Method for the preparation of rock specimens for laboratory testing

IS 9179: Scope - Key Specifications & Measurement Tolerances

Scope (Clause 7.4):

• Specimen surfaces (cylindrical surface for cylindrical specimens) must be smooth, free from abrupt irregularities.
• Specimens must be straight within 0.3 mm tolerance over the length.
• Diameter variation of cylindrical specimens shall not exceed 0.2 mm along the length.

Measurement & Tolerances Summary

Additional Notes:

• Use comparators (Clause 2.6) for final dimensional checks.
• Handle specimens with gloves to avoid contamination (Clause 4.2).
• The standard aligns with international practices while considering local field conditions.

flowchart TD
    A[Specimen Preparation] --> B[Surface Smoothness Check]
    B --> C{Is surface smooth?}
    C -- Yes --> D[Check Straightness (±0.3 mm)]
    C -- No --> E[Rework Surface]
    D --> F{Diameter Variation ≤ 0.2 mm?}
    F -- Yes --> G[Specimen Accepted]
    F -- No --> H[Reject or Rework Specimen]

This ensures specimen quality for reliable testing as per IS 9179.

IS 9179 - Definitions & Key Specifications (Clause 7.4)

• Specimen Surface Requirements:

  • Cylindrical specimen surfaces must be smooth and free from abrupt irregularities.
  • Must be straight within 0.3 mm tolerance over the length.

• Dimensional Tolerances:

  • Diameter variation along the specimen length must not exceed ±0.2 mm.

Summary Table: Specimen Tolerances (Clause 7.4)

Practical Notes:

• Ensuring these tolerances is critical for valid mechanical testing results.
• Surface finish affects stress concentration; smoothness avoids premature failure.

flowchart LR
    A[Specimen Preparation] --> B{Check Surface}
    B -->|Smooth & No Abrupt Irregularities| C[Proceed]
    B -->|Irregularities Present| D[Rework Surface]
    C --> E{Check Dimensions}
    E -->|Diameter variation ≤ 0.2 mm| F[Accept Specimen]
    E -->|Diameter variation > 0.2 mm| D
    E -->|Straightness ≤ 0.3 mm| F
    E -->|Straightness > 0.3 mm| D

For detailed procedures, refer to IS 9179 full text and related testing standards.

IS 9179: Collection and Storage of Specimens

Key Specifications:

• Moisture Proofing (Clause 3.2):

  • Specimens must be waxed immediately after collection to prevent moisture loss.
  • Transport in wooden boxes filled with sawdust to cushion and maintain moisture.
  • Store specimens in shaded areas, avoiding direct sunlight and extreme humidity or temperature fluctuations.

• Avoidance of Contamination (Clauses 4.1 & 4.2):

  • Use gloves during handling to prevent contamination.
  • Place specimens only on clean, dry surfaces.
  • If contaminated, clean specimens by soaking in solvents like benzene or acetone, then wash with clean water.

• Dimension Checking (Clause 2.6):

  • Use comparators to verify final specimen dimensions accurately.

Summary Table: Specimen Handling

flowchart LR
    A[Specimen Collection] --> B[Wax Immediately]
    B --> C[Transport in Wooden Box + Sawdust]
    C --> D[Store in Shade, Stable Environment]
    D --> E[Handle with Gloves]
    E --> F{Contamination?}
    F -- Yes --> G[Soak in Solvent + Wash]
    F -- No --> H[Dimension Check with Comparator]

This ensures specimen integrity for reliable testing per IS 9179.

IS 9179: Prevention of Contamination - Key Points

• Handling: Use gloves to avoid contamination of external surfaces (Clause 4.2).
• Surface Contact: Place specimens only on clean, dry surfaces (Clause 4.2).
• Avoid Oils/Other Substances: Specimens must be free from oils/contaminants at all stages (Clause 4.1).
• Decontamination: If contaminated, soak specimens in solvents like benzene or acetone, then wash with clean water (Clause 4.1).
• Moisture Proofing: Immediately wax specimens after collection to prevent moisture ingress (Clause 3.2).
• Transport & Storage: Transport in wooden boxes with sawdust; store in shaded, humidity- and temperature-controlled environments (Clause 3.2).
• Dimension Checking: Use comparators for final dimension verification to ensure no surface alteration (Clause 2.6).

