Cable Grout and Tunnel Guard: Reinforcing Tunnel Safety with Altecrete
Underground construction—whether in mining, civil infrastructure, or energy—requires a robust system of ground support to ensure safety, durability, and long-term performance. Two critical components of that system are cable grout and tunnel guard coatings, which play unique yet complementary roles in reinforcing tunnel walls and preventing structural failure.
In this article, we’ll explore what cable grout and tunnel guard are, how they’re used in underground environments, and why Altecrete is a leading provider of both solutions. We’ll also discuss how these products enhance tunnel integrity, reduce maintenance, and improve operational efficiency—especially in the challenging conditions of mining and large-scale infrastructure development.
What Is Cable Grout and Why Is It Used?
Cable grout is a specialized cementitious material used to secure cable bolts and other ground anchors into drilled holes in rock or soil. These bolts form part of a ground reinforcement system designed to stabilize underground excavations.
Key Purposes of Cable Grouting:
- Load Transfer: Ensures proper bonding between the bolt and the surrounding rock.
- Corrosion Protection: Seals the steel cable against moisture and air.
- Long-Term Stability: Prevents ground movement or collapse by reinforcing weak rock strata.
In mining environments, cable bolts are often several meters long and used in high-stress zones where conventional rock bolts are insufficient. Grouting them with a durable and chemically stable material is essential to maintain load capacity and tunnel safety.
Understanding Tunnel Guard Coatings
Tunnel Guard is Altecrete’s proprietary protective lining solution, designed to shield tunnel surfaces from water ingress, chemical attack, and physical abrasion. It’s a polymer-based cementitious coating applied directly to concrete or shotcrete surfaces, acting as both a sealant and barrier.
Applications of Tunnel Guard:
- Moisture Barrier: Protects against water seepage that can weaken structural integrity.
- Corrosion Resistance: Shields rebar and steel components from corrosive environments.
- Durability Enhancement: Extends the life of sprayed concrete or pre-cast linings.
- Dust Reduction: Seals fine particles and prevents spalling of tunnel walls.
Tunnel Guard is especially valuable in deep-level mining, where water, humidity, and aggressive underground conditions constantly threaten the long-term durability of tunnel infrastructure.
Why Cable Grout and Tunnel Guard Work Better Together
While cable grout strengthens the internal structure of tunnel walls by securing anchors deep into the rock, Tunnel Guard provides an external shield against wear and environmental degradation.
Together, they offer:
- 360° protection—internal structural reinforcement and external surface sealing
- Reduced ground movement, minimizing risk of rockfalls or collapses
- Enhanced water control, crucial for operational safety and maintenance
- Improved tunnel lifespan—less frequent repairs, lower operating costs
Altecrete’s Expertise in Ground Support Solutions
Altecrete is a South African leader in underground support systems, offering a full suite of materials and services that include:
- Cable bolt grouting systems
- Shotcrete and wet-mix sprayed concrete
- Thin spray liners (TSLs)
- Surface coatings like Tunnel Guard
- Customised on-site equipment solutions like the Mincreter
Their approach combines materials engineering, application expertise, and compliance with stringent mining standards, making them a trusted partner for both mining and civil projects.
Features and Benefits of Altecrete’s Cable Grout
Altecrete’s cable grout is designed to meet the harsh demands of deep mine environments. Unlike general-purpose cement or mortar, their formulations offer:
✅ High Bond Strength
Forms a secure interface between the steel bolt and the surrounding rock, ensuring reliable load transfer.
✅ Shrinkage Compensation
Maintains full encapsulation of the bolt even as the grout cures, preventing micro-cracking or voids.
✅ Low Permeability
Protects bolts from water ingress and corrosion, especially in wet tunnels.
✅ Pumpability
Designed for easy delivery through grout pumps—reducing downtime and labor.
✅ Fast Setting Time
Minimizes curing delays and supports faster tunnel re-entry in mining operations.
