Glossary of terms relating to asbestos
1986 Edition

IS 11707: Scope Summary

This standard specifies terminology and specifications relevant to asbestos cement products, ensuring alignment with global standards while considering India's practical conditions.

Scope Highlights:

• Applicable to asbestos cement-based construction materials.
• Guarantees manufacturing quality, durability, and safety.
• Harmonizes with international protocols and Indian field requirements.
• Contains definitions and terminology for asbestos-related concepts (see glossary).

Generalized Product Specifications:

Relevant Equations:

• Water-to-cement ratio (w/c):
  [ w/c = \frac{\text{Weight of Water}}{\text{Weight of Cement}} ]

• Flexural Strength (Modulus of Rupture):
  [ \sigma = \frac{3PL}{2bd^2} ] where:

  • ( P ) = Load at failure
  • ( L ) = Span length
  • ( b ) = Specimen width
  • ( d ) = Specimen depth

flowchart TD
    S[IS 11707 Scope] --> P[Asbestos Cement Products]
    S --> I[International Standard Alignment]
    S --> F[Indian Practical Applications]
    P --> C[Composition]
    P --> M[Mechanical Properties]
    P --> D[Durability and Safety]

For comprehensive details on product tables and testing, consult the full IS 11707 document.

The core of IS 11707 is the provision of precise definitions related to asbestos, focusing on terminology rather than numerical data or tables.

Key Terminology from Clause 1.1 and Glossary:

• Asbestos: Naturally occurring fibrous silicate minerals.
• Chrysotile: White asbestos belonging to the serpentine group.
• Amosite: Brown asbestos classified in the amphibole group.
• Crocidolite: Blue asbestos also in the amphibole family.
• Asbestos Cement: A composite material combining asbestos fibers with cement.
• Asbestos Fiber: Thin, elongated mineral particle with notable tensile strength and chemical resistance.

Application:

• These definitions standardize communication for design, testing, and safety practices associated with asbestos-containing materials.
• The section does not include structural formulas or tables; it emphasizes clear terminology.

For design or safety parameters involving asbestos cement products, please specify to receive relevant IS standards and formulae.

IS 11707 - Classification of Asbestos Minerals: Principal Formulas & Details

1. Definition (Clause 2.1)

• Acicular silicate minerals composed of silicon-oxygen tetrahedral chains.

2. Varieties and Their Chemical Formulas:

Note: The color ranges are indicative and may vary within mineral types.

Structural Note:

• All formulas represent silicon-oxygen tetrahedral units linked in chains, characteristic of asbestos minerals.

Simplified Summary Table:

A diagram illustrating the silicon-oxygen tetrahedral chains typical to asbestos minerals can be provided upon request.

IS 11707 - Cross-Fibre Definitions & Characteristics

• Cross-Fibre (Clause 2.5): Fibres positioned perpendicular to the plane of veins or seams within the asbestos material.

• Fiber Properties (Clause 2.10):

  • Minimum length to transverse dimension ratio: ≥ 10:1
  • Maximum cross-sectional area: 5.06 × 10⁻² mm²
  • Maximum transverse dimension (diameter if circular): 0.254 mm

• Fibre Spicules (Clause 2.13):

  • Rod-like asbestos elements not exceeding 10 mm length and 1 mm transverse dimension
  • Fibres aligned in natural parallel orientation conferring rigidity

• Fiber Cohesion (Clause 2.12):

  • The resistance to fibre separation; impacts ease of fibre opening

Fibre Dimension Summary:

Conceptual Illustration of Cross-Fibre:

graph LR
    V[Vein or Seam Plane] -->|Fibres aligned parallel| P[In-plane Fibres]
    V -->|Cross-Fibre| C[Perpendicular Fibres]

Cross-fibre orientation influences mechanical properties and fibre cohesion, critical for processing and health safety.

IS 11707 - Crude Asbestos Overview (Clause 2.6)

• Definition: Asbestos extracted manually by hammer impact (hand cobbing), consisting of natural cross-vein asbestos in unprocessed form.