Summary Table: Contamination Prevention Steps

flowchart LR
    A[Specimen Collection] --> B[Wax Immediately]
    B --> C[Transport in Wooden Box with Sawdust]
    C --> D[Store in Shade, Controlled Humidity & Temp]
    D --> E[Handle with Gloves]
    E --> F[Place on Clean, Dry Surface]
    F --> G{Contamination?}
    G -- Yes --> H[Soak in Benzene/Acetone + Wash]
    G -- No --> I[Dimension Check with Comparator]

This ensures specimen integrity for accurate testing per IS 9179.

IS 9179: Specimen Shape and Size Key Points

• Specimen Diameter (Clause 5.2):

  • Minimum diameter ≥ 10 × maximum grain size.
  • Preferably ≥ 20 × maximum grain size.
  • Absolute minimum diameter = 35 mm (with reduced tolerances).
  • Recommended minimum diameter = 45 mm.

• End Surface Requirements (Clause 7.3):

  • Ends flatness tolerance: 0.05 mm.
  • Ends parallelism tolerance: within 0.002D (D = specimen diameter).
  • Ends perpendicularity to axis: within 0.001 rad (≈ 3.5 minutes) or 0.05 mm for 45 mm diameter.

Summary Table

Notes:

• Use gloves and clean surfaces to avoid contamination (Clause 4.2).
• Specimen shape and size must conform to relevant IS test methods.

flowchart TD
    A[Select Rock Sample] --> B[Measure Max Grain Size]
    B --> C{Diameter ≥ 10× Grain Size?}
    C -- Yes --> D[Diameter ≥ 45 mm?]
    C -- No --> E[Increase Diameter or Reject]
    D -- Yes --> F[Prepare Specimen Ends]
    D -- No --> G[Reduce Tolerances]
    F --> H[Check Flatness ≤ 0.05 mm]
    F --> I[Check Parallelism ≤ 0.002D]
    F --> J[Check Perpendicularity ≤ 0.001 rad]

IS 9179: Cutting and Grinding Procedures - Key Points

1. Cutting (Clause 6.2)

• Use sawing for initial cutting of specimens.
• Ensure minimal damage to specimen edges.

2. Grinding Abrasives (Clause 6.5.3)

• Use Silicon Carbide - Aluminium Oxide compounds.
• Grit size range: 80 to 220.
• Abrasives must be carried in water to avoid overheating.

3. Edge Grinding (Clause 6.3.2)

• Use tool post grinder or stationary diamond point.
• Rotation speed: ~300 rpm (slow speed to prevent damage).

4. Surface Grinding (Clause 6.4)

• Applied on broad surfaces of prismatic specimens.
• Achieves closer dimensional tolerances.

Summary Table

flowchart LR
    A[Sawing] --> B[Edge Grinding]
    B --> C[Surface Grinding]
    C --> D[Specimen with close tolerances]

Note: Maintain cooling during grinding to avoid thermal damage and ensure dimensional accuracy.

IS 9179: Measurement and Tolerances (Clause 7)

• Specimen Surface Quality:
  Cylindrical specimen surfaces must be smooth, free from abrupt irregularities, and straight within 0.3 mm tolerance.

• Dimensional Variation:
  Diameter of cylindrical specimens shall not vary more than 0.2 mm along the length.

• Measurement Tools:

  • During machining: Use micrometer or vernier caliper.
  • Final check: Use a comparator for precise tolerance verification.
  • Final dimensions measured to nearest 0.1 mm.

• Grinding Medium (Clause 6.5.3):
  Use Silicon Carbide - Aluminium oxide compounds (80 to 220 grit) in water for grinding.

Summary Table of Tolerances

flowchart TD
    A[Specimen Machining] --> B[Measure with Micrometer/Vernier]
    B --> C{Dimensions within tolerance?}
    C -- Yes --> D[Final Measurement with Comparator]
    C -- No --> E[Re-machine Specimen]
    D --> F[Check Surface & Diameter Tolerances]
    F --> G{Pass?}
    G -- Yes --> H[Specimen Accepted]
    G -- No --> E

This ensures specimens meet IS 9179 standards for accurate and reliable testing.

