Sprayed seal trial on Coober Pedy road shows promising results

Results from the latest inspection of a long-term trial into the use of sprayed seal at Coober Pedy has shown that polymer modified binders (PMBs) are aging better than unmodified bitumen.

Austroads’ sprayed seal trial site at Coober Pedy was established in 2011 to evaluate performance of seals constructed with different grades of binders over time.

One of the main aims of the trial was to compare the ability of different PMB grades to resist reflective cracking.

Austroads has shared the results from the 11-year inspection, combined with data from previous assessments, in a new technical report.

The report includes details of the site, binder sample collection, and visual assessments, surface texture measurements, and binder analysis.

According to Austroads, the data revealed that while all binders were becoming harder and progressively more oxidised over time, PMBs demonstrated superior resistance to aging compared to unmodified bitumen.

“This research provides valuable information for road managers and industry, into the long-term performance of different binder grades,” said Ross Guppy, manager of the Transport Infrastructure program at Austroads.

“The findings help build evidence to guide decisions on pavement design and maintenance to ensure safe and durable road networks across Australia.

“We found that ageing appeared to improve binder fatigue cracking performance at low peak strain levels but reduce performance at high peak strain levels.”

“These insights allow us to better understand how our infrastructure will respond to changing traffic patterns over time and will help us develop future specifications and deterioration models for asset management.”

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