Plywood for concrete shuttering work - Specification

IS 4990 Scope - Key Specifications & Tables

IS 4990 covers structural plywood used in construction, specifying mechanical properties, testing, and quality criteria.

Key Tables:

1. Minimum Average Failing Load & Wood Failure (Table 1)

2. Static Bending Strength (Table 2)

3. Wet Bending Strength (Table 3)

Additional Notes:

• Use IS 2:1960 for rounding off test values.
• For architectural curved forms, design per Clause E-5.3.
• Refer to Annex A for related standards and updates.

flowchart LR
    A[Structural Plywood] --> B[Mechanical Properties]
    B --> C[Failing Load & Wood Failure]
    B --> D[Static Bending Strength]
   

IS 4990 Key References: Structural Plywood Properties & Design

1. Structural Plywood Strength Requirements (Table 1)

2. Static Bending Strength (Table 2)

3. Wet Bending Strength (Table 3)

4. Additional Notes:

• Use E-5.3 data for curved architectural concrete formers.
• Refer to Annex A for related standards; always check for latest editions.
• Round off test values per IS 2:1960 rules, matching significant digits.

This concise data aids in plywood formwork design and quality control per IS 4990.

IS 4990 Key Definitions & Specifications (Referencing IS 707)

1. Definitions

• As per IS 4990, all definitions are adopted from IS 707 (Plywood Specification).

2. Loading & Deflection (Clause 5.2, Table E-5.2)

• Max deflection allowed: 1/270th of span.
• Face grain of plywood must be perpendicular to bearers' length.

3. Structural Strength Requirements

Table 1: Wet Bending Strength (Clause 10.1.3.1.1)

Table 2: Static Bending Strength (MOE & MOR)

Table 3: Wet Bending Strength (MOE & MOR)

| Property | Along Face

IS 4990 - Key Formulas, Tables & Specifications for Materials (Structural Plywood)

1. Glue Shear Strength (Clause 10.1.3.1.1)

2. Static Bending Strength (Modulus of Elasticity & Rupture) (Table 2)

3. Wet Bending Strength (Table 3)

Notes:

• Tests per IS 1734 (Part 4) for glue shear strength.
• Conditions: Room temp 27 ± 2°C, samples tested dry, wet, or boiled.
• Use E-5.3 data for architectural concrete curved form design (Clause 6.8).

flowchart TD
    A[

IS 4990: Timber Species - Key Specifications & Tables

Timber Species (Annex B)

• The code lists 85 timber species with botanical names and abbreviations, e.g.:
  • Teak (Tectona grandis) - TEA
  • Sissoo (Dalbergia sissoo) - SIS
  • Gurjan (Dipterocarpus spp.) - GUR
• Use any timber species if it meets the standard's technical requirements.

Manufacturer's Data (Clause 13)

Manufacturers must provide:

• Timber species and density (mass/m²)
• Adhesive and preservative types
• Loading/deflection tables for shuttering design
• Bendable radii for architectural concrete

Strength & Performance Tables

Wood Failure & Load Requirements (Structural Plywood)

Summary

• Timber species are diverse; select based on manufacturer data.
• Verify MOE

IS 4990: Manufacture and Workmanship Key Points

1. Tolerances on Finished Boards (Clause 7.4, Table 7.4)

• Edge straightness and squareness tested as per Annex C.

2. Mechanical Properties and Workmanship (Clause 10.1.3.1.1, Tables 1-3)

Table 1: Minimum Average Failing Load & Wood Failure (%)

Table 2: Static Bending Strength (Dry)

Table 3: Wet Bending Strength

IS 4990: Dimensions and Tolerances for Plywood Boards

Key Tolerances (Clause 7.4)

• Note: Edge straightness and squareness testing as per Annex C.

Dimension Definitions (Clause 7.1.1)

• Length: Parallel to grain of faces.
• Width: Perpendicular to length.
• Thickness: Board thickness.

