About 90% of the state-controlled sealed road network is surfaced with sprayed seals. Given the
widespread use on state controlled roads, the pursuit of sustainable sprayed sealing practices by
effectively and ef�iciently delivering this form of road surfacing supports the community and the
government’s ‘Building Queensland’ and ‘Supporting Jobs’ objectives. The project was undertaken with
liaison with Australian Flexible Pavement Association (AfPA).
The project focused on identifying ways to replace and reduce cutters in sprayed sealing practice. The
objective of the project was to identify ways to reduce the use of cutters in order to improve safety and
reduce greenhouse gas emissions.
A review of various options to reduce cutter was undertaken and revealed the preferred and available
options are the use of non-standard bitumen that allows spraying at lower temperatures without cutters,
and the use of non-standard emulsions for priming new surfaces.
Two demonstration projects were identified to document the performance of non-standard bitumen as a
means to reducing cutters. Two demonstration sealing projects were conducted to compare the
performance of a low viscosity crumb rubber binder (S45R-LV) to a standard crumb rubber binder
(S45R). The projects aimed to determine if the low viscosity binder could be sprayed without cutter at
expected performance levels and to compare the two binders at lower spraying temperatures. The
projects involved two sites: Dalby-Cooyar Road and Nerang-Murwillumbah Road. The existing surface
conditions at both sites included varying texture, maintenance patching, and significant cracking.
The results showed that the low viscosity binder (S45R-LV) could be successfully sprayed without cutter
at lower temperatures, providing potential benefits such as reduced carbon emissions. The spray
application produced a uniform surface with no visual defects. Extended reduction of spraying
temperature resulted in a non-uniform spray for both binders. The low viscosity binder performed better
that the standard viscosity material at lower temperature. Ongoing monitoring of the demonstration sites
is planned to assess aggregate retention and surface texture performance.
In summary, the demonstration projects showed that non-standard binder can be successfully sprayed
without the need for cutter, but further research and testing are needed to optimize the spraying
conditions and reduce cutter usage.
Implementation of digital techniques to optimise slope remediation design across 132 sites in South-east Queensland.
June 28, 2024
Throughout early 2022 across Southeast Queensland rainfall events caused significant damage to the region’s roads causing several landslips and rockfalls. The State Road authority identified
