Methods of test for determination of permeability of natural building stones

IS 4348: Scope - Key Specifications and Requirements

• Specimen Size (Clause 5.1):

  • Cylindrical specimens
  • Dimensions: 100 mm diameter × 100 mm length
  • Three specimens per test set

• Test Reporting (Clause 9.1): Reports must include:

  • Specimen ID
  • Test duration
  • Specimen size
  • Test pressure & temperature
  • Coefficient of permeability at test temperature
  • Corrected permeability at standard temperature
  • Permeability variation over time (increase/decrease and rate)

• Reservoir Calibration (Clause 7.1):

  • Calibrate between 1.10 × actual pressure and 0.9 × actual pressure

• Rounding Off (Clause 0.3):

  • Follow IS 2:1960 for rounding final values

Example: Corrected Coefficient of Permeability (k_c)

[ k_c = k_t \times \frac{T_s + 273}{T_t + 273} ]

• (k_t) = permeability at test temperature (T_t) (°C)
• (T_s) = standard temperature (usually 27°C)

flowchart TD
    A[Specimen Preparation] --> B{Specimen Size}
    B -->|100 mm dia × 100 mm length| C[Testing]
    C --> D{Test Conditions}
    D -->|Pressure & Temperature| E[Measure Permeability]
    E --> F[Report Results]
    F --> G[Include Specimen ID, Duration, Size, Pressure, Temperature, Permeability]

This summary aligns with IS 4348's scope and specimen testing requirements.

IS 4348: Selection of Sample for Permeability Testing of Natural Building Stones

Key Points from Clauses:

• Clause 2.1:
  Sample must represent the true average quality of the stone type or grade.

• Clause 2.2:
  Sample selection by purchaser or authorized representative from quarried stone or natural rock.
  Sample size must be adequate to prepare the required number of test specimens.

• Clause 2.3:
  If quality varies perceptibly, select multiple samples to capture the range of properties.

Practical Guidelines:

Notes on Rounding:

• Follow revised rules for numerical rounding (typically nearest whole number or as per test precision).

flowchart TD
    A[Quarried Stone or Natural Rock] --> B[Purchaser/Representative selects sample]
    B --> C{Is quality uniform?}
    C -- Yes --> D[Select representative sample]
    C -- No --> E[Select multiple samples]
    D & E --> F[Adequate size for test specimens]

This ensures samples accurately reflect stone permeability characteristics per IS 4348.

IS 4348: Apparatus Key Specifications & Setup

1. Compressed Air Supply (Clause 4.1)

• Use compressed air cylinders or compressors of adequate capacity.
• Pressure must be maintained within ±2% of the set value.
• Use sensitive regulating valves and companion pressure gauges.
• Multiple cells can share a common air source (see Fig. 2).

2. Water Supply (Clause 4.2)

• Use clean, de-aired water (boil & cool to de-air).
• Store in closed, full containers to avoid air contact.

3. Water Reservoir (Clause 3.2)

• Metal pipe: 50–100 mm diameter, ~500 mm length.
• Equipped with:
  • Graduated side-arm gauge glass.
  • Valves for water/air admission, draining, and bleeding.
• Connected to permeability cell (Fig. 1 & Fig. 2).

4. Assembly Procedure (Clause 7.4)

• Secure funnel, connect cell to reservoir.
• Open air-bleeder, reservoir-cell valve, and drain-cock.
• Fill reservoir with de-aired water until water flows from drain-cock.
• Close drain-cock and fill reservoir.
• Close reservoir water inlet and air bleeder valves.

Apparatus Flow (Fig. 2 simplified):

flowchart LR
    CA[Compressed Air Source] --> PR[Pressure Regulator & Gauge]
    PR --> PC[Permeability Cell]
    WR[Water Reservoir] --> PC
    PC --> CB[Collection Bottle]
    WR --> GG[Graduated Gauge Glass]
    WR --> ABV[Air Bleeder Valve]

This setup ensures accurate permeability testing by controlling air pressure and water supply precisely.

IS 4348 - Water Supply for Permeability Tests: Key Points

1. Water Quality & Preparation (Clause 4.2)

• Use clean de-aired water.
• De-air by boiling and cooling.
• Store in closed, full containers to avoid air contact and agitation.

