Cutback bitumen

Cutback bitumen is a liquid material used in road construction. It is made by mixing standard bitumen with a solvent, like kerosene or naphtha.

This process makes the bitumen less thick, which means workers can easily apply it at lower temperatures.

Its main job is to act as a primer or base layer before the final asphalt is poured.

This material is very popular in Australia and around the world. Builders mostly use it for the first layer of a road, especially when the weather is cold or wet, making normal bitumen hard to use.

The quality and use of cutback bitumen are controlled by specific rules, mainly the AS2157 standard, and sometimes AS3568 or AS2008.

How Cutback Bitumen is Used in Road Projects

Cold Asphalt: This is a mix of stones (aggregates) and liquid bitumen made at normal room or outdoor temperatures. Both bitumen emulsions and cutback bitumen work well for making cold asphalt.

• Prime Coat: Workers spray this layer directly onto the road’s base layer. It helps prepare the surface. You can use all three types of cutback bitumen (SC, MC, and RC) here. The most common grades for prime coats include MC30, SC70, MC70, RC70, SC250, MC250, and RC250.
• Tack Coat: This is a very thin sticky layer used to glue two asphalt layers together—specifically the middle binder layer and the top surface layer. While experts often recommend bitumen emulsion for this, many projects use the MC grade of cutback bitumen instead.
• Spray Sealing: For roads with low to medium traffic that have some damage, completely re-asphalting can be too expensive. Instead, spray sealing is a budget-friendly option. Workers spray a thin layer of cutback bitumen to waterproof the road and stop water from damaging the lower layers. Then, they cover it with small stones.

Royal Bitumen – Available Product Range

Depending on the project requirements, cutback bitumen products are organized into three curing speeds: