Different Types of Bitumen for Road Construction & Their Specific Uses

Bitumen is the backbone of road construction, acting as a strong binder that holds aggregates together while providing waterproofing.

Choosing the right type of bitumen directly affects road life, maintenance costs, and safety.

Selection depends mainly on:

• Climate (hot, moderate, cold)
• Traffic load (light, medium, heavy)
• Construction technology (layer design, mixing process)

Globally, bitumen classifications and specifications follow ASTM, EN, IS, and IRC standards.

Understanding the different bitumen types, their properties, and exact uses helps engineers create long‑lasting, climate‑specific roads.

Bitumen Classification & Global Standards

Bitumen used in road construction is classified by different property‑based systems. These classifications ensure that the material meets performance, safety, and durability requirements under various climates and traffic loads.

Main Global Standards — Verified:

• ASTM
  • D5 – Penetration
  • D36 – Softening Point
  • D2171 – Viscosity
  • D113 – Ductility
• EN
  • EN 12591 – Bitumen Specifications
  • EN 1426 – Penetration
• IS
  • IS 73 – Paving Bitumen (India)
• IRC
  • IRC:SP:53 – Bitumen Guidelines

Direct Note: These standards help engineers compare bitumen types with consistent methods globally, making project design and material selection more reliable.

Penetration Grade Bitumen – bitumen types road construction uses

Definition – Verified:

Penetration Grade bitumen is classified by how deep a standard needle penetrates a sample at 25°C for 5 seconds. Measurement is in tenths of a millimetre (dmm).

Common Grades:

• 30/40 – Very hard, for extremely hot climates and heavy loads.
• 60/70 – Balanced hardness, ideal for tropical and warm climates.
• 80/100 – Softer, best for cold climates and low to medium traffic.

Typical Laboratory Values:

Applications – Direct:

• General paving works across hot or warm zones.
• Base and binder courses for highways.
• Suitable for regions with moderate temperature variation.

Viscosity Grade Bitumen – bitumen types road construction uses

Definition – Verified:

Viscosity Grade (VG) bitumen is classified by resistance to flow measured at 60°C and 135°C.

This system gives a more stable indicator of performance under different traffic loads and climates compared to penetration grading.

Common Grades & Applications – Direct:

• VG‑10 → Cold climate surface dressing, sealing in low‑temperature zones.
• VG‑20 → Moderate climates, binder and base courses with medium traffic.
• VG‑30 → Heavy traffic in hot climates; ideal for highway binder courses.
• VG‑40 → Extra‑heavy traffic, rut‑prone areas in high heat zones.

Typical Laboratory Values:

Key Engineering Point:

VG grades allow better matching of binder performance to both traffic intensity and ambient temperature than penetration grades alone.

Performance Grade (PG) Bitumen – bitumen types road construction uses

Definition – Verified:

Performance Grade bitumen is selected based on maximum and minimum pavement service temperatures and expected traffic load.

It uses a climate‑based approach, making it highly precise for extreme conditions.

Standard Reference:

• ASTM D6373 – Specifies test methods for PG classification.

Example:

• PG 64‑22 → Designed to perform at a maximum pavement temperature of 64°C and a minimum of −22°C.
• PG 76‑22 → For hotter climates and heavy traffic, max temp tolerance 76°C.

Applications – Direct:

• Expressways
• Climate‑specific highways
• Heavy‑traffic zones with demanding seasonal variations

Key Engineering Insight:

PG grades provide a targeted performance profile, ensuring the pavement resists rutting in heat and cracking in cold while matching local climate data.

Cutback Bitumen – bitumen types road construction uses

Definition – Verified:

Cutback bitumen is produced by dissolving paving grade bitumen in volatile solvents such as kerosene or naphtha. This reduces viscosity, allowing cold application without heating.

Types:

• Rapid‑Curing (RC) – Fast evaporation; used for surface dressing and patching.
• Medium‑Curing (MC) – Moderate evaporation; favours priming in road base preparation.
• Slow‑Curing (SC) – Slow evaporation; suitable for low‑temperature sealing works.

Applications – Direct:

• Prime coat before laying bituminous layers
• Cold patch repairs in remote zones
• Maintenance where heating equipment is unavailable

Key Properties:

• Flash Point: ≥38°C for RC grades
• Controlled drying time to match project pace
• Easy penetration into granular bases

Engineering Note:

Though versatile, cutback bitumen’s use is declining due to environmental concerns over volatile solvent emissions.

Emulsion Bitumen – bitumen types road construction uses

Definition – Verified:

Emulsion bitumen is a mixture of bitumen and water, stabilized with an emulsifying agent.

It allows cold application, removing the need for heating, and is more eco‑friendly than cutback bitumen.

Grades:

• RS (Rapid Setting) – Quick break; used for surface dressing.
• MS (Medium Setting) – Slower break; ideal for cold mix works.
• SS (Slow Setting) – Long break; preferred for tack coats and fog seals.

Applications – Direct:

• Cold mix paving
• Tack coats for bonding layers
• Fog seals for maintenance and waterproofing

Key Properties:

• Residue on evaporation: ≥60%
• Viscosity @ 25°C: 5‑100 seconds
• Storage stability: Good with proper handling

Engineering Note:

Emulsion bitumen is widely adopted for maintenance works, and is replacing solvent‑based cutbacks in many regions due to environmental regulations.

