Experimental analysis of structural compatibility at the interface between asphalt concrete pavements and orthotropic steel deck bridges

Steel orthotropic deck is the most suitable solution for long-span bridges in virtue of its low weight and good mechanical properties. However it shows a lack of adhesion with ordinary paving materials and for this reason special bonding coats are usually applied on the steel surface. Polymer-modified bitumen, asphalt-based mastic, epoxy asphalt and reinforced asphalt membrane have all been used at the interface between the hot mix asphalt (HMA) course and steel bridge decks. A description of these materials and their construction process is provided. In some extreme situations even mechanical reinforcement is necessary to provide adequate bonding between the steel deck and the asphalt pavement.
The aim of this experimental study was the laboratory evaluation of the shear properties of smooth and reinforced steel interfaces coated with a polymer-modified bitumen between the steel deck and the conventional HMA. A suitable specimen preparation procedure was preliminarily defined. The shear resistance was evaluated using the ASTRA shear test device in order to investigate the effects of temperature and normal stress on different types of HMA-steel interfaces.
The results showed that reinforced steel interfaces guarantee higher performance than smooth interfaces, especially with increasing temperature. Thus reinforced steel interfaces can be considered as a reliable solution in case of high shear traffic-induced stresses.