• Distinct Features:

  • Unrefined and unfiberized state.
  • Contains natural impurities and mineral matrix.
  • Serves as raw material for further processing.

• General Quality Parameters:

  • Moisture content should be minimal to prevent deterioration.
  • Fiber content low due to embedded fibers in matrix.
  • Presence of rock, soil, and other mineral contaminants.
  • Physical form is irregular and lumpy chunks.

• IS 11707 does not provide specific formulas or tables for crude asbestos.

Additional Insights:

• Crude asbestos is the initial raw stage prior to fiberization and grading.
• Related IS standards (e.g., IS 6994) address asbestos fiber quality and testing.

flowchart LR
    O[Asbestos Ore] --> C[Hand Cobbed (Crude Asbestos)]
    C --> F[Fibre Opening Process]
    F --> G[Graded Asbestos Fibres]

For detailed testing and grading procedures, consult the applicable IS codes.

IS 11707 - Crudy Asbestos: Definitions and Key Attributes (Clause 2.8)

• Crudy: Processed asbestos exhibiting low specific surface area and limited fiberization, containing unfiberized agglomerates; term derived from "crude asbestos."

• Crudiness (Clause 2.7): Measurement of the extent to which asbestos resembles its natural crude condition.

• Crudy Bundle (Clause 2.9): Dense fiber assemblies with transverse dimension ≥ 8 mm, fibers arranged parallel, potentially partially crushed.

• Crude Asbestos (Clause 2.6): Naturally occurring, unprocessed asbestos manually extracted.

Important Points:

• Crudy asbestos typically has lower fiber quality, less suitable for applications requiring fine fiber separation.
• The degree of crudiness influences processing behavior and final product properties.

Visual Overview:

flowchart LR
    C[Crude Asbestos] --> R[Crudy (Low Fiberization Processed)]
    R --> B[Crudy Bundle (≥8 mm, parallel fibers)]
    C --> H[Hand Cobbed Natural Form]
    R --> A[Contains Unfiberized Agglomerates]

This illustrates the gradation from crude to processed asbestos as outlined in IS 11707.

IS 11707 - Fiber Specifications and Terminology (Clause 2.10)

• Fiber: Defined with minimum length to maximum transverse dimension ratio of ≥ 10:1.

• Maximum cross-sectional area limited to 5.06 × 10⁻² mm².

• Maximum transverse dimension (diameter if circular) is 0.254 mm.

• Fiber Spicules (Clause 2.13):

  • Rod-like fibre segments with length ≤ 10 mm and transverse dimension ≤ 1 mm.
  • Fibres closely packed in parallel, maintaining natural relative positions to provide rigidity.

• Fiber Cohesion (Clause 2.12):

  • Resistance to separation between fibers.
  • Varies from low to high, affecting ease of fiber opening.

• Fiber Adhesion (Clause 2.11):

  • Resistance to separation from the host rock seam wall.
  • Ranges from low to high.

Summary Table:

Ensures fibers conform to dimensional and mechanical standards for quality control.

IS 11707 - Overview of Fiber Adhesion (Clause 2.11)

• Fiber adhesion refers to the resistance experienced when fibers detach from the seam wall or host rock.

• This resistance varies qualitatively from low to high and influences fiber extraction and processing efficiency.

• Related is fiber cohesion (Clause 2.12), the resistance encountered when fibers separate from each other.

• Fiber dimension requirements (Clause 2.10) include:

  • Length to transverse dimension ratio ≥ 10:1
  • Maximum cross-sectional area: 5.06 × 10⁻² mm²
  • Maximum transverse dimension: 0.254 mm

• Fiber spicules (Clause 2.13) are rod-like bundles ≤ 10 mm length and ≤ 1 mm transverse dimension.

Practical Insights:

• Both adhesion and cohesion affect the quality and ease of fiber recovery.
• IS 11707 does not provide explicit formulas; properties are described qualitatively.
• Testing involves mechanical separation and microscopic examination.

