Code of practice for field control of moisture and compaction of soils for embankment and subgrade

IS 10379: Introduction - Key Points & Specifications

Scope:

• Field control methods for moisture and compaction of soils in embankments and subgrades.
• Ensures soil properties meet design quality over earthwork areas (recommended test frequency: every 1000 m²).

Key Notes:

• Applicable to both gravely and non-gravely soils (Clause 3.4 for gravels/rockfills).
• Shear strength of compacted gravels/rockfills is less sensitive to density changes; precise water content control less critical.
• Various standard test methods referenced for water content, dry density, and in-place density (ring, sand replacement).

Rounding Off:

• Final test values rounded as per IS 2-1960 rules for numerical precision.

Relevant Test Methods (IS 2720 series excerpts):

Summary Table for Field Control Frequency

flowchart TD
    A[Soil Embankment/Subgrade] --> B[Field Control]
    B --> C{Soil Type}
    C -->|Gravely/Rockfill| D[Less sensitive to water content]
    C -->|Non-Gravely| E[Precise moisture control needed]
    B --> F[Tests per IS 2720 series]
    F --> G[Water Content]
    F --> H[Dry Density]
    F --> I[In-place Density]

**Use this standard to ensure uniform compaction and moisture control

IS 10379: Scope Summary

• Scope: Covers field control methods for soil compaction and moisture content in embankments and subgrades.
• Applies to various soil types, focusing on ensuring soil properties meet design quality.
• Suggests regular testing at intervals of about 1000 m² of earth fill.
• Includes methods for non-gravelly soils and notes gravel/rockfill soils require less precise moisture control.
• Emphasizes rounding off test results per IS 2-1960 rules.

Key Specifications:

Important References in IS 10379:

• Water Content Tests: IS Part II
• Density Relation Tests: IS Part VII (light compaction), Part VIII (heavy compaction)
• In-place Density: IS Part XXXIII (ring & water), Part XXVIII (sand replacement)

flowchart LR
    A[Soil for Embankment/Subgrade] --> B{Soil Type?}
    B --> |Non-Gravelly| C[Precise Moisture & Density Control]
    B --> |Gravel/Rockfill| D[Less Precise Moisture Control]
    C --> E[Regular Testing every 1000 m²]
    D --> F[Shear strength less sensitive to moisture]

In brief: IS 10379 guides field control of soil moisture and compaction to ensure embankment stability and performance, with tailored methods for different soil types and standardized testing intervals.

IS 10379: Methods Applicable to Non-Gravelly Soils

Key Provisions (Clause 2.3 - Method 3)

• Purpose: For weathered/non-gravelly soils where field moisture & dry density differ from lab values.
• Test Embankment:
  • Size: 3 m × 10 m test strip.
  • Procedure: Spread soil, vary water content ±6% of lab optimum, wait 5-30 min, roll with compaction roller.
  • Measure dry density after every 2 passes using methods like core cutter or sand replacement (IS 2720 Part XXVIII, XXIX).
• Graphical Analysis:
  • Plot passes vs dry density for each water content.
  • Plot max dry density vs water content to find field optimum moisture content and attainable dry density.
• Outcome: Determines minimum roller passes for max field dry density at field moisture.

Relevant IS Tests for Moisture & Density:

Summary Diagram of Method 3 Procedure

flowchart TD
    A[Prepare 3x10 m test strip] --> B[Vary water content ±6% of lab value]
    B --> C[Wait 5-30 minutes]
    C --> D[Roll soil, measure dry density every 2 passes]
    D --> E[Plot passes vs dry density]
    E --> F[Plot max dry density vs water content]
    F --> G[Determine field optimum moisture & dry density]
    G --> H[Set roller passes for compaction control]

This method enables field calibration of compaction parameters for non-gravelly soils, ensuring reliable embankment compaction control under site conditions

IS 10379 - Method 1: Standard Laboratory and Field Tests (For soils containing gravels and rockfills)

Key Specifications & Procedures

• Optimum Moisture Content (OMC) & Maximum Dry Density (MDD):
  Determined by laboratory compaction tests as per:

  • IS 2720 (Part VII)-1980 (Light compaction)
  • IS 2720 (Part VIII)-1974 (Heavy compaction)

• Field Moisture Content:
  Measured by IS 2720 (Part II)-1973 (Water content determination).

