Specification for Bitumen Mastic Wearing Courses (First Revision)

IRC 107 - Scope Summary

Scope (Clause 2) defines the application of specifications for Bitumen Mastic Asphalt used in road construction and surfacing.

Key Points on Scope:

• Covers materials, mix design, equipment, construction, and quality control for bitumen mastic asphalt.
• Applicable to industrial grade 85/25 bitumen as per Table 1.
• Specifies physical properties of bitumen critical for mastic asphalt performance.

Table 1: Physical Properties of Bitumen for Mastic Asphalt

Additional References:

• EN 13108-6 (European standard for mastic asphalt)
• BS 1446:1973 (British standard for mastic asphalt)
• IS:5317:2002 (Pitch mastic for bridge decking & roads)
• IS:702-1988 & IS:73-2006 (Bitumen specifications)

Summary Diagram: Scope Coverage

graph TD
    A[Scope of IRC 107] --> B[Materials (Bitumen, Aggregates)]
    A --> C[Mix Design]
    A --> D[Equipment for Bitumen Mastic]
    A --> E[Construction Operations]
    A --> F[Quality Control & Testing]

This scope ensures uniformity and quality in bitumen mastic asphalt for durable road surfaces.

IRC 107 - Key References, Formulas & Specifications

Bitumen Specifications (Clause 3.1.1, Table 1)

Hardness Number of Bitumen Mastic (Clause 4.1)

Test as per Appendix-D of IS:1195-1978.

Additional References

• EN 13108-6 (European Standard for Mastic Asphalt)
• BS 1446:1973 (British Standard for Mastic Asphalt)
• IS:5317:2002 (Pitch Mastic for Bridge Decking & Roads)
• IS:702-1988 (Industrial Grade Bitumen)
• IS:73-2006 (Paving Grade Bitumen)

Notes:

• Use industrial grade 85/25 bitumen for mastic asphalt.
• Hardness number indicates stiffness; lower values with aggregates imply better flexibility.
• Follow specified test methods for quality control.

flowchart LR
A[Bitumen Properties] --> B[Penetration 20-40]
A --> C[Softening Point 80-90°C]
A --> D[Ductility ≥3 cm]
A --> E[Loss on Heating ≤1%]
A --> F[Solubility ≥99%]

G[Hardness Number] --> H[Without Aggregates 30-60]
G --> I[With Aggregates 10-20]

This summary helps ensure

IRC 107: Key Specifications & Tables for Materials (Clause 3 & 4)

1. Bitumen Specifications (Clause 3.1.1, Table 1)

• Bitumen grade: Industrial grade 85/25 for mastic asphalt.

2. Binder Content & Gradation (Clause 4.2, Table 5)

• Binder content is adjusted to meet mix design requirements.

Summary:

• Use 85/25 industrial bitumen with properties per Table 1.
• Gradation and binder content must comply with Table 5 for bitumen mastic blocks.
• Follow IS test methods for quality control.

flowchart LR
    A[Bitumen] --> B{Properties}
    B --> C[Penetration 20-40]
    B --> D[Softening Point 80-90°C]
    B --> E[Ductility ≥3 cm]
    B --> F[Loss on Heating ≤1%]
    B --> G[Solubility ≥

Composition and Specifications for Bitumen Mastic (IRC 107)

• Bitumen Grade: Industrial grade 85/25 bitumen as per Clause 3.1.1.
• Physical Properties (Table 1):

• Manufacture (Clause 6.1): Bitumen mastic is prepared by heating bitumen and mixing with fillers (usually limestone dust) to form a homogeneous, viscous mixture suitable for wearing courses.

Summary:

• Use 85/25 industrial grade bitumen meeting above physical criteria.
• Ensure penetration and softening point are within specified ranges for durability.
• Maintain low loss on heating to prevent bitumen degradation.
• High solubility ensures purity and quality.

flowchart LR
    A[Bitumen 85/25] --> B[Heating]
    B --> C[Mixing with Fillers]
    C --> D[Bitumen Mastic]
    D --> E[Wearing Course Application]

This ensures a durable, flexible wearing surface per IRC 107 standards.

Mixing and Preparation as per IRC 107

Key Specifications & Process:

• Bitumen Mastic Blocks:

  • Weight: ~25 kg each (without coarse aggregates).
  • Composition limits: Refer Table 5 (bitumen, filler, fine aggregates).
  • Blocks are broken into ≤60 mm cubes before remelting.

• Remelting & Mixing:

  • Temperature range: 170°C to 200°C (never exceed 200°C).
  • Mix coarse aggregates as per Table 3.
  • Continuous mixing for 1 hour to maintain suspension until laying.

Plant Mixing Components:

Important Notes:

• Mixing time in plant mixer: ~60 seconds.
• Mixing continues in transporter until laying.
• Temperature control is critical to avoid overheating (>200°C).
• Production rate: 15-20 tonnes/hour; daily output ~2500 sqm with single plant & paver.

