Specifications for Readymade Bituminous Pothole Patching Mix Using Cut-Back Bitumen

IRC 116 - Scope Summary

The scope of IRC 116 covers specifications for readymade bituminous pothole patching mix using cut-back bitumen, focusing on materials, preparation, placing, compacting, quality control, and acceptance criteria.

Key Points:

• Materials:

  • Coarse aggregate must be crushed rock/gravel, clean, hard, durable, cubical, and meet physical requirements (Table 1).
  • Aggregate water absorption ≤ 2%, with max 2% passing 0.075 mm sieve.

• Mix Gradation (Table 2):

• Residual Bitumen Content (Table 3):

• Physical Requirements of Coarse Aggregate (Table 1):

Summary Diagram:

flowchart TD
    A[Scope: P

IRC 116 Key References: Aggregate & Mix Specifications

1. Coarse Aggregate Requirements (Clause 3.2.1 & Table 1)

• Size: Retained on 2.36 mm sieve
• Properties:

2. Gradation of Stockpile Patching Mix (Table 2)

3. Minimum Residual Bitumen Content (Table 3)

Note: Engineer may specify higher residual bitumen based on aggregate and mix performance.

Summary Diagram: Aggregate to Mix Quality Control Flow

flowchart TD
    A[Coarse Aggregate] --> B{Physical Tests}
    B -->|Cleanliness| C[Max 2% passing 0.075 µm]
    B -->|Shape| D[Flakiness & Elongation ≤ 35%

IRC 116: Key Material Specifications and Tables

Coarse Aggregate (Clause 3.2.1)

• Type: Crushed rock/gravel, retained on 2.36 mm sieve.
• Quality: Clean, hard, durable, cubical, free from dust/organic matter.

Note: Aggregate must satisfy either Los Angeles Abrasion or Aggregate Impact test.

Gradation of Stockpile Patching Mix (Table 2)

Minimum Residual Bitumen Content (Table 3)

Engineer may specify higher bitumen content based on aggregate and mix performance.

This ensures durability, strength, and proper bonding in patching mixes per IRC 116.

IRC 116 - Composition of Mixtures: Key Specifications

1. Gradation of Stockpile Patching Mix (Table 2)

• Grading must be tested per IS:2386 Part 1 (wet sieving).
• Pay special attention to the 0.075 mm sieve limit to avoid excess fines.

2. Minimum Residual Bitumen Content by Weight of Mix (Table 3)

• Residual bitumen = Total cutback bitumen - diluent (e.g., kerosene).
• Use aggregate with water absorption ≤ 1.0% where possible.

3. Quality Control

• Mix must meet grading & minimum residual bitumen content.
• Independent lab testing is mandatory before acceptance.
• Reject mix failing grading or bitumen content criteria.

Summary:
Ensure combined aggregate grading falls within Table 2 limits and residual bitumen content meets Table 3 based on aggregate absorption. Use IS:2386 Part 1 for testing.

Preparation and Storage of Mixture (IRC 116)

Key Specifications:

• Stockpile height:

  • Max 1.5 m for first 48 hours to prevent heat buildup (chimney effect).
  • After 48 hrs, stockpile can be raised and made conical.

• Storage:

  • Ready-made cold mix sealed in plastic-lined 50 kg bags on cooling.
  • Store under open shed or well-ventilated warehouse (no open flame/smoking).

• Aggregate & Bitumen Temperatures (Table 4):

• Aggregate: Clean, surface dry, pre-dried at high temp then cooled before mixing to reduce fines (<2%).

• Safety:

  • Avoid open flames near MC-800 (volatile kerosene).
  • Proper venting of pug mill necessary.

Gradation and Residual Bitumen Content

Gradation of Stockpile Patching Mix (Table 2):

Minimum Residual Bitumen Content (Table 3):

Summary

• Maintain temperature ranges during mixing.
• Limit stockpile height initially to 1.5 m.
• Ensure gradation and bitumen content meet specs.
• Store mix safely with no ignition sources.

flowchart TD
    A[Aggregate Drying] --> B[Cooling to 25

IRC 116: Preparation of Potholes (Clause 5.1)

Key Specifications for Preparation of Potholes:

• Cleaning: Use a stiff wire brush to clean the pothole thoroughly.
• Removal of debris: Remove all loose material and dust with a soft brush.
• Moisture condition: Pothole need not be dry, but excess water must be swept off to avoid weakening the patch bond.

Placing and Compacting Readymade Pothole Patching Mix:

• After preparation, the pothole patching mix is placed and compacted as per the guidelines (usually manual or mechanical compaction ensuring proper density).

