Hollow Anchor Bar vs. Threaded Bar: A Comprehensive Comparison

When it comes to construction and geotechnical applications, the choice of anchoring materials can significantly impact the stability and integrity of structures. Two commonly used options are the Hollow Anchor Bar and the Threaded Bar. 

Threaded Bar: The Backbone of Construction

Threaded bars, also known as geostructural threaded bars, are stalwarts in the world of construction and foundation work. These long, straight bars feature threads running along their entire length, providing a strong connection or anchoring point in a variety of materials, including concrete, masonry, and more.

Precision and Strength

Threaded bars are manufactured using a precision thread rolling process, ensuring high-strength and dimensionally accurate components. This precision is crucial for applications that demand structural integrity.

Material Variety

Threaded bars are available in a range of materials, including high-strength steel, medium-strength steel, stainless steel (such as 18-8 stainless steel), carbon steel, plain steel, and zinc-plated or hot-dip galvanized steel. The choice of material depends on the specific requirements of the project and environmental conditions.

Diverse Applications

Threaded bars find their place in various applications, including soil nails, rock bolts, micropiles, slope support, dam reinforcement, mountain landslide control, foundation uplift control, and more. Their versatility makes them a go-to choice in geotechnical engineering.

Grouting Method

In many cases, threaded bars are used in conjunction with a grouting method. This involves connecting components like bottom end caps, corrugated pipes, threaded rods, and coupling sleeves, and inserting grouting pipes to secure the threaded bars firmly in place, enhancing their stability.

Hollow Anchor Bar: Precision and Versatility

Hollow anchor bars, also known as hollow core anchors or hollow injection bars, are specialized components with a unique design and specific purposes in construction and geotechnical applications. They consist of a wave-thread steel bar with a hollow center, offering distinct advantages.

Thread Design

The thread shape of the hollow anchor bar is similar to ribbed reinforcement, featuring a large pitch and deep teeth. This design not only enhances bonding with cement but also provides excellent adhesion and friction resistance. Additionally, the thread can be extended as needed.

Thread Types

There are two main types of hollow anchor bar threads: R thread and T thread. R thread conforms to the ISO10208 standard, while T thread offers more support force due to its deeper teeth. In fact, the adhesive friction force of T thread bars is typically double that of R thread bars of the same type. T thread self-drilling anchor bolts are often favored, especially in micropile applications.



Hollow steel bars have a wide range of applications. In loose or collapsed formations, self-drilling hollow anchor bars shine. They solve casing demands, enable quick installation, and allow simultaneous grouting. In water-bearing rock formations, where casings can easily get stuck, the self-drilling anchor system emerges as the practical solution.

Dust Ejection: In some scenarios, hollow anchor bars, such as the R51 self-drilling hollow anchor bar, serve as dust ejector tubes before grouting. These bars play a crucial role in eliminating dust and debris from the drilling hole, ensuring a clean and effective anchor installation.

Versatility: Hollow anchor bars are versatile components used for anchoring, grouting, and tunneling applications. Their specific design and use depend on the project's requirements, making them adaptable to a wide array of geotechnical challenges.

Hollow Anchor Bar vs. Threaded Bar: Choosing the Right Solution

The choice between hollow anchor bars and threaded bars depends on several factors:

Application Requirements

Consider the specific needs of your project. Threaded bars excel in a variety of applications, while hollow anchor bars are particularly well-suited for situations where drilling, anchoring, and grouting must occur simultaneously.

Material Selection

Assess the environmental conditions and material requirements of your project. Threaded bars are available in a range of materials. The hollow anchor bar also contains corrosion-resistant types to choose from.

Thread Type

If you require high support force and enhanced bonding with concrete, T thread hollow anchor bars may be the better choice. However, for standard applications, R thread bars can be sufficient.

Installation Speed

If speed and efficiency are crucial, self-drilling hollow anchor bars offer rapid installation compared to the grouting process often required with threaded bars.


Both hollow anchor bars and threaded bars play vital roles in construction and geotechnical applications. Your choice should align with the specific demands of your project, considering factors like material requirements, application type, and installation speed. Understanding the unique advantages of each option empowers you to make an informed decision, ensuring the stability and integrity of your structures.
Sinorock's team has many years of experience in providing complete geotechnical engineering services. If you have any needs or questions in the field of geotechnical anchoring, please feel free to contact us at sinorock@sinorockco.com.

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