Guidelines on Use of Modified Bitumen in Road Construction (Second Revision)

IRC SP 53 - Introduction: Key Specifications & Formulas

1. Scope & Purpose

• Covers modified bitumen specifications, handling, testing, and quality control.
• Ensures performance enhancement of bituminous binders for pavements.

2. Handling Precautions (Clause 6.4)

• Eye protection & heat-resistant gloves mandatory.
• No smoking near hot bitumen.
• Loosen lids of sample containers before warming.

3. Quality Control (Clause 12.2)

• On-site binder storage & heating must meet demand.
• Modified bitumen must be agitated when hot.
• Avoid multiple heating cycles to retain properties.

4. Sampling & Conformity (Clause 13)

• Follow IS 15462:2004 for sampling and acceptance criteria.

5. Key Test Method: Complex Modulus (Annex-1)

• Measures Complex Modulus (G)**, Phase angle (δ), and G/sin δ using Dynamic Shear Rheometer (DSR).
• Test temperature: 35°C to 85°C.
• Specimen: 1 mm thick, 25 mm diameter or 2 mm thick, 8 mm diameter.
• Frequency: 10 rad/s.
• Indicates binder stiffness and resistance to deformation.

6. Important Parameters

flowchart TD
    A[Modified Bitumen] --> B[Handling Precautions]
    A --> C[Quality Control at Site]
    A --> D[Sampling & Testing]
    D --> E[Complex Modulus Test (DSR)]
    E --> F{Outputs}
    F --> G[Complex Modulus (G*)]
    F --> H[Phase Angle (δ)]
    F --> I[G*/sin δ]

For detailed procedures and equipment specs, refer to Annex-1 of IRC SP 53.

IRC SP 53: Scope - Key Specifications & Tables

Scope (Clause 2) covers modified bitumen for road construction, including types, properties, testing, handling, and quality control.

Key Specifications for Modified Bitumen (Table 2 Summary)

Important Quality Control (Clause 12.2)

• Agitate modified bitumen before use.
• Avoid multiple heating cycles.
• Maintain storage and handling protocols.
• Sampling per IS 15462:2004.

Complex Modulus Test (Annex-

Advantages of Modified Bitumen (IRC SP 53, Clause 3.1):

• Lower susceptibility to temperature variations: Maintains flexibility in cold and stability in heat.
• Higher resistance to deformation: Reduces rutting at high pavement temperatures.
• Delay of cracking and reflective cracking: Enhances durability by resisting crack propagation.
• Better age resistance: Slows down hardening and brittleness over time.
• Improved adhesion: Stronger bond between aggregates and binder reduces stripping.
• Higher fatigue life: Mixes endure repeated loads better, extending pavement life.
• Overall improved performance: Leads to longer-lasting, more resilient road surfaces.

Specification Requirements (General Guidance)

• Types of modifiers: Polymers (SBS, EVA), rubber, plastomers.
• Modifier content: Typically 3-6% by weight of bitumen.
• Testing: Penetration, softening point, ductility, and elastic recovery per IS/IRC standards.

Typical Performance Table for Modified Bitumen

flowchart LR
    A[Modified Bitumen] --> B[Temperature Stability]
    A --> C[Deformation Resistance]
    A --> D[Crack Resistance]
    A --> E[Age Resistance]
    A --> F[Adhesion Improvement]
    A --> G[Fatigue Life]
    A --> H[Overall Performance]

This concise summary highlights the benefits and typical specs for modified bitumen in road construction per IRC SP 53.

IRC SP 53 - General Requirements of Modifiers (Clause 4)

While the code does not list explicit formulas in Clause 4, key points on modifiers for bitumen include:

• Selection Criteria: Based on traffic intensity, climatic conditions, and life cycle cost analysis.
• Modifier Types: Polymers, rubber, plastomers, elastomers, and chemical additives.
• Performance Requirements: Improved elasticity, temperature susceptibility, rutting resistance, and fatigue life.

