Methods of test for soils, Part 34: Determination of density of soil in place by the rubber-balloon method

IS 2720 Part 34 - Scope: Key Formulas, Tables, and Specifications

1. Volume of Water per Gram Based on Temperature (Clause 3.1.1)

Volume varies slightly with temperature; important for precise moisture content calculations.

2. Minimum Field Test Hole Volumes & Moisture Sample Sizes (Clause 4.2)

Test hole size depends on particle size; larger holes improve accuracy.

Notes:

• Test holes must be carefully dug to avoid disturbing surrounding soil.
• Soil removed is stored airtight for moisture and weight tests.
• Dimensions relate to apparatus design and pressure used.
• Refer to IS 2720 Part 7 (1980) & Part 8 (1983) for related procedures.

flowchart TD
    A[Test Hole Preparation] --> B[Dig Hole (Min Volume per Table 2)]
    B --> C[Collect Soil Sample (Min Weight per Table 2)]
    C --> D[Store Soil Airtight]
    D --> E[Determine Moisture Content & Weight]

This concise scope ensures accurate field moisture testing per IS 2720 Part 34.

IS 2720 Part 34 (1972) Key References & Tables

1. Volume of Water per Gram Based on Temperature (Clause 3.1.1)

Use this table for precise water volume corrections at different temperatures during moisture content determinations.

2. Minimum Field Test Hole Volumes & Moisture Content Samples (Clause 4.2)

Larger holes improve accuracy; dimensions relate to apparatus and pressure used.

3. Dry Unit Weight Calculation (Clause 5.3)

[ \gamma_d = \frac{w}{1 + \frac{w}{100}} \times \rho_w ]

Where:

• (\gamma_d) = Dry unit weight (g/cm³)
• (w) = Moisture content (%)
• (\rho_w) = Unit weight of water (typically 1 g/cm³)

Note: The clause gives a simplified formula to calculate dry unit weight from moisture content and wet weight.

Additional Notes

• Substitute references to IS 2720 (Part 7) and (Part 8) with the latest revisions (1980 and 1983 respectively).
• For detailed procedures, apparatus design, and calibration, refer to relevant clauses in IS 2720 Part 34.

If needed, I can provide a flow diagram of the field test procedure. Would you like that?

IS 2720 Part 34: Apparatus Key Points

1. Calibrated Vessel (Clause 2.1)

• Contains liquid with a flexible elastic membrane (rubber balloon) to measure test hole volume.
• Graduated to 5 ml accuracy.
• Equipped to apply external pressure or partial vacuum.
• Size/weight must not distort test hole; surcharge weights can be added if needed.
• Membrane size must fill hole without wrinkles and withstand necessary pressures.

2. Volume of Water per Gram (Clause 3.1.1 - Table 1)

*Use interpolation for intermediate temps.

3. Minimum Test Hole Volumes & Moisture Samples (Clause 4.2 - Table 2)

4. Calibration Check (Clause 3.1.2)

• Fill apparatus with water, take initial volume reading.
• Place membrane in container, inflate fully, note final volume.
• Apply pressure until volume stabilizes; record pressure.
• Add surcharge weights if apparatus tends to rise.
• Volume difference = container volume.
• Remove membrane by partial vacuum.
• Repeat for all calibration containers.

Summary Diagram of Apparatus Setup:

flowchart LR
    A[Calibrated Vessel] --> B[Flexible Membrane (Rubber Balloon)]
    B --> C[Test Hole in Soil]
    A --> D[Volume Indicator]
    A --> E[Pressure/Vacuum Control

IS 2720 Part 34: Key Test Procedure Details

Test Hole Preparation (Clause 4.1 & 4.2)

• Dig a hole centered within the apparatus outline; avoid disturbing soil around the top edge.
• Minimum hole volume depends on max particle size (Table 2).
• Collect soil from hole in airtight container for moisture and weight tests.
• Hole dimensions should match calibration check dimensions for accuracy.

