Methods of test for autoclaved cellular concrete products, Part IX: Jointing of autoclaved cellular concrete elements

IS 6441 Part 9 — Scope & Key Specifications Summary

Scope:
This part of IS 6441 covers testing methods and reporting for joint strength in autoclaved cellular concrete elements.

Key Reporting Requirements (Clause 4.2)

Test reports must include:

• Location, date, and specimen sampling method
• Element specification and designation
• Joint design designation
• Jointing method description
• Curing rate of jointing material (wet erection)
• Joint strength for each specimen (kg/m)
• Mean joint strength for the series (kg/m), rounded per IS 2-1960

Loading Arrangement (Fig. 1)

• h = thickness of element
• b = width of element
• a = b - 2h (minimum 100 mm)
• s = rigid load spreader (e.g., 25 mm mild steel plate)
• t = 12 mm porous fibre board
• I = clearance between elements

Joint Strength Expression (Clause 4.1.1)

• Joint strength per specimen: kg/m
• Mean joint strength for series: kg/m, rounded as per IS 2-1960

Summary Table: Joint Strength Testing Parameters

flowchart LR
    A[Element Width (b)] --> B[Calculate a = b - 2h]
    B --> C{Is a < 100 mm?}
    C -- Yes --> D[a = 100 mm]
    C -- No --> E[Use calculated a]
    E --> F[Load applied via rigid plate (s)]
    D --> F
    F --> G[Joint strength measured (kg/m)]

For detailed procedures, refer to IS

IS 6441 Part 9: Test Specimens for Jointing of Autoclaved Cellular Concrete Flexural Members

Key Specifications for Test Specimens (Clause 2)

• Specimen Size (2.1):

  • Each specimen consists of 3 element parts joined together.
  • Each element part conforms to relevant IS or manufacturer’s shape and dimensions.
  • Total specimen length: 0.5 m (see Fig. 1 in the standard).
  • A series of 3 specimens shall be tested for joint strength.

• Temperature of Specimen (2.1.1):

  • Specimen temperature during testing should be close to ambient.
  • Must not be less than 0°C.

• Moisture Content (2.1.2):

  • Moisture content should be indicated.
  • Must be ≥ 10% by weight, per IS 6441 (Part 1) - 1972.

Summary Table

This ensures uniformity and reliability in testing joint strength of autoclaved cellular concrete members.

IS 6441 Part 9: Size of Specimens for Testing Joint Strength

Specimen Dimensions (Clause 2.1)

• Each specimen consists of 3 element parts joined together.
• Each element part length = 0.5 m.
• Elements conform to relevant IS or manufacturer's shape and dimension requirements.
• Width (b) and thickness (h) as per element specifications.

Loading Arrangement (Fig. 1)

• Load applied via a rigid spreading strip (s), typically a 25 mm thick mild steel plate.
• Load strip width:
  [ a = b - 2h, \quad \text{but not less than } 100 \text{ mm} ]
• Porous fibre board thickness (t) = 12 mm.
• Clearance (l) maintained between elements.

Testing Series

• Test 3 specimens per series.
• Joint strength expressed in kg/m.
• Mean value rounded per IS 2-1960 rounding rules.

Summary Table: Specimen Parameters

flowchart LR
    A[3 Element Parts (0.5 m each)] --> B[Joined Specimen]
    B --> C[Load applied via steel plate (s)]
    C --> D[Load strip width a = b - 2h (≥100 mm)]
    D --> E[Porous fibre board (t = 12 mm)]
    E --> F[Measure joint strength (kg/m)]
    F --> G[Calculate mean of 3 specimens]

This ensures consistent and standardized specimen sizing for reliable joint strength testing of autoclaved cellular concrete elements.

IS 6441 Part 9: Temperature of Specimen

• Clause 2.1.1:

  • Specimen temperature must be close to ambient test temperature.
  • Minimum temperature: 0℃ (no specimen should be tested below this).

• Clause 2.1.2:

  • Moisture content must be ≥ 10% by weight (per IS 6441 Part 1 - 1972).

