Specification for wood wool building slabs

IS 3308: Scope - Key Specifications and Tables

IS 3308 covers dimensions, tolerances, deflection, and thermal properties of asbestos cement sheets and slabs.

1. Dimensions & Weight (Clause 6.1, Table 1)

Thickness tolerance is as per Appendix A.

2. Deflection Under Test Load (Clause 8.1, Table 2)

3. Thermal Conductivity

Refer Clause 8.1 for thermal conductivity values (not detailed here).

Summary:

• Slabs: Sizes mainly 2000×500 mm & 1220×610 mm.
• Thickness: 12 mm to 100 mm.
• Max deflection: 5–6 mm under specified test loads.
• Weight: Varies with thickness/type, max 40 kg for Type 2 slabs.

flowchart LR
    A[IS 3308 Scope]
    A --> B[Dimensions & Weight]
    A --> C[Deflection Limits

IS 3308 - Wood Wool Building Slabs: Key Specifications

Types of Wood Wool Slabs (Clause 3.1)

• Type 1: Light Weight Slabs

  • Use: Non-load bearing partitions, ceilings, wall linings, permanent shuttering, roof insulation.
  • Characteristics: Lower density, lighter weight.

• Type 2: Heavy Duty Slabs

  • Use: Load-bearing applications, roof construction, also suitable for Type 1 uses.
  • Characteristics: Higher density, greater strength.

Essential Requirements (Clauses 0.2, 1.1, 12.1.1)

• Composition: Wood wool + inorganic cementing filler, chemically treated and pressed.
• Dimensions & Weight: Specified as per standard (typical slab thickness ranges from 20 mm to 50 mm).
• Strength: Must meet minimum compressive and flexural strength for durability and load-bearing capacity.

Typical Properties (Indicative)

Usage Guidance

• Type 1: Insulation, acoustic panels, decorative linings.
• Type 2: Structural elements requiring load support.

flowchart TD
    A[Wood Wool Building Slabs] --> B{Type}
    B --> C[Type 1: Light Weight]
    B --> D[Type 2: Heavy Duty]
    C --> E[Non-load bearing]
    C --> F[Ceilings, partitions]
    D --> G[Load bearing]
    D --> H[Roof construction]

For detailed manufacturing and testing methods, refer to IS 3308 clauses on quality control and performance.

IS 3308: Material Requirements Key Specifications

1. Dimensions & Weight (Clause 6.1, Table 1)

2. Deflection Limits Under Test Load (Clause 8.1, Table 2)

• Max deflection allowed: 5 to 6 mm depending on thickness and type.
• Test spans and loads vary with slab size and thickness.

3. Sampling for Quality Control (Clause 11.2.2, Table 3)

Additional Notes:

• Thickness tolerance per Appendix A.
• Deflection test ensures structural integrity under load.
• Sampling ensures batch conformity.

flowchart TD
    A[Material Slabs] --> B[Dimensions & Weight]
    A --> C[Deflection Test]
    A --> D[Sampling & Quality Control]
    B --> E[Length, Width, Thickness, Weight]
    C --> F[Test Load, Span, Max Deflection]
    D --> G[Lot Size, Sample Size, Acceptance Criteria]

This summary covers essential material requirements from IS 3308 for design and quality assurance.

IS 3308: Form and Texture of Portland Cement Slabs

Key Specifications (Clause 5.1)

• Slabs must have uniform thickness with rectangular parallel faces.
• Edges must be clean and reasonably square.
• Deviation from rectangular shape ≤ 5 mm along slab edges.
• Texture must be uniform.

Dimensions & Tolerances (Clause 6.1, Table 1)

Deflection Under Test Load (Clause 8.1, Table 2)

Summary:

• Use Fir (Abies spp.) for manufacturing slabs.
• Maintain uniform thickness and texture.
• Ensure dimensional tolerances as per Table 1.
• Deflection under load must not exceed 5-6 mm depending on slab type and thickness.

flowchart LR
    A[Raw Material: Fir (Abies spp.)] --> B[Manufacture Slab]
    B --> C{Check Form & Texture}
    C -->|Uniform Thickness & Texture| D[Pass]

IS 3308: Dimensions and Tolerances for Slabs

Key Specifications (Clause 6.1 & 6.2)

Tolerances (Clause 6.2)

• Length: ±6 mm
• Width: ±4 mm
• Thickness: ±2 mm

Additional Requirements (Clause 5.1)

• Uniform thickness with rectangular, parallel faces
• Edges reasonably square and clean
• Deviation from rectangular shape ≤ 5 mm along slab edge

Measurement Procedure

• Thickness measured as per Appendix A of IS 3308.

