Methods of physical tests for hydraulic cement, Part 3: Determination of soundness

Scope of IS 4031 Part 3 - 1988 (Physical Tests for Hydraulic Cement)

This part specifies apparatus and methods for length change measurement of hardened cement paste, mortar, and concrete.

Key Specifications & Tables:

1. Weights for Cement Weighing (Clause 5.1.3):

Permissible variations on weights used for cement weighing are as follows:

2. Autoclave Requirements (Clause 6.1.5):

• High-pressure steam boiler with safety devices.
• Capacity to raise saturated steam pressure adequately under max load.
• Safety valve set to relieve pressure at 6 to 10% above operating pressure (Clause 6.4.4).

3. Test Specimen Preparation (Clause 6.2):

• Details on preparing cement paste, mortar, or concrete specimens for length change tests.

Summary Diagram of Apparatus Setup:

flowchart LR
    A[Weighing Cement] --> B[Prepare Test Specimens]
    B --> C[Place in Moulds]
    C --> D[Autoclave Treatment]
    D --> E[Measure Length Change]
    E --> F[Analyze Results]

Note: For detailed procedures and apparatus dimensions, refer to IS 4031 Part 3 full text.

IS 4031 Part 3: Sampling and Selection of Test Specimen for Soundness Test

Key Points from Clauses:

• Clause 6.2: Preparation of test specimens must follow standard procedures ensuring uniformity and representativeness.
• Clause 5.1.1: Apparatus for Le-Chatelier test must conform to IS 5514-1969 (sampling methods & apparatus specifications).
• Clause 6.1.5: Autoclave specifications include a high-pressure steam boiler capable of generating saturated steam at required pressure with safety devices.

Sampling & Specimen Selection Summary:

• Sampling: Use representative samples as per IS 5514 to avoid bias.
• Specimen Size: Standard Le-Chatelier moulds as per IS 5514.
• Test Specimen Preparation:
  • Mix cement with water to standard consistency (see IS 4031 Part 4).
  • Fill Le-Chatelier moulds uniformly.
  • Cure specimens under saturated steam in autoclave at specified pressure and temperature.

Typical Le-Chatelier Test Setup:

Formula: Soundness Expansion (mm)

[ \text{Expansion} = \text{Final distance between indicator points} - \text{Initial distance} ]

• Expansion > 10 mm indicates unsound cement.

flowchart TD
    A[Sampling of Cement] --> B[Prepare Standard Paste]
    B --> C[Fill Le-Chatelier Mould]
    C --> D[Cure in Autoclave at 135°C]
    D --> E[Measure Expansion]
    E --> F{Expansion > 10 mm?}
    F -- Yes --> G[Unsound Cement]
    F -- No --> H[Sound Cement]

References:

• IS 5514-1969 (Sampling & apparatus)
• IS 4031 Part 4 (Consistency of cement paste)
• IS 4031 Part 3 (

IS 4031 Part 3: Temperature and Humidity Specifications

• Moulding Room, Dry Materials & Water Temperature:
  Maintain at 27 ± 2°C (Clause 3.1).

• Laboratory Relative Humidity:
  Maintain at 65 ± 5% (Clause 3.1).

• Moist Closet / Moist Room Conditions:
  Temperature at 27 ± 2°C and relative humidity ≥ 90% (Clause 3.2).

Permissible Weight Variations for Cement Testing (Clause 5.1.3)

Summary Diagram of Environmental Control

graph LR
A[Moulding Room] -->|Temp 27±2°C| B[Dry Materials & Water]
A -->|Humidity 65±5%| C[Laboratory]
D[Moist Closet] -->|Temp 27±2°C| E[High Humidity ≥90%]

Maintain these conditions for accurate and consistent cement testing as per IS 4031 Part 3.

