Damage to road surfaces cannot be avoided. Often, it occurs after only a few years of use. On national trunk roads in the Netherlands, this damage usually takes the form of stone loss from the porous surface layers. This is called ravelling, and patch repairs are normally carried out by filling the holes with cold asphalt mixes or by using rejuvenators.
The market has developed a number of maintenance techniques that, depending on the extent of the damage, can be used to extend the service life of a road surface. TNO focuses on assessing and validating these repair materials and techniques. Validation can relate to technical, economic and/or sustainability aspects. In this context we are working on the testing of preventive measures for extending the service life of national trunk roads. These can be used at an early stage, and extend service life by as much as 30%. The testing of repair techniques takes account of their social costs and benefits. Maintenance decisions are thus based on much more than the contracting price alone.
TNO has also developed methods that make is possible to postpone maintenance and repair by taking measures at the construction stage to protect roads more effectively against external effects (e.g. the effects of the air, UV radiation, water and dirt). In this field, for example, we are developing an application to combat asphalt ageing.