• Field Dry Density:
  Determined by any of the following:

  • IS 2720 (Part XXVIII)-1974 (Sand replacement method)
  • IS 2720 (Part XXIX)-1975 (Core cutter method)
  • IS 2720 (Part XXXIV)-1972 (Rubber balloon method)

• Test Procedure:

  • Remove top 5 cm soil layer before testing.

  • Measure field moisture and dry density.

  • Calculate Compaction Efficiency (CE):

    [ CE = \frac{\text{Field Dry Density}}{\text{Maximum Dry Density (Lab)}} \times 100% ]

• Notes:

  • For gravely soils and rockfills, precise water content control is less critical.
  • Controlled testing may be relaxed as shear strength varies little with small density changes.

Summary Table of Applicable IS Codes

Practical Use Flowchart

flowchart TD
    A[Start: Soil Sample] --> B[Laboratory

IS 10379 - Method 2: Rapid Compaction Control (HILF Method)

Key Points:

• Purpose: Quick field control of soil compaction and moisture without direct moisture measurement.
• Applicable to: Non-gravelly soils.
• Reference: IS 2720 (Part XXXVIII) - 1976 (Compaction control test - HILF method).

Procedure Summary:

• A test embankment is compacted rapidly.
• The relationship between moisture content, dry density, and laboratory optimum conditions is established indirectly.
• Results are obtained in less than one hour.
• Can be used for both moisture and density control or density control only.

Specifications & Formulas:

• Compaction Efficiency (η):

[ \eta = \frac{\rho_{field}}{\rho_{max}} \times 100% ]

Where:

• (\rho_{field}) = Field dry density (obtained by HILF method)

• (\rho_{max}) = Maximum dry density from laboratory compaction (IS 2720 Part VII/VIII)

• Control Limits:

  • Moisture content and dry density should be within ±6% and ±3% of laboratory optimum values respectively (typical tolerance).

Advantages:

• Rapid results.
• No need for direct moisture content measurement.
• Suitable for field conditions with quick decision-making.

Diagram: Simplified Workflow of HILF Method

flowchart TD
    A[Test Embankment Construction] --> B[Rapid Compaction with Controlled Passes]
    B --> C[Measure Dry Density by HILF Device]
    C --> D[Compare with Lab Max Dry Density]
    D --> E{Within Specified Limits?}
    E -- Yes --> F[Proceed with Construction]
    E -- No --> G[Adjust Moisture or Compaction and Repeat]

For detailed procedural steps and calibration, refer to IS 2720 (Part XXXVIII) - 1976.

IS 10379 - Method 3: Test Embankment Procedure for Weathered Soils

Procedure Summary (Clause 2.3)

• Prepare a test strip: 3 m × 10 m.
• Spread specified soil layer; water and mix.
• Wait 5 to 30 minutes (depending on soil type).
• Vary water content in ±6% range around lab optimum.
• Roll soil with compaction roller; measure dry density after every 2 passes.
• Plot:
  • Number of passes vs dry density for each water content.
  • Maximum dry density vs water content to find field optimum moisture content and attainable dry density.
• Determine minimum roller passes needed at field optimum moisture.

Key References for Testing

• Moisture content: IS 2720 (Part II)
• Dry density (in-place):
  • Sand replacement: IS 2720 (Part XXVIII)
  • Core cutter: IS 2720 (Part XXIX)
  • Rubber balloon: IS 2720 (Part XXXIV)
• Compaction control: IS 2720 (Part XXXVIII)

Practical Notes

• Use test embankment data to control compaction passes and moisture during actual embankment construction.
• For soils with gravels (up to 30%), test soil fraction passing 40 mm sieve per IS 2720 (Part VII & VIII).

