ABSTRACT
The pavements at Emerald airport, located in central western Queensland, were resurfaced in 2019. The taxiway and apron were surfaced with dense graded asphalt (DGA) and the runway was surfaced with stone mastic asphalt (SMA). The project was a pilot project to demonstrate ungrooved SMA is a viable alternate to grooved DGA for runway surfacing in Australia. The mixture designs indicated that the SMA is expected to perform in the field similarly to the DGA, with regard to fracture, deformation and moisture damage resistance. The construction trial and surface construction confirmed that the surface texture exceeded the regulatory requirements, as did the wetted surface friction values. Furthermore, the aircraft skid resistance compliance was achieved immediately following construction, which is a significant advantage over grooved DGA, which usually does not achieve compliance until the grooves are sawn some 4-8 week later. The production and construction results demonstrated the ability of the continuous drum mixing plant to achieve adequate SMA production consistence, comparable to that expected for DGA. However, it is recommended that the asphalt production binder content acceptance tolerance be increased for SMA, to reflect the more variable nature of the test results due to unavoidable contamination of the tools by the high bituminous binder content associated with SMA. The project also highlighted the need to monitor the SMA construction to minimise the risk of isolated bitumen-rich spots. Overall, the project was successful and it is recommended that other airports consider ungrooved SMA as an alternate to grooved DGA in the future. Ongoing monitoring of the SMA surface at Emerald airport is required to determine the performance with age, compared to otherwise similar DGA in the same environment.
