White Topping – Assessment of Asphalt Concrete Interfaces

For the rehabilitation of rutted asphalt pavements white topping and ultra thin white topping turned out to be adequate methods. The force-fit bonding between asphalt and concrete is a pre-condition for the functioning and durability of this method. Little attention is paid on testing of the bonding; in the majority of the cases the adhesive tensile strength is tested. The wedge splitting test is much more appropriate for the testing of the interface. It delivers mechanical and fracture mechanical properties of the interface. In a comprehensive test programme different surface treatments of the milled asphalt were investigated by means of this method. The usage of bonding agents lead to no improvement of the interface, the most important influencing factors on the interface are cleaning of the milled asphalt surface and mainly the correct surface design for the milling of the asphalt corresponding to the top size of the concrete aggregate.