Method of test for determination of water absorption, apparent specific gravity and porosity of natural building stones
1974 Edition

Overview of the standard's scope and essential requirements

• Scope: Outlines the procedure to determine the true specific gravity of natural building stones.

• Test Specimen Preparation:

  • Clause 6.6 specifies the required dimensions and shape of test pieces.
  • Clause 6.7 mandates detailed documentation of sample preparation.

• Key Parameters (Clause 6.1): Variables A, B, and C define sample weights and conditions (refer to clauses 6.1 & 6.2).

• Result Evaluation & Reporting (Clause 6.7, Table 6): Testing outcomes should be reported in the prescribed format.

Example Formula for Specific Gravity (G):

[ G = \frac{\text{Mass in air}}{\text{Mass in air} - \text{Mass in water}} ]

• Mass determined with a balance.
• Test pieces must be saturated and surface-dried.

Typical Test Piece Dimensions:

Contact Points for Testing & Reference:

• Central Lab: Sahibabad Industrial Area, Plot 20/9, Site IV
• Regional Offices: New Delhi, Kolkata, Chandigarh, Chennai, Mumbai
• Branch Offices: Ahmedabad, Bangalore, Bhopal, Bhubaneswar, Coimbatore, Faridabad, etc.

flowchart LR
    A[Prepare Test Pieces] --> B[Measure Mass in Air]
    B --> C[Measure Mass in Water]
    C --> D[Calculate Specific Gravity]
    D --> E[Assess & Report Results]

Refer IS 1124 clauses 6.1 to 6.7 for full procedural details.

Key Points on Sample Selection per the Standard

• Clause 2.1: Samples should accurately represent the average quality of the stone type or grade.
• Clause 2.2: Samples must be taken from quarried stone or natural rock in quantities sufficient to prepare the required test specimens.
• Clause 2.3: If stone quality varies notably, multiple samples reflecting this variation should be collected.
• Clause 6.6: Test specimen size and shape must be explicitly detailed.

Sample Size and Shape Recommendations

Sample Selection Flowchart

flowchart TD
    A[Quarried Stone / Natural Rock] --> B{Is Quality Variable?}
    B -- No --> C[Choose Single Representative Sample]
    B -- Yes --> D[Collect Multiple Samples]
    C --> E[Prepare Test Specimens]
    D --> E
    E --> F[Perform Tests with Specified Dimensions]

Refer to IS 1124 or IS 3495 for exact specimen dimensions and quantities.

Preparation of Test Specimens for Determination of True Specific Gravity

Essential Specifications and Steps:

• Size and Shape (Clause 6.6): Must be clearly defined.

• Material Selection (Clause 3.1): Use crushed stone passing 20 mm IS sieve but retained on 10 mm IS sieve.

• Weight per Specimen (Clause 5.1): Approximately 1 kg.

• Preparation Procedure:

  1. Clean specimens to remove dust.
  2. Soak in distilled water at 20–30°C for 24 hours.
  3. Remove trapped air by gentle agitation (both clockwise and counterclockwise).
  4. Drain water and surface dry using a dry cloth until no moisture is absorbed.
  5. Place on a second dry cloth and air dry for at least 10 minutes away from heat or sunlight.
  6. Weigh the surface-dried specimen (weight B).

• Documentation (Clause 6.7): Detailed preparation method must be recorded.

Preparation Summary Table:

Ensures reliable determination of true specific gravity through standardized specimen preparation.

flowchart TD
    A[Crushed Stone (10–20 mm)] --> B[Wash to Clean]
    B --> C[Soak in Distilled Water (24 h, 20–30°C)]
    C --> D[Remove Entrapped Air by Agitation]
    D --> E[Drain & Surface Dry on Cloth]
    E --> F[Air Dry ≥10 min (No Direct Heat)]
    F --> G[Weigh Specimen (Weight B)]

Apparatus Specifications and Calculation Methods

Equipment (Clause 4.2):

• Glass container with ~1.5 litre capacity.
• Two dry absorbent cloths, each approximately 0.5 m².
• Larger water cylinder for immersion and drainage.

Sample Preparation (Clause 5.3):

• Oven dry specimens at 100–110°C for at least 24 hours.
• Cool specimens in a desiccator to ambient temperature.
• Record dry weight (A).
• Note room temperature during testing.

Key Variables (Clause 6.1):

• Weights A, B, and C correspond to dry weight, water immersion weight, and saturated surface dry weight respectively.

True Specific Gravity Formula:

[ G = \frac{A}{B - C} ]

Where:

• A = Oven-dry weight
• B = Weight of specimen in air when saturated surface dry
• C = Weight of specimen in water

Apparatus Specifications Summary:

flowchart TD
    A[Collect Sample] --> B[Oven Dry (100–110°C, ≥24h)]
    B --> C[Cool in Desiccator]
    C --> D[Weigh Dry Sample (A)]
    D --> E[Immerse in Water to Obtain Weights (B, C)]
    E --> F[Calculate Specific Gravity G = A / (B - C)]

For detailed apparatus and procedures, consult the full IS 1124 document.

Key Procedural Steps for Testing Natural Building Stones

1. Test Piece Preparation (Clauses 6.6 and 6.7):

   • Define size and shape clearly.
   • Document preparation steps comprehensively.

2. Apparent Porosity Formula (Clause 6.3): [ \text{Apparent Porosity} = \frac{1000 - C}{C} \times 100 ]

   • C represents a specific measured parameter related to weight.

3. Parameters A, B, C (Clauses 6.1 & 6.2):

   • Use these measured values for subsequent calculations.

4. Result Evaluation & Reporting (Clause 6.7, Table):

   • Follow the standard format for tabulation and interpretation.

Testing Workflow Diagram

flowchart TD
    A[Prepare Test Pieces] --> B[Specify Size & Shape]
    B --> C[Conduct Measurements]
    C --> D[Compute Apparent Porosity]
    D --> E[Analyze & Document Results]
    E --> F[Include Preparation Details]

Refer to clauses 6.1, 6.2, and 6.7 of IS 1124 for exact values and calculations.

Guidelines for Evaluation and Reporting (Clause 6.7 and Related Sections)

Reporting Requirements:

• Provide a detailed account of specimen preparation.
• Specify specimen size and geometry (Clause 6.6).
• Outline drying conditions (Clause 5.3):
  • Oven dry at 100–110°C for 24 hours or more.
  • Cool in desiccator to room temperature.
  • Weigh dry specimen (A).
  • Record ambient temperature during testing.

Typical Report Inclusions:

• Specimen identification (dimensions, shape).
• Preparation method (drying, conditioning).
• Environmental conditions during testing.
• Recorded weights and volumes.
• Calculated values such as true specific gravity.

True Specific Gravity Calculation:

[ \text{True Specific Gravity (G)} = \frac{A}{A + B - C} ] Where:

• A = Oven-dried weight,
• B = Weight in water,
• C = Weight of saturated surface dry specimen in air.

Reporting Summary Table:

flowchart TD
    A[Specimen Preparation]
    B[Oven Drying (100–110°C, ≥24h)]
    C[Cooling in Desiccator]
    D[Weigh Dry Specimen (A)]
    E[Weigh Saturated Surface Dry Specimen (C)]
    F[Weigh Specimen in Water (B)]
    G[Calculate True Specific Gravity]

    A --> B --> C --> D
    D --> E
    E --> F
    D --> G