Influence of the Hourly variation of Temperature on the Estimation of Fatigue Damage and Rutting in Flexible Pavement Design

The work presented in this paper offers a contribution to understand to what extent different discretization modes for describing a whole day can affect the estimation of in-service durability of a flexible pavement, in relation with concomitant traffic flow fluctuations. Calculation of the stress–strain state was carried out with an elastic multi-layer model, and performance laws were implemented for verification of the major distress mechanisms that are able to affect the prediction of a flexible pavement’s service life. Results from the prediction of the fatigue life allow one to conclude that no big mistakes are made when evaluating the total damage by describing climatic conditions via daily average temperatures to be assigned to seasonal periods, as in routine design practice. The situation is completely different with regard to the estimation of damage for cumulated permanent deformation in bituminous layers: there is evidence for underestimation of the total rut depth, when calculated assuming a simple daily variation,as happens in the ordinary pavement design practice. A correct estimation of rut depth produced by accumulation of permanent deformation in bituminous mixtures cannot, in fact, leave out of consideration an accurate analysis and an equally correct superposition of the hourly variation in temperature and traffic.