Cutback Bitumen remains a key material in road construction and maintenance. This non-polymer base product is used widely in asphalt.

Knowing about this product, its specifications, and its uses helps industry owners to apply its different types wisely and effectively.

What is cutback bitumen?

Cutback bitumen is a binder produced by combining penetration-grade bitumen with a hydrocarbon solvent obtained from the oil distillation process in refineries. It is a low-viscosity liquid formed by dissolving bitumen in solvents such as kerosene, naphtha, diesel, furnace oil, paraffin, or mineral turpentine, eliminating the need for heating before application.

When the solvent evaporates, the binder returns to its original penetration grade, enabling it to effectively bind particles together. The term “cutback” reflects the solvent’s role, as it “cuts back” or evaporates, leaving the binder to fulfill its purpose.

Cut back bitumen is classified into three types based on drying time or the solvent evaporation rate:

1. Slow-Curing (SC)
2. Medium-Curing (MC)
3. Rapid-Curing (RC)

This product, introduced in the late 19th century to reduce viscosity for cold conditions, gained popularity in early road construction. Its use declined due to environmental concerns over VOC emissions, but it remains in use in colder regions and for specific applications like primer and sprayed sealing.

When engaging in international trade, it’s crucial to be familiar with the codes and identifiers for cutback bitumen.

HS Code

The Harmonized System (HS) code for this type of bitumen is 27132000, a globally recognized code used for customs clearance and statistical purposes in international trade.

Chemical Formula

This kind of bitumen does not have a specific chemical formula, as it is a complex mixture of hydrocarbons. Its composition mainly includes compounds of carbon and hydrogen.

CAS Number

Bitumen’s CAS number is 8052-42-4, while solvent CAS numbers in cutback-bitumen vary by type (e.g., kerosene, naphtha, diesel).

Different types of cutback bitumen

Three solvents used in the blending process influence the curing rate of cutback bitumen grades, determined by the solvent’s evaporation speed, which affects the setting time. The viscosity of cutback-bitumen depends on the solvent proportion—higher solvent content reduces viscosity.

1. Rapid Curing cutback-bitumen (RC)

• Description: Rapid curing cutback bitumen is made with fast-evaporating solvents at ambient temperature.
• Evaporation Rate: Solvents evaporate 0.3 times faster than acetone.
• Applications: used for tack coats, chip seals, and sand seals.

2. Medium Curing cutback-bitumen (MC)

• Description: this is produced by dissolving penetration-grade bitumen in moderately volatile solvents, usually kerosene.
• Evaporation Rate: Solvents evaporate at a rate between 0.3 and 0.8 times that of acetone.
• Applications: ideal as a binder in cold asphalt.

3. Slow Curing cutback-bitumen (SC)

• Description: Slow curing cutback bitumen is made by blending penetration-grade bitumen with heavy distillate solvents, like gasoline or fuel oil.
• Evaporation Rate: These solvents evaporate 0.8 times slower than acetone.
• Applications: used for dust suppression and cold-mix asphalt.

Cutback bitumen grades

Cutback-bitumen comes in various grades, each designed for specific applications based on viscosity, curing time, and temperature conditions.

Grade	Viscosity	Curing Time
MC-30 cutback-bitumen	Low	Medium
MC-70 cutback-bitumen	Medium	Medium
MC-250 cutback-bitumen	High	Medium
RC-30 cutback-bitumen	Low	Rapid
RC-70 cutback-bitumen	Medium	Rapid
RC-250 cutback-bitumen	High	Rapid
SC-70 cutback-bitumen	Medium	Slow
SC-250 cutback-bitumen	High	Slow

Cutback bitumen specifications

Cutback bitumen consists of two main components: bitumen and solvent. The ratio of these components varies depending on the application.

A higher solvent content makes the bitumen more liquid, and suitable for tasks like spray sealing, while a higher bitumen content is used for thicker applications like pot filling. The solvent also affects curing time and the temperature range for effective use.

Key attributes of cutback bitumen specifications:

• Viscosity: Solvents lower viscosity, easing spreading and reducing energy use.
• Adhesiveness: Excellent adhesion to aggregates for durable, stable surfaces.
• Curing Rate: Varies with solvent and temperature; rapid-curing is for fast projects, while medium and slow-curing types allow more time.
• Environmental Impact: Solvent evaporation releases VOCs, so low-VOC solvents are preferred.