IS 4031 Part 3: Determination of Soundness of Cement

Key Methods:

• Le Chatelier Method (Expansion Test)
• Autoclave Method

1. Le Chatelier Method (Clause 5.1.4)

• Measures expansion of cement paste in Le Chatelier mould after 24 hours.
• Procedure:
  • Prepare cement paste (cement + water).
  • Fill Le Chatelier mould (split ring).
  • Cure in water at 27°C for 24 hours.
  • Measure expansion (difference in indicator needle positions).

Acceptance Criteria:

• Expansion should not exceed 10 mm (typical limit for ordinary Portland cement).

2. Autoclave Method

• Cement paste cured under steam pressure (2 MPa, 2.5 hours).
• Expansion measured after autoclaving.
• Limits vary by cement type (generally < 0.8% volume expansion).

Important Formula for Expansion (Le Chatelier):

[ \text{Expansion} = (L_2 - L_1) \text{ mm} ]

Where:

• (L_1) = Initial distance between indicator needles
• (L_2) = Distance after 24 hours curing

Summary Table:

flowchart TD
    A[Prepare Cement Paste] --> B[Fill Le Chatelier Mould]
    B --> C[Cure in Water 24h at 27°C]
    C --> D[Measure Expansion (L2 - L1)]
    D --> E{Expansion < 10 mm?}
    E -- Yes --> F[Sound Cement]
    E -- No --> G[Unsound Cement]

Note: Always refer to the latest IS 4031 Part 3 for detailed procedures and apparatus specifications.

Le-Chatelier Method (IS 4031 Part 3 - 1988): Key Points

The Le-Chatelier test determines cement soundness by measuring expansion due to hydration.

Apparatus (Clause 5.1.1 & IS 5514-1969)

• Le-Chatelier moulds conforming to IS 5514.
• Water bath capable of heating specimens from 27 ± 2°C to boiling in 27 ± 3 minutes (Clause 5.1.4).
• Mould dimensions typically:
  • Length: 30 mm
  • Internal diameter: 10 mm
  • Thickness: 1.5 mm

Test Procedure Summary

1. Prepare cement paste (cement + water) and fill into Le-Chatelier mould.
2. Immerse mould in water bath.
3. Heat from 27°C to boiling in 27 ± 3 minutes.
4. Boil for 3 hours.
5. Measure expansion by the increase in distance between indicator points on the mould.

Key Formula: Expansion (%) Calculation

[ \text{Expansion (%)} = \frac{L_2 - L_1}{L_1} \times 100 ]

• (L_1) = Initial distance between indicator points (usually 30 mm)
• (L_2) = Final distance after test

Acceptance Criteria (Typical)

• Expansion should not exceed 10 mm (i.e., 0.0333 or 3.33%) for sound cement.

Summary Table

flowchart LR
    A[Prepare Cement Paste] --> B[Fill Le-Chatelier Mould]
    B --> C[Immerse in Water Bath]
    C --> D[Heat 27°C to Boiling (27 ± 3 min)]
    D --> E[Boil for 3 hours]
    E --> F[Measure Expansion \(L_2 - L_1\)]
    F -->

IS 4031 Part 3: Autoclave Method Key Points

Autoclave Specifications (Clause 6.1.5 & 2.1)

• Pressure: 2.1 ± 0.1 MPa gauge pressure (~2.2 MPa absolute)
• Temperature: 215.7 ± 1.7 °C (saturated steam)
• Heating Time: Raise pressure from ambient to 2.1 MPa within 1 to 1.5 hours
• Cooling: Pressure drops from 2.1 MPa to <0.07 MPa within 1 hour after heating stops
• Water Volume: 7-10% of autoclave volume to maintain saturated steam
• Safety: Equipped with safety devices, vent valve, and accurate pressure gauge (±0.02 MPa error max)

Test Procedure (Clause 6.3.1)

• Remove specimens at 24 ± 1 hour after molding from moist atmosphere
• Measure length before autoclaving
• Place specimens on rack ensuring all four sides are exposed to saturated steam
• Maintain saturated steam atmosphere throughout test duration

