Knowledge Base

Scuffing Test

What is the high friction surfacing scuffing test?

High Friction Surfacing (HFS) is installed in locations where vehicles are frequently braking, accelerating or turning, including approaches to pedestrian crossings, junctions, roundabouts, bends and other high-risk areas.

In these locations the surface is subjected not only to normal trafficking but also to significant shear and twisting forces from vehicle tyres. These forces can dislodge aggregate or damage a poorly performing HFS system.

The Scuffing Test is designed to assess the ability of a high friction surfacing system to withstand these demanding forces. It forms part of the performance testing used for HFS systems assessed under the BBA HAPAS framework.

StarPolymers HFS achieves a Type 1 Scuffing Test classification – the highest available classification – demonstrating excellent resistance to severe trafficking and tyre-induced stresses.

Why Is Scuff Resistance Important?

A high friction surface depends upon its hard, highly polished-resistant aggregate remaining securely bonded within the resin binder.

Vehicle tyres don't simply roll across the surface. During braking, acceleration and steering they can impose substantial horizontal and rotational forces. At locations such as roundabouts and tight junctions, these forces can be particularly severe.

If the bond between the aggregate, resin and underlying road surface is inadequate, repeated trafficking can result in aggregate loss, surface damage and progressive deterioration of the HFS system.

The Scuffing Test provides a controlled method of evaluating resistance to this type of mechanical stress before a system is approved for use on the highway.

How Is the Scuffing Test Performed?

The test is performed on prepared specimens of the complete high friction surfacing system so that the interaction between the binder and aggregate can be assessed.

The test broadly involves the following process:

Preparation of the specimen – The HFS system is applied to a suitable test substrate using the specified binder and aggregate at the required application rates.
Conditioning and curing – The specimen is allowed to cure and is conditioned in accordance with the relevant test procedure so that different systems can be compared under controlled conditions.
Mechanical trafficking – The specimen is placed within specialist scuffing equipment which applies repeated mechanical loading to the surface.
Tyre-induced scuffing action – The apparatus subjects the HFS to a combination of loading and movement intended to reproduce the severe shear, turning and scuffing forces generated by vehicle tyres.
Repeated test cycles – The surface is subjected to the specified number of cycles, progressively challenging the bond between the aggregate, resin binder and substrate.
Assessment of surface damage – Following testing, the specimen is examined and the amount and nature of deterioration are assessed in accordance with the test requirements.

This accelerated laboratory procedure allows the resistance of an HFS system to severe trafficking to be evaluated without waiting for years of exposure on a live highway.

Type 1 – The Highest Classification

The performance demonstrated during scuff testing is used to classify the HFS system according to its resistance to trafficking.

StarPolymers HFS achieves TYPE 1 – the best possible Scuffing Test classification.

Achieving Type 1 demonstrates the system's ability to withstand particularly demanding scuffing forces with a very high level of resistance to surface deterioration.

This is especially important for HFS because some of the locations where additional skid resistance is most valuable are also those where the surface experiences the greatest mechanical stresses.

Roundabouts, junctions, braking zones and approaches to crossings can subject an HFS system to repeated braking and turning forces every day. A high initial skid resistance is therefore only part of the requirement – the system must also be sufficiently durable to retain the aggregate responsible for providing that friction.

More Than Just Skid Resistance

High friction surfacing is sometimes judged primarily by its initial skid resistance, but long-term performance depends upon the complete system.

The aggregate must provide excellent resistance to polishing, the resin binder must securely retain that aggregate, and the complete system must remain bonded to the underlying road surface.

Scuff testing therefore provides an important indication of the mechanical durability of the complete HFS construction, complementing other testing used to assess skid resistance, adhesion and overall performance.

StarPolymers HFS – Proven Type 1 Performance

StarPolymers HFS is a cold-applied, three-component polyurethane high friction surfacing system developed for demanding highway applications.

Its advanced polyurethane binder provides excellent adhesion and aggregate retention while avoiding the high installation temperatures associated with hot-applied systems.

Most importantly, performance isn't based simply upon laboratory development or theoretical claims.

StarPolymers HFS has achieved the highest possible TYPE 1 classification in the Scuffing Test as part of its BBA HAPAS assessment. For specifiers, highway authorities and installers, this provides independently assessed evidence that StarPolymers HFS can withstand the severe mechanical forces encountered in some of the most demanding high friction surfacing applications.