Resin vs Cement Grouting for Rock Bolts: How to Choose the Right Anchoring System

What Is Grouting in Rock Bolts?

Grouting means filling up the gap between a reinforcement element and the surrounding rock with an anchoring material.

Grouting aims to:

• enhance the bond between bolt and rock;
• redistribute loads from unstable rock areas;
• increase reinforcement system reliability;
• decrease rock movement around underground openings.

The simplified load transfer mechanism can be described as:

Rock Movement → Bolt → Resin/Grout → Surrounding Rock

The anchoring material serves as a bonding medium between reinforcement element and the geological feature.

As such, choosing the appropriate grouting method is key to designing a quality ground support system.

Read more about underground reinforcement here: What Is Ground Support in Mining and Tunneling?

Resin Grouting vs Cement Grouting: Key Differences

Neither system is suitable for every application.

Selection should consider:

• rock conditions;
• excavation requirements;
• bolt type;
• installation method;
• required service life.

What Is Resin Grouting for Rock Bolts?

Chemical anchoring materials used for resin grouting are supplied in cartridge formats.

Basic installation process:

1. Feed a resin cartridge into the hole
2. Insert and rotate the rock bolt
3. Mix the resin components
4. Allow the resin to cure around the bolt
5. The resin bonds the bolt to the surrounding ground

Final performance will be influenced by:

• resin specification;
• site conditions affecting curing;
• borehole quality;
• installation procedures;
• surrounding ground conditions.

Types of anchors commonly used with resin systems include:

• threaded rock bolts;
• roof bolts;
• underground reinforcement;
• supporting tunnel faces.

Wanfeng provides grouting and anchoring materials to meet various ground support needs.

Advantages of Resin Grouting

Fast Installation Speed

Resin systems can achieve curing significantly faster than cement grout.

For projects that require excavation and reinforcement to keep pace, faster installation can lead to improved cycle times.

This benefit can be especially valuable during underground operations where support installation is part of the overall excavation cycle.

Rapid Development of Anchoring Strength

Resin anchorage can achieve significant strength shortly after mixing and installation.

This allows resin systems to be used in applications where early support strength is important.

Keep in mind that strength gain is affected by:

• the resin used;
• temperature;
• mixing procedures;
• installation conditions.

Easy Installation

Resin cartridges can make the installation process easier because the resin is pre-packaged.

Calculated variations in mix ratios are minimized with cartridges compared to materials mixed on site.

Ideal for Mechanized Installations

Many rock bolting installations are now performed using mechanized equipment.

Resin cartridges can be used along with bolting equipment depending on the application and support requirements.

Limitations of Resin Grouting

While there are many benefits to resin anchorage, there are some limitations that should be considered.

Temperature Sensitivity

Resin curing properties can vary based on underground temperatures.

Extreme temperatures can have adverse effects on resin curing.

Borehole Quality

Anchoring performance is impacted by:

• hole diameter;
• hole cleanliness;
• hole deviation;
• installation time.

Material Costs

Resin materials can be more costly than cement grout.

Material costs should be considered for projects that require large volumes of grouting.

What Is Cement Grouting for Rock Anchors?

Cement grouting involves cementitious materials that are mixed with water to create grout.

This grout mixture is placed into the borehole or void space and allowed to set/harden, forming a bonded reinforcement system.

Cement grouting is commonly used for:

• tunneling applications;
• underground construction;
• slope stabilization projects;
• foundation support;
• large-scale anchorages.

Injection pressure, grout properties, and site conditions may also allow cement grout to fill certain fractures or void spaces near the anchor.

Advantages of Cement Grouting

Helps Minimize Costs for Larger Projects

Due to the nature of cement-based materials being less expensive at higher volumes, cement grout is often used for applications that require large amounts of reinforcement.

Effective when used for Full-Length Grouting Applications

Full grouting refers to creating a bonded zone along the entire length of the anchor.

Cement grout can set and achieve significant bond strength along the anchor length making it ideal for:

• fully grouted rock bolts;
• hollow grouting anchors;
• deeper grouting applications.

Helps Fill and Consolidate Ground

When conditions allow, cement grout can be used to help:

• fill/discontinuities around an excavation;
• fill voids around reinforcement;
• help consolidate ground.

Results will vary based on grout characteristics, pressure maintained during injection, and surrounding rock structure.

Ideal when used with Hollow Grouting Anchors

Cement grout works well with hollow grouting anchors.

The cement grout can be pumped through the center of the anchor and pushed out into the surrounding rock.

Learn More About Wanfeng’s Rock Bolting and Anchoring Systems

Disadvantages of Cement Grouting Explained

Slower Strength Gain

Unlike some resin systems, cement grout typically takes longer to achieve strength.

This could impact project timelines.

Equipment Needs

Installing cement grout typically requires:

• mixers
• pumps
• water control
• quality assurance processes.

