All about resin bolts
Resin bolt assemblies comprise the stud, nut, bearing plate washer, and various accessories and modifications that can be configured to meet specific installation and rock support needs.
Cartridge resin bolts vs pumpable resin bolts
Rock bolts are frequently used in deep underground mining and tunnelling to ensure that the rock remains stable and safe during excavation. Placing a plain steel rod into a borehole to bear the load from the rock around the tunnel is called bolting.
Although temporary mining and tunnelling applications do not require additional support components, permanent applications will require cement-like resins to fill gaps between the bolt and rock.
Cable bolting
Cable bolting is a technique that provides additional rock support during mining and tunnelling projects. These bolts are long, grouted reinforcement tools that aid in supporting and stabilising the rock mass above the profile of a deep underground tunnel.
The mining industry used resin cartridges to inject resins around bolting for rock reinforcement for many years. The process is effective, and technological advancements have resulted in developing a pumpable resin system.
Pumpable resin bolts and cartridge resin bolts are dependable cable and rock bolting reinforcement systems.
Complications in underground mining and tunnelling
Deep underground mining and tunnelling raise the risk of serious safety issues significantly. The rock above the mine is stressed when drilling deep into the earth, affecting the strata’s stability. Although rock reinforcement is required, it becomes more difficult underground.
Mine construction necessitates large-scale movements, which increases the likelihood of a collapse. Therefore, rock reinforcement with cable or rock bolting with grout or resin becomes critical for worker and technical equipment safety.
While traditional long-term rock stability applications like sprayed concrete and rock bolts with cement-like grouts work well for mining operations, stability installations in deep mines are complex. In poor ground, installation becomes more difficult.
Mining activity and geological structure both contribute to poor ground conditions, adding to the stress of mine formation and the need for rock reinforcement.
While it is possible to install rock bolts in these conditions. Nonetheless, it may raise significant quality concerns, lengthen installation times, and increase the likelihood of the mining cycle becoming clogged.
Pumpable system resin bolts
Pumpable resin bolts for rock bolting took several years for chemical technology to catch up to the concept.
These resins are intended to combine the effectiveness of cement-like grout with the curing speed of resin. Cementitious grout typically takes 12 to 24 hours to cure and harden around a rock bolt, during which time mining professionals cannot enter the mine. On the other hand, resin bolts take a few minutes to set.
Regardless of the ground conditions in a mine, a pumpable resin bolt system is highly effective for long-term rock bolt anchoring. Because resins are fluid in motion and solidify when motionless, resin bolts can be installed overhead without the need for additional borehole sealing.
Advantages of a pumpable system resin bolts
Quick installation cycles
Deep mining with poor ground conditions necessitates quick action when it comes to rock reinforcement. As a result, the new pumpable resin bolts are used regularly in several major mining developments.
It can take up to 24 hours for cementitious grouting around a rock bolt to solidify and stabilise the area. Because work in the mine cannot resume until the curing process is completed, mine development can quickly fall behind schedule.
Cartridge resin bolts cut installation time in half by taking up the load in 10 to 15 minutes. However, a pumpable system and self-drilling resin bolt can complete the job in three minutes or less. As a result, pumpable systems are preferred because they work in all ground conditions and rock quality.
Improved mining stability
Another advantage of this system is improved long-term rock stability. The resin penetrates even minor cracks around the resin bolt and borehole. As a result, the resin quickly consolidates the ground, leading to improvement. Even if the borehole diameter is larger than expected, the operator can pump the resin until the entire space is filled.
Used with hollow and cable bolts
Pumpable resins have various applications and can be used with cable and hollow bolts, self-drilling anchors, and installed around a rock bolt.
Self-drilling anchors have an open centre and a drill bit on the tip to create boreholes. The system performs well in poor ground conditions, and the pumpable resin absorbs the load in minutes rather than hours.
Disadvantages of pumpable system resin bolts
There aren’t many drawbacks to using pumpable resins. However, they necessitate some level of adaptability.
Pumpable resins also require training on how to use the new equipment and understand the technical aspects of the system.
Cartridge resin bolts
Resin cartridges, like pumpable systems, aid in bonding bolts to the surrounding rock, both above and below ground. The resin will anchor a bolt of any size with a single operation. Therefore, it does not necessitate the use of injection equipment.
The cartridges are made up of two parts separated by a thin film. One component is polyester resin grout, and the other is the catalyst for the cartridge.
The cartridge is shaped like a tube with clipped ends. The cartridge is inserted after a hole is drilled with a drill. When a rock bolt or bar pushes through the cartridge, the components are mixed, causing the curing process to begin.
After curing, the mix is usually more rigid than the surrounding rock. Cartridges are a quick and cost-effective way to secure a bolt.
Advantages of cartridge resin bolts
Suitable for all-terrain conditions
It may be more challenging to install a resin bolt in poor ground conditions, but it is not impossible. Cartridges can be installed to form long-lasting grouting if the borehole is stable.
Simple installation
The bolting system allows a bolt to be placed in any position or angle in the mine or tunnel ceiling. First, the cartridges are injected into the holes that have been created. Then, simply insert a bolt and rotate it to mix the components inside the cartridge to start an immediate stabilising chemical reaction.
Reliable bonding
When the grouting resin and catalyst components combine within the hole, they form a strong mechanical interlock with the resin bolt and the surrounding rock.
The mixture cures in minutes, forming a solid bond with the surrounding rock that can withstand heavy loads.
The resin and catalyst measurements are meticulously calculated to allow for quick mixing while limiting the amount of resin that pours out of the hole.
Disadvantages of cartridge resin bolts
Because it has a shorter installation cycle than traditional reinforcement methods, a rock bolt grouted with cartridge resin is a popular way to reinforce bolts in underground mines.
However, unstable ground conditions can make installing the cartridge in a hole difficult. Before rock bolting can occur, the cartridge must be inserted into the hole, and the bolt rotated to combine the resin.
However, if the ground is too loose, the hole may collapse after the drill bit is removed, making cartridge installation difficult, if not impossible.
An overbreak around the hole may also impact how much resin gets into the hole. A grouted resin cartridge holds specific amounts of material, so precise hole measurements are required.
Even minor shifts in or around the borehole may necessitate using more resin than the cartridge contains to properly seal the rock bolt, significantly reducing the load the bolt can withstand.
Contact Reunko Steel for details
Reunko Steel offers high-quality resin bolts and can design them to your specifications. You can choose from pumpable resin bolts that quickly stabilise the area around a bolt for immediate and long-term results. The simple and quick installation of cartridge resin bolts means these bolts can be inserted in any position for immediate bolting.
These resin bolts have numerous advantages over traditional rock reinforcement techniques in mining and tunnelling operations.
Our resin bolts are manufactured from hot-rolled high-tensile steel deformed bar and are available in standard lengths ranging from 0.6 metres to 3 metres. In addition, our standard lengths are colour coded for simple identification. We can also colour code your load indicator washers.
To find out more about our resin bolts, get in touch with one of our representatives today.