Summary Table for Pothole Preparation:

Additional Notes:

• Proper cleaning ensures good adhesion of patching mix.
• Avoid standing water to prevent weak bonding.
• Compaction is critical for durability of the patch.

flowchart TD
    A[Start: Identify Pothole] --> B[Clean with stiff wire brush]
    B --> C[Remove dust with soft brush]
    C --> D{Is excess water present?}
    D -- Yes --> E[Sweep off excess water]
    D -- No --> F[Place patching mix]
    E --> F
    F --> G[Compact patching mix]
    G --> H[Finish]

This concise process ensures effective pothole repair as per IRC 116 standards.

Placing and Compacting the Mix (IRC 116)

Key Specifications:

• Mix Storage:

  • Stockpile height ≤ 1.5 m for first 48 hrs to avoid heat buildup.
  • Mix stored in plastic-lined 50 kg bags after cooling.
  • Store under open shed or well-ventilated area; no open flames due to volatile kerosene.

• Temperature Ranges for Mixing (Table 4):

• Aggregate Preparation:
  • Clean, surface dry aggregate.
  • Pre-dry at high temps, then cool before mixing to reduce fines (<2% passing 0.075 mm sieve).

Compacting Procedure (Clause 5.3):

• Compact outer edges first using hand rammer or small compactor.
• Proceed compaction inwards.
• To avoid mix sticking to rammer:
  • Keep rammer wet with water or
  • Place empty plastic-lined bags on loose mix before compacting.

Summary Diagram of Compacting Process:

flowchart LR
    A[Place loose mix in pothole] --> B[Compact outer edge with hand rammer]
    B --> C[Wet hand rammer or use plastic bag barrier]
    C --> D[Compact inward progressively]
    D --> E[Finish compaction]

This ensures proper bonding and density of the patch mix per IRC 116 standards.

Quality Control and Acceptance - IRC 116 (Clause 6)

Key Specifications:

• Mix Composition Testing:

  • Gradation and bitumen content tested by an independent lab before acceptance.
  • Samples must be cured (heated with stirring until constant weight) to remove kerosene before bitumen extraction.

• Contractor Tests (in presence of Engineer):

  1. Water Resistance Test (Appendix I, Test C)
     • Checks potential for stripping in presence of water.
     • Failure indicates improper anti-stripping agent use.
  2. Workability Test (Appendix I, Test D)
     • Failure indicates issues like improper bitumen type/content or gradation.

• Stockpile Acceptance:

  • Material can be rejected if >10% particles uncoated or unworkable during 6-month storage.

Important Table: Physical Properties of Coarse Aggregate (Clause 3.2.1)

Summary Flow of Quality Control

flowchart TD
    A[Sample Collection] --> B[Curing (Remove Kerosene)]
    B --> C[Independent Lab Testing]
    C --> D{Accept Mix?}
    D -- Yes --> E[Contractor Tests]
    D -- No --> F[Reject Mix]
    E --> G[Water Resistance Test]
    E --> H[Workability Test]
    G --> I{Pass?}
    H --> J{Pass

IRC 116: Packaging and Handling of Pothole Patching Mix

Key Specifications:

• Stockpile height: Max 1.5 m for first 48 hours to prevent heat buildup and bitumen stripping.
• Stockpile shape: Conical after initial 48 hours.
• Packaging: Mix sealed in plastic-lined sturdy 50 kg bags after cooling.
• Storage: Under open shed or well-ventilated area; no open flames or smoking due to volatile kerosene in MC-800.

Temperature Ranges for Mixing (Table 4)

• Aggregate pre-dried at high temps, cooled before mixing.
• Avoid high aggregate temps during mixing to reduce kerosene loss and safety hazards.

Gradation & Bitumen Content

Handling & Safety

• No open flame near MC-800 mix or stockpile.
• Store bags in ventilated areas only.
• Sprinkle clean sand on compacted patch before opening to traffic to prevent pick-up.

Quality Control Tests

• Water Resistance Test: Checks anti-stripping effectiveness.
• Workability Test: Ensures proper bitumen content and gradation.
• Samples cured by slow heating until constant weight before bitumen extraction.

flowchart TD
    A[Aggregate Drying] --> B[Cooling to ≤65°C]
    B --> C[Mixing with Bitumen (75-95°C

IRC 116: Testing Procedures for Pothole Patching Mix

Key Testing Requirements (Clause 6)

• Tests by Contractor (with Dept. Rep):

  • Water Resistance Test (Appendix I, Test C)
    • Checks potential stripping due to water.
    • Failure indicates inadequate anti-stripping agent.
  • Workability Test (Appendix I, Test D)
    • Checks mix workability.
    • Failure may indicate improper bitumen type/content or gradation.

• Bitumen Content Test:

  • Sample cured by heating to constant weight to remove kerosene before extraction.
  • Tested by approved lab for residual bitumen content.