Oxidized Bitumen – bitumen types road construction uses

Definition – Verified:

Oxidized bitumen (also called blown bitumen) is produced by blowing hot air through penetration grade bitumen. This process increases softening point and reduces ductility, making it harder and more temperature‑resistant.

Grades (Common):

• 85/25 – Softening point ~85°C, penetration ~25
• 90/40 – Softening point ~90°C, penetration ~40
• 115/15 – Very hard grade for industrial use

Applications – Direct:

• Bridge deck waterproofing
• Industrial roofing & sealing
• Pipe coating for corrosion protection
• Expansion joint sealing in concrete structures

Key Properties:

• Softening Point: ≥80°C (verified by ASTM D36)
• Penetration Value: Low, typically 10–40 (ASTM D5)
• Excellent thermal stability and water resistance

Engineering Note:

Oxidized bitumen is not commonly used for flexible road pavements, but is valuable in specialized construction where high heat resistance and sealing ability are critical.

Polymer Modified Bitumen (PMB) – bitumen types road construction uses

Definition – Verified:

Polymer Modified Bitumen is produced by blending standard paving grade bitumen with polymer additives (such as SBS – Styrene‑Butadiene‑Styrene, EVA – Ethylene Vinyl Acetate, or natural rubber) to enhance elasticity, temperature resistance, and adhesion.

Grades (Common):

• PMB 40 – High elasticity; heavy‑duty road surfaces
• PMB 70 – Medium elasticity; flexible pavements
• PMB 120 – Soft, highly flexible; low‑temperature applications

Applications – Direct:

• High‑traffic highways requiring rut resistance
• Bridge decks and expansion joints
• Airport runways
• Areas with extreme temperature variations

Key Properties:

• Softening Point: >60°C
• Elastic Recovery: ≥70% (ASTM D113)
• Excellent adhesion to aggregates
• Superior fatigue resistance under repeated loads

Engineering Note:

PMB extends pavement life by resisting deformation in summer and cracking in winter, making it ideal for performance‑based specifications (PG) under global standards.

Crumb Rubber Modified Bitumen (CRMB) – bitumen types road construction uses

Definition – Verified:

CRMB is produced by blending paving grade bitumen with crumb rubber obtained from waste tyres, under controlled temperature and mixing conditions. The rubber particles improve elasticity, crack resistance, and ageing performance.

Grades (Common):

• CRMB 50 – High rubber content, excellent durability
• CRMB 55 – Balanced elasticity and workability
• CRMB 60 – Softer blend for low‑temperature flexibility

Applications – Direct:

• High‑stress intersections to prevent rutting
• Flexible urban pavements in cold climates
• Roads requiring extended fatigue life
• Noise reduction in urban streets

Key Properties:

• Softening Point: >60°C
• Elastic Recovery: ≥70% (ASTM D113)
• Resists thermal cracking and stripping
• Improves skid resistance and safety

Engineering Note:

CRMB promotes sustainable construction by recycling waste tyres and simultaneously boosting road performance, aligning with green infrastructure goals across global road agencies.

Conclusion & Key Takeaways  

Summary – Verified:

Selecting the right type of bitumen directly impacts pavement life, maintenance costs, and safety. Global standards (ASTM, EN, IS, IRC) ensure consistency in performance parameters and help engineers match bitumen type with project conditions.

Key Takeaways:

• Match bitumen to climate and traffic:
  • Hot climates & heavy loads: Viscosity Grade VG-30, VG-40 or PMB for rut resistance
  • Cold climates: PG grades with a low‑temperature rating (e.g., PG 58‑28, CRMB)
• Prioritize environmental safety:
  • Replace cutback with emulsions where possible
• Special applications need specialized grades:
  • Oxidized bitumen for waterproofing, bridges, sealing joints
• Performance grades (PG) are ideal where temperature extremes are critical
• Sustainable innovations like CRMB save resources and meet green infrastructure targets

Engineering Recommendation:

A thorough review of traffic load data, climatic conditions, and construction equipment availability is necessary before finalizing the bitumen grade in tender documents. Always verify grade compliance via lab testing before on‑site application.

FAQ – bitumen types road construction uses

Q1: What is the difference between penetration grade and viscosity grade bitumen?

• Penetration Grade is classified by the depth a standard needle penetrates the bitumen under specific conditions (ASTM D5).
• Viscosity Grade is classified by flow time at specific temperatures (ASTM D2170, D2171).
• Viscosity grading offers better temperature-based performance prediction than penetration grading.

Q2: Which bitumen grade is best for hot climates?

• VG-30 or VG-40, or PMB grades are preferred for heavy traffic in hot climates to resist rutting and deformation.

Q3: Why is cutback bitumen use declining globally?

• Due to high VOC emissions from volatile solvents, leading to stricter environmental regulations. Emulsion bitumen is now the more eco-friendly alternative.

Q4: What does PG 64‑22 mean in performance grade bitumen?

• PG 64‑22 means the bitumen can withstand 64°C maximum pavement temperature and ‑22°C minimum pavement temperature without performance failure.

Q5: What bitumen types are considered eco‑friendly?

• Bitumen emulsions and CRMB (recycles waste tyres) are considered greener, aligning with sustainable construction practices.