A research programme has been carried out by RMT in support of the revision of Part 2 of the British Standard for strata reinforcement support system components used in coal mines, specification for birdcaged cablebolting. The present standard is written around one principal long tendon design, and since its publication, a number of resin and cementitious grout bonded systems have been introduced to the mining industry. Additionally, tests to determine bond performance, given in the present standard, are increasingly recognised as unrealistic and new tests more accurately simulating in-situ performance were required.
The laboratory short encapsulation pull test was developed initially for rockbolt evaluation and, through a comprehensive test programme, it has now been refined further for determining axial bond performance of resin and cementitious grout bonded flexible systems. It was found that different procedures and bond lengths were required depending on the grouting medium employed.
Tests on all systems currently used in the UK coal mining industry were carried out with various bond lengths and control products were chosen, the results of which were used to determine benchmark performance data. Test procedures and benchmark recommendations have been supplied to the reviewing committee.
Existing shear test data was used to refine the procedure - for resin bonded flexible reinforcement systems. However, the basic procedure, as outlined in the current Standard, is recommended for retention in the revised Standard.