Methods of Tests for Autoclave Cellular Concrete Products, Part VIII: Loading Tests for Flexural Members in Diagonal Tension

IS 6441 Part 8: Introduction - Key Points and Specifications

• Scope: Methods of tests for autoclaved cellular concrete (ACC) products, specifically loading tests for flexural members in diagonal tension.

• Test Specimen:

  • Full-size members as used in construction.
  • Must meet shape and dimension requirements per relevant IS or manufacturer.

• Test Report Requirements (Clause 7.1):

  • Moisture content of specimen.
  • Temperature of specimen.
  • Measured loads, deflections, strains, crack width, and reinforcement end movement at intervals.

• Standard Parts Overview:

  Part	Test Description
  I	Unit weight or bulk density and moisture content
  II	Drying shrinkage
  III	Thermal conductivity
  IV	Corrosion protection of steel reinforcement
  V	Compressive strength
  VI	Flexural members bending – short duration loading
  VII	Flexural members bending – sustained loading
  VIII	Loading tests for flexural members in diagonal tension
  IX	Jointing of ACC elements

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

Typical Test Parameters to Record

Conceptual Diagram: Flexural Member under Diagonal Tension Test

flowchart LR
    A[Load Applied] --> B[Flexural Member]
    B --> C[Diagonal Tension Stress]
    C --> D[Crack Formation]
    D --> E[Measure Deflection, Strain, Crack Width]
    E --> F[Record Data at Intervals]

This standard ensures reliable testing and quality control for ACC flexural members under diagonal tension, critical for structural safety and durability.

IS 6441 Part 8 (1973) — Scope Summary

1. Specimen Size (Clause 2.1)

• Use full-size members as used in actual construction.
• Must comply with relevant IS or manufacturer's specifications for shape and dimensions.

2. Specimen Condition (Clause 2.2)

• Test specimens should be in the condition representative of actual use (details in Clause 2.2).

3. Load Application (Clause 4.2)

• Include the weight of loading equipment when calculating applied load.

4. Test Report Requirements (Clause 7.1)

The report shall include:

• Moisture content of specimen.
• Temperature of specimen.
• Measured values for loads, deflections, strains, crack widths, and reinforcement end movements at specified intervals.

Key Notes:

• The standard emphasizes testing realistic, full-size specimens.
• Accurate measurement and recording of environmental and load parameters are mandatory.
• Loading calculations must consider all applied forces including equipment weight.

flowchart LR
    A[Full-size Specimen] --> B[Condition as per IS/Manufacturer]
    B --> C[Apply Load (Include Equipment Weight)]
    C --> D[Measure: Load, Deflection, Strain, Crack Width]
    D --> E[Record Moisture & Temperature]
    E --> F[Prepare Test Report]

This ensures reliable, reproducible test results aligned with actual field conditions.

IS 6441 Part 8: Test Specimen Key Points

1. Specimen Size (Clause 2.1)

• Must be full-size member as used in actual construction.
• Must conform to shape and dimensions per relevant IS or manufacturer specs.

2. Specimen Condition (Clause 2.2)

• Temperature during testing should be close to ambient.
• Concrete temperature ≥ 0°C to avoid temperature effects on strength.

3. Specimen Type

• Flexural members like floor and roof slabs of cellular concrete.
• Designed for diagonal shear loading tests.

Typical Dimensions & Preparation (General Engineering Practice)

Important Notes:

• Testing full-size members ensures realistic behavior.
• Avoid temperature gradients affecting results.
• Specimen must be free from defects and cured as per IS 456 or relevant standards.

flowchart LR
    A[Full-size Specimen] --> B[Shape & Dimension per IS / Manufacturer]
    B --> C[Condition: Temperature ≥ 0°C]
    C --> D[Testing under Diagonal Shear Loading]

This ensures accurate assessment of strength, deformation, and cracking behavior under realistic conditions.

IS 6441 Part 8: Test Arrangements - Key Points

• Specimen Size (Clause 2.1):

  • Use full-size members matching actual construction dimensions per relevant IS standards or manufacturer specs.

• Specimen Condition (Clause 2.2 & 2.2.2):

  • Concrete temperature must be close to ambient, not less than 0°C.
  • Avoid material temperature differences that affect test results.

• Measurement (Clause 5.4):

  • Measure movement of the end of main tension reinforcement relative to concrete to assess bond/slip behavior.

Typical Test Setup Overview

flowchart LR
    A[Full-size Concrete Specimen] --> B[Reinforcement Embedded]
    B --> C[Apply Load]
    C --> D[Measure Reinforcement End Movement]
    C --> E[Monitor Concrete Surface]

Important Notes:

• Ensure specimen curing and ambient conditions replicate field conditions.
• Use calibrated displacement transducers or LVDTs for measuring reinforcement slip.
• Follow IS 456 and relevant IS codes for concrete and reinforcement specifications.

This ensures reliable bond strength and slip behavior evaluation per IS 6441 Part 8.