Key Specification Parameters (from typical IRC guidelines):

General Notes:

• Modifiers enhance bitumen's resistance to deformation and cracking.
• Proper blending and quality assurance during storage and handling are critical.
• Testing methods include elastic recovery, separation, and complex modulus tests (see Annexures).

flowchart TD
    A[Traffic & Climate Analysis] --> B[Select Modifier Type]
    B --> C[Modify Bitumen]
    C --> D[Testing: Penetration, Softening Point, Elastic Recovery]
    D --> E[Mix Design & Construction]
    E --> F[Performance Evaluation & QA]

For detailed test procedures and values, refer to IRC SP 53 Annexures 1-4.

IRC SP 53 - Key Details on Bitumen Modifiers

Types of Bitumen Modifiers (Clause 5.2)

Important Notes:

• Proprietary products often contain blends of polymers for enhanced bitumen properties.
• All modifiers must comply with relevant specifications and be tested in approved labs before use (Clause 4.2).
• Modified bitumen improves elasticity, temperature susceptibility, and durability of road surfaces.

Summary Table:

This classification helps select modifiers based on climate, traffic, and performance requirements.

IRC SP 53: Modified Bitumen - Key Points

1. Applications of Modified Bitumen

• Used primarily in road surfacing where enhanced performance is needed.
• Suitable for high-temperature stability, improved flexibility, and resistance to rutting and cracking.
• Applied in surface dressing, seal coats, and bituminous mixes.

2. Specifications (Clause 8.1 & Table 2)

• Modified bitumen must meet physical and chemical properties as per Table 2 (IRC SP 53).
• Key parameters include:
  • Penetration at 25°C (dmm)
  • Softening point (°C)
  • Ductility at 27°C (cm)
  • Viscosity at 60°C (Poise)
  • Flash point (°C)

3. General Specifications (Clause 11.3)

• Same as conventional bitumen except for special conditions.
• Manufacturer’s technical literature should be referred for product-specific guidelines.

flowchart LR
    A[Modified Bitumen] --> B[Road Surfacing]
    A --> C[Surface Dressing]
    A --> D[Seal Coats]
    A --> E[Bituminous Mixes]
    B --> F[Improved Rutting Resistance]
    B --> G[Enhanced Flexibility]

Summary: Use modified bitumen where enhanced durability is needed; verify properties per Table 2; follow manufacturer’s special instructions alongside IRC SP 53 general specs.

IRC SP 53: Manufacturing of Modified Bitumen - Key Points

Clause 7: Manufacturing Quality System

• Quality system: Documented procedures, regular inspections, tests to ensure product conformity.
• Equipment: Regular inspection, calibration, and maintenance to avoid inconsistencies.

Clause 12.2: Site Quality Control Plan

• Production scheduling and binder quantity planning.
• On-site storage, heating, and pumping requirements.
• Environmental management for storage, spillage, and waste.
• Agitation/recirculation of modified bitumen before use.
• Avoid multiple heating to preserve properties.
• Manufacturer to provide site precautions or technical support.

Clause 13: Sampling & Criteria

• Conformity as per IS 15462:2004.

Key Specification Table (Clause 8.3 Extract)

Complex Modulus (G*) Test Summary (Annex-1)

• Uses Dynamic Shear Rheometer (DSR).
• Test temperature: 35°C to 85°C depending on binder grade.
• Specimen: 1 mm thick, 25 mm diameter or 2 mm thick, 8 mm diameter.
• Frequency: 10 rad/s.
• Measures: Complex modulus (G*), phase angle (sin δ), and G*/sin δ.
• Equipment

IRC SP 53: Specification Requirements for Modified Bitumen

Key Specification Points (Clause 8.1 & 11.3)

• Table 2 (Clause 8.1): Defines the physical and performance properties of modified bitumen.
• Modified bitumen must meet requirements similar to conventional bitumen except for special conditions specified by the manufacturer.
• Manufacturer’s technical literature should be referred for special conditions.

Typical Properties in Table 2 (Example)

Notes:

• Elastic recovery and complex modulus tests are crucial for assessing elasticity and stiffness.
• Modified bitumen improves performance in terms of rutting resistance and temperature susceptibility.
• Refer to Annex 1-4 for detailed test methods (complex modulus, elastic recovery, separation, torsion recovery).

