Methods of test for soils, Part 19: Determination of centrifuge moisture equivalent

IS 2720 Part 19: Scope Summary

• Scope: This part of IS 2720 specifies methods for testing soil properties related to beam scales and related apparatus used in geotechnical investigations.
• Purpose: To ensure uniformity in test procedures and accuracy in measurement of soil parameters.
• Rounding Off: Final test values must be rounded as per IS 2:1960 rules, maintaining the same number of significant digits as specified.

Key Points:

• Applies to beam scales used in soil testing.
• Ensures compliance by standardizing test result reporting.
• Requires referencing related Indian Standards for complete procedures.

No direct formulas or tables in the scope clause; these appear in subsequent clauses detailing test methods.

IS 2:1960 Rounding Rules Summary:

flowchart LR
    A[Scope: IS 2720 Part 19] --> B[Beam scales for soil testing]
    B --> C[Standardized test procedures]
    C --> D[Result rounding per IS 2:1960]
    D --> E[Compliance verification]

For detailed formulas and tables, refer to specific test method clauses within IS 2720 Part 19.

IS 2720 Part 19 - References Summary

• Key Adjunct Standard:

  • IS 1433:1965 — Specification for beam scales (used for weighing in tests).

• Rounding Off Values:

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

• Test Report Format (Clause 9.1.1):

• BIS Guidelines:
  • Standard Mark ensures compliance and quality control.
  • Periodic review and amendments issued; users should confirm latest editions.
  • Copyright protected; permission needed for reproduction.

Contact & Support

• Headquarters: Manak Bhavan, New Delhi
• Regional Offices: Calcutta, Chandigarh, Madras, Bombay, etc.
• Enquiries: Director (Publications), BIS

This summary aids in understanding references and reporting requirements per IS 2720 Part 19. For detailed test procedures and calculations, refer to the full standard and IS 1433 for weighing equipment.

IS 2720 Part 19 - Definitions (Clause 3.0)

• This clause provides standardized definitions specifically for soil testing procedures covered in this part.
• Definitions clarify terms such as "soil sample," "dry density," "water content," and other fundamental concepts used throughout the standard.
• The standard refers to IS 2:1960 for rounding off numerical values to maintain consistency in reporting test results.
• Adjunct standards like IS 1433:1965 (Specification for beam scales) are essential for equipment calibration and accuracy.

Key Notes:

• Always round off test results as per IS 2:1960 rules.
• Use definitions to ensure uniform understanding of terms like:
  • Dry Density (ρd)
  • Water Content (w)
  • Bulk Density (ρ)
  • Void Ratio (e)

Example formula (commonly used in soil testing):

[ \rho_d = \frac{\text{Mass of solids}}{\text{Volume of soil sample}} = \frac{M_s}{V} ]

Where:

• ( \rho_d ) = Dry density
• ( M_s ) = Mass of solids (oven-dried soil)
• ( V ) = Volume of soil sample

If you need specific definitions or formulas for particular tests in IS 2720 Part 19, please specify!

IS 2720 Part 19 (1992) - Apparatus Key Points

Apparatus Specifications:

• Crucible with dry filter paper: Used for moisture determination.
• Centrifuge: To separate moisture from soil samples.
• Oven: For drying samples to constant mass.
• Beam scales: As per IS 1433:1965, for precise mass measurement.

Key Measurement Parameters (Clause 9.1.1 Table 9):

Moisture Equivalent Calculation:

[ \text{Moisture Equivalent} = \frac{(M2 - M3)}{(M3 - M1)} \times 100 ]

Where:

• (M1) = Mass of crucible + dry filter paper
• (M2) = Mass after centrifuging
• (M3) = Mass after oven drying

Notes:

• Use beam scales conforming to IS 1433 for accuracy.
• Follow IS 2:1960 for rounding off numerical values.
• Ensure apparatus calibration and quality control as per BIS guidelines.

flowchart LR
    A[Soil Sample + Filter Paper in Crucible (M1)] --> B[Centrifuge] --> C[Mass after centrifuging (M2)]
    C --> D[Oven Drying] --> E[Mass after oven drying (M3)]
    E --> F[Calculate Moisture Equivalent]

This setup ensures accurate determination of moisture content using centrifuge method as per IS 2720 Part 19.

