The anti-corrosion rock bolt is widely applied to conditions which are influenced by underground water such as road, railway tunnel and which are corroded by seawater such as harbor, wharf and buildings on the sea affected. There are three classifications of anti-corrosion rock bolt.
Hot-dip galvanizing anchor bolt is one kinds of the anti-corrosion rock bolt. The oxidation film easily occurred on the zinc coating in the moist air. It can be isolated with water and air to prevent the chemical etching and the rusting. So the preservative effect is very well as a permanent support.
The duplex coating rock bolt adopts two corrosion-prevention measurements on the bolt surface, hot-dip galvanizing and epoxy coating , which can prevent corrosion very well. This kind of anti-corrosion rock bolt is mainly used in conditions which are influenced by underground water such as water conservancy project, sub-sea tunnel, etc.
Stainless steel anchor bolt is made of stainless steel materials.
Owning to its good welding performance & inoxidizability, This kind of anti-corrosion rock bolt are mainly used in the permanent support of large initial stress of surrounding rock, or other projects which have special requirement for corrosion resistance.
The main elements to cause the corrosion of rock bolting system are the environmental condition and the material composition. The environmental elements include the geologic situation and the corrosive effect of the underground water. The corrosion of the metal material is the essential problem.
The corrosion of the rock bolting system impact the useful life and construction cost immediately. If the corrosion is serious, it will be detrimental to the safety. Therefore, the anti-corrosion of the rock bolting system should be enhanced:
1)When selecting material of the rock bolting system, low carbon steel should be preferred for its reliable quality, good toughness and it does not easily affected by stress and hydrogen embrittlement.
2)When installing a self drilling rock bolt, avoid dry-wet alternate environment, and take the drainage system to reduce the corrosion speed.
3)In the construction process, control the ratio of water and cement. The cracks of cement barrier should be less than 0.1 mm to improve solid density and penetration resistance of the anchor solid.
4)If the self drilling rock bolt is used in the permanent construction environment, it can be galvanized or processed by epoxy coating.