Summary Diagram of Modified Bitumen Properties

graph LR
A[Modified Bitumen] --> B[Penetration]
A --> C[Softening Point]
A --> D[Ductility]
A --> E[Elastic Recovery]
A --> F[Complex Modulus]
B --> G[IS 1203]
C --> H[IS 1205]
D --> I[IS 1208]
E --> J[Annex-2]
F --> K[Annex-1]

Recommendation: Always verify modified bitumen properties against manufacturer specs and IRC SP 53 Table 2 for compliance.

IRC SP 53 - Transportation of Modified Bitumen: Key Points

Though Clause 9 on Transportation lacks detailed formulas, the following essential specifications and best practices apply based on IRC guidelines and general engineering principles:

Key Specifications:

• Temperature Control:

  • Maintain bitumen temperature below its softening point during transport to prevent degradation.
  • For climates exceeding 40°C, softening point ≥ 65°C is mandatory.

• Handling & Storage:

  • Use insulated, covered tankers to minimize heat loss and contamination.
  • Avoid prolonged storage at high temperatures to prevent aging.

• Viscosity and Complex Modulus:

  • Ensure complex modulus (G*/sin δ) ≥ 2.2 kPa at 10 rad/s and specified temperature (Clause 2.2).
  • This ensures adequate stiffness and resistance to deformation during transport.

General Best Practices:

• Use thermocouples or temperature sensors to monitor temperature continuously.
• Transport in closed systems to avoid oxidation.
• Minimize transit time to reduce thermal aging.

Summary Table: Transportation Temperature Limits

flowchart LR
    A[Modified Bitumen Plant] --> B[Insulated Tanker]
    B --> C{Temperature Check}
    C -->|Temp ≤ Softening Point| D[Transport to Site]
    C -->|Temp > Softening Point| E[Cooling or Reheating]
    D --> F[Storage at Site]
    F --> G[Mixing & Construction]

Note: For detailed handling and transportation procedures, refer to IRC: SP 53 Clause 9 and related MoRTH guidelines.

Design of Mixes (IRC SP 53 - Clause 10)

The design of dense graded bituminous mixes with modified bitumen follows the Marshall Method (MS 2), similar to conventional bitumen.

Key Requirements (Table 3):

Modified Binder Content by Mix Type & Grading (IRC 111 Grading 1 & 2):

Note: For aggregates with specific gravity > 2.7, reduce bitumen content proportionally. Increase bitumen by 0.5% in cold regions (≤ 30℃ max & ≤ -10℃ min daily mean).

Additional Notes:

• Mixing Temperature: Modified bitumen should be mixed at 170-185℃.
• Storage: Max holding at mixing temp is 4 days; medium storage at 130-140℃ for 14 days

IRC SP 53: Construction Operation for Modified Bitumen Mixes

Key Specifications:

• Atmospheric temperature for construction: > 15°C
• Mix properties must comply with Table 3 (Marshall mix design requirements).

Table 3: Mix Requirements (Modified Bitumen)

*Grading 1 & 2 as per IRC:111; binder content varies by mix type (BC, SDBC, DBM).

Table 4: Temperature Ranges for Construction Operation

Temperatures are higher than conventional bituminous mixes; exact values depend on modifier type and supplier advice.

Summary:

• Use Marshall Method (MS:2) for mix design.
• Ensure mix temperature control within specified ranges for quality.
• Construction should be done only when ambient temperature is above 15°C.
• Maintain minimum binder content and retained stability as per climate conditions.

flowchart TD
    A[Start Construction] --> B{Ambient Temp > 15°C?}
    B -- No

Quality Assurance in Storage & Handling of Modified Bitumen (IRC SP 53)

Key Specifications & Practices:

• Storage & Handling:

  • Modified bitumen must be stored in heated tanks/drums with agitation to maintain homogeneity.
  • Avoid multiple heating cycles to preserve bitumen properties.
  • Environment management plan for spillage and waste disposal must be followed.
  • Manufacturer's guidelines and technical support should be adhered to at site.