IS 2720 Part 19 focuses on the Determination of Centrifuge Moisture Equivalent (CME), a measure of soil moisture content under centrifugal force.

Key Specifications for Soil Specimen:

• Sample size: Typically, a disturbed soil sample of about 100 g is used.
• Specimen preparation: Soil is placed in a porous cup or filter paper to allow water flow.
• Test conditions: Centrifugation is done at a specified speed (e.g., 2000 rpm) for a set duration (e.g., 15 minutes).

Key Formula:

The Centrifuge Moisture Equivalent (CME) is calculated as:

[ \text{CME} = \frac{W_w}{W_d} \times 100 ]

Where:

• ( W_w ) = weight of water extracted by centrifuge (g)
• ( W_d ) = dry weight of soil specimen (g)

Typical Procedure Summary:

1. Weigh moist soil sample.
2. Centrifuge to extract moisture.
3. Measure extracted water.
4. Oven-dry soil to get dry weight.
5. Calculate CME.

Additional Notes:

• CME approximates field capacity in fine-grained soils.
• Useful for soil-water retention characteristics.

flowchart LR
    A[Collect Soil Sample] --> B[Weigh Moist Soil]
    B --> C[Centrifuge Sample]
    C --> D[Collect Extracted Water]
    D --> E[Weigh Extracted Water]
    B --> F[Oven Dry Soil]
    F --> G[Weigh Dry Soil]
    E & G --> H[Calculate CME]

For detailed procedural steps and apparatus, refer to the full IS 2720 Part 19 document.

IS 2720 Part 19 - Procedure Key Points

• Rounding Off (IS 2:1960): Final test values must be rounded off to the same number of significant figures as specified in the standard.

• Test Reporting Format (Clause 9.1.1):

• Moisture Equivalent Calculation:

[ \text{Moisture Equivalent} = \frac{M_2 - M_3}{M_3 - M_1} \times 100 ]

Where:

• (M_1) = Mass of crucible + dry filter paper

• (M_2) = Mass after centrifuging

• (M_3) = Mass after oven drying

• Specifications: Use beam scales as per IS 1433:1965 for mass measurements.

flowchart TD
    A[Start] --> B[Weigh crucible + dry filter paper (M1)]
    B --> C[Add sample and centrifuge]
    C --> D[Weigh crucible + contents after centrifuging (M2)]
    D --> E[Oven dry sample]
    E --> F[Weigh crucible + contents after drying (M3)]
    F --> G[Calculate moisture equivalent]
    G --> H[Report results with rounding as per IS 2:1960]

This procedure ensures consistent and accurate moisture content determination in soils.

IS 2720 Part 19: Key Calculation Guidelines

• Rounding off: Final test or analysis results must be rounded as per IS 2:1960. The number of significant digits retained should match the specified value in the standard.

• Reporting format (Clause 9.1.1): For moisture content by centrifuge method, record:

  • Mass of crucible + dry filter paper (M1)
  • Mass of crucible + contents after centrifuging (M2)
  • Mass of crucible + contents after oven drying (M3)
  • Calculate centrifuge moisture equivalent (CME) as:

[ \text{CME} = \frac{M_2 - M_3}{M_3 - M_1} \times 100 ]

• General: Use beam scales complying with IS 1433:1965 for mass measurements.