Summary Flow Diagram of Mixing Process:

flowchart LR
    A[Cold Storage Bins] --> B[Drier (up to 250°C)]
    B --> C[Hot Bin (heated & insulated)]
    D

IRC 107 - Construction Operations: Key Points

IRC 107 Clause 6 covers Construction Operations for bitumen mastic surfacing.

Key Specifications & Equipment:

• Bitumen Content: As per Clause 2.36, bitumen content is critical for mix design and durability.
• Preparation Methods:
  • Conventional Method: Uses a mastic cooker for manual preparation.
  • Mechanized Method: Fully mechanized units for large-scale projects.
• Equipment Details: Provided in Annexure-I (manual) and Annexure-II (mechanized).

Relevant Standards & References:

• IS:5317:2002 - Pitch Mastic for bridge decking and roads.
• IS:702-1988 - Industrial Grade Bitumen.
• IS:73-2006 - Paving Grade Bitumen.
• EN 13108-6 (2006) - European standard for mastic asphalt.
• BS 1446:1973 - British standard for mastic asphalt.

Construction Operation Highlights:

• Ensure proper heating and mixing temperatures.
• Uniform spreading and compaction using specified equipment.
• Follow temperature control for bitumen mastic to avoid segregation.

Typical Bitumen Content Formula (from Clause 2.36):

[ \text{Bitumen Content} = \frac{\text{Weight of bitumen}}{\text{Total weight of mix}} \times 100% ]

Equipment Flow (simplified):

flowchart LR
    A[Mastic Cooker] --> B[Heating & Mixing]
    B --> C[Manual Laying]
    D[Mechanized Unit] --> E[Heating & Mixing]
    E --> F[Machine Laying]

For detailed equipment specs and operational procedures, refer to Annexure-I & II of IRC 107.

IRC 107 - Laying Procedures for Bitumen Mastic

Key Specifications (Clauses 6.2 & 6.2.3)

• Temperature at laying: 170°C
• Width of mix laid: 1 m, confined between angle irons (25 mm to 50 mm) to maintain thickness
• Containers: Sprinkled with lime or stonedust, or lime washed to prevent sticking
• Spreading: Uniformly using wooden floats immediately in front of the spreader
• Bubble management: Puncture bubbles formed during laying while mastic is hot, then rectify surface
• Level control: Angle irons fixed carefully; levels checked frequently with instruments

Quality Control (Clause 7.1.7)

• Longitudinal profile check: Use a 3 m straight edge on hot mastic
• Transverse profile check: Use camber template on hot mastic
• Tolerance: Max irregularity allowed = 4 mm
• Correction: Areas exceeding tolerance must be fully picked up and relaid

Summary Table

flowchart TD
    A[Bitumen Mastic in container] --> B[Discharge into lime-treated containers]
    B --> C[Deposit on prepared base in 1 m width]
    C --> D[Confine with angle irons (25-50 mm)]
    D --> E[Spread uniformly with wooden floats]
    E --> F[Check for bubbles → Puncture if any]
    F --> G[Check level & profile with instruments]
    G --> H{Irregularity > 4 mm?}
    H -- Yes --> I[Pick up & relay affected area]
    H -- No --> J[Finish laying]

This ensures a uniform, defect-free bitumen mastic layer as per IRC 107 standards.

IRC 107: Joint Treatment for Bitumen Mastic Surfacing

Key Specifications (Clause 6.3)

• Joint preparation: Warm existing bitumen mastic by applying excess hot bitumen mastic.
• Trimming: Excess mastic trimmed flush with surface.
• Painting: Coat joint face with VG 30 grade bitumen.
• Treatment: Apply base mastic blocks (without coarse aggregates, rich in bitumen).
• Softening: Use blow lamps to soften and towel flush with surface.
• Penetration: Melted mastic must penetrate to bottom of joint face.
• Joint shape: Vertical face should be given a 'Y' shape to facilitate penetration.
• Timing: Joints must be made in as green a stage as possible to avoid aging/oxidation and ensure bonding.

Surface Finish (Clause 7.2)

• No depression > 4 mm when tested with a 3 m straight edge parallel to carriageway.
• Same tolerance applies transversely using camber template.

Summary Table: Joint Treatment Steps

flowchart LR
    A[Existing Bitumen Mastic] --> B[Warm with excess hot mastic]
    B --> C[Trim flush]
    C --> D[Paint joint face with VG 30 bitumen]
    D --> E[Apply base mastic blocks]
    E --> F[Soften with blow lamp & towel flush]
    F --> G[Ensure penetration to bottom]
    G --> H[Joint with 'Y' shaped vertical face]

References for Further Details

• IS:5317:2002 (Pitch Mastic)
• IS:73-2006 (Paving Grade Bitumen)
• BS 1446:1973 (Mastic Asphalt Specification)
• EN 13108-6 (Bituminous Mixtures)

IRC 107: Surface Finishing & Anti-Skid Treatment

Key Specifications (Clause 7.2 & 9.5)

• Surface Finish Tolerance:

  • No depression > 4 mm under a 3 m straight edge along the carriageway or transverse camber template.