Cutback bitumen uses

This product is mainly used in pavement construction. It can be applied at lower temperatures, reducing energy costs, and hardening as the solvent evaporates. Despite environmental concerns, it remains a popular choice for durable pavements.

Application	Description	Common Grades
Priming of Base Layers	Binds loose aggregates and creates a moisture-resistant foundation.	SC-70, SC-250
Tack Coat for Layer Bonding	Ensures strong bonding between asphalt layers.	MC-30, MC-70
Surface Dressing and Seal Coats	Protects underlying layers and provides a skid-resistant surface.	Rapid-curing cutbacks
Cold Mix Asphalt for Patching	Ideal for cooler weather repairs, requiring no high temperatures.	MC-30, SC-70, RC-70
Asphalt Concrete	Used in areas without hot mix plants, providing flexibility.	Various grades depending on needs
Dust Suppression and Soil Stabilization	Reduces dust and stabilizes soil bases for better load-bearing.	SC-70, MC-30
Prime Coat	Prepares unbound layers for bituminous overlays.	MC-30, SC-70
Surface Dressing	Improves road lifespan and grip.	Various grades

Cutback bitumen vs. emulsion

Traditionally, bitumen required heating to reduce its viscosity before application, but cutback bitumen eliminated this step by using volatile solvents. This makes heating unnecessary and allows easier application.

Cutback-bitumen also has a higher residual bitumen content (typically over 80%) compared to bitumen emulsions, which have 40-65% residual bitumen. This means that more bitumen remains on the surface after curing for the same applied volume.

However, the solvents in this product are harmful to the environment and human health, prompting the development of bitumen emulsions. Emulsions are safer, more environmentally friendly, and more energy-efficient since they only release water during evaporation.

Despite both being liquid bitumen, cut back bitumen, and emulsions differ in composition. Here are the 11 differences between cutback bitumen vs. emulsion:

1. Cost: Bitumen emulsion is less expensive.
2. Environmental Impact: Bitumen emulsion is more eco-friendly, while this type of bitumen contains harmful solvents.
3. State of Matter: Bitumen emulsion is always liquid; cut back bitumen can be semi-solid and may require preheating.
4. Preheating Impact: Preheating cutback-bitumen can damage its structure, unlike bitumen emulsion.
5. Surface Compatibility: Bitumen emulsion works on both wet and dry surfaces, while this type of bitumen needs dry surfaces.
6. Flammability: this product is highly flammable, while bitumen emulsion is safer in hot weather.
7. Phase Separation: Bitumen emulsion can separate if exposed to water, while cutback bitumen does not.
8. Phase Stability: Bitumen emulsion stays in one phase for a shorter period.
9. Surface Preparation: Bitumen emulsion needs clean surfaces, while cutback-bitumen is less sensitive to dust.
10. Curing Time: Bitumen emulsion dries in 2-15 hours; cutback-bitumen takes 24-48 hours.
11. Adhesive Properties: Bitumen emulsion has better adhesive properties once dried, due to the emulsifier.

Cutback bitumen price

Cutback-bitumen price is influenced by several factors. One of them is raw material costs that arise due to petroleum-based solvents, which are impacted by fluctuating oil prices. Production costs are relatively low, but solvent extraction and refinement add to expenses.

Next, Transportation and storage require precautions to prevent solvent loss and evaporation, increasing costs.

Moreover, Application costs are higher due to the need for heating before use and longer curing times, which raise energy and labor costs.

Maintenance is more expensive because solvent evaporation weakens bonds, leading to frequent repairs.

In the end, Environmental compliance costs are also higher due to VOC emissions, and market dynamics make the price unpredictable.

Purchasing cutback bitumen

At Kiapetro, we offer top-quality cutback-bitumen products designed to meet the specific needs of our clients, whether they require a single order or ongoing supplies.

We prioritize competitive pricing and outstanding quality, ensuring cost-effective solutions without sacrificing performance. Our dependable delivery system ensures timely arrivals, and we provide flexible payment options tailored to our clients’ preferences. Committed to delivering consistent and reliable performance, all our products comply with international standards.

FAQ

1. What is MC-30 cutback bitumen?

MC-30 is a medium-curing bitumen used for priming and tack coating.

2. What are the uses of cutback bitumen?

It is used for patching mix and as a prime coat for aggregate bases.

3. What is the exact composition of cutback-bitumen?

42% of Kerosene and 58% penetration grade 80/100.