Graphical Concept

graph TD
A[Spread soil layer on test strip] --> B[Water soil at varied moisture contents ±6%]
B --> C[Wait 5-30 minutes]
C --> D[Roll soil, measure dry density every 2 passes]
D --> E[Plot passes vs dry density for each moisture]
E --> F[Plot max dry density vs moisture content]
F --> G[Determine field optimum moisture & max dry density]
G --> H[Set minimum roller passes for field compaction control]

This method ensures realistic field compaction parameters for weathered soils where lab values differ from field conditions.

IS 10379: Methods for Soil Containing Gravels and Rockfills

Key Specifications:

• Gravel content: Up to 30% gravel (particles > 40 mm).
• Lab compaction: Conduct moisture-density relationship tests on soil passing 40 mm IS sieve
  • Refer IS 2720 Part VII (light compaction) & Part VIII (heavy compaction).
• Field density & moisture: Use IS 2720 Part XXXIII (core cutter) preferably, or Part XXVIII (sand replacement) for field density.

Procedure Summary (Clause 3.3)

Important Notes from Clause 2.3 (Method 3)

• Test embankment strip: 3 m x 10 m
• Water content variation: ±6% around lab optimum.
• Measure dry density after every 2 roller passes.
• Plot passes vs dry density; find optimum moisture and minimum passes for max dry density.

Relevant IS Code References for Tests

flowchart TD
  A[Soil Sample (passing 40mm)] --> B[Lab Compaction Test (IS 2720 Part VII/VIII)]
  B --> C[Moisture-Density Curve]
  C --> D[Determine Optimum Moisture & Max Dry Density]
  E[Field Embankment] --> F[Compaction with Controlled Water]
  F --> G

IS 10379: Additional Provisions for Gravelly Soils

Key Provisions (Clauses 3.1 & 3.3):

• Gravel Content: Applicable for soils containing up to 30% gravels.
• Laboratory Testing:
  • Perform moisture-density relationship tests on soil fraction passing 40 mm IS sieve.
  • Refer IS 2720 Part VII (1980) & Part VIII (1974) for light and heavy compaction methods.
• Field Testing:
  • Field density and moisture content to be checked using:
    • IS 2720 Part XXVIII (Sand Replacement Method) or
    • IS 2720 Part XXIX (Core Cutter Method) or
    • IS 2720 Part XXXIII (Rubber Balloon Method).
• Test Embankment (Clause 2.3 for weathered/gravelly soils):
  • Construct a test strip (3m x 10m).
  • Vary moisture content ±6% around lab optimum.
  • Roll and measure density after every two passes.
  • Plot dry density vs. number of passes and dry density vs. moisture content to find optimum field compaction parameters.

Summary Table for Gravelly Soil Compaction:

flowchart TD
    A[Soil Sample with ≤30% Gravel] --> B[Pass through 40 mm sieve]
    B --> C[Laboratory Moisture-Density Test]
    C --> D[Test Embankment Construction (3x10 m)]
    D --> E[Roll & Measure Density after every 2 passes]
    E --> F[Plot Dry Density vs Passes & Moisture Content]
    F --> G[Determine Optimum Field Moisture & Dry Density]
    G -->

Effect of Gravel Content on Density and Moisture (IS 10379)

Key Points from IS 10379:

• Gravel Content vs Density & Moisture (Clause 3.2):

  • Total soil density increases and moisture content decreases with gravel content up to 60–75%.
  • Beyond 75%, density decreases again.

• Testing Methods:

  • For soils with gravels up to 30% (Clause 3.3):
    • Establish moisture-density relation on soil passing 40 mm sieve (IS 2720 Part VII & VIII).
    • Field density and moisture measured by IS 2720 Part XXXIII or Part XXVIII.
  • For weathered soils, use a test embankment (Clause 2.3) to determine field moisture and dry density with roller passes and water content variation.
  • Rapid moisture-density control possible via IS 2720 Part XXXVIII (HILF method, Clause 2.2).