2. Water Reservoir (Clause 3.2)

• Metal pipe reservoir:
  • Diameter: 50 to 100 mm
  • Length: ~500 mm
• Equipped with:
  • Graduated side arm gauge-glass
  • Valves for water/air admission, draining, bleeding
• Calibration constant: ml per division on gauge glass

3. Filling & Calibration Procedure (Clause 7.1.1)

• Fill reservoir with water, flush air via drain-cock.
• Refill above zero mark on gauge.
• Apply air pressure, adjust water level to zero by opening drain-cock briefly.
• Collect water in 250 ml increments for flow measurement.
• Read level on gauge to calculate volume.

4. Compressed Air Supply (Clause 4.1)

• Use cylinders or compressors with:
  • Pressure regulation ±2%
  • Sensitive pressure gauges
• Common air source can serve multiple cells.

Calibration Constant Formula:

[ \text{Volume} = \text{(Gauge divisions)} \times \text{Calibration constant (ml/division)} ]

Diagram Summary (Fig. 2 Setup):

graph LR
  A[Compressed Air Source] --> B[Pressure Regulator & Gauge]
  B --> C[Air Bleeder Valve]
  C --> D[Water Reservoir with Gauge Glass]
  D --> E[Permeability Cell]
  E --> F[Collection Bottle]

This arrangement ensures precise control of water and air pressure during permeability testing.

IS 4348: Test Specimens - Key Specifications & Procedures

Specimen Dimensions (Clause 5.1)

• Shape: Cylindrical
• Size: 100 mm diameter × 100 mm length
• Set: 3 specimens per test set

Specimen Preparation (Clause 5.2)

• Use core drills or equivalent methods avoiding fractures.
• Ends must be ground plane using water and carborundum/emery on a cast iron lap.
• Axis of specimen perpendicular to stratification planes.
• Electrical polishing machines recommended for efficient polishing.

Test Water (Clause 4.2)

• Use clean de-aired water (boiled & cooled).
• Store in closed, full containers to avoid air contact and agitation.

Test Report Requirements (Clause 9.1)

Include for each specimen:

• Identification mark
• Test duration
• Specimen size
• Test pressure & temperature
• Coefficient of permeability (at test & standard temperature)
• Permeability trend (increase/decrease over time & rate)

Summary Table: Specimen Size & Preparation

flowchart TD
    A[Sample Collection] --> B[Core Drilling]
    B --> C[Cut to 100x100 mm]
    C --> D[End Grinding & Polishing]
    D --> E[Specimen Ready for Test]
    E --> F[Permeability Test with De-aired Water]
    F --> G[Record Test Data & Report]

This ensures uniformity and reliability in permeability testing as per IS 4348.

IS 4348: Test Pressure Key Points

1. Test Pressure Specification (Clause 6.1)

• Test pressure head = 1.1 × actual hydraulic head the stone will experience.
• Reservoir calibration: pressure range from 0.9 to 1.10 times actual pressure (Clause 7.1).

2. Pressure Control & Regulation (Clause 4.1)

• Compressed air supply with:
  • Pressure regulated within ±2% of set pressure.
  • Sensitive pressure gauge matching regulator sensitivity.
• Common air source can serve multiple cells (see Fig. 2).

3. Test Procedure (Clause 7.5)

• Fill system with water.
• Apply test pressure (from Clause 6).
• Record initial gauge reading and collect percolate in a weighed bottle.
• Continue test until steady state flow is reached (inflow = outflow).
• Continue test for ~100 hours after steady state; average outflow used for permeability calculation.

4. Pre-test Conditioning

• Preheat cylinder at 30–35°C for 24–30 hours for a perfect seal.

Summary Table: Test Pressure & Calibration

flowchart LR
    A[Compressed Air Supply] --> B[Pressure Regulator ±2%]
    B --> C[Water Reservoir @ 1.1 × Actual Pressure]
    C --> D[Permeability Cell]
    D --> E[Collection Bottle (Weighed)]
    E --> F[Measure Outflow & Gauge Reading]
    F --> G{Steady State Reached?}
    G -- No --> F
    G -- Yes --> H[Continue Test for 100 hrs]
    H --> I[Calculate Average Outflow]

This ensures accurate simulation of field hydraulic conditions and reliable permeability values.

