Influence of layer bonding on the prediction of pavement life

It is important to recognise that pavement performance can be seriously compromised by interface problems, even though the performance of an individual layer may be very high. This means that pavements may fail with traffic volumes far less than the design values in spite of the fact that individual layers may exhibit reasonably high dynamic stiffness modulus values, high permanent deformation resistance and high fatigue properties. Material properties and some construction practices can create weak or no interface bonding. Bond failure at one interface can cause a predicted loss of two-fifths to five-sixths, to as low as one sixth of the potential life of the pavement. Pavement analysis based on the assumption that all bound layers work as one single layer is seriously misleading if the bond at one or more layer interfaces is weak or has failed. The fatigue property of a pavement layer above an interface is very sensitive to variations in layer dynamic stiffness modulus, layer thickness and the degree of lateral movement available at the interface.