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Anti-Skid & Coloured Surface

High Friction Surfacing Systems

The introduction of Anti-skid and High Friction Surfacing Systems is becoming more common place on our highways. The use of such systems reduces breaking distances by raising the value of skid resistance, while also cosmetically enhancing the appearance of the road.

The systems can also be used to raise awareness of potential hazards such as approaches to roundabouts, intersections, traffic lights or pedestrian and school crossings.

Texture Depth and Micro Texture directly affect the performance of such systems and particular attention should be paid to the following:

• Texture Depth immediately aids the removal of surface water and the contact point between the tyre and the road is increased, which ultimately increases the value of friction
  and reduces breaking distances in wet conditions.
• Micro Texture determines the degree of friction between the vehicle tyre and the surface contact and in turn the value of skid resistance offered.
• The longevity and efficiency of the Micro Texture is determined by the aggregate's resistance to polishing through wear and tear. The resistance to polishing of an aggregate is determined by its Polished Stone Value or PSV.

Therefore the performance of a system relies upon the size of the aggregate used in conjunction with its texture depth. For example; systems that use a 1 - 3 mm aggregate with a PSV of at least 70, such as Calcined Bauxite, generally offer a design life texture of 1.2 mm when measured by Volumetric Patch Texture Depth in accordance with Ausroads SDT 02:2003.

Aggregates with a lower PSV values will polish and wear over time reducing Micro Texture and will in turn reduce the value skid resistance; and as a result should be avoided.

Decorative Surfacing Systems

Decorative Surface Coating Systems differ to High Friction Surfacing System whereby their use is often more associated with enhancing the cosmetic appearance of a section of road or to provide delineation; such examples are: Bus Lanes, Cycle Ways or Pedestrian Areas.

The same properties affect the performance of these Decorative Surfacing Systems being Texture Depth, Micro Texture and in turn the value of Skid Resistance. However these systems are more predominantly used for aesthetic or delineation purposes where Colour Retention is essential.

As a result of recent developments, synthetic coloured aggregates are now available which is generally colour coated with a clear internal matrix which allows the underlying colour to be reflected through ensuring that the physical appearance remains unchanged over time. This is as opposed to coated aggregates where the coating wears off and the aggregate beneath shows through, resulting in a loss of colour over time.

It should also be noted that some coatings use a method that blends the resin and aggregate. These systems offer less texture depth which in turn affects the Micro Texture resulting in reduced skid resistance of the system.