Methods of test for soils, Part 20: Determination of linear shrinkage

IS 2720 Part 20 - Scope: Key Points & Specifications

• Scope: This part of IS 2720 covers methods for determining linear shrinkage of soils.

• Rounding Off: Final test results must be rounded as per IS 2:1960, retaining the same number of significant digits as specified.

• Units: Quantities and dimensions are expressed in SI units.

• Reporting: Linear shrinkage shall be reported to the nearest whole number (Clause 6.2).

• Relevant Standards Referenced:

  • IS 460 (Part 1): Test sieves specification.
  • IS 2720 (Part 1): Dry soil sample preparation.
  • IS 12979: Mould specification for linear shrinkage tests.

Linear Shrinkage Calculation (General Formula)

[ \text{Linear Shrinkage (%)} = \frac{L_{wet} - L_{dry}}{L_{dry}} \times 100 ]

Where:

• (L_{wet}) = Length of the soil mould before drying
• (L_{dry}) = Length of the soil mould after drying

Summary Table: Reporting Precision

flowchart LR
    A[Prepare Soil Sample] --> B[Measure Initial Length (L_wet)]
    B --> C[Dry Soil Sample]
    C --> D[Measure Final Length (L_dry)]
    D --> E[Calculate Linear Shrinkage %]
    E --> F[Round off as per IS 2:1960]
    F --> G[Report Result (Nearest Whole Number)]

This ensures uniformity and accuracy in soil shrinkage testing as per IS 2720 Part 20.

IS 2720 Part 20 - Referenced Standards & Key Specifications

Referenced Indian Standards (Clause 2.1)

• IS 460 (Part 1): 1985 – Specification for wire cloth test sieves.
• IS 2720 (Part 1): 1983 – Methods of test for soils: Determination of dry soil samples.
• IS 12979: 1990 – Specification for mould for determination of linear shrinkage.

Rounding Off Values

• Follow IS 2: 1960 rules for rounding numerical values.
• Retain the same number of significant figures as specified in the standard.

Reporting Linear Shrinkage (Clause 6.2)

• Report linear shrinkage to the nearest whole number.

Notes

• Quantities and dimensions are in SI units.
• BIS standards ensure harmonized testing and reporting for soil properties.

Summary Table: Key Points

If you need a flowchart for the test procedure or further formulas, please specify!

IS 2720 Part 20: Apparatus and Materials Key Points

• Relevant IS Standards:

  • IS 460 (Part 1): Specification for wire cloth test sieves.
  • IS 2720 (Part 1): Methods for determination of dry soil samples.
  • IS 12979: Specification for mould for linear shrinkage.

• Apparatus Specifications:

  • Flat Glass Plate: ~10 mm thick, 45 mm square.
  • Evaporating Dish: ~15 cm diameter.

• Rounding Off Rules:

  • Follow IS 2:1960 for rounding numerical values.
  • Retain the same number of significant figures as specified in the standard.

Summary Table for Apparatus

This ensures standardized testing conditions for soil linear shrinkage as per IS 2720 Part 20.

IS 2720 Part 20: Sample Preparation Key Points

• Sample Size: Take about 150 g of soil passing through a 425-micron (0.425 mm) IS sieve (IS 460 Part 1:1985).
• Sample Source: Use a thoroughly mixed portion of the soil as per IS 2720 Part 1:1983 (dry soil sample determination).
• Mould Specification: Use moulds conforming to IS 12979:1990 for linear shrinkage tests.
• Rounding Off: Final test results must be rounded off as per IS 2:1960 rules, retaining the same number of significant figures as specified.

Summary Table for Sample Preparation

This ensures consistency and reliability in soil shrinkage testing.

IS 2720 Part 20: Test Procedure Key Points

• Rounding Off Results:
  Follow IS 2:1960 for rounding final test values, retaining the same significant figures as specified.

• Referenced Standards:

  • IS 460 (Part 1): Test sieves specification (wire cloth).
  • IS 2720 (Part 1): Dry soil sample preparation.
  • IS 12979: Mould for linear shrinkage measurement.

• Apparatus:
  Use standard moulds and test sieves as per above IS codes.

• Test Repetitions:
  Minimum 3 determinations of linear shrinkage per soil sample; report the average.

• Calculation:
  Linear shrinkage (%) is calculated by:
  [ \text{Linear Shrinkage (%)} = \frac{L_{\text{wet}} - L_{\text{dry}}}{L_{\text{wet}}} \times 100 ]
  where (L_{\text{wet}}) = length of soil sample before drying,
  (L_{\text{dry}}) = length after drying.

Summary Table for Linear Shrinkage Test

flowchart TD
    A[Prepare soil sample] --> B[Place in IS 12979 mould]
    B --> C[Measure initial length \(L_{wet}\)]
    C --> D[Dry sample]
    D --> E[Measure final length \(L_{dry}\)]
    E --> F[Calculate Linear Shrinkage]
    F --> G[Repeat 3 times]
    G --> H[Average results & round off]
    H --> I[Report]

This ensures standardized, reliable linear shrinkage measurements per IS 2720 Part 20.

