Stress Absorbing Membrane Interlayer

Asphalt overlays are often compromised not by their own properties—but by the inherent weaknesses in the surface beneath them. Without intervention, cracks and joints in the underlying layer can reflect through to the new surface, allowing water and de-icing salts to penetrate. This leads to:

• Premature surface failure
• Accelerated ageing of the asphalt
• Increased risk of potholes and surface deformation

Whether used on concrete roads, aged asphalt, or jointed surfaces, anti-crack membranes are a smart, preventative measure—protecting new investment and enhancing long-term pavement performance.

A small intervention with a big impact—preserving the life of your resurfaced asset.

The Role of Anti-Crack Membranes

To mitigate this, it is becoming increasingly common to install an anti-crack membrane prior to asphalt resurfacing. These membranes act as a stress-absorbing interlayer, designed to:

• Arrest the propagation of underlying cracks

• Prevent moisture and salt ingress

• Improve bond strength between layers

• Extend the service life of the overlay

Understanding Where Cracks Begin and How to Prevent Them

Cracks in the road surface typically originate from one of two locations:

• Top-down cracking – Occurs when the surface course becomes fatigued under repeated traffic loading, leading to splitting, ravelling, and eventual surface failure.
• Bottom-up or reflective cracking – Caused by movement or weakness in the sub-base or underlying pavement layers, which transmits stress upwards through to the surface.

The Role of Reflective Cracking

When cracks in the lower pavement layers "reflect" through an overlaid or resurfaced carriageway, this is known as reflective cracking. It is a common failure mechanism in:

• Asphalt overlays on concrete roads
• Re-surfaced cracked asphalt
• Roads with poorly stabilised sub-bases

Even when the wearing course is fully removed and replaced, if the original cause of cracking remains untreated, new cracks will form—typically propagating upwards at a rate of 25mm per year.

The Solution: Stress Absorbing Membranes

To prevent this, Stress Absorbing Membranes (SAMIs) are used beneath new asphalt layers to:

• Arrest the upward propagation of cracks
• Decouple the surface from movements below
• Improve flexibility and lifespan of the new overlay

Without a membrane, even a brand-new surface may begin to show cracks within 2–3 years—especially if the overlay is thin.

Targeted Crack Sealing and Stress-Absorbing Membrane in One Pass

Jointmaster SAMI is a polymer-modified, rubberised bitumen compound reinforced with glass fibres, designed to prevent reflective cracking at the point where it matters most—directly over existing cracks and joints.

Applied as a molten screed, Jointmaster SAMI:

• Fills and seals cracks in a single pass

• Leaves a flexible, stress-absorbing membrane focused solely over the crack line

• Prevents movement from underlying layers from reflecting into the new overlay

A Smarter Alternative to Full Surface Membranes

Unlike full-area stress-absorbing interlayers, Jointmaster SAMI targets only the zones of concentrated movement—delivering performance where it's needed without the cost of treating the entire surface.

Key Benefits:

• ✅ Seals and reinforces cracks prior to overlay
• ✅ Accommodates movement and prevents reflection cracking
• ✅ Glass fibre reinforcement adds tensile strength
• ✅ Cost-effective alternative to full-area SAMIs
• ✅ Quick installation with minimal disruption
• ✅ Ideal for overlays on cracked asphalt or jointed concrete pavements

Jointmaster SAMI combines sealing and stress relief in one simple, efficient application—ensuring longer-lasting overlays and reduced future maintenance.

Confused about the SAMI service? 

SAMI comes with a full supply and apply contracting service meaning Rhino can do it all, saving the hassle of hiring multiple contractors. Note however, that SAMI selectively treats just the cracks and joints, not the whole surface. 

Installation Speed?

Rhino crews will provide a fast installation of up to 1,000 lin.m achievable in a shift. SAMI can be applied throughout the year, night or day, with no road closures needed. SAMI is 100% safe to be driven over right after installation. 

Numbers and Specifications?

• Applied in recommended widths of 200mm for longitudinal cracking and 300mm for transverse
• Treatment applied at 5mm thickness when overlaying with 75mm of new asphalt
• Treatment rebated into the surface by 10mm or 20mm for thinner overlays 

Why SAMI is your best option?

Most membranes need curing time or protection from site traffic before the road can be re-opened. SAMI can be trafficked immediately after cooling by site traffic and/or road traffic. This means disruption is kept to a minimum.