Determination of Seasonal Effects on the Structural Strength of Asphalt Pavements

Since 2000 the Equivalent Axle Loads on the main Lithuanian roads have increased twice. Deflections in asphalt concrete pavement, caused by the axle loads of the moving vehicles, is one of the essential causes of pavement degradation. Pavement deflections are widely measured by the Falling Weight Deflectometer (FWD), since, based on the measured deflection data, it is possible to calculate the deformation modulus of the whole pavement structure as well as separate structural layers. When designing pavement strengthening, values of the pavement deformation moduli are required, describing the weakest pavement condition. Today it is an urgent task to determine the effect of Lithuanian seasonal factors to the FWD-measured deflections in order to estimate the critical deformation modulus of the road pavement. According to the FWD-measured pavement deflections on the experimental road sections at a different time of the year the effect of seasonal factors was determined for the indices of structural strength of asphalt concrete pavements. Using the relationships of the effect of Lithuanian seasonal factors, determined by FWD measurements, it is possible to calculate the minimum indices of pavement structural strength.