DEVELOPMENT OF VIA-RAL FOR POROUS ASPHALT: MORE THAN JUST RESEARCH, MORE PRAGMATISM

With the development of VIA-RAL, an acceptable maintenance technique for Porous Asphalt (PA) is available. The major damage of PA is usually ravelling. Ravelling starts by the loss of one stone at the PA surface. But as time goes by, ravelling is a kind of an ongoing domino process, resulting in an increasing number of "potholes" at the surface. And by the increasing ravelling the positive characteristics of PA, i.e. noise reduction, is decreasing. Until now, the only effective maintenance was replacing the top layer or repaving the upper 0.02 metres of the top layer. Now, with the use of VIA-RAL, it is possible to put a porous coating at the damaged PA and the process of ravelling will be stopped for several years. The PA will also regain some noise reduction. This new maintenance technique is part of the cold mixed asphalt coatings, that can be put on top of the PA easily and quickly. In fact it is merely a very thin layer, with an average thickness of about 8 till 10 mm. An additional characteristic is that some of the bitumen that is over-dimensioned in VIA-RAL covers the PA stones and, therefore, the binding between PA stones improves as well. Since the introduction of VIA-RAL, summer 2001, more than 400,000 square metres of old and ravelled PA has been repaired with it. It was found absolutely relevant, and it is right to mention it, that there was good co-operation between the contractor, as inventor of this product, and both the road authorities and the independent consultant. For innovation this is the main way to success. For the covering abstract see ITRD E121480.