Method of test for determination of weathering of natural building stones
1974 Edition

Overview of Scope and Essential Specifications

• Scope: Defines testing methods for natural stones focusing on water absorption and volume variations post cyclic exposure.

• Equipment Specifications (Clause 4.1):

  • Sealed balance with 1 kg capacity and 0.01 g sensitivity.
  • Brass suspension wire, 0.81 mm diameter.
  • Components include balance beam (A), attachment loop (B), suspension wire (C), and water level indicator (D).

• Specimen Details for Reporting (Clause 7.2):

  • Method of specimen preparation.
  • Dimensions and geometric shape.
  • Sample identification: quarry origin, stone type/location, sample date, commercial name/grade.

• Key Calculation Formula (Clause 5.3):

[ \text{Water Absorption} = \frac{W_a - W_d}{W_d} \times 100% ]

Where:

• (W_a) = weight in air after 30 cycles plus 24-hour immersion

• (W_d) = dry weight before testing

• (W_s) = weight suspended in water post-test (used for volume computation)

• Volume Post-Test:

[ V_2 = \frac{W_a - W_s}{\rho_w} ]

(\rho_w) represents water density (typically 1 g/cm³)

Apparatus Illustration (Simplified):

graph LR
A[Balance Beam] --> B[Attachment Loop]
B --> C[Suspension Wire (0.81 mm brass)]
C --> Specimen[Specimen immersed in water]
Specimen --> D[Water surface level]

Note: Numerical results should be rounded following IS 2-1960 guidelines.

Guidelines for Selecting Samples for Weathering Tests

Highlights from Clauses 2.1 to 2.3:

• Representative Sampling: Samples must accurately reflect the average characteristics of the stone type or grade (Clause 2.1).

• Source Origins: Samples may be collected from:

  • Extracted quarried stone
  • In situ natural rock formations (per Clauses 2.2.1 and 2.2.2)
  • Samples should be sufficiently large to yield the needed number of test specimens (Clause 2.2).

• Accounting for Variability: When noticeable quality differences exist, multiple samples should be taken to encompass the range of properties (Clause 2.3).

Practical Summary Table:

Flowchart Summary:

flowchart TD
    A[Identify Stone Grade] --> B{Is Stone Quality Uniform?}
    B -- Yes --> C[Select Representative Sample]
    B -- No --> D[Select Multiple Samples]
    C --> E[Ensure Adequate Quantity]
    D --> E
    E --> F[Prepare Test Specimens]

Ensure adherence to IS 1125 detailed sampling and testing guidance for accurate weathering assessment.

Key Instructions for Preparing Test Specimens

• Specimen Dimensions (Clause 3.1):

  • Cylindrical specimens: 50 mm diameter and 50 mm height
  • Cubic specimens: 50 mm edges

• Quantity of Test Specimens (Clause 3.3):

  • At least three specimens per test are required for statistically valid results.

• Reporting Details (Clause 7.2):

  • Describe preparation techniques.
  • Include size and shape of specimens.
  • Provide sample identifiers: quarry location, rock positioning, sampling date, commercial name/grade.

• Rounding Off Data:

  • Final numerical results must comply with IS 2-1960 rounding regulations.

Specimen Preparation Summary Table:

flowchart LR
    A[Obtain Sample] --> B[Prepare Test Specimens]
    B --> C{Specimen Shape}
    C -->|Cylinder| D[50 mm diameter x 50 mm height]
    C -->|Cube| E[50 mm x 50 mm x 50 mm]
    D & E --> F[Minimum of 3 Specimens]
    F --> G[Conduct Testing]
    G --> H[Document Results with Preparation and ID details]

This standardizes specimen preparation for reliable durability evaluation.

Apparatus Specifications for Weathering Test

Equipment Details (Clauses 4.1 & 1.83):

• Balance: Enclosed type with 1 kg capacity and 0.01 g sensitivity.
• Suspension Wire: Brass wire, 0.81 mm diameter.
• Basket: Constructed from 1.83 mm diameter brass wire, joints soldered securely.
• Principal Components:
  • A: Balance beam
  • B: Attachment loop
  • C: Suspension wire
  • D: Water level indicator
  • E: Basket handle (bail)
  • 7: Suspension basket
  • K: Support for water container
  • M: Basket bottom
  • N: Suspension rod for balance pan
  • P: Cutout section of basket

Weight and Volume Terminology (Clause 5.1):

Absorption Calculation Formula:

[ A_2 = \frac{W_3 - W_1}{W_1} \times 100 ]

Additional Notes:

• All weights must be obtained using the specified sensitive balance.
• Volume (V1) is typically determined via water displacement.
• Water density (d) varies with temperature; refer to IS 2-1960 for rounding rules.

flowchart LR
    W1[Oven-dry weight (W1)]
    W3[Surface-dry weight (W3)]
    W2[Weight in water (W2)]
    V1[Volume (V1)]
    d[Water density (d)]
    A2[Absorption % (A2)]

    W1 --> A2
    W3 --> A2
    W2 --> V1
    V1 --> A2
    d --> A2

This setup ensures accurate measurement of absorption and volumetric changes.

