Tentative Specification for Two-Coat Surface Dressing Using Cationic Bitumen Emulsion

IRC 96 - Scope Summary

IRC 96 covers specifications for surface dressing of roads using bituminous materials, mainly focusing on two-coat surface dressing with cationic bitumen emulsion.

Key Points on Scope:

• Applicable to surface dressing for improving skid resistance and waterproofing.
• Covers materials, aggregates, and bitumen emulsion specifications.
• Ensures durability and performance under traffic and weather conditions.

Relevant Specifications & Tables:

Typical Formula for Bitumen Emulsion Application Rate:

[ Q = \frac{W \times P}{100} ]

• (Q) = Quantity of bitumen emulsion (liters)
• (W) = Weight of aggregate (kg)
• (P) = Percentage of bitumen emulsion required (%)

flowchart TD
    A[Surface Dressing Scope] --> B[Materials]
    B --> C[Aggregates]
    B --> D[Bitumen Emulsion]
    C --> E[Physical Properties]
    D --> F[Application Rate]
    E --> G[IS 2386 & IS 6241]
    F --> H[Formulas & Specifications]

This scope ensures quality surface dressing for road longevity and safety.

Key Specifications & Formulas for Materials - IRC 96 (Surface Dressing)

1. Aggregate Physical Requirements (Table 3.2)

2. Aggregate Size for Second Coat

• Passing 9.5 mm sieve and retained on 2.36 mm sieve (6.7 mm nominal size)

3. Quantities of Materials per 10 m²

4. Important Notes

• Temperature for Application: > 10°C for surface dressing.
• Storage: Bitumen emulsions should not be stored below 0°C.
• Base Preparation: Clean, shaped, and free of loose particles.
• Binder Preparation: Roll drums slowly 5-6 times before use.

Summary Diagram: Material Flow in Surface Dressing

flowchart LR
    A[Aggregate] --> B[Physical Tests (LA Abrasion, Impact, etc.)]
    B --> C[Size Selection (9.5 mm to 2.36 mm)]
    C --> D[Application on Prepared Base]
    E[Cationic

Quantities of Materials (IRC 96)

Per 10 sq. m area:

Aggregate Specifications (Clause 3.2.2)

Aggregate Size for Second Coat

• Passing 9.5 mm sieve and retained on 2.36 mm sieve (6.7 mm nominal size)

Notes on Construction

• Temperature: Surface dressing only above 10°C; emulsion storage above 0°C.
• Base Preparation: Clean, shaped, compacted with no loose particles.
• Binder Application: Uniform spraying by mechanical sprayers; holes in pouring cans: 6 mm diameter spaced 30 mm apart.

This concise summary helps in planning material quantities and ensuring aggregate quality per IRC 96.

IRC 96 - Key Construction Specifications & Formulas

1. Aggregate Physical Requirements (Table 3.2)

2. Material Quantities per 10 m²

3. Aggregate Size for Second Coat

• Passing 9.5 mm sieve and retained on 2.36 mm sieve (6.7 mm nominal size)

4. Construction Guidelines

• Weather: Surface dressing only above 10°C; no emulsion storage below 0°C.
• Base Preparation: Uniform grade, camber; fill potholes; clean loose dust by washing.
• Binder Preparation: Roll emulsion drums 5-6 times over 10 m before use.
• Binder Application: Use mechanical sprayers or cans with 6 mm holes spaced 30 mm apart.

Summary Diagram: Surface Dressing Process

flowchart TD
    A[Prepare Base: Clean, Grade, Fill Potholes] --> B[Roll Emulsion Drums]
    B --> C[Spray First Coat Binder Uniformly]
    C --> D[Spread Aggregate (First Coat)]
    D -->

IRC 96 - Weather Limitations for Surface Dressing with Cationic Bitumen Emulsion

• Storage Temperature: Emulsions should not be stored below 0°C to prevent damage.
• Application Temperature: Surface dressing should be applied only when atmospheric temperature is above 10°C.
• Base Condition: Work can proceed if the base is damp, but all standing water in depressions must be removed prior to application.

Summary Table

Additional Notes:

• Ensure the base is clean, shaped, and free of loose particles before spraying.
• Spray cationic bitumen emulsion uniformly using mechanical sprayers.
• For two-coat surface dressing, use aggregates as per sieve sizes (6.7 mm passing 9.5 mm sieve and retained on 2.36 mm sieve).

flowchart TD
    A[Store Emulsion > 0°C] --> B[Prepare Base (clean, shaped, no standing water)]
    B --> C{Temperature > 10°C?}
    C -- Yes --> D[Apply Emulsion]
    C -- No --> E[Delay Work]

This ensures proper bonding and durability of the surface dressing per IRC 96 guidelines.

Preparation of Base for Surface Dressing (IRC 96 - Clause 4.2)

• Base Preparation:

  • Shape and correct the existing base to uniform grade and camber.
  • Fill and compact all depressions and potholes well in advance.
  • Remove all loose particles, dust, and foreign matter by thorough cleaning.
  • Preferably spray water to wash away loose dust and expose clean aggregate surface (especially for granular bases).
  • Remove standing water from depressions.

