Road surface condition generally and skid resistance in particular is now in the forefront of all highway authority engineers and highway maintenance contractors.
There is a heightened international interest in the re- lationship between skid resistance and accident levels and there is commitment to reduce all road accidents, especially fatalities. Recent developments in design of asphalt surfacing materials has produced many benefits including, noise reduction, spray reduction, faster laying with reduced cost, but it is still early days for these materials compared to over 100 years of traditional HRA and chips.
The new thin surfacing materials require high levels of quality control, both during production and laying to avoid surfaces with excess bitumen on the surface. Skid resistance of these materials is lower when first laid and may not reach its optimum for up to 2 years.
Blasting to remove the binder from the surface of the a gregate particles will give the road surface its maximum skid resistance in a uniform way across the whole ca riageway within just a few weeks of the surface course being laid. In addition when in 3 or 4 years the aggregate has become polished and the skid resistance dropped be- low an acceptable level blasting could regenerate it by exposing fresh aggregate and removing the polished sur- face. This may extend the life of the road by several years.
In addition to this safety aspect of asphalt there is also a modern trend towards using materials with different colours and textures both for aesthetic reasons to enhance town centres, commercial projects and urban regeneration schemes, and for safety reasons of lane identification, hazard warning and demarcation.
Blasting in conjunction with asphalt mix design can achieve a whole new range of decorative finishes for asphalt including blends of aggregates of several colours and textures in one surface. Professional blasting of asphalt can offer solutions with significant benefits in all these areas.
• Our techniques are purely mechanical, and therefore very clean
• None of our technologies are using chemical substances of are wasting valuable drinking water
• Perfectly clean (closed circuit precess, no waste to dispose)
• Safe (no risk of underground deterioration by the process itself or by frozen water, no damage on built-in lightning devices
• Very fast evacuation of the highway if necessary
• Permanent control can be made through grip testing devices / CFME (Continuous Friction Measuring Equipment)
• Can prolong the life by a number of years without the need to immediately invest in new top coat
Maintaining The Correct Level Of Scid Resistance
Reading all of the preceding information will clearly bring the reader to conclude that while a suitable skid resistance may be able to be achieved at the outset it will inevitably reduce as trafficking and ageing begin to take effect. How quickly the skid resistance level reduces to below what is acceptable varies significantly from site to site and will be affected by many things including, traffic levels and speeds, weather conditions, aggregate and binder properties etc. Highway authorities in most of the European countries routinely monitor the road network to assess the level of skid resistance in line with the standards set by the local Highways Agency. When the Characteristic SCRIM Coefficient (CSC) levels are at or below the assigned investigatory levels a site investigation is carried out to determine whether to improve the skid resistance or some other action is needed.