Summary Table: Gravel Content vs Soil Properties

Recommended Procedure for Gravelly Soils

flowchart TD
    A[Soil Sample] --> B{Gravel Content?}
    B -- ≤ 30% --> C[Lab Moisture-Density Test on <40mm fraction]
    B -- > 30% --> D[Test Embankment Method]
    C --> E[Compare Field & Lab Density]
    D --> F[Determine Field Moisture & Density by Rolling & Water Variation]
    E & F --> G[Control Compaction & Moisture in Field]

References to IS 2720 Parts for Tests:

• Part II: Water Content Determination
• Part VII: Light Compaction Moisture-Density Relation
• Part VIII: Heavy Compaction Moisture-Density Relation
• Part XXVIII: Dry Density by Sand Replacement
• Part XXXIII

Moisture-Density Relationship for Soils with Gravel up to 30% (IS 10379)

Key Points from IS 10379 Clause 3.3:

• Test fraction: Use soil passing 40 mm IS sieve for lab tests.
• Laboratory tests: Follow IS 2720 Part VII (light compaction) or Part VIII (heavy compaction) to establish moisture-density curves.
• Field density & moisture: Measure by IS 2720 Part XXVIII (sand replacement) or Part XXIX (core cutter).
• Comparison: Field density compared with lab maximum dry density to assess compaction quality.

Procedure Summary:

1. Prepare sample: Sieve soil through 40 mm.
2. Lab compaction test: Obtain dry density vs moisture content curve.
3. Field test: Measure moisture and density using sand replacement or core cutter.
4. Compare: Field dry density should approach lab maximum dry density at optimum moisture content.

Additional Notes:

• Gravel content up to 30% generally increases total density.
• For soils with gravels >30%, density behavior varies (see Clause 3.2).
• Test embankment method (Clause 2.3) can be used for field verification with varying water content and compaction passes.

Typical Moisture-Density Curve (Conceptual):

graph LR
A[Moisture Content] --> B[Dry Density]
B --> C[Maximum Dry Density at Optimum Moisture Content]

Reference Standards:

Summary: For soils with gravel ≤30%, test moisture-density relationship on soil passing 40 mm sieve per IS 2720 (VII/VIII), then verify field compaction using sand replacement or core cutter methods per IS 2720 (XXVIII/XXIX).

IS 10379: Compaction Control for Gravel and Rockfill Soils

Key Points & Methods:

• Test Embankment Method (Clause 2.3):

  • Construct a test strip (3m x 10m) with the soil layer.
  • Vary water content ±6% around lab optimum.
  • Roll soil; measure dry density after every 2 passes.
  • Plot passes vs dry density for each moisture content.
  • Plot max dry density vs moisture content to find:
    • Field Optimum Moisture Content (FOMC)
    • Maximum Attainable Dry Density (MDD)
  • Determine minimum roller passes for max density at FOMC.

• For Gravels up to 30% (Clause 3.3):

  • Use soil fraction passing 40 mm sieve for lab moisture-density test (IS 2720 Part VII & VIII).
  • Field density & moisture tested by:
    • Core cutter method (IS 2720 Part XXXIII) preferred
    • Sand replacement method (IS 2720 Part XXVIII) alternative

Summary Table:

Formula for Dry Density:

[ \text{Dry Density} (\rho_d) = \frac{\text{Wet Density} (\rho)}{1 + w} ]

Where:

• ( w ) = moisture content (decimal)

Diagram: Test Embankment Method Workflow

flowchart TD
    A[Prepare Test Strip 3x10 m] --> B[Apply Water Content ±6% around Lab Optimum]
    B --> C[Roll Soil - Measure Dry Density after every 2 passes]
    C --> D[Plot Passes vs Dry Density for each Moisture Content]
    D --> E[Plot Max Dry Density vs Moisture Content]
    E --> F[Determine Field Optimum Moisture

Frequency and Interval of Field Testing (IS 10379 Highlights)

• Clause 3.4: For gravel and rockfill soils, shear strength varies little with density changes; hence, controlled testing frequency can be reduced compared to fine-grained soils.

