Friday, 7 June 2019
Austroads has released a report, Relationships Between Cutter Oil Properties and Sprayed Seal Performance, to inform the update of Australian Standard AS 3568 Oils for Reducing the Viscosity of Residual Bitumen for Pavements. Australian government agencies use this standard to specify the properties of hydrocarbon oils used during the construction of sprayed seal but it has not been updated since 1999.
"The existing AS 3568 specifies some materials which are no longer commercially available. Some cutter oils that fail AS 3568 requirements also appear to perform satisfactorily during sprayed seal construction," says Robert Urquhart ARRB Principal Technology Leader and report author.
"The current issues with AS 3568 have required many agencies to maintain their own local specification standards. We are aiming for agencies to adopt the updated AS 3568 to save themselves time and extra work."
In Australia and New Zealand cutter oils (cutters) are added to hot binders when sprayed seals are constructed at cooler temperatures to enhance the adhesion between binder and aggregate.
"The objective of the research in this report was to produce an updated version of AS 3568 which was performance-based that also allowed the use of currently available commercial oils," says Robert. "We blended seven commercially available cutter oils with C170 bitumen and assessed their sprayed seal performance using four different laboratory tests. The main factors that affected sprayed seal performance were the cutter oils’ final boiling point and viscosity at 40°C."
The new AS 3568 Standard will contain the results of this study and input from Austroads Bituminous Surfacings Working Group (BSWG) members.
Proposed changes include removing tests from the specification which do not provide information about the performance of cutter oils and deleting the specification table for heavy flux oil as this material is no longer used in Australia or New Zealand. Flux oil used in sprayed sealing operations will be required to comply with national specified requirements for automotive diesel fuel.