Methods of test for autoclaved cellular concrete products, Part I: Determination of unit weight or bulk density and moisture content
1972 Edition

Scope of This Standard:

• Defines testing procedures for autoclaved cellular concrete products.
• Focuses on determining:
  • Moisture content
  • Unit weight (bulk density)

Related IS 6441 Series Parts:

Rounding Convention:

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

This part ensures uniform testing for essential physical properties critical for quality evaluation of autoclaved cellular concrete.

Dimensions and Shape of Test Specimens

• Minimum thickness: 50 mm
• Two opposite large faces each with an area ≥ 20,000 mm²
• Minimum edge length: 100 mm
• Typical specimen size: 100 mm × 200 mm × 50 mm

Preparation Details

• Specimens are to be cut using rotating carborundum blades or equivalent tools.
• Surfaces must be plane and cleanly cut with maximum deviation from flatness of 0.1 mm measured diagonally.

Specimen Origin

• Specimens may be taken from previously tested items provided they are cut at least 15 cm away from any visible damage or altered zones.
• Specimens must be free of reinforcement.

Measurement Protocol

• Measure length, width, and thickness before drying at 105°C.
• Measurement accuracy should be ±0.1 mm.
• Volume error should not exceed 1%.

Bulk Density Calculation:

[ \text{Bulk Density} = \frac{\text{Weight after drying at } 105^\circ C}{\text{Specimen Volume}} ]

Where volume ( V = L \times W \times T )

Summary Table:

flowchart TD
    A[Cut Specimen] --> B{Is specimen from a prior test?}
    B -- Yes --> C[Cut specimen ≥ 15 cm from damage]
    B -- No --> D[Cut fresh specimen]
    C --> E[Verify no reinforcement]
    D --> E
    E --> F[Measure dimensions (±0.1 mm)]
    F --> G[Dry specimen at 105°C]

Specimen Preparation Highlights:

• Shape and Size:

  • Thickness at least 50 mm
  • Two opposite large surfaces each at least 20,000 mm²
  • Minimum edge length of 100 mm
  • Standard size approximately 100 × 200 × 50 mm

• Cutting Methods:

  • Use rotating carborundum blades or similar cutting tools
  • Surfaces must be flat and cleanly cut
  • Maximum allowed flatness deviation: 0.1 mm diagonally

• Source of Specimens:

  • Specimens can be taken from previously tested pieces if cut at least 15 cm away from any visible defect
  • Reinforcement must not be present

• Dimension Measurement:

  • Length, width, and thickness recorded before drying at 105°C
  • Measurement accuracy should be within ±0.1 mm
  • Volume error must not exceed 1%

• Drying and Weighing:

  • Dry specimens at 105 ± 5°C until constant weight is achieved
  • Cool specimens in a desiccator before weighing
  • Weighing error must be within 0.1%
  • Constant weight is defined as a weight change of ≤0.2% after 4 hours of drying

Volume Calculation

[ V = L \times W \times T ]

Where:

• (L) = length in mm
• (W) = width in mm
• (T) = thickness in mm

Preparation Workflow

flowchart TD
    A[Select Sample] --> B[Cut specimen ≥ 15 cm from damaged areas]
    B --> C[Check surface flatness and dimensions]
    C --> D[Measure length, width, thickness (±0.1 mm)]
    D --> E[Dry at 105 ± 5°C until constant weight]
    E --> F[Cool in desiccator]
    F --> G[Weigh specimen (±0.1% accuracy)]

These steps ensure accurate determination of bulk density, moisture content, and strength according to the standard.

Measurement and Weighing Guidelines:

• Measurement Before Drying:

  • Record length, width, and thickness prior to drying at 105°C
  • Accuracy: ±0.1 mm
  • Volume error must be ≤ 1%

• Drying Procedure:

  • Dry at 105 ± 5°C until weight remains constant
  • Constant weight defined as change ≤ 0.2% after 4 hours of further drying
  • After drying, cool specimens in a desiccator to avoid moisture uptake

• Weighing:

  • Weigh specimens immediately after drying and cooling
  • Weighing error should not exceed 0.1% of specimen weight

• Weights:

  • Weight before drying (wet weight) = (W_1)
  • Weight after drying (dry weight) = (W)

Important Formulas

• Volume:

[ V = L \times W \times T ]

• Moisture Content (%):

[ \text{Moisture Content} = \frac{W_1 - W}{W} \times 100 ]

Where:

• (W_1) = initial weight before drying
• (W) = weight after drying

Summary Table:

flowchart TD
    A[Specimen] --> B[Measure L, W, T (±0.1 mm)]
    B --> C[Dry at 105 ± 5°C to constant weight]
    C --> D[Cool in desiccator]
    D --> E[Weigh specimen (±0.1% error)]

Calculation Formulas and Requirements:

1. Measurement of Dimensions:

• Length (L), width (W), thickness (T) measured before drying
• Accuracy: ±0.1 mm
• Volume calculated as (V = L \times W \times T)
• Volume error limited to ≤ 1%

2. Drying and Weighing:

• Dry specimens at 105 ± 5°C until constant weight within 4 hours
• Weigh immediately after cooling to get dry weight (W)

3. Bulk Density Calculation:

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

• Bulk density (\rho) is weight divided by volume
• Report individual specimen density to three decimal places
• Report mean density of three specimens to two decimal places

Summary Table:

flowchart TD
    A[Measure specimen dimensions] --> B[Calculate volume V = L×W×T]
    B --> C[Dry specimen at 105 ± 5°C]
    C --> D[Weigh dry specimen to get W]
    D --> E[Compute bulk density ρ = W/V]
    E --> F[Report results with required precision]

Essential Elements for Test Reporting:

• Identification:

  • Standard code reference (IS 6441 Part 1)
  • Product identification details
  • Date of manufacture

• Sampling Information:

  • Location, method, and timing of sampling

• Test Results:

  • Bulk density for each specimen and their average
  • Moisture content for each specimen and the average

• Precision and Rounding:

  • Bulk density reported to three decimals for individual specimens and two decimals for the average
  • Moisture content reported as whole percentages
  • Follow rounding procedures as per IS 2:1960

Summary Table:

This format ensures clarity, uniformity, and reliability in presenting test outcomes for autoclaved cellular concrete.