Austroads have 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.
The standard is used by Australian government agencies to specify the properties of hydrocarbon oils used during sprayed seal construction.
Australian Road Research Board Principal Technology Leader and report author Robert Urquhart said the standard had 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,” Mr. Urquhart said.
“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 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,” Mr. Urquhart said.
“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 report will contain the results of the study and input from Austroads Bituminous Surfacing Working Group 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,” Mr. Urquhart said.
“Flux oil used in sprayed sealing operations will be required to comply with national specified requirements for automotive diesel fuel.”