Specification trials of high-performance hot rolled asphalt wearing courses

A specification clause, Clause 943, and associated notes for guidance were prepared for hot rolled asphalt in terms of its resistance to permanent deformation, as measured by the wheel-tracking test, and durability, as measured by the air voids content. Clause 943 was trialled on a series of road contracts, during which the specific requirements of the clause were refined. The results of the testing carried out during the construction of the trials, together with subsequent monitoring of the earliest trials laid, are analysed to show that the approach employed by the Clause is practicable. Nevertheless, the reported results allow further conclusions to be drawn as to the development and use of Clause 943. (A)