Summary Table:

flowchart LR
    FA[Fibre Adhesion] --> R[Resistance to Separation from Host Rock]
    FA --> V[Varies from Low to High]
    FC[Fibre Cohesion] --> S[Resistance to Fibre-Fibre Separation]
    FC --> W[Varies from Low to High]
    F[Fibre] --> L[Length:Width ≥ 10:1]
    F --> D[Max Diameter 0.254 mm]

IS 11707 - Definition and Importance of Fiber Cohesion (Clause 2.12)

• Fiber cohesion describes the resistance encountered when fibers are separated from each other.

• This property ranges from low to high and determines how easily fibers can be teased apart.

• Related terms include fiber adhesion (Clause 2.11) and soft fibers (Clause 2.29), which possess high flexibility and low cohesion.

• Fiber dimensional standards (Clause 2.10):

  • Length to transverse dimension ratio ≥ 10:1
  • Maximum cross-sectional area = 5.06 × 10⁻² mm²
  • Maximum transverse dimension = 0.254 mm

Practical Considerations:

• Fibers with high cohesion are harder to separate, affecting processing and handling.
• Fibers with low cohesion (soft fibers) are easier to open but may increase airborne fiber release.

Conceptual Relation (No direct formula in IS 11707):

[ \text{Fibre Cohesion} \propto \frac{F}{A} ] where (F) is the force required to separate fibers and (A) is the contact area between fibers.

flowchart LR
    FC[Fibre Cohesion] -->|High| Hard_to_Separate
    FC -->|Low| Easy_to_Separate
    FP[Fibre Properties] --> FD[Fibre Dimensions]
    FD --> LDR[Length:Diameter ≥ 10:1]
    FD --> MXTD[Max Transverse Dimension = 0.254 mm]

For detailed testing procedures, refer to IS 11707 methods on fiber separation resistance.

IS 11707 - Characteristics of Fibre Spicules (Clause 2.13)

• Fibre spicules are rod-like asbestos fiber pieces:

  • Length not exceeding 10 mm
  • Transverse dimension not exceeding 1 mm
  • Fibers closely packed in parallel, preserving natural orientation to provide rigidity

• Fiber dimension criteria (Clause 2.10):

  • Length to transverse dimension ratio ≥ 10:1
  • Maximum cross-sectional area = 5.06 × 10⁻² mm²
  • Maximum transverse dimension = 0.254 mm

• Non-fibrous spicules (Clause 2.24) are acicular particles ≥ 0.1 mm transverse dimension composed of non-fibrous or semi-fibrous minerals (e.g., picrolite).

• Pencil (Clause 2.26) refers to rod-like asbestos fiber assemblies with uniform diameter exceeding fiber spicule dimensions (longitudinal > 10 mm or transverse > 1 mm) and capable of fiberization.

Summary Table:

flowchart LR
    F[Fibre] -->|Length:Transverse ≥ 10:1| FS[Fibre Spicule]
    FS -->|Length ≤ 10 mm & Transverse ≤ 1 mm| P[Pencil]
    NFS[Non-Fibrous Spicule] -.-> FS

This clarifies dimensional boundaries and relationships among fibers, spicules, and pencils.

IS 11707 - Floats: Air-Floated Fibrous Fraction (Clause 2.16)

• Floats are fibrous asbestos fractions recovered via air filtration in asbestos milling operations.

• Fiber characteristics (Clause 2.10):

  • Minimum length to diameter ratio: 10:1
  • Maximum cross-sectional area: 5.06 × 10⁻² mm²
  • Maximum transverse dimension: 0.254 mm

• Loftiness (Clause 2.20):

  • Defined as a measure of loose specific volume of fibers
  • Inversely related to dry bulk density

Typical Properties:

Conceptual Relationship:

graph LR
    D[Dry Bulk Density] -- inversely related --> L[Loftiness]
    L -- High loftiness --> B[Enhanced insulation and lightness]

Floats are characterized by their lightweight fibrous nature, important for performance in asbestos-containing products.

