Optimisation of Roof Bolt Length Based on Improved Resin Performance

Underground » Strata Control and Windblasts

Published: March 17Project Number: C21023

Get ReportAuthor: Kent McTyer | Mine Advice

This study compared the performance of two types of resin capsules used for full encapsulation of roof bolts in underground coal mines. The first, a 15:1 mastic to catalyst capsule which is the predominant system used in Australian mines, despite some well-documented problems. The second, a 2:1 mastic to catalyst capsule, is commonly used in US mines. The basis for the study is that if the 2:1 resin capsules are found to perform better than the current Australian resin capsules, then shorter bolt lengths may be possible with no associated increase in geotechnical risk. The cost and productivity benefits are obvious.

Australian researchers identified the endemic problems of gloved and poorly mixed (uncured) resin in Australian underground mines more than a decade ago, yet, the widely used 15:1 mastic to catalyst resin bolt systems have not significantly changed in response. This study tested whether 2:1 mastic to catalyst resin systems used in the US will improve the integrity and reliability of Australian resin bolts.

Published research into gloving, uncured resin, roof bolt installation pressure, and load transfer guided the surface testing method developed as part of this project. This methodology replicated installations of fully encapsulated resin-anchored roof bolts as used in the Australian underground coal industry. Two parameters were tested:

· The resin capsule mastic-to-catalyst ratios of 2:1 and 15:1; and

· Bolt hole diameters of 28 mm and 30 mm (to represent a typical bolt hole diameter, and a bolt hole subject to overbreak).

Data was collected and analysed for gloving, uncured resin, installation pressure, and load transfer performance. Key results included:

· The magnitude of gloving was up to eight times greater for the 15:1 resin bolts (12-15% of the bolt) compared with the 2:1 resin bolts (2% of the bolt);

· The magnitude of uncured resin was far greater for 15:1 resin bolts installed into both the in 28 mm and the 30 mm diameter holes (5% and 26% respectively), than for 2:1 resin bolts (0.2% for both diameters).

The results clearly indicate that the 2:1 catalyst to mastic resin is a far more reliable in terms of the endemic problems of gloving and uncured resin, and that it performs far more robustly across two 'typical' bolt hole sizes.

The implications are that if industry wants a roof bolt resin system that offers both reliable mixing and minimal gloving of the capsule film, then it should adopt the use of 2:1 resins as an industry standard. Further, the resin system can be readily introduced into Australian coal mines without major changes to bolting systems or procedures.

An e-newsletter has also been published for this project, highlighting its significance for the industry.


Health and safety, productivity and environment initiatives.

Recently Completed Projects

C22003Investigation Of The Potential Lightning Impacts On Underground Coal Mines

The objective of this research was to develop and apply computer mod...

C21023Optimisation Of Roof Bolt Length Based On Improved Resin Performance

This study compared the performance of two types of resin capsules u...

C25070Shuttle Car Steering System Optimisation

The condition of roadways in underground mines is of great importance, a...


Open Cut

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

Recently Completed Projects

C24067Mine Rehabilitation And Closure Knowledge Management WIKI: MRC-WIKI

This research project was undertaken over two years following completion...

C22028Rangal Supermodel 2015: The Rangal-Baralaba-Bandanna Coal Measures In The Bowen And Galilee Basins

This project compiled over 7000 company boreholes supplemented by more t...

C25005Interim Report: Alternative And Sustainable Explosive Formulations To Eliminate Nitrogen Oxide Emissions

This report focuses on the development of novel mining explosives with t...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C24048Thickener Underflow Monitor

The aim of this project was to develop an instrument that is capable of ...

C24044RFID Residence Time Modelling

The project had two main objectives, the first to provide residence ...

C23046Economic Effect Of Low Amounts Of Non-Magnetics In The Correct Medium

This project has developed a methodology by which the economic loss ...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C24056Relationship Between Internal Pressure And Coke Strength And Implications For Semi Soft Coking Coals In Blends

The objective of this project was to explore the relationships between t...

C25044Stage One: Trace Elements In Coal; Status Of Test Methods In Use And Their Applicability

The key objectives of this ACARP funded study (for arsenic, boron, cadmi...

C24055Physical And Chemical Interactions Occurring During Coke Making And Their Influence On Coke Strength

This project contains a study on the interactions occurring between coal...

Technical Market Support

Mine Site Greenhouse Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C24017Improving Methods For Quantifying Fugitive Emissions From Open Cut Coal Mining

Fugitive emissions from open cut coal mines are usually estimated fo...

C21065Flame Arresting Mechanisms And Flameproof Device For VAM Mitigation

The overall goal of this project was to study the gas flammability limit...

c21064Development Of A Catalytic Mitigation System For VAM - Stage 3 - 20 Litre Per Min VAM Flow Technical Development Unit

This report describes work undertaken towards the development of a p...

Mine Site Greenhouse 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

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 ...

C19025Governance Strategies To Manage And Monitor Cumulative Impacts At The Local And Regional Level

ACARP levy contributors should order this report in the normal manner – ...

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