Published: 2008 | Category: Activity management , Research programme , Research & reports | Audience: General
In recent years, the standard practice in New Zealand regarding binder selection for state highways has been to use harder penetration grade binders and reduced diluents, after some research indicated that the use of harder binders slowed the onset of flushing.
However, the use of harder binders and less diluents increases the risk of early failure of chipseals, because the higher viscosity of the binders causes chipseal construction issues and increased brittleness at low temperatures, both of which can lead to chip loss.
This report discusses the development and trial of a guideline based on the performance of a binder at the high and low temperatures likely to be encountered at the chipseal construction site. The research follows on from initial work in developing and trialling a ‘Surface Performance Grade (SPG) Specification’ by the Texas Transportation Institute (TTI) for the Texas Department of Transportation (TxDOT). Our research, conducted between 2005 and 2007, involved developing climatic zones for New Zealand and testing binders against the SPG specification, and then comparing the actual field performance of the seals with the expected/predicted performance from the binder test results (measured in the laboratory).
Keywords: aggregate loss, application, binder, bleeding, chip, chipseal, climate, flushing, grade, guideline, New Zealand, performance, road, seal, SPG, spray, surface, temperature, viscosity