Important Notes

• Autoclave must vent air early in heating to ensure saturated steam environment
• Retest after aeration (7 days at 27 ± 2°C, 50-80% RH) if cement fails soundness test (Clause 5.4)

Summary Table: Autoclave Conditions

flowchart TD
    A[Specimens at 24±1 hr] --> B[Measure Length]
    B --> C[Place in Autoclave Rack]
    C --> D[Maintain Saturated Steam @ 2.1 MPa, 215.7°C]
    D --> E[Heating: 1-

IS 4031 Part 3 - Apparatus: Key Points

• Autoclave (Clause 6.1.5):

  • High-pressure steam boiler with safety devices.
  • Heating capacity must raise saturated steam pressure under maximum load (water + specimens).
  • Safety valve set to relieve pressure at 6-10% above operating pressure (Clause 6.4.4).

• Le-Chatelier Test Apparatus (Clause 5.1.1):

  • Must conform to IS 5514-1969 (specifications for Le-Chatelier apparatus).
  • Used for determining soundness of cement.

• Moulds:

  • As per IS specifications for cement and concrete testing.

• Specimen Preparation (Clause 6.2):

  • Standardized preparation for consistent test results.

Summary Table of Apparatus Specifications:

flowchart LR
    A[Start] --> B[Prepare Specimens (6.2)]
    B --> C[Place in Moulds]
    C --> D[Use Autoclave for curing (6.1.5)]
    D --> E[Apply Safety Valve (6.4.4)]
    E --> F[Conduct Le-Chatelier Test (5.1.1)]
    F --> G[Results]

This ensures safe, standardized testing conditions per IS 4031 Part 3.

IS 4031 Part 3: Preparation of Test Specimens (Clause 6.2 Highlights)

• Mould Preparation (6.2.1):

  • Thinly coat moulds with mineral oil for easy demoulding.
  • Insert stainless steel/non-corroding metal reference inserts with knurled heads to maintain effective gauge length = 250 mm.
  • Keep inserts clean and oil-free.

• Moulding Specimens (6.2.3):

  • Immediately after mixing, mould specimens in 1 or 2 layers.
  • Compact each layer using thumb/forefinger, pressing paste into corners, around inserts, and along mould surfaces for homogeneity.
  • After final compaction, trim paste flush with mould top and smooth surface with a trowel.
  • Use rubber gloves during mixing and moulding for hand protection.

• Autoclave (6.1.5):

  • High-pressure steam boiler with safety devices.
  • Heating capacity must raise saturated steam pressure adequately for specimen curing.

Summary Table for Specimen Preparation

flowchart TD
    A[Mix Cement Paste] --> B[Mould Preparation]
    B --> C[Apply Mineral Oil]
    C --> D[Insert Reference Inserts (250 mm)]
    D --> E[Moulding Specimens]
    E --> F[Compact in 1 or 2 layers]
    F --> G[Trim & Smooth Surface]
    G --> H[Cure Specimens in Autoclave]

For detailed physical test methods and mould specifications, refer to IS 4031 Part 4 and relevant mould standards.

IS 4031 Part 3 - Testing Procedure for Soundness of Cement

Key Specifications & Preparation (Clause 6.2)

• Mould Preparation (6.2.1):

  • Moulds must be thinly coated with mineral oil.
  • Insert stainless steel or non-corroding metal reference inserts with knurl heads.
  • Ensure an effective gauge length of 250 mm.
  • Inserts must be clean and oil-free.

• Autoclave Requirements (6.1.5):

  • High-pressure steam boiler with safety devices.
  • Heating capacity to raise saturated steam pressure with maximum load (water + specimens).

Testing Procedure Summary

1. Prepare cement paste as per IS 4031 Part 4 for consistency.
2. Cast specimens in prepared moulds with reference inserts.
3. Cure specimens in saturated steam in autoclave at specified pressure and temperature.
4. Measure length change using gauge length (250 mm) to assess soundness.

