Innovation in mechanical characterization of bituminous mixtures and application to the modelling of asphaltic pavements’ behaviour

Abstract

Modelling of mechanical behaviour of asphalt pavements has been fundamentally based on bituminous materials’ fatigue cracking resistance. Analytical softwares allow estimating stresses that are generated by traffic and from such stresses and fatigue laws, service life of the pavement can be deduced. These calculations are based on laboratory tests carried on recently fabricated mixtures and do not take into account aging processes that could accelerate cracking. The Road Research Laboratory of the Universitat Politècnica de Catalunya has developed a procedure, the EBADE test that enables the obtention of bituminous materials’ fatigue laws in a much faster and precise way than traditional methods. This test has also allowed the obtention of fatigue laws of a bituminous mixture under different temperatures and aging conditions, and the study of their effect on the fatigue life of the pavement. The analyzed sections are the flexible ones from the Spanish Road Instruction. These sections have been increasing their thickness on different editions of the catalogue (1975, 1990, 2003). Nevertheless, the application of such design methods draws the conclusion that the initial sections (1975) were enough to resist the expected loads during the design periods. Such service life would be even longer if fatigue laws of aged mixtures are taken into account for the calculation. Observation of various roads shows that their failure can be associated with other distress mechanisms, mixture ageing and breaking by thermal and traffic stresses. Such calculation hypothesis fits the behaviour observed in Spanish pavement sections in a more precise manner. In its application, the data provided by the EBADE test to determine the breaking resistance of aged mixtures under cyclic loadings have also been used.