On the gluing and interlocking of asphalt on concrete

Paving asphalt on existing concrete is very common for mass transit roads, bridges, and highway constructions. For this, detailed knowledge of material behavior and bond interactions is vital for understanding the adhesion mechanism of these construction methods. A thorough comprehension of the bond mechanism is highly significant for assessing the service life of such traffic pavements. In this study, the influence of gluing and interlocking on the bond layer was examined through a close-range measurement method consisting of photogrammetry evaluated by a digital image correlation method. This testing method allowed a detailed detection of local failure points at the bond layer between asphalt and concrete. Tests were carried out on different asphalt-concrete combinations where the combination with a milled base showed the largest strain absorption at failure. Test specimens with bitumen emulsion exhibit higher strains at the boundary layer before failure than those without bitumen emulsion. In addition, the test specimens with a milled grounded substrate achieved higher shear values than those with a smooth substrate. Based on these experimental findings a finite element model was developed to show the effects of the local stress distribution and degree of gluing on the layer bond behavior, which opens possibilities for material optimization.