Rockbolts are used in mines and tunnels to reinforce wall strata and provide stability. For years, steel was the material of choice for its strength, but its downside was significant. When the time came to remove the bolts they were difficult to cut and any sparks created a potentially fatal hazard. Alternatively, forcibly extracting the bolts risked a catastrophic cave-in.
We've been making composite rock bolts for 30 years, but the team at Hilti asked us to develop the next generation – a one-step composite rock bolt that could be installed in a single process using customized pultrusions.
We developed a self-drilling One-Step composites rock bolting system that, after multiple tests at Hilti’s R&D tunnel site in Switzerland, was found to be superior in every way to steel. The advantages of GFRP (glass fiber-reinforced polymer) had the same strength but with corrosion-free properties that eliminated the risk of premature bolt failure. High resistance to shock loading and outstanding torsional and shear strength meant it was easier and faster to install – even where there were unstable seams. As importantly, safety requirements were exceeded for miners as GFRP rock bolts could be cut through easily without risk to equipment or danger of sparks.