Altecrete can customize grout properties for different environments, such as long anchor holes, steep angles, or aggressive groundwater conditions.
Features and Benefits of Tunnel Guard by Altecrete
Tunnel Guard, one of Altecrete’s flagship solutions, offers a long-lasting, versatile surface coating ideal for both new constructions and remedial projects.
✅ Superior Adhesion
Bonds tightly to shotcrete, concrete, and rock surfaces, even in damp conditions.
✅ Flexible Formulation
Withstands thermal expansion and contraction, maintaining integrity over time.
✅ Chemical and Abrasion Resistance
Perfect for environments exposed to sulphates, chlorides, and wear from equipment or debris.
✅ Environmentally Friendly
Water-based formula with low toxicity, suitable for enclosed environments.
✅ Quick Application
Can be applied using brush, roller, or spray, minimizing downtime during maintenance or new build phases.
Tunnel Guard is particularly effective in ventilation shafts, decline tunnels, ore passes, and transport drifts, where airflow, water, and impact can degrade unprotected surfaces over time.
Use Case: Deep Gold Mine Tunnel Reinforcement
A gold mine in South Africa faced recurring rockfalls in a high-traffic ore pass. Altecrete implemented a two-phase support system:
- Cable bolting with deep anchors, followed by injection of high-strength, fast-setting cable grout.
- Surface application of Tunnel Guard over shotcrete lining to reduce water ingress and abrasion.
Results:
- 70% reduction in rockfall incidents
- Increased production uptime
- Extended tunnel maintenance cycle by 18 months
This case demonstrates the synergy between internal reinforcement and external protection, reducing risks and operational costs simultaneously.
How to Know If You Need Tunnel Guard and Cable Grout
If you’re involved in mine planning, shaft sinking, tunnel rehabilitation, or even civil tunneling (such as subway systems or hydropower projects), you may need cable grout and tunnel coatings if:
- You’re working in geologically unstable rock zones
- Your tunnels are subject to groundwater infiltration
- You experience accelerated corrosion or tunnel degradation
- Your anchors need long-term load retention
- You want to extend the life of existing infrastructure without major reconstruction
Conclusion
The structural stability of underground spaces isn’t just about one product or application—it’s about using the right combination of systems. Cable grout and Tunnel Guard work in tandem to reinforce tunnels from the inside out, delivering safer, more durable, and lower-maintenance underground environments.
With decades of experience and innovative products tailored to the demands of mining and civil infrastructure, Altecrete offers complete ground support solutions—from grouting and lining to spraying and sealing.
Whether you’re reinforcing cable bolts in deep-level mines or protecting tunnel walls from corrosion and wear, Altecrete’s technologies ensure you build smarter, safer, and more cost-effectively.
Frequently Asked Questions (FAQs)
- What is the purpose of cable grout in underground mining?
Cable grout secures long cable bolts in place by filling the drilled hole and bonding the cable to the surrounding rock. It transfers load, prevents bolt corrosion, and ensures long-term tunnel stability. - What makes Tunnel Guard different from regular cement coatings?
Tunnel Guard is a polymer-modified coating with high adhesion, flexibility, and chemical resistance. It provides a stronger, longer-lasting barrier compared to basic cementitious linings. - Can Tunnel Guard be applied over existing shotcrete?
Yes, Tunnel Guard is designed to adhere to shotcrete, concrete, and other substrates—even in damp conditions—making it ideal for both new applications and tunnel rehabilitation. - How long does Altecrete’s cable grout take to set?
Setting time depends on the formulation but is typically designed for quick curing to allow rapid re-entry in mining environments. Fast-setting variants are available upon request. - Is Tunnel Guard environmentally safe?
Yes. Tunnel Guard is water-based and low in toxicity, making it suitable for enclosed spaces with limited ventilation like underground mines and tunnels. - Does Altecrete provide application services or just materials?
Altecrete offers both materials and full-service application, including grouting, spraying, and tunnel coating, using specialized equipment and trained personnel.