• Key Specification:

  • Maintain specimen at ambient temperature during testing to avoid thermal effects on strength.

Summary Table: Specimen Temperature Requirements

Important Notes:

• Jointing methods must follow manufacturer instructions (Clause 2.2).
• Strength of jointing expressed in kg/m (Clause 4.1.1).

flowchart LR
    A[Ambient Temperature] --> B[Specimen Temperature]
    B -->|Maintain close to ambient| C[Test Specimen]
    C --> D[Strength Measurement]
    B -.->|Must not be < 0℃| E[Minimum Temperature Limit]

This ensures reliable and consistent test results per IS 6441 Part 9.

Moisture Content of Specimen (IS 6441 Part 9)

• Requirement: Moisture content during testing ≥ 10% by weight.
• Reference Method: Determined as per IS 6441 (Part 1) - 1972, which covers methods for unit weight and moisture content of autoclaved cellular concrete.

Key Points:

• Moisture content is critical to maintain specimen integrity and test accuracy.
• Specimen temperature should be close to ambient, not less than 0°C (Clause 2.1.1).
• Moisture content is expressed as:

[ \text{Moisture Content (%)} = \frac{W_{wet} - W_{dry}}{W_{dry}} \times 100 ]

Where:

• ( W_{wet} ) = Weight of specimen before drying
• ( W_{dry} ) = Weight after drying to constant mass

Typical Procedure (from IS 6441 Part 1):

1. Weigh specimen immediately after removal from curing (wet weight).
2. Dry specimen in an oven at 105°C ± 5°C until constant weight.
3. Calculate moisture content using formula above.

Additional Notes:

• Maintaining moisture content ≥10% ensures realistic behavior under load.
• Specimen joints (if any) should be prepared as per manufacturer’s instructions (Clause 2.2.1).

flowchart TD
    A[Wet Specimen] --> B[Weigh Wet (W_wet)]
    B --> C[Dry in Oven at 105°C]
    C --> D[Weigh Dry (W_dry)]
    D --> E[Calculate Moisture Content %]

IS 6441 Part 9 - Jointing: Key Points & Formulas

Specimen Size & Preparation (Clause 2.1)

• Each test series: 3 specimens.
• Each specimen: 3 elements, length 0.5 m each.
• Elements conform to relevant IS or manufacturer's shape/dimensions.
• Jointing as per manufacturer's directions.

Jointing Method (Clause 2.2 & 2.2.1)

• Follow manufacturer's prescribed jointing method.
• For cold weather, use modified jointing if prescribed.
• If no jointing material is needed, joint without material as directed.

Loading Arrangement (Fig. 1)

• Load applied via 25 mm thick mild steel plate (s).
• Dimensions:
  • h = element thickness
  • b = element width
  • a = b - 2h, but ≥ 100 mm
  • t = 12 mm porous fibre board
  • I = clearance between elements

Strength Calculation (Clause 4.1.1)

• Joint strength per specimen expressed in kg/m.
• Mean joint strength = average of 3 specimens, rounded per IS 2-1960.

Summary Formula for Load Application Width:

[ a = \max(b - 2h, 100 \text{ mm}) ]

Diagram: Loading Setup for Jointed Elements

graph LR
A[Steel Plate (s) 25mm thick] --> B[Specimen Element 1]
B --> C[Joint]
C --> D[Specimen Element 2]
D --> E[Joint]
E --> F[Specimen Element 3]
subgraph Dimensions
    h[Thickness h]
    b[Width b]
    a[a = b - 2h (≥100 mm)]
    t[Porous fibre board 12mm]
end

Note: Always refer to the manufacturer's instructions for jointing specifics and cold weather modifications.

IS 6441 Part 9: Jointing Without Material - Key Points

• Specimen Size (Clause 2.1):

  • Each specimen = 3 elements, length = 0.5 m each, conforming to shape/dimensions per IS or manufacturer.
  • Test series = 3 specimens.