Minimum Bending Radii (Clause 5.3, Table E-5.3)

Summary Diagram of Dimensions

graph LR
A[Length (parallel to grain)] --> B[Width (perpendicular to length)]
B --> C[Thickness]

This concise guide ensures plywood boards conform to IS 4990 tolerances for quality and fit in construction applications.

IS 4990: Workmanship and Finish - Key Specifications & Tolerances

1. Dimensional Tolerances (Clause 7.4, Table 7.4)

• Edge straightness and squareness tested as per Annex C.

2. Workmanship and Finish (Clause 8.3)

• Faces of plywood for concrete shuttering with plastic coating or overlay must be:
  • Dense and smooth
  • Free from blisters and patch marks
  • Uniform color
• Sampling & conformity as per IS 7638.

3. Mechanical Properties

a) Wet Bending Strength (Clause 10.1.3.1.1, Table 1)

b) Static Bending Strength (Table 2)

IS 4990 Sampling - Key Specifications & Tables

The code does not explicitly detail sampling procedures but emphasizes test result rounding per IS 2:1960.

Key Tables for Structural Plywood Testing:

1. Failing Load & Wood Failure % (Table 10.1.8)

2. Static Bending Strength (MOE & MOR) (Table 2)

3. Wet Bending Strength (Table 3)

Rounding Off Test Results:

• Follow IS 2:1960 rounding rules.
• Retain same significant figures as specified values.

Summary

• Sampling results are evaluated against above tables for compliance.
• Wood failure % and failing load thresholds define pass/f

IS 4990: Tests and Test Methods - Key Formulas & Tables

1. Wet Bending Strength Requirements (Clause 10.1.3.1.1, Table 1)

2. Static Bending Strength (Clause 10.1.7, Table 2)

3. Wet Bending Strength (Table 3)

4. Additional Notes

• Tests conducted at 27 ± 2°C (room temperature).
• Final test values must be rounded off as per IS 2:1960.
• Wet bending strength test method is newly specified.

flowchart TD
    A[Sample Preparation] --> B[Conditioning at 

IS 4990 - Additional Requirements for ECO-Mark (Clause 11)

• ECO-Mark Purpose:
  Label for environment-friendly plywood under Ministry of Environment and Forests (MEF), administered by BIS.

• Certification:
  Manufacturer must provide documentary evidence (certificate/declaration) to BIS for ECO-Mark application.

• Compliance:
  Plywood must meet all relevant ECO-specific clauses within IS 4990, plus general quality tests (Clauses 10.1.1 to 10.1.9).

• Testing Procedure:

  • If initial sample fails, two additional samples from the same batch are tested.
  • All tests must pass; otherwise, batch is rejected (Clause 10.1.1).

• Marking:
  ECO-Mark is combined with ISI Mark as a single BIS Standard Mark for eco-friendliness.
  Use of ECO-Mark is optional; manufacturers may choose ISI Mark alone.

Summary Table: ECO-Mark Requirements

flowchart TD
    A[Manufacture Plywood Batch] --> B[Test Initial Sample]
    B -- Pass --> C[Apply for ECO-Mark with Documentation]
    B -- Fail --> D[Select 2 Additional Samples]
    D --> E[Test Additional Samples]
    E -- All Pass --> C
    E -- Any Fail --> F[Reject Batch]

This ensures only environmentally compliant plywood is ECO-Mark certified as per IS 4990.

IS 4990: Marking and Certification for Plywood

Key Specifications (Clauses 12.1 & 12.2)

Each plywood panel must be legibly and indelibly marked with:

• Manufacturer's identification mark
• Year of manufacture
• Type of plywood (see Clause 4)
• ECO-Mark labelling criteria (if applicable)
• BIS Standard Mark (optional, per Clause 12.2)

Certification Marking (Clause 12.2.1)

• Use of BIS Standard Mark is governed by the Bureau of Indian Standards Act, 1986.
• Licence conditions for use of the Standard Mark must be obtained from BIS.

