Methods of physical tests for hydraulic cement, Part 12: Determination of air content of hydraulic cement mortar

IS 4031 Part 12 – Scope: Key Specifications & Tables

• Rounding off results:
  Final test/analysis values must be rounded as per IS 2-1960, retaining the same significant figures as the specified value (Clause 0.4).

• Standard Weights & Permissible Variations (Clause 5.3, Table 1):

• Mass of 400 ml Mortar (Clause 6.2):
  After determining water quantity for flow (80–95% with 10 drops in 6 s), remix the mortar for 15 s before testing mass.

• Apparatus Specifications:

  • Flow table per IS 5512-1983 (Clause 5.5)
  • Planetary mixer, moulds, and other apparatus as per referenced IS standards.

This scope ensures standardized measurement precision and apparatus conformity for cement testing.

IS 4031 Part 12: Sampling and Selection of Test Specimens

Key Points from Clause 2: Sampling and Selection

• Sampling Method:
  Samples of cement must be taken as per IS 3535-1986 (Methods of sampling hydraulic cements). This ensures representativeness.

• Sample Preparation:
  The representative cement sample should be thoroughly mixed before testing to ensure uniformity.

Additional Notes:

• Sampling should follow the relevant cement type standard to maintain consistency.
• The final test results must be rounded off according to IS 2-1960, maintaining the same number of significant figures as specified.

Summary Table: Sampling & Specimen Selection

If you need detailed sampling procedures or test specimen sizes, refer directly to IS 3535 and the relevant cement standard.

IS 4031 Part 12: Temperature and Humidity Requirements

• Temperature Control:

  • Moulding room, dry materials, and water must be maintained at 27 ± 2℃ (Clause 3.1).

• Humidity Control:

  • Laboratory relative humidity should be 65 ± 5% (Clause 3.1).

• Sampling:

  • Cement samples must follow IS 3535-1986 for representative sampling and thorough mixing before testing (Clause 2.1).

• Rounding Off Results:

  • Test results should be rounded as per IS 2-1960, maintaining the same significant figures as specified (Clause 0.4).

• Weights for Cement Testing (Clause 5.3, Table 1):

This ensures accuracy in weighing cement samples for tests.

flowchart TD
    A[Maintain Temperature 27 ± 2℃] --> B[Dry Materials & Water]
    A --> C[Moulding Room]
    D[Maintain Humidity 65 ± 5%] --> E[Laboratory Environment]
    F[Sampling as per IS 3535-1986] --> G[Representative Sample]
    G --> H[Thorough Mixing]
    I[Weighing Cement] --> J[Use weights with permissible variation]

Summary: Strict control of temperature and humidity ensures consistent test conditions for cement. Accurate sampling and weighing per IS codes are critical for reliable results.

IS 4031 Part 12: Standard Sand Specifications

• Standard Sand: Must conform to IS 650:1966 - Specification for standard sand for testing cement.
• Key Characteristics of IS 650 Sand:
  • Grain size: 90% passing 600 microns, retained on 150 microns.
  • Fineness modulus: 2.75 to 3.00.
  • Silt content: Less than 1%.
  • Shape: Rounded grains.
• Cylinder Measure: Use as per IS 11263:1985 for measuring mortar volume (typically 200 ml or 400 ml).
• Mass of Mortar for 400 ml: Determined after mixing water adjusted for flow (80-95% flow with 10 drops in 6 s).
• Permissible Variation on Weights (for weighing cement):

Summary of Use:

• Use IS 650 sand for all cement mortar tests to ensure consistency.
• Weigh cement with calibrated weights within permissible variation.
• Adjust water content to achieve standard flow before testing.

flowchart LR
    A[Standard Sand (IS 650)] --> B[Prepare Mortar]
    B --> C[Adjust Water Content]
    C --> D[Measure Flow (80-95%)]
    D --> E[Determine Mass of 400 ml Mortar]
    E --> F[Perform Cement Tests]

This ensures uniformity in cement testing as per IS 4031 Part 12.

IS 4031 Part 12 - Apparatus Key Points

1. Standard Weights (Clause 5.3 & Table 1)

Permissible variation on weights used for weighing cement:

2. Flow Table and Accessories (Clause 5.5)

• Must conform to IS 5512:1983.
• Used for determining flow of mortar (80-95% flow with 10 drops in 6 seconds).

3. Mortar Mixing (Clause 6.2)

• After determining water quantity for desired flow, remix mortar for 15 seconds.
• Use planetary mixer as per specified standards.

4. Rounding Off Results

• Follow IS 2:1960 for rounding test results.
• Maintain significant digits as per standard values.

This ensures accuracy and consistency in testing cement using standardized apparatus and procedures.

IS 4031 Part 12: Preparation of Mortar & Determination of Mass

1. Preparation of Mortar (Clause 6.1)

• Prepare mortar as per IS 4031 Part 7, but adjust water to produce flow of 80-95% with 10 drops in 6 seconds on the flow table.
• Use planetary mixer and flow table conforming to IS specifications.

2. Determination of Mass of 400 ml Mortar (Clause 6.2)

• After determining water for required flow, remix mortar for 15 seconds.
• Fill a 400 ml measuring container on a flat support.
• Wipe excess and weigh to find mass (Mm) in grams.

3. Calculation of Air Content (Clause 7.1)

[ A = \frac{V - \frac{M_m}{D}}{V} \times 100 ]

Where:

Density of air-free mortar:

[ D = \frac{M_1 + M_2 + V_w}{\frac{M_1}{S_1} + \frac{M_2}{S_2} + V_w} ]

Summary Table for Air Content Calculation

IS 4031 Part 12: Calculation & Reporting of Air Content of Hydraulic Cement Mortar

Key Formula for Air Content (Clause 7.1)

[ A = \frac{(D - M_m)}{D} \times 100 ]

Where:

• ( A ) = Percentage of entrained air by volume (%)
• ( M_m ) = Mass of 400 ml of mortar (g)
• ( D ) = Density of air-free mortar (g/cm³)

Density ( D ) is calculated as:

[ D = \frac{M_1 + M_2 + V_w}{\frac{M_1}{S_1} + \frac{M_2}{S_2} + V_w} ]

Where:

Reporting

• Report air content ( A ) to the nearest 0.1%.
• Use standardized equipment as per latest instrument specifications for reproducible results.

Summary Table

flowchart LR
    Cement(Mass M1) -->|Density S1| DensityCalc
    Sand(Mass M2) -->|Density S2| DensityCalc
    Water(Volume Vw) --> DensityCalc
    DensityCalc --> CalculateD(D)
    MortarMass(Mm) --> CalculateA
    CalculateD --> CalculateA
    CalculateA --> AirContent(A%)

References:

• IS 4031 Part 12 (latest revision)
• IS 4031 Part 11 (Density determination)