Sustainable Enhancement of Asphalt Performance Using Biochar, Waste Plastic Aggregate, and Mining Waste

The Challenge

Mining generates Australia’s largest waste stream (~620 Mt/yr), dominated by tailings that pose long‑term environmental, social and cost burdens. Lithium production adds ~9–10 t slag per tonne of lithium carbonate, with WA’s Greenbushes a major source, yet most by‑products lack high‑value uses. Meanwhile, road construction relies on costly, emissions‑intensive virgin materials. This research addresses the gap by integrating lithium slag, biochar and engineered plastic aggregates into asphalt and quantifying performance, durability and environmental compliance.

Proposed Solution

1) Optimise biochar content for C170/C320 binders to enhance rheology and high-temp resistance.

2) Quantify effects of engineered waste plastic aggregate replacement on mixture strength, stiffness and rutting/fatigue.

3) Evaluate lithium slag as filler on density, stiffness and moisture resistance.

4) Test synergistic effects of biochar+plastic+slag on integrated mixes.

Hypotheses: (H1) Biochar increases complex modulus and reduces phase angle at service temperatures; (H2) Engineered plastic aggregate restores or improves mixture skeleton; (H3) Lithium slag filler improves stiffness without detrimental leaching; (H4) The tri-material system delivers superior rutting/fatigue and lifecycle benefits vs. control.

Proposed Benefits to WA

This research delivers economic, environmental and social benefits for Western Australia. Economically, it valorises waste from WA’s lithium industry, lowering disposal costs while enabling cheaper, longer‑lasting roads. Environmentally, it addresses major waste streams—biomass, plastics and lithium slag—supporting circular economy and net‑zero goals. Socially, it enhances the sustainability of the critical minerals sector, builds local expertise through ECU and Curtin, and supports employment in a key state industry.

Supervisors

Dr Themelina Paraskeva, Dr Nuha S. Mashaan and Professor Mohamed Shahin

DOI

10.71342/385253911605