ABSTRACT
Abstract The mechanism of the cracking of bituminous layers on the cement bound subbase consists in two processes: thermal cracking and mechanical cracking under a traffic load. Both modes of failure may perform separately or simultaneously. In the most cases actual cracking mechanism, its initiation and propagation are caused by tensile stresses exceeding local tensile strength of bituminous material. The analysis consisted in tensile stresses calculation at the bottom and top of bituminous layers regarding wheel and thermal loads at various temperatures and bituminous layers thicknesses. Tensile stresses were compared to tensile strength of bituminous materials. As a conclusion three cases were defined: Case A - crack initiation at bottom of the subbase due to tensile radial stresses under a wheel load, Case B - crack initiation at top of bituminous layers as a result of thermally induced tensile stresses exceeding tensile strength of bituminous layers, Case C - superposition of load conditions, i.e. the thermal stresses exceeding the tensile strength of a bituminous material on the pavement surface and the radial stresses exceeding the tensile strength of a cement bound material in the bottom of the subbase. Keywords: bituminous pavement, mechanical and thermal cracking, stress analysis
Cracking of bituminous layers on the cement bound subbase is one of the distress
modes of the road pavements and one of the most discussed ones these days. The mechanism of the failure consists in two processes: • thermal cracking • mechanical cracking under a traffic load. The two listed modes of failure may perform separately or simultaneously.
