Challenge

Across Australian underground mines, roof support systems play a critical role in maintaining excavation stability and protecting workers. However, existing steel‑based bolts present several fundamental challenges: 

• Corrosion and reduced service life, particularly in humid and chemically aggressive environments.

• High manual handling loads, increasing the risk of strain injuries for operators.

• Limited installation flexibility, as fixed‑length rigid bolts constrain roadway design and complicate deployment in tight or irregular geometries.

• Poor compatibility with future automation, including continuous installation systems and real‑time ground monitoring.

Australian Coal Industry’s Research Program (ACARP) industry advisers identified a need for a fundamentally different type of roof bolt; one that could deliver equivalent structural performance while improving safety, durability and adaptability. 

Solution

The Carbolt project responded to this need by developing a carbon‑fibre‑based roof bolt engineered to replace traditional steel bolts while overcoming their key limitations. 

Phase 1 – Feasibility and concept development 

The first phase of the project demonstrated the feasibility of a lightweight, corrosion‑resistant, carbon‑fibre roof bolt that could: 

• Achieve tensile performance comparable to conventional steel bolts.

• Provide controlled, ductile extension under load, offering early warning prior to failure.

• Be manufactured as a flexible element capable of being coiled and cut to length.

• Eliminate corrosion‑driven degradation over time.

This phase confirmed that carbon‑fibre composites could meet the functional requirements of underground roof support while enabling new design freedoms not possible with steel.  

Phase 2 – Pre‑commercial prototype development 

Building on the feasibility results, Phase 2 focused on translating the concept into a pre‑commercial fixed‑length Carbolt prototype suitable for mine‑relevant installation and testing. 

Key Outcomes Included: 

• Design and manufacture of full‑scale Carbolt prototypes using braided carbon fibre and resin systems.

• Development of anchoring and load‑transfer mechanisms compatible with standard grouting practices.

• Laboratory testing to characterise tensile and shear performance against industry benchmarks.

• Demonstration that Carbolt could meet or exceed the performance of comparable steel roof bolts while weighing significantly less and remaining non‑corrosive.

This phase established Carbolt as a credible next‑generation roof support technology, capable of improving health and safety, strata control, and future mining productivity.  

Impact and future potential 

Across its ACARP‑funded phases, the Carbolt project showed that carbon‑fibre roof support systems can fundamentally change how underground ground support is designed, installed and managed. By replacing rigid, corrosion‑prone steel with a lighter, flexible and durable alternative, Carbolt opens pathways to: 

• Safer manual handling and reduced injury risk.

• Longer‑life roof support in challenging environments.

• Greater flexibility in tunnel design and development.

• Future integration with automated installation systems and smart geotechnical monitoring.

The Carbolt program has laid the technical foundation for future underground trials and commercialisation, positioning the technology as a potential step‑change in underground mining safety and productivity.