Corrosion Protection of IBO Anchor Drill Bar

In some occasions of Anchorage engineering, serious damage resulting from the corrosion of anchor bolts occurred frequently. IBO hollow bar anchor is a kind of rock bolt which can provide better anti-corrosion property. Thanks to its good performance in fully grouting, the corrosion is less happened than normal solid anchor bars.

However, it is not enough in some aggressive soil conditions. Because the underground environment of the anchor bolt is quite complicated, there are many precipitating factors for corrosion. Below are the 3 main elements which cause the corrosion of IBO anchor rock bolts.

1. Rock/Soil Environment

The anchor rod is directly contacted with air, water, and soil (rock) in the ground. The pH of the three-phase medium, the concentration of corrosive ions and gas, and the speed of supply and exchange will directly affect the corrosion rate.

2. Anchor Bolting Materials

It mainly concerns the material selection of anchor bar and anchor accessories. Anchor steel products should be selected with stable quality, uniform material, and little impurity.

As to material selection, ONTON self-drilling anchors are made from high-quality steel rods from the reliable steel plant. The good stability will benefit to your long-term business in tunnel projects and soil nailing engineering.

3. Anchor Bolting Construction

The uniformity and density between the anchor and injection grout determine the corrosion of the anchor bar influence.

The water cement ratio and cement quantity should be controlled strictly, to avoid excessive shrinkage caused by cracks.

For the permanent installations (life spans more than two years), additional processing is required to ensure the anti-corrosion function. The IBO hollow bar systems are generally considered acceptable for low-risk applications. For instance, soil nails or rock bolts.

Supplementary protection can be added in the form of:

1. Galvanized coating

Self-drilling anchor hollow bar assemblies can be supplied galvanized to ASTM A153.

2. Epoxy coating

The standard for epoxy coating on IBO drill rod is ASTM A934.

Alternatives:

1. Dacromet coating

This is a new method tested on ONTON IBO hollow bars. The Dacromet coated hollow bars have more ability of anti-corrosion and heat resistance.

2. Sacrificial Corrosion allowance

This method involves classification of soils into different categories of aggressivity based on a ranking procedure that incorporates tests for moisture content, pH value, the presence of sulfates and chlorides and resistivity. Once the aggressivity of the soil is known, a corrosion allowance can be made for the design life of the drill anchor bar.

Images of anti-corrosion coated IBO hollow bars:

anticorrosion coating of IBO anchor bar

Final Solution for corrosion of IBO anchor bars:

Stainless Steel IBO hollow bars.

The material of Stainless Steel Anchor rod: AISI 316.

More details about Stainless Steel IBO Anchor Rod

It was an under the high requirement of environment protection that current anti-corrosion technologies in the domestic markets meet with resistance. The production of galvanized or epoxy coated IBO hollow bars has decreased greatly. Stainless Steel self-drilling anchors are very good but cost too much. Hope we can find a better method to solve the corrosion problems.