Summary Table for Quick Reference

flowchart LR
    A[Specified Dimensions] --> B[Measure Thickness (Appendix A)]
    B --> C{Check Tolerances}
    C -->|Within ±2 mm| D[Accept Slab]
    C -->|Outside Tolerance| E[Reject/Remanufacture]

This ensures slabs meet quality and dimensional

IS 3308: Physical Properties Summary

1. Dimensions and Weight (Clause 6.1, Table 1)

2. Deflection Under Test Load (Clause 8.1, Table 2)

• Deflection limits are 5-6 mm max under specified test loads.
• Load application rate: max 110 kg/min.
• Deflection measured with a deflectometer on a 5 cm diameter metal plate.

3. Thermal Conductivity

• Referenced in Clause 8.1; details in Appendix B (not fully provided here).
• Wood wool slabs have low thermal conductivity, enhancing insulation.

Key Notes:

• Thickness tolerance per Appendix A.
• Deflection testing per Appendix B.
• Weight and size must comply with Table 1.
• Deflection limits ensure structural performance under load.

flowchart LR
    A[Slab Dimensions] --> B[Thickness & Weight per Table 1]
    B --> C[Load Application per Table 2]
    C --> D[Deflection Measurement]
    D --> E[

IS 3308: Mechanical Strength & Deflection Key Points

Deflection Limits (Clause 8.1 & Table 2)

Testing Method (Appendix B)

• Load applied as per Table 2.
• Deflection measured at mid-span.
• Steel plates (5cm × 5cm × 10mm) placed on slab surfaces at measurement points.
• Thickness measured with calipers over steel plates; slab thickness = measured thickness - 2 × plate thickness.

Notes

• Deflection limits ensure slab serviceability under specified loads.
• Test spans and loads vary by slab size and thickness.
• Deflection values are maximum allowable under test load.

Formula for Deflection (General Beam Theory)

For a simply supported slab under uniform load ( w ):

[ \delta_{max} = \frac{5 w L^4}{384 E I} ]

Where:

• ( \delta_{max} ) = max deflection
• ( L ) = span length
• ( E ) = modulus of elasticity
• ( I

IS 3308 - Thermal Conductivity (Clause 9.1)

• Thermal conductivity (k) is measured by the guarded hot plate method as per IS 3346:1966.
• Test conditions:
  • Hot plate temperature = 30°C
  • Cold plate temperature = 25°C
• Maximum thermal conductivity:
  [ k \leq 0.08 , \text{W/m·K} ]

Key Points:

Notes:

• This low thermal conductivity indicates good insulation properties of wood wool slabs.
• Ensure test specimens conform to these conditions for valid results.

flowchart LR
    A[Hot Plate @ 30°C] -->|Heat Flow| B[Specimen (Wood Wool Slab)]
    B -->|Heat Flow| C[Cold Plate @ 25°C]
    B --> D[Measure Heat Flux & Temperature Gradient]
    D --> E[Calculate Thermal Conductivity k]

IS 3308 - Sound Absorption Key Data

Sound Absorption Coefficient (Clause 10.1)

Measured by reverberation chamber method per IS:8225-1976 for 25 mm thickness with rigid backing:

• For other thicknesses, α values are subject to supplier-purchaser agreement (Clause 10.1.1).
• Absorption coefficient α = (Sound energy absorbed) / (Sound energy incident).

Notes:

• Values apply to wood wool slabs of 25 mm thickness, commonly used for acoustical purposes.
• Measurements follow IS:8225 (Reverberation Room Method).
• Final test values should be rounded per IS:2-1960 rules.

Summary Diagram: Sound Absorption Coefficient vs Frequency

graph LR
A[125 Hz: 0.1] --> B[250 Hz: 0.2] --> C[500 Hz: 0.2] --> D[1000 Hz: 0.3] --> E[2000 Hz: 0.5] --> F[4000 Hz: 0.5]

For design, use these coefficients to estimate sound absorption in spaces with 25 mm wood wool slabs backed rigidly.

IS 3308: Sampling and Criteria for Conformity

Sampling Procedure (Clause 11.2.2 & Table 3)

• Select samples randomly from the lot based on lot size:

Criteria for Conformity:

• Clause 11.3.1: Lot is conforming if the number of failing samples ≤ acceptance number.
• Clause 11.4.1: No failures are allowed in the sub-sample for the lot to conform.

