Methods of Tests for Autoclave Cellular Concrete Products, Part VIII: Loading Tests for Flexural Members in Diagonal Tension
1973 Edition

Overview of Testing Methods for Autoclaved Cellular Concrete Flexural Members under Diagonal Tension

• Scope: Procedures for testing autoclaved cellular concrete (ACC) products, focusing on load testing of flexural elements under diagonal tension.

• Specimen Details:

  • Full-scale members reflecting actual construction use.
  • Must meet shape and size requirements as per relevant IS or manufacturer.

• Reporting Essentials (Clause 7.1):

  • Specimen moisture content and temperature.
  • Recorded loads, deflections, strains, crack widths, and reinforcement displacement during the test.

• Standard Parts Summary:

  Part	Description
  I	Determining unit weight/bulk density and moisture content
  II	Measuring drying shrinkage
  III	Assessing thermal conductivity
  IV	Evaluating corrosion protection of steel reinforcement
  V	Testing compressive strength
  VI	Flexural testing – short-term loading
  VII	Flexural testing – sustained loading
  VIII	Load tests for flexural members in diagonal tension
  IX	Jointing techniques for ACC elements

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

Typical Test Parameters

Conceptual Flowchart: Flexural Member Diagonal Tension Test

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

This specification ensures consistent testing and quality control of ACC flexural members subjected to diagonal tension, critical for structural integrity.

Scope Summary for Testing Flexural Members in Diagonal Tension (1973 Edition)

1. Specimen Dimensions (Clause 2.1)

• Use full-scale members identical to those employed in actual structures.
• Must adhere to shape and size requirements from the relevant Indian Standard or manufacturer's guidelines.

2. Specimen Condition (Clause 2.2)

• Test specimens should reflect real use conditions as detailed in Clause 2.2.

3. Load Considerations (Clause 4.2)

• The weight of the loading apparatus must be included when calculating total applied load.

4. Reporting (Clause 7.1)

• Test reports must document:
  • Moisture content and temperature of specimens.
  • Recorded loads, deflections, strains, crack widths, and reinforcement displacement at specified intervals.

Important Points:

• Emphasis on testing realistic full-size specimens.
• Precise measurement and recording of environmental and load parameters.
• Inclusion of all loads (including equipment weight) in calculations.

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

This approach guarantees reproducible results that mirror actual field performance.

Key Specifications for Test Specimens

1. Specimen Size (Clause 2.1)

• Must be full-size members identical to those used in construction.
• Conform to the shapes and dimensions specified by relevant IS or the manufacturer.

2. Specimen Condition (Clause 2.2)

• Testing temperature should be near ambient.
• Concrete temperature not below 0°C to avoid temperature-induced strength variations.

3. Specimen Types

• Includes flexural members such as floor and roof slabs made from cellular concrete.
• Designed for diagonal shear load testing.

Typical Dimensions and Preparation

Notes:

• Full-size specimens ensure testing represents in-service behavior.
• Avoid temperature gradients during testing.
• Specimens should be defect-free and cured following IS 456 or equivalent standards.

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

This ensures precise evaluation of strength, deformation, and cracking under realistic conditions.

Key Aspects of Test Setup for Diagonal Tension Loading

• Specimen Size (Clause 2.1): Must be full-scale members matching actual construction dimensions per relevant IS or manufacturer.

• Specimen Condition (Clauses 2.2 & 2.2.2): Concrete temperature should be near ambient and not less than 0°C to prevent temperature-related effects.

• Measurement (Clause 5.4): Monitor displacement of the main tension reinforcement end relative to the surrounding concrete to evaluate bond and slip.

Typical Setup Overview

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

Additional Notes:

• Specimens should be cured and tested under conditions simulating field environment.
• Utilize calibrated devices such as LVDTs for displacement measurement.
• Follow IS 456 and applicable IS codes for concrete and reinforcement standards.

This setup ensures accurate assessment of bond strength and slip behavior as per the standard.

