Methods of test for soils, Part 18: Determination of field moisture equivalent

IS 2720 Part 18: Scope - Key Points & Specifications

Scope Summary:

• IS 2720 Part 18 covers methods for testing soil properties (e.g., moisture equivalent).
• Final test results must be rounded per IS 2:1960 rules, retaining the same significant figures as specified.
• Field Moisture Equivalent results are reported to two significant figures (Clause 8.2).

Important Specifications & Guidelines

Notes on Standard Mark & BIS

• The Standard Mark certifies compliance with BIS standards.
• BIS conducts ongoing inspections and quality control.
• Permission needed for reproduction of BIS publications, except for implementation details.

flowchart TD
    A[Soil Testing as per IS 2720 Part 18] --> B[Rounding Off Results]
    B --> C[Use IS 2:1960 Rules]
    A --> D[Report Field Moisture Equivalent]
    D --> E[To 2 Significant Figures]
    A --> F[Quality Assurance]
    F --> G[Standard Mark by BIS]
    G --> H[Continuous Inspection & Testing]

For detailed test procedures, refer to the full IS 2720 Part 18 document and related BIS publications.

IS 2720 Part 18 - References Summary

• Related Standard:

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

• Rounding Off Rules:

  • Follow IS 2:1960 for rounding numerical values.
  • Retain the same number of significant figures as specified.
  • Example: Field Moisture Equivalent reported to 2 significant figures (Clause 8.2).

• BIS Standard Mark:

  • Ensures compliance with IS standards via inspection and quality control.
  • Use governed by Bureau of Indian Standards Act, 1986.

• Revision & Amendments:

  • IS standards are periodically reviewed and amended.
  • Users must verify possession of the latest edition or amendments.

• Contact for BIS:

  • Headquarters: Manak Bhavan, New Delhi.
  • Regional offices in major cities (Delhi, Calcutta, Chandigarh, Madras, Bombay).
  • Telegram: Manaksanstha (common to all offices).

Quick Reference Table for Reporting

For detailed implementation, always refer to the latest edition of IS 2720 Part 18 and related standards.

IS 2720 Part 18 - Definitions: Key Points

• The standard refers to IS 1433:1965 for beam scales specifications.
• Numerical results in tests must be rounded off as per IS 2:1960, retaining the same significant figures as specified.
• Field Moisture Equivalent values are reported to two significant figures (Clause 8.2).
• Use of the Standard Mark indicates compliance with BIS quality control and inspection systems.
• BIS periodically reviews and amends standards; users should ensure they have the latest version.

Rounding Off Rule (IS 2:1960)

• Round off to the number of significant figures as per the standard.
• Example: If a value is 12.345 and the standard specifies 3 significant figures, report as 12.3.

Reporting Example for Field Moisture Equivalent:

For detailed definitions, refer to the initial clauses of IS 2720 Part 18 and related standards like IS 1433.

IS 2720 Part 18 (1992) primarily covers methods for soil testing, but it does not explicitly detail apparatus specifications or formulas within the provided context.

Apparatus Key Points (General IS 2720 Guidance)

• Apparatus must comply with relevant IS standards (e.g., IS 1433:1965 for beam scales).
• Instruments should be calibrated and accurate as per IS 2:1960 rounding rules.
• Typical apparatus includes:
  • Beam balance or scales (accurate to 0.01 g or better)
  • Containers (metal or glass, non-absorbent)
  • Sieves (standard IS sieve sizes)
  • Oven (maintained at 105 ± 5°C for drying)
  • Compaction molds and proving rings for load measurement.

Rounding Off Values (IS 2:1960)

• Round off test results to the same number of significant figures as the specified value.

Example: Beam Scale Specification (IS 1433)

If you need apparatus for a specific test from IS 2720 Part 18 (e.g., liquid limit, plastic limit), please specify for detailed formulas and apparatus.

IS 2720 (Part 18): Preparation of Soil Sample

Key Specifications:

• Sieves used:
  • 4.75 mm IS Sieve
  • 2 mm IS Sieve
  • 425 micron (0.425 mm) IS Sieve (per IS 460 Part 1:1985)

Sample Preparation Steps:

1. Initial Sample: Air-dried soil is sieved using a 2 mm IS sieve.

2. Grinding: Soil retained on 2 mm sieve is ground to break aggregates.

3. Sieving:

   • Ground soil is sieved again through 2 mm sieve.
   • Material passing 2 mm sieve is sieved through 425 micron sieve.
   • Soil retained on 425 micron sieve is discarded.
   • Soil passing 425 micron sieve is used for testing.

