Method of Test for Permeability of Cement Mortar and Concrete

IS 3085 Scope & Key Specifications Summary

• Scope: IS 3085 covers methods for determining the permeability of concrete using a permeability cell and test setup.

• Permeability Cell Dimensions (Fig. 1):

• Test Setup (Fig. 2) includes:

  • Permeability cell
  • Pressure regulator & gauge
  • Air bleeder valve
  • Water reservoir with graduated gauge glass and safety shield
  • Collection bottle

• Pressure Lines: Use heavy-duty armored rubber hose or suitable metal tubing; all joints must be leakproof.

• Test Report Must Include (Clause 9.1):

  • Specimen ID, mix details, age at test start
  • Test duration, specimen size
  • Test pressure & temperature
  • Coefficient of permeability at test and corrected to standard temperature

• Rounding Off Values: Follow IS 2-1960 for rounding test results, maintaining significant digits as per specified values.

Typical Permeability Cell Setup (Mermaid.js)

flowchart LR
    A[Water Reservoir] --> B[Pressure Regulator & Gauge]
    B --> C[Permeability Cell]
    C --> D[Collection Bottle]
    B -.-> E[Air Bleeder Valve]

This standard ensures reliable permeability testing by specifying apparatus, procedure, and reporting requirements.

Principle of the Test (IS 3085)

The permeability test measures the coefficient of permeability (k) of concrete or similar materials by passing de-aired water through a specimen under a specified pressure and temperature.

Key Points from IS 3085:

• De-aired Water Supply (Clause 4.2):

  • Water must be clean and de-aired by boiling and cooling.
  • Store in closed, full containers to avoid air contact.
  • Avoid agitation to maintain de-airing.

• Test Specimen Details (Clause 9.1): Report must include:

  • Specimen ID, mix details, age, size
  • Test pressure & temperature
  • Duration of test
  • Coefficient of permeability at test temperature
  • Corrected permeability at standard temperature

• Permeability Cell Dimensions:

Typical Formula for Coefficient of Permeability (k):

[ k = \frac{Q \times L}{A \times t \times h} ]

Where:

Test Setup (Schematic Overview):

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

• Water reservoir feeds de-aired water.
• Pressure regulator controls test

IS 3085 - Apparatus for Permeability Test: Key Points

Apparatus Specifications (Clause 3.3 & Fig. 1 & 2)

• Pressure Lines: Use heavy-duty armoured rubber hose, suitable metal tubing, or equivalent, ensuring leakproof joints.
• Permeability Cell Dimensions (mm):

• Components:
  • Threaded nipple, sealing compound, sheet metal funnel
  • Air bleeder valve, pressure regulator & gauge
  • Graduated gauge glass with safety shield
  • Water reservoir connected to permeability cell and collection bottle

Assembly (Clause 7.5)

• Secure funnel after sealing.
• Connect cell to water reservoir.
• Open air bleeder valve, reservoir-cell valve, and drain cock to fill with de-aired water.
• Close drain cock when water flows freely; fill reservoir.
• Close reservoir water inlet and air bleeder valves before testing.

Compressed Air Supply (Clause 4.1)

• Pressure: 5 to 15 kg/cm²
• Use compressed air or nitrogen cylinders/compressor.
• Provide pressure regulators and gauges.
• One source may serve multiple cells.

Test Report Details (Clause 9.1)

• Specimen ID, mix particulars, age at test start
• Test duration, specimen size, test pressure & temperature
• Coefficient of permeability at test temp & corrected at standard temp

flowchart TD
    A[Compressed Air Source] -->|Regulated Pressure| B[Pressure Regulator & Gauge]
    B --> C[Permeability Cell Assembly]
    C --> D[Water Reservoir]
    C --> E[Collection Bottle]
    C --> F[Air Bleeder Valve]

This setup ensures accurate permeability testing per IS 3085.

IS 3085: Test Setup & Equipment Requirements for Permeability Tests

Key Equipment (Clause 3.3 & Fig. 2)

• Pressure Lines: Heavy-duty armoured rubber hose or metal tubing; leakproof joints mandatory.
• Permeability Cell Dimensions (mm):

• Additional Apparatus:
  • Threaded nipple, sealing compound, sheet metal funnel
  • Air bleeder valve, pressure regulator & gauge
  • Graduated gauge glass (with safety shield)
  • Water reservoir, collection bottle

Water Supply (Clause 4.2)

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

Test Report Requirements (Clause 9.1)

Include:

• Specimen ID, mix details, age, size
• Test pressure & temperature
• Duration of test
• Coefficient of permeability (test & corrected for standard temperature)

Diagram: Permeability Test Setup (Simplified)

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

Note: Round off test results per IS 2-1960 guidelines (significant figures matching specified values).

IS 3085: Test Specimens - Key Specifications & Tables

1. Specimen Size (Clause 5.1)

• Shape: Cylindrical with height = diameter.
• Standard size: Diameter = Height = 150 mm.
• For aggregates ≤ 20 mm: Diameter = Height = 100 mm.
• For aggregates > 40 mm: Diameter & Height ≥ 4 × nominal aggregate size.

2. Report Details (Clause 9.1)

Include in test report:

• Identification mark
• Mix particulars
• Age at test start
• Test duration
• Specimen size
• Test pressure & temperature
• Coefficient of permeability at test & standard temperature (corrected)

3. Permeability Cell Dimensions (Table from Clause 3.3)

4. Water for Testing (Clause 4.2)

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

Visual: Permeability Test Setup (Simplified)

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

This ensures standardized specimen preparation and reliable permeability testing per IS 3085.