• Anti-Skid Treatment:

  • While bitumen mastic is hot (80°C - 100°C) and plastic, spread bitumen precoated hard stone chips (9.5 mm to 13.2 mm size).
  • Bitumen content on chips: 2-3% VG 30 grade bitumen.
  • Aggregate quantity: 0.05 m³ per 10 m² (~5.4 - 8.1 kg/m²).
  • Chips must protrude 3-4 mm above mastic surface.
  • Flakiness Index of aggregates: < 25% for skid resistance.

Summary Table

Additional Notes

• Traffic allowed only after mastic cools to ambient temperature.
• Use aggregates with approved quality and hardness.
• Follow IS:5317:2002 and IS:73-2006 for bitumen specifications.

flowchart LR
    A[Hot Bitumen Mastic (80-100°C)] --> B[Spread Bitumen Precoated Chips (9.5-13.2 mm)]
    B --> C[Press Chips into Mastic]
    C --> D[Chips Protrude 3-4 mm]
    D --> E[Cool to Ambient Temperature]
    E --> F[Allow Traffic]

This ensures a smooth, skid-resistant surface as per IRC 107 standards

IRC 107: Quality Control & Testing for Bitumen Mastic Asphalt

Key Specifications (Clause 3.1.1 & Table 1)

Quality Control Tests

• Hardness Test: Prepare two specimens (10 cm dia or square, 2.5 cm thick) and test hardness number.
• Bitumen Content: Extract bitumen from ~1000 gm sample; determine content per IS:1195-1978 (App. C).
• Aggregate Gradation: After bitumen extraction, sieve aggregates and analyze gradation as per IS:2386 (Part 1).

References for Standards & Methods

• IS:5317-2002 (Pitch Mastic for Bridges)
• IS:702-1988 (Industrial Grade Bitumen)
• IS:73-2006 (Paving Grade Bitumen)
• BS 1446:1973 (Mastic Asphalt Spec.)
• EN 13108-6 (Mastic Asphalt Material Spec.)

flowchart TD
    A[Sample Collection] --> B[Specimen Preparation]
    B --> C[Hardness Test]
    B --> D[Bitumen Extraction]
    D --> E[Bitumen Content Determination]
    D --> F[Aggregate Sieve Analysis]
    C & E & F --> G[Quality Control Evaluation]

This workflow ensures compliance with IRC 107 for mastic asphalt quality control.

Precautions for Bridge Deck Applications (IRC 107: Clauses 6.2.4 & 6.2.5)

1. Surface Preparation:

   • Roughen new concrete deck using stiff broom, wire brush, or milling machine.
   • Remove ridges/troughs with compressed air.
   • Repair cracks or replace deteriorated concrete before bitumen mastic application.

2. Camber and Crossfall:

   • Ensure adequate camber and crossfall.
   • If lacking, provide by concrete or bituminous treatment before surfacing.

3. Tack Coat Application:

   • Use bitumen grade VG 10 as tack coat.
   • Quantity per IRC:16 standards.
   • Apply before pouring bitumen mastic for bonding.

4. Reinforcement:

   • Place chicken mesh reinforcement (22 gauge / 0.76 mm wire diameter).
   • Mesh openings: 20–25 mm (hexagonal or rectangular).
   • Position longitudinally on the deck before bitumen mastic laying.

5. Expansion Joints & Drainage:

   • Check and secure expansion joint elements.
   • Ensure proper water drainage spouts function.

Summary Table for Key Specifications

flowchart TD
    A[New/Existing Bridge Deck] --> B{Check Camber/Crossfall}
    B -- Adequate --> C[Surface Preparation]
    B -- Inadequate --> D[Provide Camber/Crossfall]
    C --> E[Apply Bitumen Tack Coat (VG 10)]
    E --> F[Place Chicken Mesh Reinforcement]
    F --> G[Lay Bitumen Mastic]
    D --> C

Note: Always verify expansion joints and drainage before surfacing to avoid structural issues.

IRC 107: Equipment for Manual and Mechanized Laying of Bitumen Mastic

Key Points from Clause 6.2.3 & Annexure-I/II:

• Two Methods of Laying Bitumen Mastic:
  • Manual (Conventional) Method: Uses a mastic cooker.
  • Mechanized Method: Uses fully mechanized units for large-scale works.