• Jointing Method (Clause 2.2 & 2.2.1):

  • Jointing without any jointing material when no load interaction is needed.
  • Follow manufacturer's directions strictly, including cold weather modifications.

• Load Application (Fig. 1 & Clause 2.2):

  • Load applied through a rigid steel plate (25 mm thick).
  • Dimensions:
    • h = element thickness
    • b = element width
    • a = b - 2h (minimum 100 mm)
    • t = 12 mm porous fibre board
    • I = clearance between elements

• Strength Expression (Clause 4.1.1):

  • Joint strength = kg/m (kilogram per meter length).
  • Mean joint strength = average of 3 specimens, rounded per IS 2-1960.

Load Application Formula for Jointing Test

[ a = \max(b - 2h, 100 \text{ mm}) ]

Summary Table

flowchart TD
    A[Specimen: 3 elements, 0.5 m each] --> B[Jointing without material]
    B --> C[Load applied via 25mm steel plate]
    C --> D[Load spread length a = b - 2h ≥ 100 mm]
    D --> E[Strength measured in kg/m]
    E --> F[Average of 3 specimens]
``

Support of Interjacent Element as per IS 6441 Part 9

Key Specifications:

• Supports for External Element Parts (Clause 3.1):

  • Each external element part shall rest on 3 firm supports.
  • Two supports placed at a distance equal to the thickness (h) of the element from the joint.
  • Third support placed centrally between the two.

• Support Removal (Clause 2.2.2):

  • Support of the interjacent element must not be removed until testing is completed.

Loading Arrangement (Fig. 1):

• Parameters:
  • ( h ) = thickness of element
  • ( b ) = width of element
  • ( s ) = rigid load spreading device (e.g., 25 mm thick mild steel plate)
  • ( a = b - 2h ), but not less than 100 mm
  • ( t = 12 \text{ mm porous fibre board} )
  • ( I ) = clearance between elements

Strength Calculation (Clause 4.1):

[ \text{Joint Strength} = \frac{\text{Total load at rupture (including weight of interjacent element + loading equipment)}}{\text{length of joint}} \quad \text{(kg/m)} ]

Summary Table for Support Positions:

graph LR
A[External Element Part] -- Support 1 at h --> S1[Support 1]
A -- Support 3 at midpoint --> S3[Support 3]
A -- Support 2 at h --> S2[Support 2]
S1 & S2 & S3 --> Joint[Jointed Element]

This arrangement ensures proper load transfer and stability during testing of jointed cellular concrete elements.

IS 6441 Part 9: Key Points on Curing of Cellular Concrete

• Curing Method:
  Follow the manufacturer's directions strictly for curing the mortar and specimens (Clause 2.3).
  Specimens must not be moved between jointing and testing.

• Moisture Content:
  Moisture content during testing should be ≥ 10% by weight (Clause 2.1.2), measured as per IS 6441 Part 1 (1972).

• Jointing & Curing:
  Jointing is done per manufacturer’s instructions (Clause 2.2). Modified jointing methods for cold weather are allowed and tested similarly.

• Load Application Setup (Fig.1):

  • Thickness of element: h
  • Width of element: b
  • Load spreading plate: s = 25 mm thick mild steel
  • Load strip width: a = b - 2h, minimum 100 mm
  • Porous fiber board thickness: t = 12 mm
  • Clearance between elements: I

Summary Table for Moisture Content & Curing

flowchart LR
    A[Mixing & Jointing] --> B[Curing as per Manufacturer]
    B --> C[Maintain Moisture ≥ 10%]
    C --> D[No Movement till Testing]
    D --> E[Load Application Setup]

Note: For detailed curing duration and environmental conditions, always refer to the specific manufacturer's guidelines as IS 6441 Part 9 defers to them.

IS 6441 Part 9 - Testing Key Points

1. Loading Procedure (Clause 3.3)

• Loading start: Not before manufacturer's recommended curing period.
• Loading rate: ~50 kg/min until rupture.
• Accuracy: Rupture load measured with ±1.5% permissible deviation.

