Towards performance-related design criteria and specifications for modified binders

Abstract

The reflection of primary cracks through overlays and seals on roads is recognised as a serious problem. The ingress of rain-water through these cracks can cause pumping which leads to forms of distress such as potholing and/or deformation. This can, in turn, lead to the premature failure of an otherwise sound pavement. Asphalt overlays and bituminous seals are often used to rehabilitate both flexible and rigid pavements. However, the reflection of cracks through these treatments will cause a recurrence of the same problems, thus invalidating the expenditure involved. Special or innovative materials such as bitumen-rubber, geofabrics and low-viscosity asphalt have been used in attempts to solve this problem with varying degrees of success. There is currently a lack of performance-related design criteria and specifications for the use of bitumen-rubbers and especially homogeneous modified binders. This is true for surface treatments as well s premix.