IS 11707 - Mass Fibre Overview (Clause 2.21)

• Fiber specifications (Clause 2.10):

  • Length to maximum transverse dimension ratio ≥ 10:1
  • Maximum cross-sectional area: 5.06 × 10⁻² mm²
  • Maximum transverse dimension (diameter if circular): 0.254 mm

• Mass fibre refers to asbestos fibers randomly dispersed in host rock rather than occurring in veins or seams.

• Fibre spicules (Clause 2.13) are rod-like fiber bundles ≤ 10 mm length and ≤ 1 mm transverse dimension, arranged parallel to provide rigidity.

• Loftiness (Clause 2.20) is inversely proportional to dry bulk density and quantifies the loose specific volume of fibers.

Summary Table:

Visualization of Fibre Dimensions:

graph LR
L[Fibre Length] -->|≥ 10 times| T[Max Transverse Dimension (0.254 mm)]
T --> C[Cross-sectional Area ≤ 5.06 × 10⁻² mm²]

This ensures fibers have suitable aspect ratio and controlled size for desired material properties.

IS 11707 - Milled Asbestos: Definition and Processing (Clause 2.22)

• Milled asbestos is the main product derived from asbestos ore through mechanical beating and washing, sometimes followed by sieving; also referred to as raw asbestos.

• Further processing involves freeing fibers from unfiberized agglomerates for specific product manufacturing.

Typical Industry Parameters:

Usage Notes:

• Milled asbestos is the foundational raw material for products like asbestos cement and friction materials.
• Quality depends on effective fiber opening and removal of aggregates.
• No specific formulas are provided in IS 11707; milling aims to optimize fiber separation and purity.

flowchart LR
    O[Asbestos Ore] --> M[Milling: Beating & Washing]
    M --> R[Milled Asbestos (Raw)]
    R --> F{Further Processing?}
    F -->|Yes| O[Opened Fibres]
    F -->|No| U[Used as Raw Milled Asbestos]

Refer to product-specific standards for detailed mechanical and physical properties.

IS 11707 - Milling: Definitions and Specifications (Clause 2.23)

• Milling involves mechanical treatment of asbestos ore through beating and washing, potentially including sieving, producing milled asbestos as a primary output.

• Milled asbestos (Clause 2.22) may undergo additional processing to free fibers from agglomerates for specialized applications.

• Fiber criteria (Clause 2.10):

  • Length to width ratio ≥ 10:1
  • Maximum cross-sectional area = 5.06 × 10⁻² mm²
  • Maximum transverse dimension = 0.254 mm

Notes:

• Milling is primarily a physical process consisting of beating and washing.
• IS 11707 contains no direct formulas for milling operations.
• Quality control focuses on fiber dimensions and cleanliness post-milling.

Process Flow:

flowchart LR
    O[Asbestos Ore] --> B[Beating]
    B --> W[Washing]
    W --> M[Milled Asbestos (Raw)]
    M --> F[Further Fiber Opening]
    F --> S[Separated Fibres]

This sequence outlines conversion from raw ore to usable fibers.

IS 11707 - Silky Fibres Overview (Clause 2.27)

• Silky fibers possess:

  • Low fiber cohesion
  • Soft tactile sensation
  • High flexibility, akin to "soft" fibers (Clause 2.29)

• Fiber dimensions (Clause 2.10):

  • Length to diameter ratio ≥ 10:1
  • Maximum cross-sectional area of 5.06 × 10⁻² mm²
  • Maximum transverse dimension of 0.254 mm

• Fiber spicules (Clause 2.13):

  • Rod-like fiber bundles ≤ 10 mm length and ≤ 1 mm diameter
  • Parallel fiber arrangement preserving natural positioning

Summary Table:

flowchart LR
    F[Asbestos Fibre] --> D[Dimensional Criteria]
    D --> M[Max Diameter 0.254 mm]
    F --> S[Silky Fibre]
    S --> L[Low Cohesion]
    S --> T[Soft Feel]
    S --> F2[High Flexibility]

Silky fibres are characterized by flexibility, softness, and low cohesion within defined size limits.