This paper deals with strains in thin asphalt surfacings on granular pavement layers, the purpose being to find whether highest tensile strains occur in the road surface or at the bottom interface of the asphalt layer. The study was based on an analysis by the BISAR program of an asphalt pavement loaded by a 10-ton axle dual-wheel load. The modulus of the asphalt layer was 1,000-5,000 MPa and of the granular road base 150 and 250 MPa, the thickness of the asphalt layer varying from 20 mm and up. Tensile and shear strains were calculated in the road surface and the asphalt interface at the point of load symmetry and at the centre of one of the contact areas. Comparison was made with a crude tire tread pattern model. Thin asphalt surfacings showed the highest tensile strain in the road surface. At increasing thickness there was a transition of highest strain from the surface to the lower interface of the asphalt layer, the transition thickness varying with assumed modulus values. Considering tensile strain, the transition thickness varied between 30 and 40 mm, depending upon assumed modulus values, whereas on the basis of shear strain the transition thickness varied between 30 and 50 mm. The assumed tire tread pattern model showed no significant difference in this strain distribution.
Samenvatting