Whilst it is well known that the long term performance of asphalt is critically linked to the maintenance of high standards of manufacturing, construction, and in particular asphalt compaction, it has attracted relatively little fundamental research. In 1996 Pioneer Road Services (PRS) conducted controlled field trials of the AMIR compactor (Asphalt Multi-Integrated Roller) in Sydney. The trials provided substantial evidence that not only was the new compaction process more efficient, it produced asphalt materials with significantly improved properties. The success encouraged PRS to develop and manufacture an advanced asphalt compactor known as "HIPAC" (Hot Iron Principle Asphalt Compactor). This paper describes the field trial carried out prior to commissioning HIPAC for commercial operations. The trial showed the HIPAC equipment and process to be more efficient, giving improved density with fewer passes, and effective, giving an asphalt product with improved performance related properties. The trial data are provided. An explanation of HIPAC's superior performance is presented, derived following the review of fundamental performance characteristics of typical pavement materials. It is postulated that asphalt compaction is best represented by a fluid flow model, and that the conventional compaction processes (derived from the compaction of unbound granular materials) are inappropriate for asphalt materials. The performance benefits offered by the revolutionary HIPAC process are explored. (A)
Abstract