Crumb rubber: a legacy investigation


Primary Roads WA is working with the Australian Highway Analysis Board (ARRB) and Tyre Stewardship Australia to validate the usage of recycling asphalt pavement that comprises crumb rubber.

In Western Australia crumb rubber consumption has doubled previously two years, from between 800–1000 tonnes to just about 2000 tonnes. Alongside the motion to make use of a wide range of recycled supplies in asphalt, highway base and spray seal, the highway building business has been rising its functionality to recycle asphalt itself.

As asphalt is 100% recyclable, contractors are more and more opting to mill out roads, save the supplies and re-use them in new asphalt mixes, which is a fabric properly often called reclaimed asphalt pavement (RAP).

Nonetheless, one of many main unanswered questions within the business is: can these mixes containing recycled merchandise then be recycled as RAP when the pavements attain their finish of life?

When Zia Rice, Senior Skilled Chief at ARRB, sat down to analyze literature on this matter, she discovered there wasn’t a lot proof to reply this query so a examine venture commenced.

“Once we make asphalt mixes that comprise RAP, if we’re at percentages larger than 20% we have to characterise the RAP viscosity so we will tailor the brand new combine to a goal viscosity. So, we did a laboratory investigation to see how the RAP characterisation was affected by the presence of crumb rubber alongside the practicality testing,” Rice defined.

There weren’t any points throughout this stage when claiming, processing, mixing and repaving the RAP. Nonetheless, when a bigger tonnage of the crumb rubber was examined, the staff discovered some points with build-up throughout processing that would scale back efficiencies.

“Regardless of the slight build-up throughout processing of bigger tonnages, we might see that is one thing that may very well be simply rectified by business in the event that they perceive that when they’re going by excessive volumes of this combine, they may must tailor their plans,” Rice mentioned.

The laboratory investigation additionally returned attention-grabbing outcomes.

“We discovered it troublesome to characterise the viscosity of a crumb rubber RAP binder because of the presence of the rubber particles. Via our present strategies it’s exhausting to get a consultant reply so additional investigation is required there,” Rice mentioned.

“This might facilitate a brand new design course of for degree two and three RAP mixes with excessive percentages; maybe we’ll have a look at another efficiency indicator reasonably than goal viscosity.”

From right here, the following steps will probably be to analyze easy methods to design new recycled asphalt with crumb rubber and the significance of RAP traceability and separation.

TSA CEO Lina Goodman was thrilled with the venture: “This collaborative venture is a good instance of how necessary innovation is within the round economic system. Australia generates the equal of 56 million used automobile tyres yearly. Round 30% of these find yourself in landfill or are stockpiled,” Goodman mentioned. “That’s the reason TSA has dedicated nearly $6 million so far to assist particular initiatives and research, corresponding to this RAP venture, geared toward discovering revolutionary and sustainable methods of turning a waste stream right into a helpful commodity.”

The venture was a part of the Western Australia Highway Analysis and Innovation Program (WARRIP), involving Primary Roads and ARRB, and was supported by TSA.

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