IS 3085 - Test Pressure for Permeability Test

Key Specifications (Clause 6.1):

• Standard test pressure head: 10 kg/cm² (approx. 0.98 MPa)
• Reduced pressure: 5 kg/cm² for more permeable specimens (to achieve steady flow faster)
• Increased pressure: Up to 15 kg/cm² for less permeable specimens, ensuring effective sealing

Test Procedure (Clause 7.6):

• Fill system with water, apply desired test pressure.
• Record initial gauge-glass reading.
• Collect percolated water in a weighed bottle.
• Monitor inflow and outflow until steady state (inflow = outflow).
• Continue test for ~100 hours after steady state.
• Average outflow during this period gives permeability.

Permeability Cell Dimensions (Fig. 1)

Report Must Include (Clause 9.1):

• Specimen ID, mix, age, test duration, size
• Test pressure & temperature
• Coefficient of permeability at test and standard temperatures

flowchart TD
    A[Water Reservoir] -->|Pressure 5-15 kg/cm²| B[Permeability Cell]
    B --> C[Collection Bottle (weighed)]
    B --> D[Gauge Glass (readings)]
    D --> E{Steady State?}
    E -->|No| B
    E -->|Yes| F[Continue 100 hrs, average outflow]

This ensures accurate permeability measurement under controlled pressure conditions per IS 3085.

IS 3085: Test Procedure Key Points

Test Report Must Include (Clause 9.1):

• Specimen ID
• Mix particulars
• Age at test start
• Test duration
• Specimen size
• Test pressure & temperature
• Coefficient of permeability at test temperature
• Corrected permeability coefficient at standard temperature

Specimen Dimensions (Typical Permeability Cell)

Apparatus & Setup Highlights (Clause 3.3)

• Use heavy-duty armoured rubber hose or metal tubing for pressure lines.
• All joints must be leakproof.
• Use de-aired water (boiled and cooled) to avoid air bubbles affecting permeability.

Permeability Coefficient Correction Formula

[ k_{std} = k_{test} \times \frac{\mu_{test}}{\mu_{std}} ]

Where:

• (k_{std}) = permeability coefficient at standard temperature
• (k_{test}) = permeability coefficient at test temperature
• (\mu) = dynamic viscosity of water at respective temperatures

Test Setup Schematic (Simplified)

flowchart LR
    Water_Reservoir --> Permeability_Cell
    Permeability_Cell --> Collection_Bottle
    Pressure_Regulator --> Permeability_Cell
    Air_Bleeder_Valve --> Permeability_Cell
    Pressure_Regulator --> Pressure_Gauge

Note: Follow IS:2-1960 for rounding off test results.

IS 3085: Calculation of Permeability Coefficient (Clause 8.1)

The coefficient of permeability, K, is calculated by:

[ \boxed{ K = \frac{Q \times L}{A \times T \times H} } ]

Where:

• K = Coefficient of permeability (cm/sec)
• Q = Quantity of water percolated (ml) after steady state
• A = Area of specimen face (cm²)
• T = Time interval of flow measurement (sec)
• H = Ratio of pressure head to specimen thickness (both same units)
• L = Thickness of specimen (cm)

Key Specifications & Precautions (Clauses 2.1, 7.7, 7.8):

• Specimen: Known dimensions, tested under hydrostatic pressure.
• Seal: Must be leak-proof to avoid erroneous results.
• Air Content: Water entering specimen should have <0.2% dissolved air to prevent air locks.
• Steady State: Flow must reach steady state before calculating K.
• Evaporation: Correct for evaporation loss during outflow collection.
• Surface Preparation: Sand blasting or chiseling to remove impervious skin.
• Temperature: Test at 27 ± 2°C. Adjust K by ±10% for every 5°C deviation.

Temperature Correction Formula:

[ K_{corrected} = K_{measured} \times \left(1 + 0.10 \times \frac{T_{actual} - 27}{5}\right) ]

flowchart TD
    A[Apply Hydrostatic Pressure] --> B[Water Percolates Through Specimen]
    B --> C[Measure Q (Water Volume)]
    C --> D[Calculate K using formula]
    D --> E[Apply Temperature Correction if needed]

This concise approach ensures accurate permeability measurement per IS 3085.

IS 3085 - Reporting of Results: Key Points

Rounding Off (Clause 0.5)

• Final test or analysis values must be rounded as per IS 2:1960.
• Number of significant digits retained = number of digits in the specified standard value.

Report Contents (Clause 9.1)

Each specimen report must include:

• Identification mark of specimen
• Mix particulars
• Age at test start
• Test duration
• Specimen size
• Test pressure
• Test temperature
• Coefficient of permeability at test temperature
• Corrected coefficient of permeability at standard temperature

Typical Cell Dimensions (For Reference)

Notes:

• Use leakproof heavy-duty hoses or metal tubing for pressure lines.
• All joints must be sealed properly.

flowchart TD
    A[Test Specimen] --> B[Identification Mark]
    B --> C[Mix Details]
    C --> D[Age at Test]
    D --> E[Duration of Test]
    E --> F[Specimen Size]
    F --> G[Test Pressure & Temperature]
    G --> H[Coefficient of Permeability]
    H --> I[Corrected Coefficient at Standard Temp]
    I --> J[Final Report]

This ensures clarity, consistency, and compliance with IS 3085 for permeability testing results.