Equipment Specifications:

Important Parameters:

• Bitumen Content (Clause 2.36): Critical for mix stability, typically around 10-15% by weight of mix.
• Mix Temperature: Maintain 160°C to 180°C during laying for workability.
• Layer Thickness: As per design, usually 15-25 mm for surface courses.

Reference Standards:

• IS:5317:2002 (Pitch Mastic)
• IS:73-2006 (Paving Grade Bitumen)
• BS 1446:1973 (Mastic Asphalt Spec.)
• EN 13108-6:2006 (Bituminous Mixtures)

Summary Diagram of Manual vs Mechanized Laying:

flowchart LR
    A[Bitumen + Filler] --> B{Method}
    B --> C[Manual: Mastic Cooker]
    B --> D[Mechanized: Paver Unit]
    C --> E[Mix Heating & Mixing]
    D --> F[Automated Mixing & Laying]
    E --> G[Manual Spreading & Compaction]
    F --> H[Automatic Laying & Compaction]

Use mechanized units for large projects to improve uniformity and speed. Manual laying suits smaller or repair works.

IRC 107: Temperature Control for Bitumen Mastic Asphalt

Key Specifications:

• Aggregate Heating:

  • Aggregates must be dry before heating to avoid adverse effects on output (Clause 7.1.4).
  • Monitor aggregate temperature periodically; do not exceed prescribed limits (typically around 160-180°C).

• Bitumen Temperature at Laying:

  • Temperature range: 170°C to 200°C (Clause 7.1.6).
  • Exceeding 200°C risks bitumen degradation; below 170°C affects workability.

Bitumen Properties (Table 1):

Practical Notes:

• Maintain dry aggregates before heating.
• Use industrial grade 85/25 bitumen meeting above specs.
• Control heating to avoid bitumen overheating and aggregate moisture.

flowchart LR
    A[Dry Aggregates] --> B[Heating (≤ Prescribed Temp)]
    B --> C[Mixing with Bitumen]
    C --> D[Bitumen Mastic Temp: 170°C to 200°C]
    D --> E[Proper Laying & Compaction]

This ensures quality and durability of the mastic asphalt layer.

Handling and Storage of Bitumen Mastic (IRC 107 - Clause 6.1.2)

• Storage:

  • Bitumen mastic (bitumen + filler + fine aggregates) not for immediate use shall be cast into blocks ~25 kg each (without coarse aggregates).
  • Blocks must conform to composition limits as per Table 5 (IRC 107).

• Transport & Re-melting:

  • Transport blocks to site, break into pieces ≤ 60 mm cube.
  • Remelt in cooker at 170℃ to 200℃.
  • Incorporate coarse aggregates as per Table 3.
  • Mix continuously for 1 hour to keep aggregates suspended.
  • Temperature must not exceed 200℃ during mixing.

• Laying Temperature:

  • Mastic temperature at laying: 170℃ (Clause 6.2.3.1).
  • Lay in 1 m width confined by angle irons (25–50 mm size).
  • Puncture bubbles during laying if blowing occurs.

Key Specifications Summary

Process Flow Diagram

flowchart TD
    A[Cast Bitumen Mastic Blocks (~25 kg)] --> B[Transport to Site]
    B --> C[Break into ≤60 mm pieces]
    C --> D[Remelt at 170-200℃]
    D --> E[Add Coarse Aggregates (per Table 3)]
    E --> F[Mix continuously for 1 hour]
    F --> G[Laying at 170℃ between angle irons]
    G --> H{Blowing?}
    H -- Yes --> I[Puncture bubbles & rectify surface]
    H -- No --> J[Complete laying]

References:

• Composition limits: IRC 107 Table 5
• Coarse aggregate quantities: IRC 107 Table

IRC 107: Safety and Environmental Considerations - Key Specifications

The code does not explicitly detail safety/environmental clauses but emphasizes material standards and equipment for bitumen mastic, indirectly ensuring safety and environmental compliance.

Bitumen Specifications (Table 1: Physical Properties)

Safety & Environmental Notes:

• Use industrial grade 85/25 bitumen to reduce volatile emissions.
• Follow proper heating limits to minimize bitumen loss and fumes.
• Equipment for manual laying (Annexure-I) ensures controlled application, reducing environmental contamination.
• Refer to IS:5317:2002 and IS:73-2006 for environmental compliance in bitumen use.
• Handling and storage must comply with local safety standards to prevent fire hazards and environmental pollution.

flowchart LR
    A[Bitumen Selection] --> B[Check Physical Properties]
    B --> C{Meets IRC 107 Specs?}
    C -->|Yes| D[Safe Heating & Application]
    C -->|No| E[Reject Material]
    D --> F[Use Proper Equipment (Annexure-I)]
    F --> G[Minimize Emissions & Spills]
    G --> H[Environmental Compliance]

Summary: Adhere strictly to bitumen physical properties, heating limits, and equipment standards to ensure safety and environmental protection in mastic asphalt works.