Two internal repair designs partially sealed damaged rock bolts and improved aspects of shear resistance in a peer-reviewed laboratory study. One releases material when capsules break; the other uses electrical heating to melt an adhesive. The comparison addresses how damage opens paths for corrosion in steel supports used to reinforce rock, with long-term underground durability still requiring field validation.
Steel rock bolts reinforce rock masses in underground and other engineering structures. Damage can open pathways for water and corrosive substances to enter these supports. A peer-reviewed laboratory study compared two internal repair designs with conventional hollow threaded bolts. Both released or mobilized repair material after damage, partially sealing affected regions and improving some measures of resistance to shearing forces.[1]
One design held brittle capsules that broke during damage and released a repair agent. The other used externally supplied electrical heat to melt a thermoplastic adhesive. Capsule-based repair spread more widely, while heat-activated repair remained more local. When the double-shear test was repeated, average peak resistance in the capsule group exceeded the control value by 16.49 percent. Deformation and external work were also assessed.[1]
The investigation included chloride wetting-and-drying cycles alongside shearing tests on a simplified representation of jointed rock. Corrosion and shearing were examined in separate specimen groups, rather than combined over years in one installation. Groundwater flow, chemistry and temperature may change the spread of repair material. The heated design also needs active triggering. Long-term durability across natural fracture networks remains a matter for field validation.[1]