Guidelines for Applying Load on Flexural Members (1973 Edition)

Loading Configuration (Clauses 4.1 & 4.2)

• Apply a single load near the support using a steel platen at least 25 mm thick.
• Platen width should be at least 100 mm and increased in 50 mm increments to maintain contact pressure at or below 20% of the concrete's compressive strength.
• Place a soft fibreboard pad at least 12 mm thick between the platen and the specimen.
• The load point must be at a minimum distance of three times the member depth from the inner edge of the steel support.
• Include the weight of loading equipment in the total load calculation.

Loading Rate and Measurements (Clauses 6.1 & 6.2)

• Record zero deflection immediately after specimen placement.
• Increase load gradually at approximately one-quarter of the design live load per minute.
• Take measurements at regular intervals.
• Maintain the load that causes the diagonal tension crack for two hours.
• Continue increasing load until failure occurs.

Additional Monitoring (Clause 5.4)

• Measure relative displacement of main tension reinforcement versus concrete.

Contact Pressure Formula

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

Where ( f_{ck} ) is the characteristic compressive strength of concrete.

Loading Setup Illustration

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

This methodology ensures even load distribution, controlled loading speed, and precise monitoring of deflection and cracking.

Measurement Protocols as per the Standard (1973 Edition)

• Specimen Size (Clause 2.1): Use full-scale specimens matching actual construction members.

• Load Consideration (Clause 4.2): Total applied load must include the weight of the loading apparatus.

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

  • Moisture content of the specimen
  • Specimen temperature
  • Loads applied, deflections, strains, crack widths
  • Relative displacement of main reinforcement end regarding concrete (Clause 5.4)

• Displacement Measurement (Clause 5.4): Monitor the slip between main tension reinforcement and concrete.

Measurement Summary

Load Calculation Including Equipment Weight

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

Where:

• ( P_{total} ): Total load for analysis
• ( P_{applied} ): Load applied to specimen
• ( W_{equipment} ): Weight of loading apparatus

flowchart TD
    A[Begin Testing] --> B[Prepare Full-size Specimen]
    B --> C[Measure Moisture & Temperature]
    C --> D[Apply Load + Equipment Weight]
    D --> E[Record Deflection, Strain, Crack Width]
    E --> F[Measure Reinforcement Displacement]
    F --> G[Compile and Submit Report]

This ensures measurement accuracy and compliance with the standard.

Detailed Testing Steps According to the Standard

1. Specimen Criteria (Clauses 2.1 & 2.2)

• Use full-size members identical to those used in practice, matching dimensions and shape per IS or manufacturer.
• Maintain concrete temperature near ambient (≥ 0°C) to avoid thermal influences.

2. Test Setup (Clause 3)

• Properly support specimens and apply loads to simulate actual service conditions.
• Ensure reinforcement anchorage and loading devices distribute stresses uniformly.

3. Measurement Protocol (Clause 5.4)

• Record the displacement of main tension reinforcement ends relative to concrete using precise instruments like LVDTs.

Procedure Summary

flowchart TD
    A[Prepare Specimen] --> B[Set Temperature ≥ 0°C]
    B --> C[Install Displacement Sensors]
    C --> D[Apply Tensile Load Gradually]
    D --> E[Measure Reinforcement Slip]
    E --> F[Record and Analyze Data]

Ensure adherence to IS 6441 Part 8 for calibration and loading rate details.

Reporting Requirements for Flexural Members under Diagonal Tension (1973 Edition)

Essential Report Contents (Clause 7.1):

Reports must include:

• Moisture content of the specimen
• Specimen temperature during testing
• Recorded values at different intervals for:
  • Load (kN or N)
  • Deflection (mm)
  • Strain (microstrain or mm/mm)
  • Crack width (mm)
  • Displacement of main reinforcement end (mm)

Additional Details:

• Specimens tested should be full-scale, matching actual construction dimensions (Clause 2.1).
• Values should be rounded following IS 2-1960.
• This ensures consistency and comparability of test results.

Report Content Table

flowchart TD
    A[Specimen Testing] --> B{Measurements at Intervals}
    B --> C[Load]
    B --> D[Deflection]
    B --> E[Strain]
    B --> F[Crack Width]
    B --> G[Reinforcement Displacement]
    C & D & E & F & G --> H[Compile Report]
    H --> I[Include Moisture & Temperature]
    I --> J[Submit Final Report]

This structured reporting supports clear evaluation of flexural response under diagonal tension.