Carbolt Self Monitored, Yieldable Carbon Fibre Cable Bolt for Ground Control

Underground » Strata Control and Windblasts

Published: April 21Project Number: C28019

Get ReportAuthor: Karsten Hoehn, Scott Barnes, Ian Greyvensteyn | Mining3, CSIRO

In general, there is a variety of rockbolts and roof support systems available on the market for mines to choose from. The most common type is the rock bolt, which consists of a metal rod with an anchoring component and a face plate. Some bolts are manufactured out of glass fibre reinforced polymer. They are more expensive than the traditional metal bolt but have special applications, for example on the panel sides of the longwall coal mines to protect the shearer from getting damaged as would occur if metal rockbolts were used.

In addition to these fixed-length rockbolts cable-bolts are available for longer holes and other challenging conditions.  The disadvantage of cable-bolts is that, although they have a high tensile strength, they are usually not designed to tolerate sheer stress. Hence, there is a technology gap and a need for a long or deep hole support system which is also tolerant to sheer loads that is also corrosion resistant. This project conducted a feasibility study for the next generation of advanced rock support systems in the form of a carbon fibre rope, the Carbolt, that can either be manufactured in pre-determined lengths, or in bulk and rolled onto a drum for deployment into a drill hole by a to-be designated machine before being cut to length as needed during the installation.

For single tows the full carbon fibre strength, as specified by the manufacturer, could be achieved when using a high extension (>130%) epoxy resin. When four strands of tow were combined the strength was reduced by 15-30% which is indicative of uneven tension in the tow strands, a risk when forming by hand and not seen in commercial pultrusion. The strength reduction in twisted 4 ply was of the same order (19-32%) indicating that the twisting was not impacting significantly on the overall tensile strength. The same fluctuations in the pre-tension of different strands caused by variations in the manual manufacturing process prevented the full Carbolt from achieving the desired load capacity. Nevertheless, it can be extrapolated that an industrially produced Carbolt at 510g/m (with a resin fraction of 60%) and 25mm diameter could have a strength in excess of 400kN (40 tonnes).

While there are more engineering refinements required in a potential next phase, the project was also able to demonstrate that the Carbolt can withstand significant shear forces. Due to its flexibility, it was able to deform, undergoing a displacement of 30mm before the shear test box ran out of travel. Further, the ductile behaviour, required to release the load stresses in the roof, was demonstrated with a Carbolt containing a modified core.

In a pre-commercial Carbolt development, twisting significantly longer carbon strands would allow uniform pretension in all carbon filaments during the twisting and cable forming phases to be achieved, as is routinely done in the commercial production of technical ropes and cables. This would then enable the Carbolt to achieve the tensile and shear strengths desired while retaining good ductile properties.

The Carbolt requires a novel locking mechanism that locks the carbon fibre strands of the rope without damaging them. This locking mechanism forms part of a new bearing plate design and a number of different designs have been investigated as part of this project.

Throughout the duration of the road way lifetime, wall and rock movement is evident, but often not monitored. The ability of integrating optical sensing fibres into the carbon fibre composite structure of the Carbolt has been demonstrated, enabling the monitoring of tensile stresses continuously along the bolt during future field trials.

Overall, during this project the feasibility of the Carbolt design has been demonstrated on a component level, bringing the concept from TRL 0 to TRL 2, see appendix C for details. In addition, a road map has been developed, see appendix B, outlaying the next steps to progress the Carbolt technology from the current feasibility stage to a number of possible realisations and application.


Health and safety, productivity and environment initiatives.

Recently Completed Projects

C26047Real Time Dust Monitor

The aim of this project was to develop a real time respirable dust m...

C29034Integrated Roadway Development: A Strategic Industry Review

This report describes the outcomes of a strategic review of Australi...

C26062New Outburst Risk Determination Measures Along With Data Gathering And Analysis For Coal Burst Assessment

Bursts are events that expel material at velocity at the time of eje...


Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C27030Examination Of Past And Present Mine Rehabilitation To Grazing Land As A Guide To Future Research

This study follows on from project C23053 which found ...

C28045Coal Spectral Libraries For Scanning Devices

The objective of this project was to create a public spectral librar...

C29041Preconditioning Plants To Withstand Flooding On A Tailings Dam

Repeated flooding of the tailings dam at Mangoola mine under project...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27026Ultra-Low Ash Coal By 3D Binder Flotation

The objective of this project was to investigate the potential to pr...

C28052Agglomeration To Minimize Moisture And Maximize Yield

The objective of this project was to determine the potential to effe...

C28051Reducing Diesel Consumption While Improving Fine Coal Flotation Through Controlled Diesel Emulsification In Saline Water

Diesel collector used in coal flotation is not soluble in water and ...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C28072Mineral Re-Distribution From Raw Coal To Pulverised Fuel (Pf) Coal To Ash In Commercial Power Stations

This project was based on understanding how minerals in thermal coal...

C28070Development Of A Combustibility Predictor For Thermal Coal Utilisation In Pulverized Fuel Boilers

Coal is a heterogeneous material, consisting of a range of carbonace...

C27022Slagging And Fouling In HELE Plants: Assessment Of Fusibility And Particle Size In Deposition

Key markets for Australian black coal have been moving to supercriti...

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C23052Novel Stone Dust Looping Process For Ventilation Air Methane Abatement

This multi‐phase project is concerned with the mitigation of m...

C27054Optimisation Of A Thermal Flow Reversal Reactor For Ventilation Air Methane Mitigation

Ventilation air methane (VAM) generally accounts for 50-85% of the t...

C28076Selective Absorption Of Methane By Ionic Liquids (SAMIL) - Phase 2 Demonstration In A Packed Bed Reactor

An alternative approach to high temperature oxidation of ventilation...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community


National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook