Methods of test for soils, Part 9: Determination of dry density- moisture content relation by constant mass of soil method

IS 2720 Part 9: Scope Summary

• Scope: This part deals with the determination of the relative density of cohesionless soils by standard procedures.
• Reference Standards: Definitions from IS 2809:1972 (Glossary of soil engineering terms) apply.
• Related Standards: Adjuncts include:
  • IS 460 (Part 1): Test sieves specifications
  • IS 2720 (Parts 1 & 2): Dry soil sample prep and water content determination

Key Table: Compaction Test Data Sheet (Clause 8.1)

Important Formula

[ \text{Dry density}, \rho_d = 10^{-2} \times R \quad \text{(g/cm}^3\text{)} ]

Where R = reading on the rod in cm.

This standard is essential for soil compaction and density testing in geotechnical investigations.

IS 2720 Part 9 (1992) — Key References & Specifications

Relevant IS Codes (Clause 2.1):

• IS 460 (Part 1): Specification for wire cloth test sieves (1985)
• IS 2720 (Part 1): Preparation of dry soil samples (1983)
• IS 2720 (Part 2): Determination of water content (1973)
• IS 2809: Glossary of soil engineering terms (1972)

Compaction Test Data Sheet (Clause 8.1):

• ( w ) = Moisture content of air-dried soil (%)
• ( W_a ) = Water added (ml)
• ( R ) = Reading on rod (cm)

Notes:

• The dry density formula relates rod reading ( R ) to dry density.
• Water content accounts for initial moisture plus half the added water.
• These references ensure standardized soil compaction testing.

For detailed procedures and definitions, refer to IS 2809 and the associated parts of IS 2720.

IS 2720 (Part 9) - Definitions Summary

• Reference for Definitions:
  Clause 3.1 states that all definitions used in IS 2720 (Part 9) refer to IS 2809:1972 - Glossary of terms and symbols relating to soil engineering.

• Key Terms from IS 2809 (Relevant to Part 9):

  • Moisture Content (w): Ratio of the mass of water to the mass of dry soil, expressed as a percentage.
  • Dry Density (ρ_d): Mass of solids per unit volume of soil excluding pore water.
  • Compaction: Process of increasing soil density by mechanical means.

• Compaction Test Data Sheet (Clause 8.1):
  For constant mass method with 200 g oven-dried soil:

  Parameter	Formula / Value
  Moisture content (%)	( w + 0.5 \times W_a )
  Dry density (g/cm³)	( \rho_d = 10^{-2} \times R )

  Where:

  • ( W_a ) = Water added (ml)
  • ( R ) = Reading on rod (cm)

Quick Reference Table for Compaction Test

Additional Notes:

• Use IS 2809:1972 for detailed definitions of soil engineering terms.
• Dry density and moisture content are fundamental for soil compaction quality control.
• IS 2720 Part 9 focuses on the determination of dry density and water content by core cutter and sand replacement methods.

flowchart TD
    A[Start: Soil Sample] --> B[Determine Moisture Content (w)]
    B --> C[

IS 2720 Part 9: Apparatus Specifications for Compaction by Constant Mass Method

Apparatus Dimensions & Features (Clause 1.5)

• Tube internal diameter: 50 mm
• Tube height: 435 mm
• Base: Detachable base plate with flange (see Fig. 1 in IS 2720 Part 9)
• Surface: Smooth internal surface
• Holes:
  • At ~100 mm from bottom: 8 holes, 1.5 mm diameter, equally spaced around the circumference
  • At ~50 mm from top: 4 holes, 1.5 mm diameter, spaced at 90° to each other

Key Table: Compaction Test Data Sheet (Clause 8.1)

• ( W_a ) = Water added in ml
• ( w ) = Moisture content of air-dried soil (%)
• ( R ) = Reading on rod in cm

Summary Diagram of Tube Hole Locations

cylinder
    title Compaction Tube with Holes
    diameter 50
    height 435
    hole at 100 from bottom: 8 holes equally spaced (1.5 mm dia)
    hole at 385 from bottom: 4 holes at 90° (1.5 mm dia)

Note: The apparatus design ensures uniform water distribution and compaction during the constant mass method test. Always refer to the original IS 2720 Part 9 for detailed drawings and calibration procedures.

IS 2720 Part 9: Soil Specimen Key Points

• Soil Specimen (Clause 5.1):
  The soil specimen for testing must be obtained as per Clause 5.2 (not detailed here), ensuring representativeness and proper preparation.

• Mixing Tools (Clause 4.8):
  Use tools like mixing pan, spoon, trowel, spatula, or mechanical devices to thoroughly mix soil with water for uniformity.

• Relevant Standards for Soil Specimen Preparation:

  • IS 2720 Part 1: Preparation of dry soil samples
  • IS 2720 Part 2: Determination of water content
  • IS 460 Part 1: Specification for test sieves (wire cloth test sieves)

Typical Soil Specimen Preparation Steps (from IS 2720 series):

1. Sampling: Obtain representative soil sample from the field.
2. Drying: Air dry or oven dry (usually at 105°C) depending on test.
3. Sieving: Use IS sieves (e.g., 4.75 mm) to separate particle sizes.
4. Mixing: Thoroughly mix soil with water using specified tools for consistency.

