Trials underway using 100pc recycled material for pipeline backfill

Recycled materials with self-compacting properties that could be used as an alternative backfill for sewer pipeline trenches are being tested in a new Australian study.

Current sewer pipeline backfill practice is to use natural aggregates that need to be excavated, crushed, and often trucked in from great distances.

To identify alternatives, researchers from Victoria University, the University of Melbourne, geotechnical firm Ground Science, and City West Water, are trialling blends of recycled tyres, plastic and glass, and glass comprising between 70-80 per cent of the final formulation.

While other research projects have used backfill mixes with a limited percentage of recycled materials, the Victoria University project uses 100 percent recycled content for the purpose, a likely world-first.

Victoria University engineer Dr Ehsan Yaghoubi said: “Civil engineering projects require more materials than most people realise, whether it is a road, or backfilling kilometres and kilometres of sewer trenches.

“Together with our collaborators, we came up with the idea of using a blend of recycled materials because we can control their compaction and density,” he said.

While the project is still in its early stages, researchers have run geotechnical and environmental testing on various recycled blends, and plan to move to the construction and instrumentation of the trial sites in September.