Austroads proposes merging PMB grades

A new Austroads technical study has proposed merging four grades of polymer modified binders (PMBs) into two.

Australian Road Research Board Principal Technology Leader and study author Robert Urquhart said extensive testing revealed comparable PMB grades showed similar performance in asphalt and sprayed seals.

“Reducing the number of PMB grades will simplify technical specifications in each jurisdiction,” Mr. Urquhart said.

“Production costs should also be cheaper, as fewer tanks will be needed to store different products.”

The study, Performance of Asphalt and Spray Grade PMBs in Sprayed Seals, compared the difference between samples of S20E and A20E grade PMBs, and S25E and A15E grade PMBs, to determine whether using comparable asphalt and spray grade PMBs influenced sprayed seal performance.

“Samples of each PMB underwent four laboratory tests, which investigated the ability of each binder to initially wet aggregate during construction, retain aggregate when a sprayed seal was first subjected to traffic in the presence and absence of water and resist traffic‑induced cracking,” Mr. Urquhart said.

“Results concluded that the representative S20E and A20E grade PMBs, and S25E and A15E grade PMBs, performed very similarly and effectively in all tests.”

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