Polymer modified binder test methods updated

Image courtesy of Austroads.

Three updated test methods have been published by Austroads to safeguard people who handle polymer modified binders (PMB) or use them in road construction.

The test methods support the recently published technical specification “ATS 3110: Supply of Polymer Modified Binders” that sets out the requirements for supplying PMBs and crumb rubber modified binders for use in sprayed seals and asphalt.

These test methods were developed in consultation with Austroads members and industry.

Robert Urquhart, test method developer, said it specifies minimum flash points for PMBs to minimise the risk of flammable vapours from PMBs accumulating in storage containers or while they’re being transported, and possibly catching on fire.

“Test method AGPT-T112-20, Flash Point of Polymer Modified Binders, sets out the procedure for determining a flash point by slowly heating a PMB in an open metal cup until vapours on its surface are ignited or ‘flash’ when exposed to a test flame.”

Another test method developed indicates whether volatile components are present in PMBs that could be emitted as fumes during pavement construction and maintenance which could affect air quality and human health.

“Test method AGPT-T103-20, Mass Change or Loss on Heating of Polymer Modified Binders after Rolling Thin Film Oven (RTFO) Treatment explains how to detect these components in a PMB by determining its change in mass after applying the RTFO treatment,” Dr. Urquhart said.

Austroads found PMBs are heat-sensitive so test results can be significantly affected by the amount of exposure PMBs have to high temperatures and the length of time they are exposed.

The modifier in some PMBs can also separate out while the binder is heated therefore improper heating and mixing of samples can produce test results which may not be representative of the original material.

The Austroads AGPT-T102-20, Protocol for Handling Modified Binders in Preparation for Laboratory Testing, minimises the changes that occur in binder samples when they are heated before testing so the test results accurately reflect the product.

The new methods have been developed in line with Australian and New Zealand standards to provide information about how bitumen emulsion and cutback bitumen samples should be prepared for testing.

“The methods will enable more accurate test results to be obtained for PMBs and also provide safety information regarding protecting human health and the surrounding environment,” Dr. Urquhart said.

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