IS 6441 Part 8 (1973) — Loading Procedure Key Points

Loading Setup (Clause 4.1 & 4.2)

• Load Application: Single load near support via steel platen ≥ 25 mm thick.
• Platen Width: ≥ 100 mm, increased in 50 mm multiples to keep contact pressure ≤ 20% of concrete compressive strength.
• Packing: Soft fibreboard ≥ 12 mm thick between platen and specimen.
• Load Position: Distance from load axis to inner edge of end steel support ≥ 3 × member depth.
• Load Weight: Include loading equipment weight in applied load calculation.

Loading Rate & Measurement (Clauses 6.1 & 6.2)

• Zero Deflection: Take immediately after member placement.
• Loading Rate: ~1/4 of design live load per minute.
• Measurements: At intervals during loading.
• Crack Load: Maintain load causing diagonal tension crack for 2 hours.
• Failure: Increase load until failure.

Additional Measurement (Clause 5.4)

• Measure relative movement of main tension reinforcement to concrete.

Contact Pressure Calculation

[ \text{Contact Pressure} = \frac{\text{Applied Load}}{\text{Platen Area}} \leq 0.2 \times f_{ck} ]

Where:

• ( f_{ck} ) = Characteristic compressive strength of concrete.

Loading Setup Diagram (Simplified)

graph LR
A[Steel Loading Platen ≥ 25 mm thick] --> B[Soft Fibreboard Packing ≥ 12 mm thick]
B --> C[Concrete Member]
C --> D[Steel Support Plate]
A -. Load applied here .-> C
C -. Distance ≥ 3 × depth .-> D

This ensures uniform load distribution, controlled loading rate, and accurate deflection and crack monitoring per IS 6441 Part 8.

IS 6441 Part 8 (1973) - Key Points on Measurements

• Specimen Size (Clause 2.1):
  Use full-size test specimens matching actual construction members per relevant IS or manufacturer specs.

• Load Consideration (Clause 4.2):
  Include the weight of loading equipment in applied load calculations.

• Measurement Parameters (Clause 7.1):
  Test reports must include:

  • Moisture content of specimen
  • Temperature of specimen
  • Measured loads, deflections, strains, crack widths
  • Movement of the main reinforcement end relative to concrete (Clause 5.4)

• Movement Measurement (Clause 5.4):
  Track relative displacement between main tension reinforcement end and concrete.

Summary Table for Measurements

Formula for Applied Load Including Equipment Weight

[ P_{total} = P_{applied} + W_{equipment} ]

Where:

• (P_{total}) = Total load considered
• (P_{applied}) = Load applied on specimen
• (W_{equipment}) = Weight of loading equipment

flowchart TD
    A[Start Testing] --> B[Prepare Full-size Specimen]
    B --> C[Measure Moisture & Temperature]
    C --> D[Apply Load + Equipment Weight]
    D --> E[Measure Deflection, Strain, Crack Width]
    E --> F[Measure Reinforcement End Movement]
    F --> G[Record & Report All Data]

This ensures compliance with IS 6441 Part 8 measurement requirements.

IS 6441 Part 8 – Test Procedure: Key Points

1. Specimen Requirements (Clause 2.1 & 2.2)

• Size: Full-size member as used in construction, matching shape & dimensions per relevant IS or manufacturer specs.
• Condition: Concrete temperature close to ambient, ≥ 0°C to avoid thermal effects on test results.

2. Test Setup (Clause 3)

• Specimen must be properly supported and loaded to simulate actual service conditions.
• Reinforcement anchorage and loading devices should ensure uniform stress distribution.

3. Measurement (Clause 5.4)

• Displacement Measurement: Movement of the end of main tension reinforcement relative to concrete must be recorded.
• Use precise instruments (e.g., LVDTs) to capture slip or bond slip.

Typical Test Procedure Summary:

flowchart TD
    A[Prepare Specimen] --> B[Set Ambient Temp ≥ 0°C]
    B --> C[Attach Displacement Sensors]
    C --> D[Apply Tensile Load]
    D --> E[Measure Reinforcement Slip]
    E --> F[Record Data & Analyze]

Note: Follow IS 6441 Part 8 for detailed calibration and loading rates.

IS 6441 Part 8 (1973) — Test Report Requirements for Flexural Members in Diagonal Tension

Key Report Specifications (Clause 7.1):

The test report must include:

• Moisture content of the specimen
• Temperature of the specimen during testing
• Measured parameters at various intervals (as per Clause 6):
  • Loads applied (in kN or N)
  • Deflections (mm)
  • Strains (microstrain or mm/mm)
  • Crack width (mm)
  • Movement of the end of main reinforcement (mm)

Additional Notes:

• Specimens should be full size members matching actual construction dimensions (Clause 2.1).
• Report values should be rounded off according to IS 2-1960.
• This ensures consistency and comparability across tests.

Summary Table for Report Contents:

flowchart TD
    A[Test Specimen] --> B{Test at intervals}
    B --> C[Measure Load]
    B --> D[Measure Deflection]
    B --> E[Measure Strain]
    B --> F[Measure Crack Width]
    B --> G[Measure Reinforcement Movement]
    C & D & E & F & G --> H[Compile Report]
    H --> I[Include Moisture Content & Temperature]
    I --> J[Submit Test Report]

This structured reporting ensures clarity in evaluating flexural behavior under diagonal tension per IS 6441 Part 8.