The Microstructure and Durability of an Asphalt–Mortar Pavement

Asphalt pavements are widely used along the roads due to their versatile properties. The materials together with a layered construction system consisting of a road base, a connecting, and an upper surface layer allow to create a smooth surface, that carries the traffic load. Nonetheless, the ductile and flexible nature of such pavements may exhibit durability concerns. A reduced service life shortens the repair work frequency and promotes a regular congestion of the traffic flow. In this regard, open space asphalt pavements, similar as drainage asphalts, were added with cement-based materials. The spaces filled with cement mortar allow the surface structure to be more rigid and to resist the shear stresses that may arise for instance in roundabouts or on bus stops. The mechanical performance of these materials are interesting, but the durability is still questioned. In this work, an asphalt surface layer with open pores was filled with cementitious material and placed on a bus stop. Cored specimens were taken from a test surface and the microstructure was characterized. Especially the bond between the mortar matrix and the bituminous material. Furthermore, the samples were exposed to cyclic temperature variation from +15°C to –15°C for 28 cycles. The surface exhibited a variable resistance to temperature changes, which was partially related to the formation of microcracks within the microstructure. This may suggest a particular attention on the climate to which these open space-bearing asphalts filled with mortar may be applied.