Resources

Safety and environmental drivers are pushing the New Zealand road construction industry away from hot, cutback binders and towards the use of emulsified bitumen as the delivery medium for chipseal binders. However, there is no agreed standard method for recovery and testing of the emulsified binder.

The absence of such a method could potentially lead to dispute over the quality and contractual compliance of emulsified binders due to the effects of differing laboratory techniques for binder extraction and sample preparation.

This research project reviews techniques used worldwide and recommends a method suitable for New Zealand materials and conditions. Results from the trials of the new test method show that, in spite of completing the extraction of the binder under conditions similar to those encountered in the field, the binder must be reheated to remove water and air from the test sample.

This treatment changes the binder rheological properties compared with the same binder prior to emulsification and extraction. Thus the objective of this research was to develop a simple repeatable method acceptable to suppliers and purchasers to extract the emulsified binder to allow confirmation of the binder properties for quality assurance purposes.

This report outlines the literature review, the method development, the laboratory trials of the method and results from contractor trials of the method.

Keywords: binder, chipseal, cutback, emulsion, extraction, properties, residual