A new study by The University of South Australia (UniSA) has tested and verified the structural integrity of walls constructed from tires packed with earth, with the results potentially providing new opportunities for the reuse of end-of-life tires in the construction industry.

Tire waste represents a major sustainability challenge globally, with Australia alone generating an average of 55 million (450,000 tonnes) end-of-life tires each year.

While earth-packed tire walls have been used in niche construction scenarios for decades, there has previously been no strong empirical data available to support their use, a fact that has limited their wider uptake by architects and engineers.

Supported by tire Stewardship Australia, a UniSA team consisting of Yachong Xu, Martin Freney, Reza Hassanli, Yan Zhuge, Mizanur Rahman and Rajibul Karim, has rigorously assessed the structural integrity of a test tire wall to examine how the structure performed under various stressors.

Earthship built from recycled tires at Ironbank, SA.

According to Dr Martin Freney, the wall proved to be as structurally sound as conventional walls used in residential applications. In considering expanded uses for tire walls, Dr Freney suggests several unique characteristics of the structures may offer benefits over some traditional building approaches, particularly for retaining walls.

Not only are the tire walls as structurally sound as concrete or wood sleeper retaining walls, they are also extremely resilient. Unlike a concrete wall, we found these walls have the ability to ‘bounce back into shape’ following impact, such as from an earthquake.

And if a drainage material such as recycled concrete rubble or crushed bricks is used to fill the tires, they also offer excellent drainage, which can be a major consideration in many retaining wall scenarios. Furthermore, the use of recycled fill materials reduces the environmental impact of the wall.

—Dr Martin Freney

While the study only tested one real world wall as part of the project, UniSA PhD candidate Yachong Xu developed software models that allow the data obtained to be extrapolated to other designs, making the results applicable to a wide range of scenarios and stakeholders.

We really believe this research provides a strong evidence base for the expanded use of tire walls in housing and other applications, and the next step will be to engage with an industry partner to develop a range of real-world applications for tire walls.

—Dr Freney