Parameter
IS Value
International
Source
Drop Height of Cup
10 ± 0.25 mm
10 ± 0.2 mm
ASTM D4318 / ISO 17892-12
Grooving Tool Type
'V' shaped groove (Casagrande type)
Flat bottom, 2mm wide (ASTM type)
ASTM D4318 / AASHTO T 89
Base Hardness Specification
Min 8mm rebound of 8mm steel ball dropped from 250mm
Durometer hardness of 80 to 90 (Shore A)
ASTM D4318
Mass of Cup (with Hanger)
~100 g (for cup alone; assembly mass not specified)
200 ± 20 g
ASTM D4318
Rate of Drops
About 2 revolutions/second
1.9 to 2.1 drops/second
ASTM D4318
Cup Material
Brass
Brass or other material with similar wear characteristics
ASTM D4318
Cup Internal Radius
27 mm
54 mm (radius of sphere forming the cup)
ASTM D4318
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Height of fall of cup10 ± 0.2 mm
Mass of cup with suspension200 ± 20 g
Speed of cam rotation2 revolutions/second (120 rpm)