4. Specimen for Test: Take ~30 g of soil passing 425 micron sieve.

5. Moistening Procedure:

   • Add distilled water gradually to air-dried soil until it forms balls.
   • Smooth surface, place a water drop; if water disappears in <30 sec, add more water and repeat.
   • When water drop spreads but does not disappear in 30 sec, sample is ready.

6. Moisture Determination:

   • Weigh container (M1), container + wet soil (M2), oven-dry soil + container (M3).
   • Oven dry at 105-110°C to constant weight.

Field Moisture Equivalent (FME) Formula:

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

Where:

• (M_1) = Mass of container (g)
• (M_2) = Mass of container + wet soil (g)
• (M_3) = Mass of container + oven-dried soil (g)

Summary Table

IS 2720 Part 18: Procedure Key Points

• Rounding off: Follow IS 2:1960 rules; retain same significant figures as specified values.

• Test Result Tabulation (Clause 8.1):

• Calculation of Moisture Content (w):

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

• Field Moisture Equivalent (FME): Expressed as percentage moisture content calculated above.

• Equipment: Use beam scales conforming to IS 1433:1965 for weighing.

flowchart TD
    A[Weigh container (M1)] --> B[Add wet soil and weigh (M2)]
    B --> C[Oven dry sample and weigh (M3)]
    C --> D[Calculate moisture: (M2 - M3)/(M3 - M1) * 100]
    D --> E[Field Moisture Equivalent (FME)]

This procedure ensures consistent moisture content determination in soils as per IS 2720 Part 18.

IS 2720 Part 18: Key Calculation Guidelines

Rounding Off (per IS 2:1960)

• Final test values must be rounded to the same number of significant figures as specified.
• Example: Field Moisture Equivalent (FME) reported to 2 significant figures.

Test Result Tabulation (Clause 8.1)

Calculation of Moisture Present

[ \text{Mass of moisture} = M_2 - M_3 ]

Field Moisture Equivalent (FME)

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

• Express FME to two significant figures.

Summary Diagram of Masses and Calculations

flowchart LR
    A[Container Mass (M1)] --> B[Container + Wet Soil (M2)]
    B --> C[Container + Oven-dried Soil (M3)]
    C --> D[Mass of Moisture = M2 - M3]
    D --> E[Field Moisture Equivalent = ((M2 - M3)/(M3 - M1)) * 100]

Note: Always ensure compliance with rounding rules and report results accordingly.

IS 2720 Part 18 – Reporting Guidelines (Clause 8.2)

• Field Moisture Equivalent (FME) must be reported to two significant figures.
• Numerical results should be rounded off as per IS 2:1960 (Rules for rounding off numerical values).
• The number of significant figures in the reported value should match the specified precision in the standard.

Key Reporting Specifications:

Additional Notes:

• Use the Standard Mark only under BIS licensing and quality control.
• Ensure compliance with the latest edition/amendments of the standard.
• For detailed rounding rules, refer to IS 2:1960.

flowchart LR
    A[Test/Analysis Result] --> B[Rounding as per IS 2:1960]
    B --> C[Report with 2 significant figures (FME)]
    C --> D[Submission/Documentation]

This ensures consistency and clarity in reporting soil moisture test results under IS 2720 Part 18.

IS 2720 Part 18: Precision and Accuracy Key Points

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

  • Example: If the standard specifies 2 significant figures, report results accordingly.

• Balance Sensitivity (Clause 4.5):
  Use a balance with sensitivity of 0.01 g (per IS 1433:1965).

• Reporting Precision (Clause 8.2):
  Field Moisture Equivalent values must be reported to two significant figures.

Summary Table: Precision Requirements

Notes:

• Precision ensures reproducibility; accuracy ensures closeness to true value.
• Maintain calibration and verification of balances regularly.
• Follow IS 2 for rounding to maintain uniformity in reporting.

flowchart TD
    A[Test Result] --> B[Rounding Off (IS 2:1960)]
    B --> C[Report with specified significant figures]
    A --> D[Measurement using balance (0.01 g sensitivity)]
    D --> C
    C --> E[Final Report]

This ensures consistent precision and accuracy in soil testing results per IS 2720 Part 18.