Manufacturer's Information to Supply (Clause 13)

• Adhesive type
• Preservative type
• Recommended bending radii for architectural concrete work
• Loading and deflection tables for support design
• Density or mass per square meter
• Timber species used (see Annex B for species list)

Important Tables and References

Testing & Batch Acceptance (Clause 10.1.1)

• If initial samples fail, two more batches tested.
• Batch rejected if further samples fail.

Summary Diagram: Marking & Certification Flow

flowchart TD
    A[Plywood Panel] --> B[Mark with Manufacturer ID]
    B --> C[Mark Year of Manufacture]
    C --> D[Mark Type of Plywood]
    D --> E[Mark ECO-Mark Criteria (if any)]
    E --> F[Apply BIS Standard Mark (optional)]
    F --> G[Supply Technical Data on Demand]

This ensures traceability, quality assurance, and compliance with IS 4990 for plywood products.

IS 4990: Information to be Supplied by Manufacturer

Key Specifications & Requirements:

• Glue Shear Strength (Clause 10.1.3.1.1 & 10.1.5.1):

  • Test method: IS 1734 (Part 4)
  • The average failing load must meet or exceed values in Table 1 (values depend on plywood type/thickness).

• Rounding Off Values (General Clause):

  • Follow IS 2:1960 for rounding numerical results.
  • Maintain the same number of significant digits as specified in the standard.

• Curved Surface Design Data (Clause E-6.8):

  • Use data from Clause E-5.3 for architectural concrete and curved form design.

Typical Table 1 (Glue Shear Strength) Example:

(Note: Refer to IS 4990 Table 1 for exact values)

Summary for Manufacturer:

• Provide glue shear strength test results per IS 1734 (Part 4).
• Specify plywood thickness and type.
• Confirm curved form design data compliance if used for architectural concrete.
• Round off test values per IS 2:1960 rules.

flowchart TD
    A[Manufacturer] --> B[Provide Glue Shear Strength Data]
    B --> C[Test per IS 1734 (Part 4)]
    C --> D[Compare with Table 1 Values]
    A --> E[Provide Curved Form Design Data]
    E --> F[Use Data from Clause E-5.3]
    A --> G[Round off Values]
    G --> H[Follow IS 2:1960]

IS 4990: List of Referenced Indian Standards & Timber Species

Key Referenced IS Standards (Annex A)

Timber Species (Annex B)

• Common species with botanical names and abbreviations:

Full list includes 80+ species with trade and botanical names.

Important Notes for Manufacturers (Clause 13)

• Must supply technical data on adhesives, preservatives, bending radii, loading/deflection tables, density, and timber species.

Certification Marking (Clause 12.2.1)

• Use of BIS Standard Mark governed by BIS Act 1986 and related rules.

flowchart TD
    A[IS 4990 Standard] --> B[Annex A: Referenced IS]
    A --> C[Annex B: Timber Species]
    B --> D[IS 707 - Glossary]
    B --> E[IS 1734 - Plywood Tests]
    B --> F[IS 5539 - Preservative Plywood]
    C --> G[Teak (TEA)]
    C --> H[Sissoo (SIS)]
    C --> I[Mango (MAN)]

This summary aids quick cross-reference of standards and timber species critical for plywood and timber product compliance under IS 4990.

IS 4990: Timber Species for Plywood - Key Points

Timber Species (Clause 5.1 & Annex B)

• Any timber species can be used for plywood for concrete shuttering.
• Annex B lists 86 species with trade and botanical names for selection.
• For ECO-Mark plywood, only plantation or non-natural forest species (e.g., rubber, coconut, cashew) are allowed.

(Full list in Annex B of IS 4990)

Mechanical Properties (Clause 10.1.3.1.1 & Tables)

Adhesion & Strength Requirements (Table 1)