Acceptance Criteria

Gradation Limits of Stockpile Mix (Table 2)

Additional Notes

• Mix failing tests or showing >10% uncoated particles can be rejected anytime within 6 months.
• Sprinkle clean sand on compacted patch to prevent pick-up by traffic (Clause 5.4).

flowchart TD
    A[Prepare Sample] --> B[Cure sample by heating]
    B --> C[Bitumen Extraction Test]
    C --> D{Residual Bitumen Content?}
    D -->|Meets Min. Content| E[Accept Mix]
    D -->|Fails| F[Reject Mix]
    A --> G[Water Resistance Test]
    G --> H{Pass?}
    H -->|Yes| I[Proceed]
    H -->|No| F
    A --> J[Workability Test]
    J --> K{Pass?}
    K -->|Yes| I
    K -->|

Safety and Environmental Considerations per IRC 116

Key Points:

• Stockpile Height & Shape:

  • Initial stockpile height ≤ 1.5 m for first 48 hours to avoid heat buildup (chimney effect).
  • After 48 hours, stockpile can be conical and higher.

• Temperature Limits (Table 4):

• Aggregate Handling:

  • Aggregate must be clean & surface dry.
  • Pre-dry aggregate at high temp, then cool before mixing to reduce fines (<2%).

• Safety Hazards:

  • MC-800 contains volatile kerosene → No open flames or smoking near plant or stockpile.
  • Adequate venting of pug mill mandatory to avoid kerosene vapor buildup.

• Storage:

  • Store mix in plastic-lined, sturdy 50 kg bags.
  • Store under open shed or well-ventilated area; never in closed warehouse.

• Environmental:

  • Avoid kerosene vapor release by controlling temperature and ventilation.
  • Reject mix if stripping >10% or unworkable.

Summary Diagram

flowchart TD
    A[Aggregate Pre-Drying] --> B[Cooling to ≤ 65°C]
    B --> C[Mixing with Bitumen MC-800]
    C --> D[Stockpile ≤ 1.5 m for 48 hrs]
    D --> E[Conical Stockpile Shape]
    E --> F[Storage in Plastic-lined Bags]
    F --> G[Open/Ventilated Storage]
    C --> H[Safety Precautions: No Flames, Ventilation]

Additional Notes

• Sand Application: Sprinkle clean sand on compacted patch before opening to traffic to prevent pick-up.
• Testing: Water resistance and workability tests mandatory during storage life (6 months max).
• Bitumen Content: Minimum residual bitumen content depends on aggregate water absorption (Table 3).

This ensures safe handling, storage, and environmental protection during pothole patching operations per IRC 116.

IRC 116: Limitations and Usage Guidelines for Readymade Cold Mix Patching

Key Specifications:

• Stockpiling:
  • Max height: 1.5 m for first 48 hours to avoid heat buildup.
  • Shape: Conical after initial 48 hours.
  • Packaging: Sealed in plastic-lined sturdy 50 kg bags on cooling.
  • Storage: Under open shed or well-ventilated warehouse; no open flames or smoking nearby due to volatile kerosene.

Temperature Ranges for Mixing (Table 4):

• Aggregate may be pre-dried at high temp and cooled before mixing.
• Avoid high aggregate temps during mixing to prevent kerosene loss and safety hazards.

Gradation Requirements (Table 2):

Residual Bitumen Content (Table 3):

Summary:

• Use clean, surface-dry aggregates.
• Control temperatures strictly during mixing.
• Ensure gradation and bitumen content meet minimum standards.
• Store mix safely to avoid fire hazards.

flowchart TD
    A[Aggregate Preparation] --> B[Drying & Cooling]
    B --> C[Mixing with Bitumen (MC-800)]
    C --> D[Stockpiling (Max 1.5m height)]
    D --> E[Packaging in 50kg Bags]
    E --> F[Storage in Ventilated Shed

IRC 116 Appendices: Key Specifications & Tests

Gradation & Bitumen Content (Tables)

• Residual bitumen = total cutback bitumen - diluent (kerosene).
• Engineer may specify higher bitumen content based on aggregate and mix performance.

Quality Control Tests (Appendix I)

• Water Resistance Test: Ensures mix resists stripping by water.
• Workability Test: Checks proper bitumen type, content, and gradation.

Important Procedures

• Curing before bitumen extraction: Heat mix with stirring till constant weight (removes kerosene).
• Sand application: Sprinkle clean sand on compacted patch to prevent traffic pick-up.

flowchart TD
    A[Stockpile Patching Mix] --> B{Check Gradation}
    B -->|Pass| C[Check Residual Bitumen Content]
    C -->|Pass| D[Water Resistance Test]
    D -->|Pass| E[Workability Test]
    E -->|Pass| F[Accept Mix]
    B -->|Fail| G[Reject Mix]
    C -->|Fail| G
    D -->|Fail| G
    E -->|Fail| G

This summarizes key tables, tests, and acceptance criteria from IRC 116 Appendices for pothole patching mixes.