2. Test Specimen Conditions (Clause 2.1.1)

• Specimen temperature ≈ ambient temperature, minimum 0°C.

3. Jointing Material (Clause 2.2.1)

• If no jointing material is required, joint specimens without it per manufacturer’s directions.

4. Load Application Setup

• Use a rigid load spreading strip (e.g., 25 mm thick mild steel plate).
• Dimensions:
  • Thickness of element = h
  • Width of element = b
  • Load spread length = a = b - 2h, minimum 100 mm
  • Porous fibre board thickness = t = 12 mm
  • Clearance between elements = I

5. Reporting Test Results (Clause 4.2)

Test report must include:

• Place, date, specimen method
• Element and joint designations
• Jointing method description
• Curing rate (wet erection)
• Individual and mean joint strength values
• Numerical values rounded as per IS rules

Load Application Diagram (Conceptual)

flowchart TB
    A[Load Application Strip (25mm Steel Plate)]
    B[Specimen Element]
    C[Porous Fibre Board (12mm)]
    D[Joint Clearance (I)]
    
    A --> B
    B --> C
    C --> D

This ensures standardized, accurate testing of joint strength in cellular concrete elements per IS 6441 Part 9.

IS 6441 Part 9 - Laying on Supports: Key Specifications & Formulas

1. Support Arrangement (Clause 3.1)

• Each external element part is laid on 3 firm supports.
• Two supports are placed at a distance from the joint equal to the thickness (h) of the element.
• The third support is central, under the joint (see Fig. 1 in code).

2. Loading Appliances (Clause 3.2)

• Load applied as a linear load along the center line of the central element, parallel to joints.
• Load transmitted through a 12 mm thick porous fibre board (t).
• Load uniformly distributed over an area with:
  • Length = 500 mm
  • Width = ( a = b - 2h ), but not less than 100 mm

Where:

• ( h ) = thickness of element
• ( b ) = width of element

3. Load Spreading Device

• A rigid device (e.g., 25 mm thick mild steel plate) spreads the load.

Summary Formula for Load Area Width:

[ a = \max( b - 2h, , 100 \text{ mm} ) ]

Diagram (Simplified):

graph LR
A[External Element Part] -->|Supported on| B(Firm Support 1 at distance h)
A -->|Supported on| C(Firm Support 2 at distance h)
A -->|Supported on| D(Firm Support 3 at center joint)
E[Load Applied] -->|Through| F[12 mm Porous Fibre Board]
F -->|On| G[Load Spreading Device (25 mm steel plate)]

Note:

• Supports must remain until testing if interjacent elements are supported (Clause 2.2.2).
• Jointing material may be omitted if not required (Clause 2.2.1).

This ensures uniform load distribution and stability during testing of cellular concrete elements.

IS 6441 Part 9: Loading Appliances for Cellular Concrete Elements

Key Specifications (Clause 3.2 & Fig. 1)

• Load application: Linear load along the centerline of the central element, parallel to joints.
• Load pad: Porous fibre board, 12 mm thick.
• Load distribution area:
  • Length = 500 mm
  • Width = ( a = b - 2h ), but not less than 100 mm
    • where:
      • ( b ) = width of element
      • ( h ) = thickness of element
• Load spreading device: Rigid plate (e.g., 25 mm thick mild steel plate)

Load Width Calculation Formula

[ a = \max(100, \text{mm}, b - 2h) ]

Loading Procedure (Clause 3.3)

• Load increase rate: ~50 kg/min until rupture.
• Measure rupture load with max deviation ±1.5%.
• Do not load joints before manufacturer's recommended curing period.