IS 4348: Test Procedure Key Points

1. Water Supply for Permeability Test (Clause 4.2)

• Use clean, de-aired water.
• De-air by boiling and cooling.
• Store in closed, full containers to avoid air contact and agitation.

2. Test Temperature (Clause 7.6)

• Maintain at 27 ± 3°C for consistency.

3. Reporting Requirements (Clause 9.1)

Include in test report:

• Specimen identification mark
• Duration of test
• Size of specimen
• Test pressure
• Test temperature
• Coefficient of permeability at test temperature
• Corrected permeability coefficient at standard temperature
• Permeability trend over time (increase/decrease and rate)

4. Rounding Off Results

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

Additional Notes:

• Proper specimen preparation and handling are critical.
• Avoid unnecessary disturbances during testing to ensure accuracy.

flowchart TD
    A[Start Test] --> B[Prepare Specimen]
    B --> C[Use De-aired Water]
    C --> D[Maintain Test Temp 27±3°C]
    D --> E[Apply Test Pressure]
    E --> F[Measure Permeability]
    F --> G[Record Data & Observations]
    G --> H[Report Results as per Clause 9.1]
    H --> I[End Test]

This concise summary ensures compliance with IS 4348 test procedures for permeability.

IS 4348: Key Formulas and Specifications for Calculation

• Coefficient of Permeability (K):
  [ K = \frac{Q}{A \times T} \times \frac{L}{H} ] where:

  • (K) = coefficient of permeability (cm/sec)
  • (Q) = quantity of water percolated (ml)
  • (A) = cross-sectional area of specimen (cm²)
  • (T) = time over which (Q) is measured (sec)
  • (H/L) = ratio of pressure head to specimen thickness (same units)

• Specimen Selection:
  Samples must represent the true average of the stone type or grade (Clause 2.1).

• Test Reporting Requirements (Clause 9.1):
  Include specimen ID, test duration, specimen size, test pressure, temperature, permeability coefficient at test and standard temperatures, and permeability variation over time.

• Rounding Off:
  Follow IS 2-1960 rules for rounding numerical values (Clause 0.3).

Summary Table for Calculation

flowchart LR
    Q[Quantity of Water (ml)]
    A[Area of Specimen (cm²)]
    T[Time (sec)]
    HL[Pressure Head / Thickness (H/L)]
    K[Coefficient of Permeability (cm/sec)]

    Q --> K
    A --> K
    T --> K
    HL --> K

This formula and reporting framework ensure consistent and comparable permeability test results per IS 4348.

IS 4348 - Report Requirements for Permeability Test on Stone

Per Clause 9.1, the test report must include:

• Identification mark of the specimen
• Duration of test
• Size of specimen (dimensions)
• Test pressure
• Test temperature
• Coefficient of permeability (k) at test temperature
• Corrected coefficient of permeability at standard temperature (usually 27°C)
• Trend of permeability change over time (increase/decrease and rate)

Key Formula for Temperature Correction of Permeability (typical approach):

[ k_{27} = k_t \times \frac{\mu_t}{\mu_{27}} ]

Where:

• (k_t) = permeability at test temperature (t)
• (k_{27}) = permeability corrected to 27°C
• (\mu_t), (\mu_{27}) = dynamic viscosity of water at temperature (t) and 27°C respectively

Additional Notes:

• Use de-aired water (Clause 4.2) for testing to avoid air bubbles affecting permeability.
• Report rounding off values as per IS 2:1960 for numerical consistency.
• Specimen selection should represent the true average stone quality (Clause 2.1).

flowchart TD
    A[Specimen Preparation] --> B[Permeability Test]
    B --> C{Record Test Data}
    C --> D[Specimen ID]
    C --> E[Test Duration]
    C --> F[Specimen Size]
    C --> G[Test Pressure & Temperature]
    C --> H[Calculate k at test temp]
    H --> I[Correct k to 27°C]
    I --> J[Analyze permeability trend]
    J --> K[Prepare Report]

This ensures a comprehensive and standardized report as per IS 4348.