Crumb Rubber Roads

Crumb rubber can be incorporated into several mainstream asphalt types. These mixes are all well understood, compatible with existing equipment and supported by state specifications:

Dense Graded Asphalt (DGA)

The most widely used asphalt in Australia. Crumb rubber modified DGA offers improved fatigue resistance, greater flexibility and better deformation control, making it suitable for arterial roads, intersections and areas with high traffic loading.

Open Graded Asphalt (OGA)

A porous surface layer designed for wet‑weather safety and lower tyre noise. Adding crumb rubber improves durability and flexibility while maintaining OGA’s drainage and acoustic benefits. Common on freeways, high‑speed corridors and tunnels.

Stone Mastic Asphalt (SMA)

A high‑stone-content mix with strong rut resistance and long service life. Incorporating crumb rubber into the binder or mortar enhances elasticity and performance under heavy traffic. Suitable for freight routes and high‑stress pavements.

Gap Graded / Dry Process Mixes

Used in states that specify dry‑process crumb rubber (e.g., Victoria, NSW). These mixes create additional void space for rubber‑modified binders, supporting higher binder contents and delivering durable, long‑life surface courses.

CRMB is produced by blending crumb rubber into bitumen to increase elasticity, flexibility and resistance to fatigue and cracking. It is used across DGA, OGA, SMA and gap graded mixes, and can be manufactured through both wet and dry processes.

CRMB underpins many long‑life pavement strategies, particularly where pavements experience high temperatures, repeated heavy loads or thermal movement. It is a proven, low‑risk binder option recognised in national and state specifications.

Crumb rubber bitumen and asphalt mixes deliver several engineering and operational advantages:

• Improved flexibility to manage thermal and load‑related cracking
• Greater fatigue and rutting resistance, extending pavement life
• Lower whole‑of‑life maintenance costs
• Noise reduction, depending on mix design
• Potential skid and drainage benefits, particularly in open‑graded applications
• A productive circular economy outcome, using Australian end‑of‑life tyres in road infrastructure

These benefits contribute to longer‑lasting pavements and more reliable network performance.

Crumb rubber bitumen is used across a wide range of project types, including:

• Urban arterials and high‑volume corridors
• Intersections, signalised zones and turning movements
• Freeways, tunnels and high‑speed environments
• Freight routes and heavy‑vehicle networks
• Council resurfacing programs and regional road upgrades

Its versatility makes it suitable for both new construction and rehabilitation works.

A spray seal is a widely used road surfacing technique in Australia, involving the application of a thin layer of bituminous binder onto a prepared pavement surface, followed by the spreading of aggregate. This method creates a waterproof, skid-resistant surface suitable for various traffic conditions.

Incorporating crumb rubber from end-of-life tyres into the binder enhances the flexibility and durability of spray seals. Crumb Rubber Modified Binders (CRMB) have been utilised in Australia for several decades to improve the performance of sprayed seals.

Key Benefits of CRMB in Spray Seals:

• Enhanced Flexibility: Improves resistance to cracking under thermal stress and heavy traffic loads.
• Increased Durability: Extends the lifespan of the seal, reducing maintenance requirements.
• Environmental Sustainability: Utilises recycled tyre rubber, supporting circular economy initiatives.
• Improved Performance: Offers better adhesion and cohesion properties, leading to a more robust seal.

Application Process:

1. Surface Preparation: The existing pavement is cleaned and prepared to ensure proper adhesion.
2. Binder Application: A hot mixture of bitumen and crumb rubber is sprayed onto the surface using specialized equipment.
3. Aggregate Spreading: A layer of aggregate (typically 7mm, 10mm, or 14mm in size) is spread over the binder.
4. Compaction: The aggregate is embedded into the binder using rollers, creating a uniform and skid-resistant surface.

Crumb rubber bitumen provides a technically robust pathway for end‑of‑life tyres, enabling their reuse in high‑value infrastructure. This diverts material from disposal, reduces reliance on imported polymers and supports local manufacturing of modified binders and asphalt products.