• Clause 2.1 (Method 1):

  • Determine Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) per IS 2720 Part VII & VIII.
  • Field moisture content per IS 2720 Part II.
  • Field dry density per IS 2720 Parts XXVIII, XXIX, or XXXIV.
  • Remove top 5 cm soil before testing.
  • Calculate Compaction Efficiency:

  [ \text{Compaction Efficiency} = \frac{\text{Field Dry Density}}{\text{Laboratory MDD}} \times 100% ]

• Clause 2.3 (Method 3):

  • Use test embankment (3m x 10m) with varied moisture content ±6% of lab OMC.
  • Measure dry density after every 2 roller passes.
  • Plot number of passes vs dry density and water content vs max dry density.
  • Determine minimum roller passes needed for max dry density at field moisture.

Summary Table for Field Testing Frequency:

Key References for Testing Methods:

• IS 2720 Part II, VII, VIII, XXVIII, XXIX, XXXIV

flowchart LR
    A[Test Embankment Setup] --> B[Water content varied ±6% OMC]
    B --> C[Roller passes in increments of 2]
    C --> D[Measure Dry Density]
    D --> E[Plot Passes vs Dry Density]
    E --> F[Determine Minimum Passes for Max Dry Density]

This approach ensures optimized field testing intervals based on soil type and compaction behavior per IS 103

IS 10379: Key Points for Calculation and Reporting of Compaction Efficiency

1. Compaction Efficiency Formula (Clause 2.1 - Method 1)

[ \text{Compaction Efficiency} = \frac{\text{Field Dry Density}}{\text{Maximum Dry Density from Lab}} \times 100% ]

• Maximum Dry Density & Optimum Moisture Content: From IS 2720 Part VII (light compaction) or Part VIII (heavy compaction).
• Field Moisture Content: IS 2720 Part II.
• Field Dry Density: IS 2720 Part XXVIII (Sand Replacement), Part XXIX (Core Cutter), or Part XXXIV (Rubber Balloon).
• Remove top 5 cm soil before testing.

2. Test Embankment Method (Clause 2.3 - Method 3)

• Prepare test strip (3m x 10m), vary water content ±6% around lab optimum.
• Roll in passes, measure dry density after every 2 passes.
• Plot:
  • Number of passes vs Dry density
  • Max dry density vs Moisture content
• Determine field optimum moisture content and attainable dry density.
• Find minimum passes for max compaction.

3. Special Cases - Gravels up to 30% (Clause 3.3)

• Use soil fraction passing 40 mm sieve for lab moisture-density curve (IS 2720 Part VII/VIII).
• Field density & moisture: IS 2720 Part XXXIII (preferred) or Part XXVIII.

Summary Table

flowchart TD
    A[Lab Tests] --> B[Max Dry Density & Optimum Moisture]
    C[Field Tests] --> D[Field Moisture & Dry Density]
    B --> E[Calculate Compaction Efficiency]
    D --> E
   

Rounding Off Test Results - IS 10379 Key Points

• Reference for Rounding: Final test results (observed/calculated) must be rounded off as per IS 2:1960.
• Significant Figures: The number of significant places in the rounded value should match the number of significant places in the specified value of IS 10379.
• This ensures uniformity and consistency in reporting soil moisture and compaction test results.

Summary Table for Rounding Off (Per IS 2:1960)

Application in Soil Testing

• Moisture content, dry density, and compaction values are reported after rounding.
• Example: If specified moisture content is 12.5%, report test results to one decimal place.
• Ensures comparability with design and specification values.

Useful References in IS 10379 for Field Control of Moisture and Compaction

• IS 2720 (Part II): Determination of water content.
• IS 2720 (Part VII & VIII): Water content-dry density relation using light/heavy compaction.
• IS 2720 (Part XXVIII & XXIX): In-place dry density by sand replacement and core cutter methods.

flowchart TD
    A[Test/Analysis Result] --> B[Round off per IS 2:1960]
    B --> C[Match significant figures with Specified Value]
    C --> D[Report Final Value]

In brief: Always round soil test results according to IS 2:1960 rules, keeping significant figures consistent with IS 10379 specifications for reliable field control of compaction and moisture.