Method of test for surface softening of natural building stones by exposure to acidic atmospheres

IS 4122: Scope & Key Specifications

Scope:

• Relates to test methods for stone materials, aligning with international and Indian practices.
• Applies to preparation and testing of stone samples (prisms or cubes).

Key Specifications & Test Sample Preparation

Test Reporting Requirements (Clause 6.2)

• Sample identification (name, quarry location)
• Ledge name/position
• Sample collection date
• Stone trade name/grade
• Specimen size & shape
• Specimen preparation method

Summary Diagram: Sample Preparation & Testing Flow

flowchart TD
    A[Sample Collection] --> B[Specimen Preparation]
    B --> C[Surface Grinding (IS Grit No. 80)]
    C --> D[Scraping with Tool (7.5x2 cm blade)]
    D --> E[Testing & Reporting]
    E --> F[Report Details: Quarry, Date, Grade, Specimen Info]

This concise framework ensures standardized stone testing consistent with IS 4122.

IS 4122: Sampling and Sample Selection for Stone

Key Specifications:

• Clause 2.1: Sample must represent the true average of the stone type/grade.
• Clause 2.2: Sample selected by purchaser or authorized representative from quarried stone or natural rock; size must allow preparation of required test specimens.
• Clause 2.3: Multiple samples required if perceptible quality variations exist to determine property range.

Test Specimen Information (Clause 6.2):

• Identification: quarry name/location, ledge name/position
• Date of sampling
• Trade name/grade of stone
• Specimen size and shape
• Specimen preparation method

Practical Notes:

• Sampling should cover variability to ensure representativeness.
• Adequate sample size ensures multiple tests (compressive strength, water absorption, etc.).
• Record keeping is essential for traceability and quality control.

flowchart LR
    A[Quarried Stone or Natural Rock] --> B[Sample Selection by Purchaser]
    B --> C{Quality Variation?}
    C -- Yes --> D[Multiple Samples]
    C -- No --> E[Single Representative Sample]
    D & E --> F[Specimen Preparation]
    F --> G[Testing & Reporting]

For detailed test specimen dimensions and preparation, refer to IS 1121 series related to stone testing.

IS 4122: Test Specimens - Key Specifications & Preparation

Specimen Dimensions (Clause 3.1)

• Prisms: 10 cm × 10 cm × 20 cm
• Cubes: 10 cm × 10 cm × 10 cm
• Faces must be ground smooth using abrasive of IS Grit No. 80 (IS:715-1966) and brushed clean.

Number of Specimens (Clause 5.1)

• Minimum 3 specimens per test.

Specimen Preparation (Clause 5.1)

• One face scraped at the center (center located by diagonals).
• Scraping depth (da) = Thickness before scraping - Thickness after scraping (accuracy ±0.02 mm).
• Scraping at room temperature (20° to 30°C).

Reporting Information (Clause 6.2)

• Sample ID, quarry name & location.
• Ledge name/position.
• Date of sampling.
• Trade name/grade.
• Specimen size & shape.
• Preparation method description.

Summary Table: Specimen Size & Preparation

flowchart TD
    A[Sample Collection] --> B[Specimen Preparation]
    B --> C{Shape?}
    C -->|Prism| D[10x10x20 cm]
    C -->|Cube| E[10x10x10 cm]
    D & E --> F[Surface Grinding (IS Grit No. 80)]
    F --> G[Scraping Center Face]
    G --> H[Measure Thickness Before & After]
    H --> I[Calculate Scraping Depth (da)]
    I --> J[Testing]

This ensures uniformity and reliability in stone testing per IS 4122.

