VU’s world-first research into recycled materials

The project team installing sensors during construction of trial site. (Supplied/Victoria University).

Researchers from Victoria University’s (VU) College of Engineering and Science are conducting world-first research exploring the use of recycled materials as backfill in utilities trenches, located metres below busy city roads.

The industry’s standard practice is to use natural aggregates for backfill.

This material usually needs to be excavated and crushed, and often trucked across great distances.

However, VU’s Dr Ehsan Yaghoubi, Professor Sam Fragomeni and Associate Professor Maurice Guerrieri have received a $220,000 grant from Sustainability Victoria for their research into using an alternative of crushed recycled concrete aggregates from demolished structures – such as buildings and bridges – that normally go to landfill.

The latest research project follows the team’s successful delivery of another Sustainability Victoria-funded project in 2020, at a demonstration site in Wyndham.

This project showed that a blend of recycled plastic, glass and tyres, with self-compacting properties, could serve as backfill in “non-trafficked” trenches.

“In the new project, we are looking at stronger materials that can perform well when roads with moving vehicles are built on top of the trenches,” Dr Yabhoubi said.

These world-first solutions could keep tonnes of demolition rubble, as well as waste plastic, glass and tyres, out of landfills.

It is estimated about 7000 tonnes of waste that would otherwise go to landfills could be used for building non-trafficked trenches.

Both of the 2020 project and the new initiative are being conducted through a collaboration between VU and the University of Melbourne, with Greater Western Water and Ground Science as industry partners.

“The latest project is important as rapid urbanisation is creating more roads and the percentage of sewer pipelines constructed beneath areas with traffic is increasing,” Dr Yaghoubi said.

VU’s geotechnical and pavement laboratories, at its Footscray Park Campus, have refurbished for the projects including with new state-of-the-art facilities for performance-testing of the recycled blends.

Dr Yagyoubi said the project demonstrated VU’s commitment to the circular economy by proving the suitability of recycled materials to build the infrastructure for essential services.

The team’s latest project was awarded the VU’s Vice-Chancellor’s Award for innovation in 2021.