Table 2: Minimum Field Test Hole Volumes & Moisture Sample

Volume of Water per Gram by Temperature (Table 1, Clause 3.1.1)

Procedure Summary:

1. Prepare a plane test site.
2. Set apparatus, record initial volume reading, pressure, surcharge.
3. Dig hole per Table 2 volumes.
4. Collect soil for moisture content.
5. Use water volume correction per temperature (Table 1).
6. Report results rounded per IS 2-1960.

flowchart TD
    A[Prepare Test Site] --> B[Set Apparatus & Record Initial Reading]
    B --> C[Dig Test Hole (Volume per Table 2)]
    C --> D[Collect Soil Sample for Moisture Content]
    D --> E[Perform Volume & Pressure Measurements]
    E --> F[Calculate & Report Results (Use Table 1 for Water Volume)]

This ensures accurate in-situ volume and moisture content measurement per IS 2720 Part 34.

IS 2720 Part 34 — Key Formulas, Tables & Specifications for Calculations

1. Volume of Water per Gram (Clause 3.1.1)

Use Table 1 to find the volume of water (ml/g) at the observed temperature to calculate container volume:

Formula:

[ \text{Volume of container (ml)} = \text{Weight of water (g)} \times \text{Volume of water (ml/g at temp.)} ]

2. Dry Unit Weight of Soil (Clause 5.3)

Calculate dry unit weight (Y_d) (g/cm³) of soil removed from test hole:

[ Y_d = \frac{W}{V} \times \frac{100}{100 + w} ]

Where:

• (W) = weight of moist soil (g)
• (V) = volume of soil (cm³)
• (w) = moisture content (%)

Note: Clause 5.3 in the context gives a partial formula; the standard formula is as above.

3. Minimum Field Test Hole Volumes & Moisture Sample (Clause 4.2, Table 2)

Summary Diagram of Calculation Flow

flowchart TD
    A[Determine weight of water in container] --> B[Measure water temperature]
    B --> C[Find volume of water per gram from Table 1]

IS 2720 Part 34: Accuracy & Limitations Key Points

1. Volume of Water per Gram (Clause 3.1.1)

• Volume of water varies with temperature; use Table 1 for precise volume conversion (ml/g).

• Formula to calculate container volume:

  [ V = W \times V_w(T) ]

  Where:

  • (V) = volume of container (ml)
  • (W) = weight of water to fill container (g)
  • (V_w(T)) = volume of water per gram at temperature (T) (from Table 1)

2. Minimum Field Test Hole Volumes & Sample Sizes (Clause 4.2, Table 2)

• Larger holes improve accuracy.
• Hole size relates to apparatus design and pressure.

3. Reporting & Rounding (IS 2-1960)

• Final values must be rounded as per IS 2-1960 guidelines.

Summary Flowchart of Procedure

flowchart TD
  A[Fill container with water] --> B[Weigh water (W)]
  B --> C[Measure water temperature (T)]
  C --> D[Look up volume per gram Vw(T) from Table 1]
  D --> E[Calculate container volume V = W × Vw(T)]
  E --> F[Repeat 3 times; variation ≤ 3 ml]
  F --> G[Use volume

IS 2720 Part 34: Reporting of Results - Key Formulas & Tables

1. Rounding Off Results

   • Follow IS 2-1960 for rounding off final observed or calculated values.

2. Volume of Water per Gram (Table 1, Clause 3.1.1)
   Volume varies with temperature (ºC):

3. Minimum Field Test Hole Volumes & Moisture Content Samples (Table 2, Clause 4.2)

• Use larger holes for better accuracy.
• Hole dimensions should match apparatus design and calibration.

Summary:
Report results rounded per IS 2-1960, use temperature-dependent water volume values, and ensure minimum test hole volumes and moisture samples based on particle size for reliable soil testing.

IS 2720 Part 34 (1972) – Notes and Precautions

Key Table: Volume of Water per Gram vs Temperature (Clause 3.1.1)

Important Notes & Substitutions:

• References updated for related IS codes:
  • IS 2720 (Part 7) updated from 1965 to 1980
  • IS 2720 (Part 8) updated from 1965 to 1983
  • IS 2720 (Part 28) updated from 1966 to 1974

Precautions:

• Use the correct volume of water based on temperature for accurate soil testing.
• Always refer to the latest IS codes for related procedures and corrections.
• Ensure temperature measurement is precise as volume changes affect test results.

This table and notes ensure accurate water volume correction in soil testing, critical for consistency in compaction and moisture content determination.