Underground » Strata Control and Windblasts
This project developed, manufactured, and tested two prototypes of new-generation fibreglass rock bolts, including RE6 (22 mm) and RE7 (35 mm), which were engineered with a 26° braiding angle and infused in a graphene-enhanced epoxy matrix to improve interfacial toughness and stiffness. The project proceeded from material/manufacturing optimisation to a suite of large- and component-scale tests designed to capture shear, axial and torsional performance under conditions representative of underground ground-support practice. In parallel, the properties of concrete and grout were controlled and verified to ensure test validity and repeatability.
After manufacturing several prototypes, early screening with single guillotine shear tests against a benchmark M24-X steel bolt showed that the larger-diameter RE7 delivered a strong single-shear capacity (191.6 kN at 10.55 mm), whereas RE6 reached a lower peak load but demonstrated greater ductility. Comparison with other commercially available fibreglass bolts indicated that both prototypes offered superior shear capacity. These results validated the chosen braiding and resin systems and justified scaling up to concrete-embedded tests that better represent field confinement and load transfer.
In the large-scale concrete-embedded double-shear test, the shear moulds and testing frames were modified to suit the prototype geometries. The results highlighted the influence of diameter and system compliance: RE7 reached 266.919 kN and demonstrated a longer linear-elastic region with a smoother post-peak response; RE6 peaked at 185.473 kN and showed more pronounced, energy-dissipating load cycling after the first peak, behaviour consistent with progressive interlocking and debonding rather than tendon rupture.
Double-embedding pull-out tests confirmed that the bonding mechanism is the primary axial mechanism. Post-test inspections confirmed debonding and local grout distress, with the fibreglass cores remaining undamaged.
Double-embedment tensile tests returned high peak loads with controlled post-peak softening rather than brittle failure.
Torsional behaviour was evaluated with a lever-arm rig (1.00 m) driven by a hydraulic jack and recorded via a high-capacity DAQ chain.
Taken together, the results show that the proposed braided GFRP/epoxy-graphene designs provide strong shear and axial strength with energy-absorbing, non-brittle post-peak behavior. These qualities are especially valuable for ground-support systems that need to be cuttable and resistant to corrosion. The consistent lack of tendon damage in pull-out, tensile, and torsion tests highlights a key design feature: the braiding architecture and bonding interface can be adjusted to optimize peak capacity, residual load, and stiffness, all while maintaining the benefits of the composite cores.
The work also provided practical test infrastructure, specimen preparation controls, and verified materials characterisation, all of which support the credibility and transferability of the findings to field settings.
Based on these results, the report suggests specific next steps to turn laboratory performance into mine-ready products.