• Site Quality Control Plan (Clause 12.2):

  • Daily production and binder quantity schedules.
  • Heating and pumping requirements for on-site storage.
  • Agitation/re-circulation of modified bitumen before use.
  • Avoid overheating or prolonged heating.

• Sampling & Conformity:

  • Sampling and acceptance criteria per IS 15462:2004.

Important Test: Complex Modulus (G*) Determination (Annex-1)

Significance:

• G* indicates stiffness and deformation resistance of binder under load.
• Phase angle (δ) shows elastic vs viscous behavior.

Summary of DSR Test Setup:

flowchart LR
    A[Prepare Specimen] --> B[Place Between Parallel Plates]
    B --> C[Control Temperature (±0.1°C)]
    C --> D[Oscillate Plate at 10 rad/s]
    D --> E[Measure Torque & Angular Displacement]
    E --> F[Calculate G*, Phase Angle]

Note: Follow IRC:111 for mixing and laying controls of bituminous mixes.

IRC SP 53 — Sampling and Criteria for Modified Bitumen

Key References:

• Sampling and conformity criteria per IS 15462:2004.
• Complex modulus (G*), phase angle (δ), and G*/sin δ measured by Dynamic Shear Rheometer (DSR).

Important Specifications:

Sampling & Testing Procedure Summary:

• Use Dynamic Shear Rheometer (DSR) with parallel plates.
• Oscillate one plate sinusoidally at 10 rad/s.
• Control temperature precisely (±0.1°C).
• Measure G* (complex shear modulus) and phase angle δ.
• Calculate G/sin δ* as a performance indicator.

Acceptance Criteria (Example):

Refer IS 15462:2004 for detailed precision values.

Safety Precautions (Clause 6.4):

• Use eye protection and heat-resistant gloves.
• No smoking near hot bitumen.
• Handle sample containers carefully (loosen lids when cold).

flowchart TD
    A[Prepare Specimen] --> B[Place between parallel plates]
    B --> C[Set Temperature (35-85°C)]
    C --> D[Oscillate upper plate at 10 rad/s]
    D --> E[Measure Torque & Deflection]
    E --> F[Calculate G*, Phase Angle δ, G*/sin δ]
    F --> G[Evaluate Binder Performance]

Summary:
For sampling and criteria, follow IS 154

IRC SP 53: Method for Determination of Complex Modulus (Annex-1)

Purpose:
Determines complex modulus (G*), phase angle (sin δ), and G*/sin δ of modified bituminous binders using a Dynamic Shear Rheometer (DSR).

Key Specifications:

• Test specimen:
  • Thickness: 1 mm (25 mm diameter) or 2 mm (8 mm diameter)
• Test temperature: 35℃ to 85℃ (±0.1℃ control)
• Frequency: 10 rad/s (~1.59 Hz)
• Shear strain: 1% (hard binders) to 12% (soft binders)
• Complex modulus range: 100 Pa to 10 MPa

Test Procedure:

1. Specimen placed between parallel plates.
2. One plate oscillates sinusoidally at 10 rad/s.
3. Rheometer software controls strain and measures torque.
4. Specimen conditioned with 10 cycles before data collection.
5. Calculate:
   • Complex modulus: ( G^* = \frac{\tau_0}{\gamma_0} ) (shear stress / shear strain)
   • Phase angle: δ (lag between stress and strain)
   • Shear modulus: ( \frac{G^*}{\sin \delta} )

Important Parameters to Report:

Performance Criterion (Clause 2.2):

• Minimum ( \frac{G^*}{\sin \delta} = 2.2 \text{ kPa} ) at 10 rad/s and test temperature.
• If max temperature > 40℃, softening point ≥ 65℃.

Summary Diagram:

flowchart TD
    A[Prepare Specimen] --> B[Place between parallel plates

Method for Elastic Recovery Test (IRC SP 53 - Annex-2)

This test evaluates the elastic recovery (%) of modified bitumen by elongating a specimen and measuring its recovery after conditioning.