IS 9179: Cleaning of Contaminated Specimens

Key Specifications from IS 9179:

• Clause 4.1:

  • Specimens must be free from oils or contaminants at all stages.
  • If contamination occurs, soak specimens in benzene or acetone solvent.
  • After soaking, wash thoroughly with clean water to remove solvent residues.

• Clause 4.2:

  • Avoid contamination by:
    • Handling specimens with gloves.
    • Placing specimens on clean, dry surfaces only.

Additional Handling & Storage Guidelines:

• Clause 3.2:
  • Immediately moisture-proof specimens by waxing after collection.
  • Transport in a wooden box with sawdust to prevent damage.
  • Store specimens in shade, avoiding humidity and temperature fluctuations.

Summary Table:

flowchart TD
    A[Specimen Collection] --> B[Wax for Moisture Proofing]
    B --> C[Transport in Wooden Box with Sawdust]
    C --> D[Store in Shade, Controlled Humidity]
    D --> E{Contamination?}
    E -- Yes --> F[Soak in Benzene/Acetone]
    F --> G[Wash with Clean Water]
    E -- No --> H[Handle with Gloves]
    H --> I[Place on Clean, Dry Surface]

This ensures specimen integrity for testing as per IS 9179.

IS 9179: Equipment and Tools - Key Specifications & Formulas

1. Specimen Surface & Dimensional Tolerances (Clause 7.4)

• Surface finish: Specimen surfaces (cylindrical surface for cylindrical specimens) must be smooth, free from abrupt irregularities.
• Straightness tolerance: Within 0.3 mm deviation.
• Diameter variation: Must not vary by more than 0.2 mm over the specimen length.

2. Drilling Equipment (Clause 2.1)

• Use a heavy rigid laboratory coring drill with:
  • Suitable clamping device.
  • Drill travel of at least 150 mm, preferably 250-300 mm.
  • Preferably constant force hydraulic feeding.
  • Electrical overload breaker for protection.

3. Sawing and Cutting (Clause 6.2)

• Use appropriate sawing tools ensuring clean cuts without damaging the specimen.

4. Lapping Machine (Clause 2.5)

• Rotating iron disc or automatic machine.
• Must have clamping arrangements.
• Handles multiple specimens simultaneously for smooth finishing.

Summary Table: Specimen Dimensional Tolerances

Diagram: Specimen Dimensional Control

graph LR
A[Specimen Surface] --> B[Smooth & Free from Irregularities]
B --> C[Straightness ≤ 0.3 mm]
C --> D[Diameter Variation ≤ 0.2 mm]

Note: Always ensure equipment calibration and maintenance per IS 9179 for accuracy and repeatability.

IS 9179: Reporting and Documentation Key Points

• Rounding Off Results:
  As per Clause 0.4, final test or analysis values must be rounded according to IS 2-1960 (Rules for rounding off numerical values).

• Specimen Dimensions & Tolerances (Clause 7.4):

  • Cylindrical specimens must have surfaces smooth and free from abrupt irregularities.
  • Straightness tolerance: within 0.3 mm.
  • Diameter variation over the specimen length: max 0.2 mm.

• Measurement Tools:
  Use comparators for checking final specimen dimensions (Clause 2.6).

• Reporting Format:

  • Include all observed/calculated values with proper rounding.
  • Mention specimen preparation details and measurement tolerances.
  • Document equipment and methods used.

Summary Table: Specimen Dimensional Tolerances (Clause 7.4)

For detailed rounding rules, refer to IS 2-1960.

flowchart TD
    A[Test/Analysis] --> B[Measurement]
    B --> C[Check Dimensions]
    C --> D{Within Tolerances?}
    D -->|Yes| E[Record & Round off (IS 2-1960)]
    D -->|No| F[Re-prepare Specimen]
    E --> G[Report Results]

For official clarifications, contact the Central Laboratory, Sahibabad or regional offices listed in the standard.