Hand Scraping Tool - IS 4122 Key Specifications & Procedure

Tool Dimensions (Clause 4.1)

• Blade length: 7.5 cm
• Blade width: 2 cm
• Blade end: Ground to a plane surface perpendicular to length, forming sharp cutting edges on both sides
• Material: Steel T-90 V23 as per IS:1570-1961

Scraping Procedure (Clause 5.1.1)

• Pressure: ~1.5 kg on cutting edge
• Angle: 30° between blade and specimen surface
• Stroke length: ~4 cm forward
• Strokes: 8 strokes per cutting edge, repeated on both edges (total 16 strokes per specimen)
• Sharpening: Sharpen cutting edge before each specimen

Sample Preparation (Clause 5.1 & 3.1)

• Specimen size: 10×10×20 cm prism or 10 cm cube
• Surface finish: Ground smooth, finished with IS Grit No. 80 abrasive (IS:715-1966)
• Number of samples: Minimum 3
• Scraping location: Center of one face, found by diagonals intersection
• Temperature: 20° to 30°C (room temperature)

Measurement

• Depth of scraping (da):
  [ d_a = t_{before} - t_{after} ] where thickness is measured to nearest 0.02 mm before and after scraping.

flowchart LR
    A[Prepare Specimen] --> B[Grind & Abrade Surface]
    B --> C[Sharpen Scraping Tool]
    C --> D[Apply 1.5 kg Pressure at 30°]
    D --> E[Make 8 Strokes on One Edge]
    E --> F[Make 8 Strokes on Other Edge]
    F --> G[Measure Thickness Before & After]
    G --> H[Calculate Depth of Scraping]

This concise summary covers essential tool specs, test procedure, and measurement for hand scraping per IS 4122.

IS 4122: Test Procedure - Key Points & Specifications

1. Sample Preparation (Clause 5.1):

• Minimum 3 specimens per test.
• Scrape one face at the center (locate center by diagonals).
• Scraping depth (dₐ) = thickness before scraping − thickness after scraping (measured to ±0.02 mm).
• Scraping at room temperature (20° to 30°C).

2. Scraping Tool (Clause 4.1):

• Blade length: 7.5 cm, width: 2 cm.
• Blade ground to a sharp, perpendicular cutting edge on both sides.
• Material: Steel T-90 V23 as per IS:1570-1961.

3. Reporting (Clause 6.2): Include:

• Sample ID, quarry location, ledge position.
• Date of sampling.
• Trade name/grade.
• Specimen size & shape.
• Preparation method.

4. Rounding Off (Clause 0.5):

• Follow IS:2-1960 for rounding final test values.

Summary Table: Scraping Tool Dimensions

flowchart TD
    A[Sample Collection] --> B[Specimen Preparation]
    B --> C[Scraping at Center Face]
    C --> D[Measure Thickness Before & After]
    D --> E[Calculate Scraping Depth dₐ]
    E --> F[Test Execution]
    F --> G[Report Results with Details]

This ensures uniformity and reliability in stone testing per IS 4122.

IS 4122: Calculation and Reporting of Results

Key Formulas:

• Depth of Softening (d):
  [ d = d_2 - d_1 ] where,

  • (d_1) = initial depth before test
  • (d_2) = depth after test (see clauses 5.1 & 5.3)

• Average Depth of Softening:
  [ \bar{d} = \frac{\sum d_i}{n} ] where (n) = number of specimens tested.

• Rounding Off:
  Final reported value rounded as per IS 2-1960.

Reporting Requirements (Clause 6.2):

• Sample identification (name & quarry location)
• Ledge name/position
• Date of sampling
• Trade name/grade of stone
• Size & shape of specimen
• Specimen preparation method description

Reporting Precision:

• Depth of softening to be reported to nearest 0.02 mm.

Summary Table for Reporting

flowchart TD
    A[Sample Collection] --> B[Specimen Preparation]
    B --> C[Measure Initial Depth (d1)]
    C --> D[Test Procedure]
    D --> E[Measure Final Depth (d2)]
    E --> F[Calculate Depth of Softening (d2 - d1)]
    F --> G[Compute Average Depth]
    G --> H[Report Results with Required Details]

This ensures clarity, traceability, and compliance with IS 4122 for stone testing results.