Test Setup & Procedure

• Specimen: Prepare 3 samples in ductility mould (Fig.1) per IS:1208-1978.
• Conditioning: Heat specimens at specified temperature for 1 hour.
• Elongation: Stretch specimen to 10 cm at 5 ± 0.25 cm/min.
• Cutting: Cut specimen at midpoint immediately after elongation.
• Recovery: Keep elongated half undisturbed in water bath at test temperature for 1 hour.
• Measurement: Bring two halves close; measure recombined length ( X ) cm.

Calculation

[ \text{Elastic Recovery} (%) = \frac{10 - X}{10} \times 100 ]

Where:

• 10 cm = original elongation length
• ( X ) = length after recovery

Equipment

• Ductility machine (IS:1208-1978)
• ASTM 63℃ thermometer
• Scissors (cutting at test temperature)
• Transparent scale (±1 mm accuracy)

Key Specification (Table 2)

Summary Flowchart

flowchart TD
    A[Prepare 3 specimens] --> B[Condition at specified temp for 1 hr]
    B --> C[Elongate to 10 cm at 5±0.25 cm/min]
    C --> D[Cut specimen at midpoint]
    D --> E[Keep elongated half in water bath for 1 hr]
    E --> F[Bring halves together, measure length X]
    F --> G[Calculate Elastic Recovery % = ((10 - X)/10)*100]

This test helps optimize polymer/rubber dosage and assess PMB/RMB quality per IRC SP 53.

Method for Separation Test - IRC SP 53 (Annex-3)

Purpose:
Evaluate separation of modifier and bitumen during hot storage by comparing Ring and Ball Softening Points (R&B) of top & bottom portions of modified bitumen after conditioning.

Procedure Summary:

1. Sample Preparation:

   • Heat modified bitumen until fluid.
   • Pass through IS sieve (600 micron).
   • Stir thoroughly.
   • Pour 50 g into vertical sealed tube; crimp and seal.

2. Conditioning:

   • Place tubes vertically in oven at 163 ± 5°C for 48 ± 4 hours.
   • Immediately transfer tubes to freezer at 6.7 ± 5°C for minimum 4 hours.

3. Sample Division:

   • Cut tube into 3 equal parts.
   • Discard middle portion.
   • Separate top and bottom portions.

4. Testing:

   • Melt samples at 163 ± 5°C to remove aluminum.
   • Stir and pour into R&B test rings.
   • Conduct Ring and Ball Softening Point test as per IS 1205 simultaneously for top & bottom samples.

5. Evaluation:

   • Calculate difference in softening points (°C) between top and bottom samples.
   • Report average difference from three specimens.

Key Specifications:

Formula for Elastic Recovery (from Annex-3):

[ \text{Elastic Recovery (%)} = \frac{10 - X}{10} \times 100 ]

• Where X = length (cm) of recombined specimen after 1 hour in water bath.

Visual Summary (Mermaid Diagram):

flowchart TD
    A[Heat Bitumen & Pass Sieve] --> B[Pour 50g into Vertical Tube]
    B --> C[Seal & Place in Oven at 163±5°C for 48±4 hrs

Torsion Recovery of Modified Binders (IRC SP 53, Annex-4 & Clause 8.3)

Key Points:

• Test Temperature: 25°C for field testing torsion recovery.
• Requirement: Torsional recovery ≥ 50% of elastic recovery at 15°C (lab test).
• Purpose: Measures elastic properties of polymer-modified binders via torsional recovery using bolt and cup assembly.

Elastic Recovery (Annex-2, Table 2)

• Test: Elongate a bitumen thread to 10 cm at specified temperature, then measure recovery after 1 hour.
• Minimum Elastic Recovery at 15°C:
  • 50% to 60% depending on climate zone (see Table 2 below).

Table: Key Properties of Modified Bitumen (Selected)

Procedure Summary for Torsion Recovery

1. Prepare sample in bolt and cup assembly.
2. Condition sample at 25°C.
3. Apply torsion and measure recovery.
4. Compare torsion recovery with elastic recovery at 15°C.
5. Ensure torsion recovery ≥ 50% of elastic recovery.

Formula for Temperature Selection (Clause 2.2)

[ \text{Test Temperature} = \text{Temperature where } G^*/\sin \delta =