Strength Calculation (Clause 4.1)

[ \text{Joint Strength} = \frac{\text{Total Load at Rupture (kg)}}{\text{Length of loaded area (m)}} ]

Expressed in kg/m including weight of interjacent element and loading equipment.

flowchart LR
    A[Load applied along centerline] --> B[Through 12 mm porous fibre board]
    B --> C[Load spread on area 500 mm x a]
    C --> D{Width a = b - 2h}
    D -->|If a < 100 mm| E[a = 100 mm]
    D -->|If a ≥ 100 mm| F[a = b - 2h]
    F --> G[Load applied at 50 kg/min until rupture]
    E --> G
    G --> H[Measure rupture load ±1.5%]
    H --> I[Calculate joint strength kg/m]

Summary: Apply a linear load via a 12 mm porous fibre board over a minimum 500 mm length and width (a = \max(100, b-2h)) mm. Increase load at ~50 kg/min until rupture, then calculate strength as load per meter

IS 6441 Part 9: Loading Procedure Key Points

Loading Arrangement (Clause 3.2 & Fig. 1)

• Load applied linearly along the centerline of the central element, parallel to joints.
• Load transmitted through a 12 mm thick porous fibre board.
• Load distributed uniformly on an area:
  • Length = 500 mm
  • Width ( a = b - 2h ), but not less than 100 mm
    • where:
      • ( b ) = width of element
      • ( h ) = thickness of element

Load Application Strip Parameters

Loading Rate & Testing (Clause 3.3)

• Load increase rate: ~50 kg/min
• Load at rupture measured with max deviation of ±1.5%
• Testing to start after manufacturer recommended curing time.

Strength Calculation (Clause 4.1)

[ \text{Strength of joint} = \frac{\text{Total load at rupture (kg)}}{\text{Length of loaded area (m)}} ] Expressed in kg/m including weight of interjacent element and loading equipment.

flowchart LR
    A[Load applied] --> B[Porous fibre board (12 mm)]
    B --> C[Load spreading device (25 mm steel plate)]
    C --> D[Central element centerline]
    D --> E[Jointed elements]

This ensures uniform linear load distribution and accurate joint strength measurement.

IS 6441 Part 9: Reporting Test Results - Key Points

Testing Procedure (Clause 3.3)

• Load joint after manufacturer-recommended curing period.
• Increase load at ~50 kg/min until rupture.
• Measure rupture load with max ±1.5% deviation.

Reporting Requirements (Clause 4.2)

Test report must include:

Strength Expression (Clause 4.1.1)

• Express joint strength in kg/m.
• Round off values per IS 2-1960 rounding rules.

Load Application Setup

• Use a rigid load spreading strip (e.g., 25 mm thick mild steel).
• Dimensions:
  • Thickness ( h )
  • Width ( b )
  • Load strip length ( a = b - 2h ), minimum 100 mm
  • Porous fiber board thickness ( t = 12 ) mm

Summary Table: Reporting Test Results

flowchart TD
    A[Start Test] --> B[Wait Manufacturer Curing Period]
    B --> C[Apply Load at 50 kg/min]
    C --> D{Rupture Occurs?}
    D -- No --> C
    D -- Yes --> E[Record Rupture Load (±1.5% accuracy)]
    E --> F[Calculate Joint Strength (kg/m)]
   

IS 6441 Part 9: Key Details for Test Report

Test Report Must Include (Clause 4.2):

• a) Place, date, and method of specimen collection
• b) Specification and designation of the element tested
• c) Designation of the joint design
• d) Description of jointing method
• e) Rate of curing of jointing material (for wet erection)
• f) Joint strength for each specimen
• g) Mean joint strength for the test series

Testing Conditions (Clause 3.3 & 2.1):

• Load applied at ~50 kg/min until rupture
• Loading at rupture measured with max ±1.5% deviation
• Specimen temperature ≥ 0°C, close to ambient
• Moisture content ≥ 10% by weight (per IS 6441 Part 1)

Rounding Rules:

• Numerical values should be rounded as per the revised rules (not detailed here).

Summary Table for Test Report Content:

flowchart TD
    A[Specimen Collection] --> B[Test Setup]
    B --> C[Load Application @ 50 kg/min]
    C --> D[Measure Rupture Load ±1.5%]
    D --> E[Record Joint Strength per Specimen]
    E --> F[Calculate Mean Strength]
    F --> G[Prepare Test Report with Required Details]

This ensures compliance with IS 6441 Part 9 for joint testing and reporting.