ABSTRACT
The European Commission Study Cost 333 undoubtedly showed that the cracks in the observed pavements begin to occur on the surface and not on the lower edge of asphalt layers. Besides in Study mentioned causes, combinations of wheel loads, four times surface flexion (before, behind, left and right) and frequency of critical loads is of fundamental importance. The combination of all these influences gives essentially different bases for designing flexible pavements. For the selected bowl lines measured by the FWD measuring device the curvature of bound flexible construction has been evaluated and the critical tensile stresses on the top and on the bottom of the pavement structure has been compared. The findings require that more attention shall be given to tensile stresses on the pavement surface, to dimensioning and to permit loads. With surface tensile stresses also the modulus of asphalt can be re-calculated and compared with the origin values computed by ELMOD.