• Aggregate Size for Second Coat (Clause 6.7):

  • Aggregate size: 6.7 mm nominal size
  • Passing 9.5 mm sieve and retained on 2.36 mm sieve.

• Material Quantities per 10 m² (Clause 3.3):

• Weather Conditions (Clause 4.1):
  • Emulsion storage > 0°C.
  • Surface dressing when ambient temperature > 10°C.
  • Base can be damp but no standing water.

flowchart TD
    A[Existing Base] --> B[Shape & Grade Uniformly]
    B --> C[Fill & Compact Depressions]
    C --> D[Clean Surface]
    D --> E[Spray Water (if granular base)]
    E --> F[Apply First Coat: Bitumen Emulsion + Aggregate]
    F --> G[Apply Second Coat: Bitumen Emulsion + Aggregate]

This ensures a clean, stable base for effective bonding and durability of surface dressing.

Preparation of Binder (IRC 96 - Surface Dressing with Cationic Bitumen Emulsion)

• Binder Type: Cationic bitumen emulsion, RS Grade (Rapid Setting) per IS: 8887-1978.
• Bitumen Content: Minimum 60% by weight.
• Setting Criterion: Emulsion sets when water breaks away, leaving black residual bitumen on surface.

Key Steps for Binder Preparation:

• Mixing: Roll unopened emulsion drums slowly to and fro over 10 m, 5-6 times for thorough mixing.
• Storage: Do not store below 0°C.
• Application Temperature: Surface dressing should be applied above 10°C ambient temperature.

Quantities per 10 m²:

Aggregate Size for Second Coat:

• Passing 9.5 mm sieve and retained on 2.36 mm sieve (6.7 mm nominal size).

Application Notes:

• Spray uniformly using mechanical sprayers or a 30-litre pressurized tank.
• For pouring cans, use 6 mm diameter holes spaced 30 mm apart to avoid clogging.

flowchart TD
    A[Unopened Emulsion Drum] --> B[Roll Slowly 5-6 times over 10 m]
    B --> C[Ready for Spraying]
    C --> D{Ambient Temp > 10°C?}
    D -- Yes --> E[Spray Uniformly on Prepared Base]
    D -- No --> F[Delay Application]

This ensures uniform binder distribution and proper setting for durable surface dressing.

IRC 96 Key Specifications for First Coat (Two-Coat Surface Dressing)

Aggregate Size (Clause 13.2)

• First coat aggregate size: Passing 19 mm sieve and retained on 9.5 mm sieve
• Typical size: 13.2 mm

Quantities per 10 m² (Clause 3.3)

Application (Clause 4.4)

• Binder (bitumen emulsion) sprayed uniformly by mechanical sprayers.
• If using pouring cans: holes of 6 mm diameter, spaced 30 mm apart to avoid clogging.
• Emulsion tank: ~30 litres capacity, pressurized by compressed air.

Additional Notes

• Weather: Apply only when temperature > 10°C.
• Base: Clean, shaped, free from loose particles and standing water.
• Bitumen emulsion drums should be rolled 5-6 times over ~10 m before use for uniform mixing.

flowchart LR
    A[Prepare Base] --> B[Clean & Shape Surface]
    B --> C[Roll Emulsion Drums]
    C --> D[Spray Bitumen Emulsion (12-14 kg/10m²)]
    D --> E[Spread Aggregate (0.10-0.12 m³/10m²)]
    E --> F[Compact Surface]

This ensures proper bonding and durability of the first coat in surface dressing.

IRC 96: Key Specifications for Second Coat (Two-Coat Surface Dressing)

Aggregate Size (Clause 6.7)

• Second coat aggregate: 6.7 mm nominal size
• Passing 9.5 mm sieve and retained on 2.36 mm sieve

Quantities of Materials per 10 m² (Clause 3.3)

Construction Notes

• Temperature: Surface dressing with emulsion only above 10°C
• Base Preparation: Clean, shaped, free of loose particles and standing water
• Binder Application: Uniform spraying using mechanical sprayers or spraying-can with 6 mm holes spaced 30 mm apart

Summary Table for Second Coat Aggregate & Binder

flowchart TD
    A[Base Preparation] --> B[Clean Surface]
    B --> C[Spray Bitumen Emulsion (16-18 kg / 10 m²)]
    C --> D[Spread Aggregate (6.7 mm size)]
    D --> E[Compaction & Rolling]

This ensures proper bonding and durability of the second coat in two-coat surface dressing per IRC 96.