Summary of Testing Methodology

Equipment Used (Clause 4.1):

• Enclosed balance with 1 kg capacity and 0.01 g precision.
• Accessories for weighing specimens while submerged.
• Main parts include balance beam (A), attachment loop (B), 0.81 mm brass suspension wire (C), and water level indicator (D).

Test Cycle Description (Clause 5.2):

• Place each specimen in a dish of 9 cm diameter and 1.5 cm depth.
• Add 2 g powdered gypsum and 25 ml water.
• Dry in a ventilated oven at 105 ± 2°C for a minimum of 5 hours until dry.
• Cool to 25 ± 5°C.
• Repeat this cycle 30 times, adding only 25 ml water (no gypsum) after the first cycle.

Measurement Parameters (Clause 5.3):

• ( W_A ): Weight in air after 30 cycles plus 24-hour water immersion.
• ( W_s ): Weight suspended in water after the same treatment.
• ( V_2 ): Volume after completing the 30 cycles.

Data Rounding (Clause 0.3):

• Follow IS 2-1960 for rounding off numerical results.

Volume Calculation Formula:

[ V_2 = \frac{W_A - W_s}{\rho_w} ]

Where (\rho_w) is the density of water (usually 1 g/cm³).

flowchart LR
    A[Begin Test] --> B[Place specimen in dish]
    B --> C[Add 2g gypsum + 25ml water]
    C --> D[Oven dry at 105±2°C for ≥5 hours]
    D --> E[Cool to 25±5°C]
    E --> F{Repeat 30 cycles}
    F -- Yes --> G[Add 25 ml water only]
    G --> C
    F -- No --> H[Weigh specimen in air (W_A)]
    H --> I[Weigh specimen suspended in water (W_s)]
    I --> J[Calculate volume (V_2)]
    J --> K[Report findings]

This procedure guarantees uniform testing and accurate reporting.

Essential Formulas and Data for Calculations

This standard emphasizes quantifying water absorption and volume changes after immersion and repeated weathering cycles.

Symbols and Their Definitions:

Key Equations:

• Specimen Volume:

[ V = \frac{W_3 - W_2}{d} ]

• Water Absorption Post 30 Cycles:

[ A_2 = \frac{W_A - W_1}{W_1} \times 100 ]

• Specimen Density:

[ \rho = \frac{W_1}{V} ]

Required Equipment:

• Enclosed balance (1 kg capacity, 0.01 g sensitivity)
• Suspension wire (0.81 mm brass)
• Water container with level control

Reporting Instructions:

• Apply IS 2-1960 rounding standards.
• Clearly document weights, volumes, and absorption percentages.

flowchart LR
    W1[Oven-dry weight (W1)]
    W3[Surface-dry weight (W3)]
    W2[Weight in water (W2)]
    d[Water density (d)]
    V1[Volume after 24h immersion (V1)]
    A2[Water absorption (%) (A2)]

    W3 -->|Subtract| W2
    W2 -->|Divide by| d
    d --> V1
    W1 -->|Calculate absorption with W_A| A2

This summary aids in precise calculation of volume, density, and absorption as per the code.

Guidelines for Recording and Reporting Test Outcomes

Important Definitions (Clause 5.3):

• ( W_A ): Final weight of surface-dried specimen in air after 30 cycles plus 24-hour immersion.
• ( V_2 ): Final specimen volume after 30 cycles.
• ( W_s ): Weight of specimen suspended in water after 30 cycles plus 24-hour immersion.

Reporting Protocols (Clause 7):

• 7.1: Provide the average values from three specimens for:

  • Percentage increase in water absorption
  • Percentage increase in volume

• 7.2: Include supplemental information:

  • Test specimen preparation method
  • Dimensions and shape of specimens
  • Sample identification including quarry source, rock position, sampling date, and trade name or grade

• Rounding: Final reported values should conform to IS 2-1960 rounding standards.

Calculation Formulas:

[ \text{Percentage Increase in Absorption} = \frac{W_A - W_0}{W_0} \times 100 ]

[ \text{Percentage Increase in Volume} = \frac{V_2 - V_0}{V_0} \times 100 ]

Where ( W_0 ) and ( V_0 ) denote initial weight and volume prior to testing.

Reporting Workflow Diagram:

flowchart TD
    A[Initial Specimen] --> B{Perform 30 Cycles + 24h Immersion}
    B --> C[Measure W_A (Air Weight)]
    B --> D[Measure W_s (Water Suspended Weight)]
    B --> E[Measure V_2 (Volume)]
    C --> F[Calculate % Increase in Absorption]
    E --> G[Calculate % Increase in Volume]
    F & G --> H[Report Averaged Results with Sample Details]

Ensure averages are derived from three specimens and reports include full sample identification and preparation particulars.