Summary:

• Take the specified number of random samples (Table 3).
• Check each sample against requirements.
• If failures ≤ acceptance number, lot passes.
• Sub-sample must have zero failures for final conformity.

flowchart TD
    A[Select Lot] --> B[Random Sampling per Table 3]
    B --> C{Failures ≤ Acceptance Number?}
    C -- Yes --> D{Failures in Sub-sample?}
    C -- No --> E[Reject Lot]
    D -- No --> F[Lot Conforms]
    D -- Yes --> E

This ensures statistically valid quality control per IS 3308.

IS 3308: Marking and Certification - Key Points

1. Marking (Clause 12.1.1)

• Each slab may be marked with the ISI Certification Mark.
• ISI mark ensures:
  • Compliance with IS 3308 requirements.
  • Quality control supervised by ISI.
  • Continuous conformity checks by ISI.
• Use of ISI mark is governed by the Indian Standards Institution (Certification Marks) Act.

2. Certification (Clause 12.2)

• Slabs must meet specific ECO Mark requirements.
• Manufacturer must provide certificate or declaration to BIS for ECO Mark application.

3. Key Tables for Reference

Summary Diagram of Certification Process

flowchart TD
    A[Manufacturer Produces Slabs] --> B[Quality Control & Inspection]
    B --> C[Apply for ISI Certification]
    C --> D[BIS Verification & Testing]
    D --> E{Conforms to IS 3308?}
    E -- Yes --> F[Grant ISI Mark License]
    E -- No --> G[Rectify & Reapply]
    F --> H[Continuous ISI Surveillance]

For detailed procedures and licensing conditions, refer to BIS guidelines on Certification Marks.

IS 3308: Additional Requirements for ECO Mark (Clause 12)

• ECO Mark Purpose:
  Label for environment-friendly wood substitute products, administered by BIS under Ministry of Environment & Forests (MEF).

• Mandatory for ECO Mark Application:

  • BIS Standard Mark (ISI + ECO logo)
  • Environmental consent clearance from State Pollution Control Board as per:
    • Water (Prevention & Control of Pollution) Act, 1974
    • Air (Prevention & Control of Pollution) Act, 1981
    • Water (Prevention & Control of Pollution) Cess Act, 1977
    • Authorization under Environment (Protection) Act, 1986
  • Compliance with Forest Department rules.

• Specific Product Requirements:
  Wood wool building slabs must meet ECO Mark criteria specified in the relevant clauses of IS 3308.

• Documentation:
  Manufacturer must provide certificates/declarations proving environmental compliance when applying for ECO Mark.

Summary Table for ECO Mark Compliance

This ensures products are both structurally compliant and environmentally responsible.

IS 3308: Methods of Measuring Thickness of Asbestos Cement Slabs

Key Procedure (Clause 1.2: Appendix A-1.2)

• Place steel plates (5 cm × 5 cm × 10 mm thick) on both top and bottom slab surfaces at the measurement point.
• Use calipers to measure the total thickness = slab + 2 steel plates.
• Calculate slab thickness as:

[ \text{Slab Thickness} = \text{Measured Total Thickness} - 2 \times \text{Steel Plate Thickness} ]

Measurement Points (Clause 1.1: Appendix A-1.1)

• Measure thickness at points of maximum and minimum apparent thickness.
• Maintain a minimum distance of 10 cm from slab edges.

Relevant Tables

(Refer Table 1 for full details)

Summary:

• Use calipers with steel plates to avoid damage and ensure accuracy.
• Measure at specified points away from edges.
• Thickness tolerance and slab weight limits are defined in Table 1.

flowchart TD
    A[Place Steel Plates (5x5x10 mm)] --> B[Measure Total Thickness with Calipers]
    B --> C[Subtract 2 × Plate Thickness]
    C --> D[Obtain Slab Thickness]

This method ensures precise, non-destructive thickness measurement as per IS 3308 standards.

IS 3308: Loading and Deflection Test Procedures - Key Points

1. Test Setup (Clauses 1.1, 1.2, 27.5, Appendix B)

• Test rig: Spreaders and bearers length ≥ slab width.
• Bearers: 12 mm wide, flat, parallel.
• Spreaders: Timber, 50×75 mm, symmetrically placed.
• Thickness measurement: Place 5×5×10 mm steel plates top & bottom; measure total thickness and subtract steel plates thickness.

2. Loading and Deflection Test (Clause 8.1, Table 2)

3. Notes

• For 1220 mm slabs on steel bearers 27.5 cm apart, spreader distance = 168 mm.
• Deflection limits are strict to ensure slab serviceability.

Summary Diagram of Test Setup

flowchart LR
    A[Slab] -- Thickness measurement --> B[Steel plates (5x5x10