Important Formula for Soundness (Length Change)

[ \text{Soundness} = \frac{\Delta L}{L_0} \times 100% ]

• (\Delta L) = Change in length after autoclaving (mm)
• (L_0 = 250 \text{ mm (gauge length)})

Acceptable soundness limit: Typically less than 10 mm expansion or as per IS specifications.

flowchart TD
    A[Prepare Moulds] --> B[Apply Mineral Oil]
    B --> C[Insert Reference Inserts (250 mm gauge)]
    C --> D[Cast Cement Paste Specimens]
    D --> E[Cure in Autoclave (Steam, High Pressure)]
    E --> F[Measure Length Change]
    F --> G[Calculate Soundness]

This procedure ensures reliable measurement of cement soundness per IS 4031 Part 3.

IS 4031 Part 3 - Safety Precautions Summary

• Safety Valve Setting (Clause 6.4.4):
  Set the safety valve to relieve pressure at 6% to 10% above the test pressure to prevent overpressure hazards.

• Handling Autoclave Lid (Clause 6.4.5):

  • Use heavy leather gloves to protect hands from burns.
  • Tilt the lid to direct escaping steam away from the operator.
  • Ensure the vent valve is pointed away from personnel.
  • Avoid contact with any hot liquid in the autoclave well to prevent scalding.

Key Safety Measures

flowchart LR
    A[Start Test] --> B[Set Safety Valve (6-10% above pressure)]
    B --> C[Wear Leather Gloves]
    C --> D[Complete Test]
    D --> E{Remove Autoclave Lid}
    E -->|Tilt Lid| F[Steam Directed Away]
    E -->|Do Not Tilt| G[Risk of Scalding]
    F --> H[Dispose Hot Liquids Safely]
    G --> H

Follow these precautions strictly to ensure operator safety during testing.

IS 4031 Part 3 - Retests for Soundness of Cement

Key Specifications (Clause 6.6):

• When to Retest: If cement fails the soundness test.
• Aeration Procedure:
  • Spread the cement sample in a 75 mm thick layer.
  • Store for 7 days.
  • Maintain environment at 27 ± 2°C temperature and 50-80% relative humidity.
• Retesting: After aeration, retest as per Clauses 6.2 and 6.3 (preparation and soundness test methods).

Summary Table for Retest Conditions

Retest Procedure Flow

flowchart TD
    A[Fail Soundness Test] --> B[Spread sample 75 mm thick]
    B --> C[Store 7 days at 27 ± 2°C, 50-80% RH]
    C --> D[Retest as per Clauses 6.2 and 6.3]
    D --> E{Pass?}
    E -->|Yes| F[Accept Cement]
    E -->|No| G[Reject Cement]

This ensures cement quality by allowing hydration and carbonation effects to stabilize before retesting soundness.

IS 4031 Part 3: Calculation and Expression of Results

Key Points from Clauses

• Clause 5.3 (Calculation of Expansion):

  • Calculate the mean of two readings for cement expansion.
  • Round the mean to the nearest 0.5 mm.

• Clause 5.1.3 & 6.1.2 (Weights Permissible Variations):

  • Use weights with permissible variations as per Table 1 below.

• Clause 5.1.2 (Balance Requirements):
  • Permissible variation at 1000 g load: ± 1.0 g (new balance: ± 0.5 g).
  • Sensibility reciprocal ≤ twice permissible variation.
  • Self-indicating balances with equivalent accuracy are allowed.

Summary Formula for Expansion Mean

[ \text{Mean Expansion} = \text{round}\left(\frac{L_1 + L_2}{2}, 0.5 \text{ mm}\right) ]

Where:

• (L_1, L_2) = two measured expansion lengths.

This ensures accuracy and consistency in cement expansion measurement and weighing for testing.