The report reviews the performance of thin surfacings developed from the separation of function concept. The concept proposes that a surfacing need not contribute to the load bearing capacity of the pavement, this being entirely met by the structural layers, but can be optimised to meet specific road user requirements. Comparative road trials in the UK of the new thin and ultra thin surfacing type, and of high friction surfaces, are reviewed, together with an Australian surfacing trial, surfacing developments in Austria, and Australian work on the development of stone mastic asphalt. The effectiveness of the surfacings in meeting road user requirements related to skid resistance, noise spray generation and cost are discussed. It is concluded that a range of new and recently developed surfacing types are available to meet the increasingly stringent demands of road users. Through minimisation of layer thickness, it will be possible to deliver high performance at minimal cost. Although the service life of the new surfacings may be shorter than conventional dense graded asphalt, this is likely to be considered acceptable given the improved level of service provided. (A)
Abstract