Factors Affecting Performance

Success with cement grouting also depends on factors such as:

• mix design (e.g. water-cement ratio)
• mixing methodology
• pressure applied during grouting
• degree of fill achieved
• curing conditions

When to Use Resin or Cement Grouting

There is no simple answer to this question. Instead, you should consider what your engineering project requires.

Need Fast Reinforcement? Consider Resin.

You may want to select resin for underground projects where:

• speed of installation is critical
• early strength is required
• mechanical bolting rigs will be used.

Need Lots of Cement Grout? Go Ahead.

You may prefer cement grout when you need to:

• install large volumes of grout
• achieve full-column anchoring
• fill the ground as part of your reinforcement strategy.

Weak Ground? It Depends.

When dealing with poor ground conditions, your choice of resin or cement will depend on factors such as:

• geology
• groundwater conditions
• depth of required reinforcement
• excavation planning

Your technician may recommend:

• using hollow grouting anchors
• using fully-grouted bolts
• using resin-anchored bolts
• using some combination of the above.

Remember, there is no one-size-fits-all solution to ground reinforcement.

Can Resin and Cement Grouting Be Used in the Same Project?

Absolutely.

While some projects use both resin and cement grouts, they typically don’t serve the same function. One may be used for initial anchoring while the other provides main longitudinal reinforcement.

It all depends on the project specifications. As a rule, the two are not used together as a hybrid grout.

Resin Bolt vs Cement Grouted Bolt

Guide of Choosing Appropriate Anchoring Material

Before selecting resin grouting or cement grouting, you should ask yourself these questions.

1.Geo- mechanical Conditions

• rock strength.
• fractures.
• groundwater.
• stress conditions.
• deformation characteristics.

2.How long do you need the support to last?

• How soon after drilling do you need to reinforce?
• Do you need to support as you excavate?
• How long is the expected service life?

3.Bolt Type

Which ever anchoring material you choose, it needs to be compatible with your reinforcement system.

Example uses:

• Resin ‣ threaded rock bolts/roof bolts
• Cement grout ‣ hollow anchors/fully grouted bolts

4.Installation Conditions

• Drilling Equipment
• Underground access
• Workers and equipment available
• Grouting equipment

5.Long Term Environment

• groundwater
• corrosion potential
• exposure to chemicals
• lifetime of project

Applications of Resin and Cement Grouting

Under Ground Mining

There are many ground reinforcement systems that can be used underground such as:

Rock Bolt + Resin Cartridge + Bearing Plate + Mesh

or

Fully Grouted Bolt + surface support components.

Which ever you choose will be based on your mine design and geological conditions.

Tunnel

When reinforcing tunnels there are also many options such as:

• rock bolts
• cement grouting anchors
• mesh
• steel supports

At Wanfeng we provide complete Steel Support Systems

That can be used for underground reinforcement

Slope

You can also use anchor systems used with grouting for:

• highway slopes
• quarry slopes
• excavation support

Why Pick Wanfeng?

At Wanfeng we offer a variety of ground support products for underground mining, tunneling, slope stabilization and foundation projects. Products ranging from Rock Bolting and Anchoring systems to Grouting and Anchoring materials, Surface Support/Reinforcement materials and Steel Support Systems.

By offering bolts, anchors, plates, mesh and anchoring materials all in one place, we allow our customers to create compatible ground support solutions that can be used in various types of engineering conditions.

FAQ

Q1 : Is resin stronger than cement grout?

A: Not necessarily. One isn’t inherently stronger than the other. They have unique advantages. For example, resin systems typically allow for faster curing. Full-length cement grouting is preferred for long-anchorages and large-scale reinforcement projects.

Q2 : Which one is cheaper, resin or cement grout?

A: Cement grout typically has a lower material cost for volume applications, but resin systems allow for faster installation.

Q3 : Can resin bolts be used underground?

A: Absolutely. Resin bolts are very common in underground mines that require fast installation and early reinforcement support.

Q4 : Can you use cement grout with rock bolts?

A: Yes. Cement grout is used commonly with fully grouted rock bolts and hollow grouting anchors.

Q5 : Which grouting method is better for tunnels?

A: It is not a matter of one being better than the other. The correct solution is based on tunnel geology, construction method, reinforcement design and overall project requirements.

Q6 : Can I use both resin and cement grouting on the same project?

A: Absolutely! Many projects use both systems because different areas of the project have different reinforcement needs.

Conclusion: Both Systems Have Their Place

While resin and cement grouting have unique advantages and disadvantages, both are commonly used anchoring techniques in today’s mining, tunneling and geotechnical environments.

Here are some things to consider when evaluating your grouting needs:

Resin is used for most applications where:

• quick installation is desired
• early strength is needed
• project crews prefer cartridge-based installation

Cement grout is used for most applications where:

• large scale reinforcement is needed
• full-length grouting is desired
• project budget is a main concern

One is not inherently better than the other. The best solution for your project will be based on project geology, bolt type, installation method and project requirements.

At Wanfeng, we offer customized ground support solutions for your mining, tunneling and ground reinforcement projects. Our products include rock bolts, anchoring systems, grouting materials, plates and more.