Summary Table for Moisture Content Calculation

Notes:

• Ensure all masses are measured accurately.
• Follow IS 2 rounding rules for final values.
• Use calibrated beam scales as per IS 1433.

flowchart TD
    A[Start] --> B[Weigh crucible + dry filter paper (M1)]
    B --> C[Add sample and centrifuge, weigh (M2)]
    C --> D[Oven dry sample and weigh (M3)]
    D --> E[Calculate CME = ((M2 - M3)/(M3 - M1)) * 100]
    E --> F[Report results with proper rounding]

This ensures compliance with IS 2720 Part 19 for moisture content by centrifuge method.

Reproducibility of Results (IS 2720 Part 19)

• Test Duplication: Tests must be performed in duplicate.
• Acceptable Variation:
  • For CME ≤ 15%, variation between duplicates ≤ 1%
  • For CME > 15%, variation between duplicates ≤ 2%
• Action on Disagreement: If variation exceeds above limits, tests must be repeated.

Key Formula for Centrifuge Moisture Equivalent (CME):

[ \text{CME} = \frac{(M_2 - M_1 - 0.02) - (M_3 - M_1)}{M_3 - M_1} \times 100 ]

Where:

• (M_1) = Mass of crucible + dry filter paper (g)
• (M_2) = Mass after centrifuging (g)
• (M_3) = Mass after oven drying (g)
• 0.02 g = moisture allowance in filter paper

Reporting Table Format (Clause 9.1.1):

This ensures precision and reliability in moisture content determination by centrifuge method per IS 2720 Part 19.

IS 2720 Part 19: Reporting of Results - Key Points

• Rounding Off (IS 2:1960):
  Final test values must be rounded off to the same number of significant figures as the specified values in the standard.

• Reporting Format (Clause 9.1.1):
  Test results for Centrifuge Moisture Equivalent (CME) should be tabulated as below:

• Calculation of Centrifuge Moisture Equivalent (CME):
  [ \text{CME} = \frac{(M2 - M3)}{(M3 - M1)} \times 100 ]

• Final Reporting (Clause 9.1):
  Report the average of two determinations as the final CME value.

Summary:

• Use precise rounding per IS 2:1960.
• Report two test results and their average.
• Use the formula above for CME.
• Include remarks if necessary.

flowchart TD
    A[Start Test] --> B[Measure M1]
    B --> C[Measure M2 after centrifuging]
    C --> D[Measure M3 after oven drying]
    D --> E[Calculate CME = ((M2 - M3) / (M3 - M1)) * 100]
    E --> F[Repeat for 2 determinations]
    F --> G[Calculate average CME]
    G --> H[Report results with rounding as per IS 2:1960]

This ensures clarity and consistency in reporting moisture content by centrifuge method as per IS 2720 Part 19.

IS 2720 Part 19: Precision and Accuracy - Key Points

The code emphasizes proper rounding and reporting for test results to ensure precision and accuracy:

Rounding Off (IS 2:1960)

• Final test values must be rounded according to IS 2:1960.
• Number of significant digits retained should match the specified value in the standard.

Reporting Format (Clause 9.1.1 Example)

Precision & Accuracy Control

• Use calibrated beam scales complying with IS 1433:1965.
• Repeat determinations to calculate average and assess repeatability.
• Report remarks on observations for quality control.

General Formula for Moisture Content (Example)

[ \text{Moisture Content} = \frac{M2 - M3}{M3 - M1} \times 100 ]

Where:

• (M1) = Mass of crucible + dry filter paper
• (M2) = Mass after centrifuging
• (M3) = Mass after oven drying

flowchart TD
    A[Sample Preparation] --> B[Weigh Crucible + Filter Paper (M1)]
    B --> C[Centrifuge Sample]
    C --> D[Weigh Crucible + Contents (M2)]
    D --> E[Oven Dry Sample]
    E --> F[Weigh Crucible + Contents (M3)]
    F --> G[Calculate Moisture Content]

Summary:

• Follow IS 2 for rounding.
• Use IS 1433 beam scales for weighing.
• Report results with clear mass measurements and calculated moisture equivalents.
• Repeat tests for accuracy and precision verification.