Rolling in Surface Dressing (IRC 96 - Clause 4.4.3)

• Roller weight: 6 to 8 tonnes, preferably smooth wheeled tandem type.
• Rolling sequence: Start at edges → proceed towards center, parallel to centerline.
  • On superelevated sections: roll from inner edge to outer edge.
• Overlap: Each pass overlaps at least 1/3 of the previous track.
• Objective: Embed aggregates into binder, achieve uniform closed surface.
• Avoid: Excessive rolling to prevent aggregate crushing.
• Aggregate adjustment: Add/remove aggregates during rolling to maintain uniform coverage.

Aggregate Size & Quantities (from Clauses 3.2, 6.7 & 3.3)

Aggregate Physical Requirements (IS 2386, IS 6241)

Summary Diagram of Rolling Process:

flowchart LR
    A[Spr

Opening to Traffic — IRC 96 (Surface Dressing)

Key Specifications:

• Minimum waiting time before opening:

  • Preferably 24 hours after completing rolling of the second coat.
  • Road may be opened after 4 hours, but 24 hours is recommended for better curing.

• Traffic speed on single-lane roads:

  • Max 10 km/h (slow speed) initially to avoid surface damage.

• Surface maintenance:

  • Add aggregate and emulsion wherever surface is picked up by traffic during early use.

Summary Table for Opening to Traffic

Rolling & Aggregate Application (for context)

• Aggregate sizes:

  • First coat: 13.2 mm
  • Second coat: 6.7 mm

• Rolling:

  • 6 to 8 passes with 6-8 tonne smooth wheeled roller.
  • Rolling starts from edges inward, overlapping 1/3 of previous pass.

flowchart TD
    A[Complete 2nd Coat Rolling] --> B{Wait Time}
    B -->|4 hours| C[Open to Traffic (Not Preferred)]
    B -->|24 hours| D[Preferred Opening Time]
    C --> E[Allow Slow Traffic ≤ 10 km/h]
    D --> E
    E --> F[Monitor Surface]
    F --> G{Surface Picked Up?}
    G -->|Yes| H[Add Aggregate & Emulsion]
    G -->|No| I[Normal Traffic Allowed]

Note: This guidance ensures proper curing of the emulsion and aggregate embedment, reducing surface damage and improving durability.

Quality Control & Testing for Aggregates (IRC 96, Table 3.2)

Key Points:

• Los Angeles Abrasion & Impact Values assess aggregate toughness and resistance to degradation.
• Flakiness Index limits flaky particles affecting workability.
• Stripping Value checks adhesion loss between aggregate and bitumen.
• Water Absorption controls porosity affecting durability.
• Soundness Test evaluates resistance to weathering (freeze-thaw cycles).

These tests ensure durability, strength, and stability of aggregates used in pavement construction.

flowchart TD
    A[Aggregate Sample] --> B[Physical Tests]
    B --> C[Los Angeles Abrasion]
    B --> D[Impact Value]
    B --> E[Flakiness Index]
    B --> F[Stripping Value]
    B --> G[Water Absorption]
    B --> H[Soundness Test]

IRC 96: Trial and Performance Evaluation - Key Specifications

For aggregates used in surface dressing, IRC 96 refers to physical requirements ensuring durability and performance:

Notes on Trial and Performance Evaluation:

• Trial mixes should be prepared to verify the compatibility of aggregate and bitumen emulsion.
• Performance tests include checking adhesion, stripping resistance, and surface texture.
• Use cationic bitumen emulsion as per tentative specifications for two-coat surface dressing.
• Evaluate surface roughness and skid resistance post-application.

Summary Diagram of Aggregate Testing Flow:

flowchart TD
    A[Aggregate Sample] --> B[Los Angeles Abrasion Test]
    A --> C[Aggregate Impact Test]
    A --> D[Flakiness Index Test]
    A --> E[Stripping Value Test]
    A --> F[Water Absorption Test]
    A --> G[Soundness Test]
    B & C & D & E & F & G --> H{Meets IRC 96 Limits?}
    H -- Yes --> I[Use in Surface Dressing]
    H -- No --> J[Reject or Treat Aggregate]

This ensures the aggregate quality meets IRC 96 for durable surface dressing performance.

IRC 96: Safety and Handling Key Points

1. Material Specifications & Handling

• Aggregate for 2nd coat: Size passing 9.5 mm sieve, retained on 2.36 mm sieve.
• Physical Requirements of Aggregate:

2. Quantities per 10 m² Surface Dressing

3. Safety & Handling Guidelines

• Temperature: Store bitumen emulsion above 0°C; apply only if ambient temperature >10°C.
• Surface Preparation: Remove all loose particles and standing water.
• Binder Preparation: Roll drums slowly 5-6 times over 10m before use.
• Application: Use mechanical sprayers for uniform binder application; if using cans, holes should be 6 mm diameter spaced 30 mm apart to avoid clogging.

Summary Diagram: Surface Dressing Process

flowchart TD
    A[Prepare Base] --> B[Clean Surface]
    B --> C[Prepare Binder]
    C --> D[Apply First Coat Binder]
    D --> E[Spread Aggregate]
    E --> F[Apply Second Coat Binder]
    F --> G[Spread Aggregate]