A Critical Appraisal on the Performance of Porous Asphalt Mixtures
WOODSIDE A, WOODWARD W and BAIRD J, University of Ulster, and PHILLIPS P, Bardon Roadstone, UK
Pervious or porous surfacing materials were initially developed in the United KIngdom In the 1950's. However, it was not until recently that Porous Asphalt, (formerly known as Pervious Macadam or Friction Course) has been used to any significant degree on
Pervious or porous surfacing materials were initially developed in the United KIngdom In the 1950's. However, it was not until recently that Porous Asphalt, (formerly known as Pervious Macadam or Friction Course) has been used to any significant degree on British highways. This has not been the case on mainland Europe where, over the past 5 to 10 years, the use of Porous Asphalt (PA) has expanded dramatically in countries such as France, Belgium, Holland, Austria and Switzerland to name just a few (1).
Pervious Macadam was developed in the 1950's as a 10ram open textured bitumen macadam to overcome problems of aqua-planing and skidding on aircraft runways.
This led to the development of the material for road pavement use. However, apparent conservatism on behalf of theDepartment of Transport hindered it's development for many years. Until recently all PA laid on British roads had been as trial sections. The earliest of these was recorded in May 1967 on the M40 High Wycombe by-pass in Buckinghamshire. A second was laid in September of the same year on the A452 Leamington to Stonebridge road in Warwickshire.
Throughout the 1970's and 1980's trials were undertaken throughout the country with varying levels of success. In 1984 extensive trials were undertaken on the A38 Burton by-pass in Staffordshire as a joint research project by the British Aggregates and Construction Materials Industries (BACMI), Refined Bitumen Association (RBA) and the Transport Research Laboratory (TRL) (2)(3). A wide range of aggregate gradings and binders were tried out on 15 trial sections. The long term performance of these sections ranged from very good to disastrous.
Almost 30 years after the first UK trials of Pervious Macadam, serious interest in PA has started to grow and several county councils, under the guidance of the DTp, have begun to specify PA as a wearing course material for major road projects in England such as the Blackwater Valley Relief Road for Surrey County Council.
Association for European Transport