IS 2720 Part 20: Calculations and Reporting of Linear Shrinkage

Key Points from Clauses 5.3 and 6.2:

• Number of Tests: Minimum 3 determinations of linear shrinkage on the same soil sample.
• Result: Take the average of the three values.
• Reporting: Report the linear shrinkage to the nearest whole number (rounded as per IS 2:1960).

Linear Shrinkage Calculation

[ \text{Linear Shrinkage (%)} = \frac{L_{dry} - L_{wet}}{L_{wet}} \times 100 ]

• (L_{wet}) = Length of soil sample before drying
• (L_{dry}) = Length of soil sample after drying

Reporting Format (Clause 6.2 Table Summary)

Notes:

• Use IS 12979:1990 for mould specifications.
• Use IS 460 (Part 1):1985 for test sieves.
• Follow IS 2:1960 for rounding off numerical values.

flowchart TD
    A[Take 3 samples] --> B[Measure wet length \(L_{wet}\)]
    B --> C[Dry samples]
    C --> D[Measure dry length \(L_{dry}\)]
    D --> E[Calculate linear shrinkage %]
    E --> F[Average 3 values]
    F --> G[Report nearest whole number]

This ensures consistent and standardized reporting of linear shrinkage as per IS 2720 Part 20.

IS 2720 Part 20: Precision and Repeatability Key Points

• Number of Tests: At least three determinations of linear shrinkage on the same soil sample are mandatory (Clause 5.3).
• Result Reporting: The average of these three tests is taken as the final value.
• Rounding Off: Final values must be rounded off per IS 2:1960 rules, retaining the same significant figures as specified (Clause on rounding).
• Reporting Precision: Linear shrinkage should be reported to the nearest whole number (Clause 6.2).
• Test Sieves & Moulds: Use apparatus as per IS 460 (Part 1) and IS 12979:1990 for accurate and repeatable results.

Summary Table for Precision & Repeatability

This ensures repeatability by averaging multiple tests and precision by standard rounding and apparatus specifications.

flowchart TD
    A[Sample Preparation] --> B[Perform 3 Linear Shrinkage Tests]
    B --> C[Calculate Average Shrinkage]
    C --> D[Round off per IS 2:1960]
    D --> E[Report Result (Nearest Whole Number)]

This workflow guarantees compliance with IS 2720 Part 20 requirements for precision and repeatability.

IS 2720 Part 20: Specimen Handling and Drying - Key Points

Specimen Handling (Clause 5.2)

• Moisture content near 2% above liquid limit is acceptable within a few percent tolerance.
• Avoid moisture levels causing segregation of coarse particles at the mold bottom.
• For low plasticity/shrinkage soils with no cracking risk, specimens can be dried immediately in a high-temperature oven.
• If specimens crack or break, repeat drying at a slower rate.

Testing Procedure (Clause 5.3)

• Conduct at least 3 linear shrinkage tests on the same soil.
• Use the average value for reporting.

Linear Shrinkage Calculation (Clause 6.1)

[ \text{Linear Shrinkage (%)} = \left(1 - \frac{\text{Length of oven-dry specimen}}{\text{Initial length of specimen}}\right) \times 100 ]

Rounding Off

• Follow IS 2:1960 for rounding results to the same significant figures as specified values.

flowchart TD
    A[Prepare soil specimen] --> B[Adjust moisture ~2% above liquid limit]
    B --> C{Is soil low plasticity?}
    C -- Yes --> D[Dry immediately in oven]
    C -- No --> E[Dry slowly to avoid cracking]
    E --> F{Specimen cracked?}
    F -- Yes --> E
    F -- No --> G[Measure length]
    D --> G
    G --> H[Calculate linear shrinkage]
    H --> I[Report average of 3 tests]

This ensures reliable and reproducible shrinkage test results.

IS 2720 Part 20 (1992) primarily focuses on methods of testing soils for safety and environmental considerations but does not explicitly provide formulas or tables dedicated solely to "Safety and Environmental Considerations."

Key Points on Safety and Environment (General Practice):

• Rounding off results: Follow IS 2:1960 for rounding numerical test values to maintain consistency.
• SI Units: All quantities and dimensions are in SI units for standardization.
• Safety: Ensure proper handling of soil samples to avoid contamination and hazards.
• Environmental: Testing should minimize disturbance to the site and prevent pollution.

Typical Safety & Environmental Considerations in Soil Testing (General Knowledge):

• Use PPE (Personal Protective Equipment) during sampling/testing.
• Avoid soil contamination by using clean tools.
• Proper disposal of waste generated during testing.
• Monitor groundwater contamination potential if tests involve chemicals.

No specific formulas or tables are provided in IS 2720 Part 20 for these considerations; instead, follow general laboratory safety and environmental protocols.

flowchart LR
    A[Soil Sampling] --> B[Use PPE]
    B --> C[Prevent Contamination]
    C --> D[Safe Waste Disposal]
    D --> E[Minimize Site Disturbance]
    E --> F[Accurate Testing Results]

For detailed safety/environmental guidelines, refer to relevant environmental standards and workplace safety codes.