Common Formula: Water Content (from IS 2720 Part 2)

[ w = \frac{W_w}{W_d} \times 100 ]

Where:

• ( w ) = water content (%)
• ( W_w ) = weight of water in soil sample
• ( W_d ) = weight of dry soil

Summary Table: Soil Specimen Preparation Tools

flowchart LR
    A[Field Soil Sample] --> B[Drying (Air/Oven)]
    B --> C[Sieving (IS Sieve)]
    C --> D[Mixing with Water]
    D --> E[Soil Specimen for Testing]

This summarizes the key points for soil specimen preparation per IS 2720 Part 9 and related parts.

IS 2720 Part 9: Procedure Key Points & Formulas

Procedure Overview (Clause 8.1)

• Use constant mass of soil = 200 g (oven-dried) for each test.
• Record moisture content of air-dried soil: w%.
• Add water incrementally: Wa ml.
• Measure compacted soil height by rod reading: R cm.

Key Formulas (from Table in Clause 8.1)

• Dry density is calculated by multiplying rod reading (R) (cm) by 0.01.

Recommended Data Sheet Columns:

• Test No.
• Water added (W_a) (ml)
• Rod reading (R) (cm)
• Moisture content (%) = ( w + 0.5 W_a )
• Dry density (g/cm³) = (10^{-2} R)

Apparatus (Fig. 1)

• Compaction by constant mass method with 4 or 8 holes of 1.5 mm diameter spaced equally at 90°.

Summary:

• Maintain constant soil mass.
• Incrementally add water.
• Record rod reading and compute dry density.
• Use provided proforma (Annex A) for consistent data recording.

flowchart TD
    A[Start: Oven-dried soil 200g] --> B[Add water Wa ml]
    B --> C[Compact soil sample]
    C --> D[Measure rod reading R (cm)]
    D --> E[Calculate moisture content: w + 0.5*Wa]
    E --> F[Calculate dry density: 10^-2 * R]
    F --> G[Record data in proforma]

This ensures repeatability and accuracy in compaction testing per IS 2720 Part 9.

IS 2720 Part 9 - Key Formulas and Table for Compaction Test (Constant Mass Method)

1. Test Data Sheet Parameters (Clause 8.1)

2. Key Formulas

• Moisture Content after water addition:

[ w_m = w + 0.5 W_a ]

• Dry Density:

[ \rho_d = 10^{-2} \times R \quad \text{(in g/cm}^3\text{)} ]

(Where ( R ) is the rod reading in cm)

3. Procedure Summary

• Use 200 g oven-dried soil.
• Add water ( W_a ) ml, measure rod penetration ( R ).
• Calculate moisture content and dry density.
• Plot dry density vs moisture content to find optimum moisture content and maximum dry density.

Visualization of Data Flow

flowchart TD
    A[Start: Oven-dried soil 200g] --> B[Add water \(W_a\) ml]
    B --> C[Measure rod reading \(R\) cm]
    C --> D[Calculate moisture content \(w_m = w + 0.5 W_a\)]
    D --> E[Calculate dry density \(\rho_d = 10^{-2} \times R\)]
    E --> F[Plot \(\rho_d\) vs \(w_m\)]
    F --> G[Determine optimum moisture content and max dry density]

Note: Always round off results per IS 2:1960 rules. Use the proforma in Annex A for recording

IS 2720 Part 9 — Recording & Reporting of Results

Key Points from Clause 8:

• Recording: Use the recommended proforma (Annex A) for test data.
• Rounding: Final values must be rounded as per IS 2:1960.
• Reporting: Plot and report the dry density vs. moisture content curve, highlighting:
  • Maximum dry density (MDD)
  • Corresponding optimum moisture content (OMC)

Compaction Test Data Sheet (Constant Mass Method)

Formula Summary:

[ \text{Moisture content} = w + 0.5 \times W_a ]

[ \text{Dry density} , (\rho_d) = 10^{-2} \times R \quad \text{(in g/cm}^3\text{)} ]

Reporting Steps:

1. Record all test values in the data sheet.
2. Calculate moisture content and dry density for each test.
3. Plot dry density vs. moisture content curve.
4. Identify and report MDD and OMC values.
5. Round off results per IS 2:1960 rules.

graph LR
A[Record Test Data] --> B[Calculate Moisture Content]
B --> C[Calculate Dry Density]
C --> D[Plot Dry Density vs Moisture Content]
D --> E[Identify MDD & OMC]
E --> F[Report Results (Rounded as per IS 2:1960)]

This ensures consistent, standardized reporting for soil compaction tests under IS 2720 Part 9.

IS 2720 Part 9: Recommended Proforma for Compaction Test Data (Constant Mass Method)

Key Specifications (Clause 8.1 & Annex A):

• Mass of oven-dried soil: 200 g (constant)
• Moisture content of air-dried soil: ( w % )
• Water added: ( W_a ) ml (variable per test)
• Reading on rod: ( R ) cm (measured for each test)

Calculations:

• Moisture content for each test: [ w_{test} = w + 0.5 \times W_a ]

• Dry density (g/cm³): [ \rho_d = 10^{-2} \times R ]

Recommended Data Sheet Format:

Notes:

• Use IS 2:1960 for rounding off numerical values.
• Ensure consistent units: mass in grams, volume-related readings in cm or ml.
• This proforma facilitates plotting compaction curves (dry density vs moisture content).

flowchart LR
    A[Start: Oven-dried soil (200 g)] --> B[Add water \(W_a\) ml]
    B --> C[Measure rod reading \(R\) cm]
    C --> D[Calculate moisture content \(w + 0.5 W_a\)]
    D --> E[Calculate dry density \(10^{-2} R\)]
    E --> F[Record data in proforma]

This standardized format ensures uniform reporting and easy comparison of compaction test results.